US20070233407A2 - Magnetic sensing system and method - Google Patents
Magnetic sensing system and method Download PDFInfo
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- US20070233407A2 US20070233407A2 US11/535,481 US53548106A US2007233407A2 US 20070233407 A2 US20070233407 A2 US 20070233407A2 US 53548106 A US53548106 A US 53548106A US 2007233407 A2 US2007233407 A2 US 2007233407A2
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- B—PERFORMING OPERATIONS; TRANSPORTING
- B60—VEHICLES IN GENERAL
- B60R—VEHICLES, VEHICLE FITTINGS, OR VEHICLE PARTS, NOT OTHERWISE PROVIDED FOR
- B60R21/00—Arrangements or fittings on vehicles for protecting or preventing injuries to occupants or pedestrians in case of accidents or other traffic risks
- B60R21/01—Electrical circuits for triggering passive safety arrangements, e.g. airbags, safety belt tighteners, in case of vehicle accidents or impending vehicle accidents
- B60R21/013—Electrical circuits for triggering passive safety arrangements, e.g. airbags, safety belt tighteners, in case of vehicle accidents or impending vehicle accidents including means for detecting collisions, impending collisions or roll-over
- B60R21/0136—Electrical circuits for triggering passive safety arrangements, e.g. airbags, safety belt tighteners, in case of vehicle accidents or impending vehicle accidents including means for detecting collisions, impending collisions or roll-over responsive to actual contact with an obstacle, e.g. to vehicle deformation, bumper displacement or bumper velocity relative to the vehicle
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- B—PERFORMING OPERATIONS; TRANSPORTING
- B60—VEHICLES IN GENERAL
- B60R—VEHICLES, VEHICLE FITTINGS, OR VEHICLE PARTS, NOT OTHERWISE PROVIDED FOR
- B60R21/00—Arrangements or fittings on vehicles for protecting or preventing injuries to occupants or pedestrians in case of accidents or other traffic risks
- B60R2021/0002—Type of accident
- B60R2021/0006—Lateral collision
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- B—PERFORMING OPERATIONS; TRANSPORTING
- B60—VEHICLES IN GENERAL
- B60R—VEHICLES, VEHICLE FITTINGS, OR VEHICLE PARTS, NOT OTHERWISE PROVIDED FOR
- B60R21/00—Arrangements or fittings on vehicles for protecting or preventing injuries to occupants or pedestrians in case of accidents or other traffic risks
- B60R21/01—Electrical circuits for triggering passive safety arrangements, e.g. airbags, safety belt tighteners, in case of vehicle accidents or impending vehicle accidents
- B60R2021/01013—Means for detecting collision, impending collision or roll-over
- B60R2021/01027—Safing sensors
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- B—PERFORMING OPERATIONS; TRANSPORTING
- B60—VEHICLES IN GENERAL
- B60R—VEHICLES, VEHICLE FITTINGS, OR VEHICLE PARTS, NOT OTHERWISE PROVIDED FOR
- B60R21/00—Arrangements or fittings on vehicles for protecting or preventing injuries to occupants or pedestrians in case of accidents or other traffic risks
- B60R21/01—Electrical circuits for triggering passive safety arrangements, e.g. airbags, safety belt tighteners, in case of vehicle accidents or impending vehicle accidents
- B60R2021/01122—Prevention of malfunction
- B60R2021/01184—Fault detection or diagnostic circuits
- B60R2021/01197—Warning devices
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- B—PERFORMING OPERATIONS; TRANSPORTING
- B60—VEHICLES IN GENERAL
- B60R—VEHICLES, VEHICLE FITTINGS, OR VEHICLE PARTS, NOT OTHERWISE PROVIDED FOR
- B60R21/00—Arrangements or fittings on vehicles for protecting or preventing injuries to occupants or pedestrians in case of accidents or other traffic risks
- B60R21/01—Electrical circuits for triggering passive safety arrangements, e.g. airbags, safety belt tighteners, in case of vehicle accidents or impending vehicle accidents
- B60R21/013—Electrical circuits for triggering passive safety arrangements, e.g. airbags, safety belt tighteners, in case of vehicle accidents or impending vehicle accidents including means for detecting collisions, impending collisions or roll-over
- B60R21/0134—Electrical circuits for triggering passive safety arrangements, e.g. airbags, safety belt tighteners, in case of vehicle accidents or impending vehicle accidents including means for detecting collisions, impending collisions or roll-over responsive to imminent contact with an obstacle, e.g. using radar systems
Definitions
- FIG. 1 illustrates a schematic block diagram of a magnetic crash sensor in a vehicle
- FIG. 2 illustrates a flow chart of a magnetic crash sensing algorithm
- FIG. 3 illustrates a plot of a signal from a magnetic sensor of a magnetic crash sensor associated with a front door of a vehicle responsive to a relatively high speed slam of the front door;
- FIG. 4 illustrates a plot of a signal from a magnetic sensor of a magnetic crash sensor associated with a front door of a vehicle responsive to a relatively high speed slam of the front door, for various opening angles of the associated rear door;
- FIG. 5 illustrates a plot of a signal from a magnetic sensor of a magnetic crash sensor associated with a rear door of a vehicle responsive to a relatively high speed slam of the rear door, for various opening angles of the associated front door;
- FIG. 6 illustrates a schematic block diagram of a magnetic crash sensor in a vehicle
- FIG. 7 illustrates a schematic block diagram of a magnetic crash sensor in a vehicle
- FIG. 8 illustrates a schematic block diagram of a seventh embodiment of a magnetic crash sensing system in a vehicle
- FIG. 9 illustrates a schematic block diagram of a eighth embodiment of a magnetic crash sensing system in a vehicle
- FIG. 10 illustrates a detailed view of several coils from the eighth embodiment illustrated in FIG. 9 , and illustrates several coil embodiments;
- FIG. 11 illustrates various locations for a coil around a door hinge
- FIG. 12 illustrates a coil mounted so as to provide for sensing a door opening condition
- FIG. 13 illustrates an encapsulated coil assembly
- FIG. 14 illustrates a portion of a coil assembly incorporating a magnetically permeable core
- FIG. 15 illustrates a portion of a coil assembly adapted for mounting with a fastener
- FIG. 16 illustrates a portion of a coil assembly adapted for mounting with a fastener, further comprising a magnetically permeable core
- FIG. 17 illustrates a coil assembly comprising a plurality of coils arranged in a variety of orientations
- FIG. 18 illustrates a schematic block diagram of a nineth embodiment of a magnetic crash sensing system in a vehicle
- FIG. 19 illustrates a schematic block diagram of a tenth embodiment of a magnetic crash sensing system in a vehicle
- FIGS. 20 a and 20 b illustrate eddy currents, associated magnetic fields and axial magnetic fields in various ferromagnetic elements
- FIG. 21 illustrates a toroidal helical coil
- FIG. 22 illustrates a toroidal helical coil assembly
- a first magnetic crash sensor 10 . 1 incorporated in a vehicle 12 comprises at least one first coil 14 at a corresponding at least one first location 16 of the vehicle 12 , and an associated at least one first magnetic sensor 18 at a corresponding at least one second location 20 of the vehicle 12 .
- a first coil 14 is located around an upper hinge 22 . 1 of a front door 24 of the vehicle 12
- the at least one first magnetic sensor 18 comprises a second coil 26 around the striker 28 . 1 of the door latch assembly 30 . 1 of the front door 24 , wherein the striker 28 . 1 is operatively coupled to the B-pillar 32 of the vehicle 12 and the second coil 26 is proximate thereto.
- the at least one first coil 14 is operatively coupled to a first coil driver 34 . 1 , which is in turn operatively coupled to a first oscillator 36 . 1 , wherein an oscillatory signal from the first oscillator 36 . 1 is applied by the first coil driver 34 . 1 to cause an associated current in the at least one first coil 14 , responsive to which the at least one first coil 14 generates a first magnetic field 38 . 1 comprising magnetic flux 40 in an associated first magnetic circuit 42 . 1 comprising the A-pillar 44 , front door 24 , B-pillar 32 , and the body 46 , frame 48 or powertrain 50 of the vehicle 12 .
- the first oscillator 36 is operatively coupled to a first coil driver 34 . 1 , which is in turn operatively coupled to a first oscillator 36 . 1 , wherein an oscillatory signal from the first oscillator 36 . 1 is applied by the first coil driver 34 . 1 to cause an associated current in the at least one first coil 14 , responsive to which
- the oscillation frequency would typically be less than about 100 KHz for a steel structure, e.g. 20 to 30 KHz in one embodiment.
- An oscillation frequency in the audio range e.g.
- the first magnetic field 38 . 1 is responsive to the reluctance of the associated first magnetic circuit 42 . 1 , which is affected by a crash involving the elements thereof and/or the gaps 52 therein.
- the first magnetic field 38 . 1 is sensed by the at least one first magnetic sensor 18 , and the signal therefrom is conditioned by an associated first signal conditioner 54 . 1 , demodulated by a first demodulator 56 . 1 , converted from analog to digital form by a first analog-to-digital converter 58 .
- the first signal conditioner 54 . 1 may incorporate buffering, amplification, high-pass, low-pass, or band-pass filtering,
- the first demodulator 56 . 1 may provide amplitude demodulation, constant sampling relative to the phase of the first oscillator 36 . 1 , or constant sampling relative to the phase of the signal sensed by the first magnetic sensor 18 .
- any envelope detection or phase or frequency demodulation technique could be used to obtain the demodulated signal.
- the particular demodulation method will, for example, depend upon the particular implementation and the cost of the components used to perform this function.
- the analog-to-digital conversion function and the demodulation function are combined a single process.
- the first demodulator 56 . 1 may also provide for amplification, and that the first analog-to-digital converter 58 . 1 would incorporate an associated sampler. Changes to the first magnetic field 38 . 1 at a particular location in the first magnetic circuit 42 . 1 propagate within the associated first magnetic circuit 42 . 1 at the speed of light and are seen throughout the first magnetic circuit 42 . 1 . Accordingly, the first magnetic field 38 . 1 sensed by the at least one first magnetic sensor 18 contains information about the nature of the remainder of the magnetic circuit, including the front door 24 and adjacent A-pillar 44 and B-pillar 32 , any of which could be involved in and affected by a side-impact crash.
- the vehicle 12 further incorporates a second magnetic crash sensor 10 . 2 comprising at least one third coil 64 at a corresponding at least one third location 66 of the vehicle 12 , and an associated at least one second magnetic sensor 68 at a corresponding at least one fourth location 70 of the vehicle 12 .
- a third coil 64 is located around an upper hinge 72 . 1 of a rear door 74 of the vehicle 12
- the at least one second magnetic sensor 68 comprises a fourth coil 76 around the striker 28 . 2 of the door latch assembly 30 . 2 of the rear door 74 , wherein the striker 28 .
- the at least one third coil 64 is operatively coupled to a second coil driver 34 . 2 , which is in turn operatively coupled to a second oscillator 36 . 2 , wherein an oscillatory signal from the second oscillator 36 . 2 is applied by the second coil driver 34 . 2 so as to cause an associated current in the at least one third coil 64 , responsive to which the at least one third coil 64 generates a second magnetic field 38 . 2 comprising magnetic flux 40 in the associated second magnetic circuit 42 .
- the second oscillator 36 . 2 generates a oscillating signal, for example, having either a sinusoidal, square wave, triangular or other waveform shape, or a single frequency or a plurality of frequencies that, for example, are either stepped, continuously swept or simultaneous.
- the frequency is adapted so that the resulting second magnetic field 38 . 2 is conducted through the second magnetic circuit 42 . 2 with sufficient strength so as to provide a useful signal level from the second magnetic sensor 68 , which cooperates therewith.
- the second magnetic field 38 . 2 is responsive to the reluctance of the associated second magnetic circuit 42 .
- the second magnetic field 38 . 2 is sensed by the at least one second magnetic sensor 68 , and a signal therefrom is conditioned by an associated second signal conditioner 54 . 2 , demodulated by a second demodulator 56 . 2 , converted from analog to digital form by a second analog-to-digital converter 58 . 2 and input as a second magnetic sensor signal 80 to the processor 62 , which processes the signal as described more fully hereinbelow.
- the second signal conditioner 54 . 2 may incorporate buffering, amplification, high-pass, low-pass, or band-pass filtering.
- the second demodulator 56 may incorporate buffering, amplification, high-pass, low-pass, or band-pass filtering.
- the second demodulator 56 may provide amplitude demodulation, constant sampling relative to the phase of the second oscillator 36 . 2 , or constant sampling relative to the phase of the signal sensed by the second magnetic sensor 68 .
- any envelope detection or phase or frequency demodulation technique could be used to obtain the demodulated signal.
- the particular demodulation method will, for example, depend upon the particular implementation and the cost of the components used to perform this function.
- the analog-to-digital conversion function and the demodulation function are combined a single process. It should be understood that the second demodulator 56 .
- the second magnetic field 38 . 2 sensed by the at least one second magnetic sensor 68 contains information about the nature of the remainder of the magnetic circuit, including the rear door 74 and adjacent B-pillar 32 and C-pillar 78 , any of which could be involved in and affected by a side-impact crash.
- the first coil 14 could be located around the lower hinge 22 . 2 of the front door 24 ; the at least one first coil 14 , could comprise first coils 14 . 1 , 14 . 2 around the upper 22 . 1 and lower 22 . 2 hinges respectively; the third coil 64 could be located around the lower hinge 22 . 2 of the rear door 74 ; or the at least one third coil 64 , could comprise third coils 64 . 1 , 64 . 2 around the upper 72 . 1 and lower 72 . 2 hinges respectively.
- the first 36 . 1 and second 36 . 2 oscillators could be one and the same, or could be separate, operating at the same or different frequencies with the same type or different types of waveforms.
- magnétique sensor 10 can be used to provide the first 60 or second 80 magnetic sensor signals—for example, as described in U.S. Pat. Nos. 6,407,660 (ASL-250), 6,433,688 (ASL-249), 6,587,048 (ASL-243), 6,777,927 (ASL-241), which are incorporated herein by reference.
- the magnetic sensor 18 , 68 could comprise a coil located either on the door 24 , 74 , inside the door 24 , 74 , or on the frame 48 near a gap 52 between the door 24 , 74 and the frame 48 .
- Changes in the position of metal surrounding a single coil can be sensed by monitoring a measure of—or one or more measures responsive to—the self-inductance of the coil, for example, when excited with a time varying voltage, e.g. of constant amplitude.
- a single coil can act to both generate and sense and associated magnetic field because current flowing through the coil is responsive to changes in the inductance thereof, whereby the inductance is responsive to both the properties of the coil itself, and to the shape and position of conductive and/or ferromagnetic materials (e.g. metals like steel or aluminum) proximate to the coil that affect the magnetic field associated therewith.
- conductive and/or ferromagnetic materials e.g. metals like steel or aluminum
- the first 36 . 1 and/or second 32 . 2 oscillators may be replaced with pulse sources, whereby the pulse amplitude may be adapted to provide for sufficient signal-to-noise ratio and the pulse width may be adapted to provide for reduced power consumption.
- first 10 . 1 and/or second 10 . 2 magnetic crash sensors need not necessarily incorporate associated first 36 . 1 or second 36 . 2 oscillators, or first 56 . 1 or second 56 . 2 demodulators, but instead the associated first 60 and second 80 magnetic sensor signals could be responsive to magnetostriction signals, magnetic coil pair signals, ferromagnetic shock signals, or other time varying magnetic signals that do not have a carrier from which the information must be extracted prior to analysis.
- the first magnetic sensor signal 60 from the first magnetic crash sensor 10 . 1 for a vehicle 12 with one magnetic crash sensor 10 on a particular side of the vehicle 12 ,—or the first 60 and second 80 magnetic sensor signals from the first 10 . 1 and second 10 . 2 magnetic crash sensors—for a vehicle 12 with two magnetic crash sensors 10 on a particular side of the vehicle 12 ,—are processed, for example, in accordance with a magnetic crash sensing algorithm 200 as illustrated by the flow chart of FIG. 2 , which is executed separately for each side of vehicle 12 .
- the processor 62 samples the i th sample of the first 60 or second 80 magnetic sensor signal responsive to the associated magnetic flux 40 at the location of the associated first 18 or second 68 magnetic sensor.
- a sampling rate of about 6 KHz in one embodiment provides for medium-to-high frequency content in the raw sampled signal.
- this signal is designated as Y 0 (i), which corresponds to the sampling of either the first 60 or second 80 magnetic sensor signal, depending upon which is being processed.
- the sampled signal Y 0 (i) is filtered with a first filter to remove noise from the raw magnetic signal, using a relatively lower frequency filter, for example, a running average filter with a sufficiently wide associated time window.
- the filter is adapted to balance between providing for noise reduction, maintaining a relatively fast step response, and providing for relatively fast computation.
- the first filter incorporates a window of about 6 milliseconds, which corresponds to a low-pass cutoff frequency of about 100 Hz.
- a second embodiment of this filter could be a band-pass filter set produce a signal with relatively lower frequency content, for example from 50 Hz to 250 Hz.
- the output of the first filter is a first filtered signal Y 1 (i).
- step ( 206 ) if the core crash detection algorithm ( 214 - 250 ) has been previously entered following step ( 212 ) and not subsequently exited at step ( 252 ), the process continues with step ( 216 ). Otherwise, in step ( 208 ), the opening state of the door is detected from the first filtered signal Y 1 (i), or another similar relatively longer time constant/lower frequency signal derived from the sampled signal Y 0 (i) (e.g. about a 1 Hz low-passed signal). The relatively slow motion of the doors 24 , 74 (or of one of the doors 24 in a two-door vehicle 12 ) can be tracked from the magnitude of the associated first filtered signals Y 1 (i).
- the magnetic flux 40 interacting with the magnetic sensor 18 , 78 associated therewith changes, usually diminishing, in a predictable manner.
- the amount that the door 24 is open i.e. degrees of rotation open
- the amount that door 24 , 74 is open on a given side of the vehicle 12 can be estimated by comparing the first 60 and second 80 magnetic sensor signals from a particular side of the vehicle 12 with the associated calibration data to determine the associated door state of the associated door 24 , 74 , so to provide for classifying the door state as either fully closed, partially latched, or open.
- first 10 . 1 or second 10 . 2 magnetic crash sensor comprises a coil 14 , 64 located inside the door 24 , 74 of the vehicle 12 , wherein the associated first 60 or second 80 magnetic sensor signal was responsive to the self-inductance of the coil 14 , 64 , and if this coil 14 , 64 was not substantially responsive to the position of the associated door 24 , 74 relative to the frame 48 of the vehicle 12 , then steps ( 208 ) and ( 210 ) of the magnetic crash sensing algorithm 200 would be omitted when processing that first 60 or second 80 magnetic sensor signal.
- the interpretation of the first 60 and second 80 magnetic sensor signals can be adjusted to avoid inadvertent deployments, alter deployment thresholds, or temporarily disable the safety restraint actuator 82 , in accordance with the vehicle manufacturer's specifications.
- Recognition of the door state of the door 24 , 74 provides for preventing inadvertent actuation of safety restraint actuator(s) 82 responsive to hard door slams or other “abuse events” when the doors 24 , 74 are not fully latched.
- Levels of magnetic flux 40 that cannot be attributed to one of the possible door states can be indicative of a system failure or a change in the properties or geometry of the door 24 , 74 beyond acceptable levels.
- the processor 62 can use an indicator 84 , or an alarm, to alert an occupant of the vehicle of a potential system failure.
- an indicator 84 or an alarm, to alert an occupant of the vehicle of a potential system failure.
- Such recognition is possible within a relatively short period of time—e.g. within seconds—after occurrence and the monitoring for such a failure can occur continuously while the system is active.
- FIG. 3 illustrates a first magnetic sensor signal 60 generated responsive to a front door 24 being slammed shut by a hydraulic robot in accordance with a less than worse case condition, wherein the magnitude of the resulting first magnetic sensor signal 60 approaches an associated crash detection threshold.
- the crash detection algorithm would prevent a safety restraint actuator 82 , e.g. side air bag inflator, associated with that side of the vehicle 12 from actuating, so as to prevent an inadvertent deployment thereof.
- a safety restraint actuator 82 e.g. side air bag inflator
- the responsiveness of the first 60 and second 80 magnetic sensor signals to the position of the door 24 , 74 can be used to provide an indication to the driver if the door 24 , 74 were open or not fully closed and could also control the activation of interior vehicle lighting, replacing the conventional door ajar switch. Such a door ajar detection function could also occur when the vehicle 12 was not turned on if the magnetic field were applied at a low duty cycle to conserve power.
- the magnitude of the corresponding first 60 or second 80 magnetic sensor signal responsive to a crash can be substantially greater than that for a fully closed door 24 , 74 , however, if detected, this condition can be compensated by adjusting associated discrimination thresholds so as to avoid an inadvertent deployment of the safety restraint actuator 82 responsive to a significant, non-crash event (also known as an “abuse event”), as described more fully hereinbelow.
- the magnitude of the impact response of a coil 14 , 64 operated in a self-inductance mode and located inside the door 24 , 74 is not substantially affected by latch state of the door 24 , 74 (i.e fully latched or partially latched).
- the first magnetic sensor signal 60 from the first magnetic sensor 18 proximate to the B-pillar 32 is responsive to the angle of the front door 24 and is nearly independent of the angle of the rear door 74 . Accordingly, it is possible to estimate the angle of the front door 24 from the magnitude of the first magnetic sensor signal 60 , particularly the associated first filtered signal Y 1 (i), using calibration data, for example, as illustrated in FIG. 4 .
- the sensitivity of the first magnetic sensor signal 60 is greater for smaller door angles than larger door angles, and for angles less than about 15 degrees, the door angle can be estimated relatively accurately.
- relatively short term signal offsets caused by effects other than door angle, such as temperature or recent mechanical changes to the front door 24 be maintained to less than an equivalent of about ⁇ 1 degree, in order to estimate the associated door state of the front door 24 sufficiently accurately
- Longer term signal offsets caused by effects such as door droop or accumulated damage can be characterized by monitoring the offset over time, and compensated by subtracting the offset from the signal.
- Another way to adjust for changes in door alignment over time is to compare the voltage applied to the at least one first coil 14 with the corresponding resulting current passing therethrough.
- Faraday's Law can be used to derive a relationship between the inductance L of the at least one first coil 14 , which is influenced by the proximity to nearby metal (i.e.
- the measure of coil inductance derived from the known current (I) and voltage (V) in the at least one first coil 14 can provide for adapting the expected response of the first magnetic crash sensor 10 . 1 as a function of door angle.
- the second magnetic sensor signal 80 from the second magnetic sensor 68 proximate to the C-pillar 78 is a strong function of the angle of the rear door 74 and is also a function of the angle of the front door 24 . Accordingly, because the second magnetic sensor signal 80 has significant response to the angle of the front door 24 , the angle and associated door state of the front door 24 is determined first, and then used in the determination of the angle of the rear door 74 . If the door state of the front door 24 is open, e.g. having an angle greater than about three degrees, then the door state of the rear door 74 need not be determined because, in that case, the safety restraint actuator 82 on that side of the vehicle 12 would be disabled anyway.
- the angle of the rear door 74 can be determined from the offset of the second magnetic sensor signal 80 using calibration data, for example as illustrated in FIG. 5 .
- relatively short term signal offsets in the second magnetic sensor signal 80 caused by effects other than door angle, such as temperature or recent mechanical changes to the rear door 74 be maintained to less than an equivalent of about ⁇ 1 degree, in order to estimate the associated door state of the rear door 74 sufficiently accurately.
- Longer term signal offsets caused by effects such as door droop or accumulated damage can be characterized by monitoring the offset over time, and compensating by subtracting the offset from the signal.
- step ( 210 ) if a front 24 or rear 74 door is detected as being either open or slammed, the core crash detection algorithm ( 214 - 250 ) is not entered, but instead, the process repeats with step ( 202 ).
- a potential adverse affect of a door slam condition can be avoided by delaying the confirmation of a partially latched or closed door state for a brief period of time following the initial detection thereof.
- step ( 212 ) if criteria for commencing the core crash detection algorithm ( 214 - 250 ), i.e. entrance criteria, are satisfied, then the core crash detection algorithm ( 214 - 250 ) is entered commencing with step ( 214 ).
- the first filtered signal Y 1 (i) is compared with one or more previous values thereof for each door 24 , 74 , and if there is a sudden change in the first filtered signal Y 1 (i) for either door 24 , 74 exceeding a minimum rate threshold, and if the magnitude of the first filtered signal Y 1 (i) exceeds a threshold, then the entrance criteria is satisfied.
- the algorithm entrance requirement of a significant and rapid shift in the magnitude of the magnetic flux 40 reaching the magnetic sensor 18 , 68 provides a relatively simple way to reject various forms of AC electrical or mechanical noise.
- the absolute magnitude of the first filtered signal Y 1 (i) for the rear door 74 exceeds a threshold of about 0.6 volts, then the entrance criteria is satisfied.
- FIG. 2 illustrates a single step ( 212 ) at which the entrance criteria is tested, it is anticipated that there may be a plurality of different entrance criteria for associated different portions of the overall magnetic crash sensing algorithm 200 , whereby there would be more than one associated step at which it would be determined if the associated entrance criteria satisfied the corresponding criteria necessary to commence that particular portion of the magnetic crash sensing algorithm 200 .
- the core crash detection algorithm ( 214 - 250 ) and associated steps ( 202 ) and ( 204 ) continue to be executed in sequence until either the safety restraint actuator 82 is actuated in step ( 248 ), or until the core crash detection algorithm ( 214 - 250 ) exits with step ( 252 ) because of either damped-out values of the associated discrimination metrics or because of a time-out condition.
- step ( 214 ) Upon entrance of the core crash detection algorithm ( 214 - 250 ), in step ( 214 ), associated variables of the magnetic crash sensing algorithm 200 are initialized. Then in step ( 216 ), the sampled signal Y 0 (i) is filtered, for example, with a second low-pass filter with a relatively higher cut-off frequency, so as to extract relatively higher frequency information from the raw magnetic signal, for example, by using a running average filter with a relatively narrower associated time window.
- the first filter incorporates a window of about 1.1 millisecond which provides information in the range from DC to 250 Hz.
- the output of the second filter is a second filtered signal Y 2 (i).
- K 1 is set so that the width of the running average window is about 5 milliseconds.
- the AC measure Y AC is a running average of the difference between the raw data and the mid-frequency low-pass filtered data that provides a measure of the fluctuation (AC) content of the magnetic signal, which is related to the door gap velocity, vibration, and crushing energy being transferred to the door 24 , 74 by the crash.
- a third filtered signal Y 3 (i) is generated by band-pass or high-pass filtering the sampled signal Y 0 (i), and the AC measure Y AC is calculated from a running average, or low-pass filtering, of the third filtered signal Y 3 (i).
- the magnitude of a component of the relatively lower frequency first filtered signal Y 1 (i) at the at least one first frequency is greater than the corresponding magnitude of a component of the relatively higher frequency second filtered signal Y 2 (i) or the AC measure Y AC at the same at least one first frequency; and the magnitude of a component of the relatively lower frequency first filtered signal Y 1 (i) at the at least one second frequency is less than the corresponding magnitude of a component of the relatively higher frequency second filtered signal Y 2 (i) or the AC measure Y AC at the same at least one second frequency.
- the frequency ranges of the filters associated with the relatively lower frequency first filtered signal Y 1 (i), and the relatively higher frequency second filtered signal Y 2 (i) or the AC measure Y AC may be separated from one another, or may partially overlap, depending upon the nature of the particular vehicle, as necessary to provide for adequate discrimination of various crash and non-crash events from one another, and as necessary to provide for adequate detection speed.
- data can be collected for a variety of impacts, e.g.
- pole, soft-bumper, ECE cart, FMVSS 214 barrier, and non-crash events, of various severities, and the associated filter types and cut-off frequencies may be adjusted, along with other parameters of the magnetic crash sensing algorithm 200 , so as to provide for generating a timely safety restraint actuation signal when necessary, and so as to not generation a safety restraint actuation signal when not necessary.
- step ( 220 ) if the magnitude of the first filtered signal Y 1 (i) exceeds a threshold, in steps ( 222 )-( 226 ) the relatively higher frequency AC measure Y AC is combined, e.g. linearly, with the relatively lower frequency first filtered signal Y 1 (i) to form first crash metric M 1 B or M 1 C , corresponding to the front 24 or rear 74 door respectively. Otherwise, in step ( 228 ), the first crash metric M 1 B or M 1 C is set to the value of the corresponding first filtered signal Y 1 (i). The requirement of step ( 220 ) lessens the possibility of high frequency noise (which is not expected to have significant DC content) falsely enhancing the first crash metric M 1 B or M 1 C during non-crash conditions.
- the coefficients a and b associated with the linear combination are specific to the particular type of vehicle 12 , and would be determined from associated crash and non-crash data associated with “abuse events”.
- the coefficients a and b determine the relative weighting or contribution of the relatively lower frequency first filtered signal Y 1 (i) and the relatively higher frequency AC measure Y AC in the first crash metric M 1 B or M 1 C .
- the value of b might be set greater than that of a so as to relatively emphasize the higher frequency information in the first crash metric M 1 B or M 1 C .
- the coefficients a and b may be constants.
- the sign and or magnitude of coefficients a and b may be a dynamic function of time of the sign or value of the second filtered signal Y 2 (i).
- the transition-smoothing algorithm provides for smoothing the effect of a transition between an inclusion of the AC measure Y AC in the first crash metric M 1 B or M 1 C , in step ( 226 ), and the exclusion thereof in the first crash metric M 1 B or M 1 C , in step ( 228 ). More particularly, the transition smoothing algorithm provides for determining a value for the transition smoothing factor ⁇ in equation (2) a) has a value that is bounded between 0.0 and 1.0; b) is initialized to 0.0; c) is incremented by a factor, for example, between 0.04 and 1.0 (i.e. no smoothing), e.g. 0.09 (i.e. 9%), for each iteration for which the result of step ( 220 ) is affirmative; and d) is decremented by that factor each iteration for which the result of step ( 220 ) is negative.
- a safing criteria is evaluated so as to provide an independent basis for determining whether or not to enable actuation of the associated safety restraint actuator 82 .
- the safing strategy is adapted so as to prevent a single point failure from causing an inadvertent actuation of the associated safety restraint actuator 82 .
- the evaluation of the safing criteria may be performed by an independent processor so as to preclude the prospect of a failure of the processor 62 causing an inadvertent deployment.
- the safing strategy is adapted so the first 60 and second 80 magnetic sensor signals are used to safe one another.
- signals—e.g. associated current and voltage—from the first 34 . 1 and second 34 . 2 coil drivers are also monitored to verify the operation of the associated first 14 and third 64 coils, e.g. to verify the fidelity and operativeness of the coils and associated signals and to monitor the associated noise level.
- one or more signals—e.g. a measure of current through the at least one first coil 14 and/or the associated voltage thereacross—from the first coil driver 34 . 1 are operatively coupled to at least one associated third demodulator 86 . 1 , the output(s) of which is/are operatively coupled to an associated at least one third analog-to-digital converter 88 .
- the safing criteria are satisfied for a particular magnetic crash sensor 10 . 1 , 10 . 2 if the associated coil driver 34 . 1 , 34 . 2 generates a substantially noise-free signal at the proper amplitude and frequency, and both the first 60 and second 80 magnetic sensor signals exhibit substantial nominal signal levels and variation over time.
- the current though the first 14 or third 64 coil is processed to calculate two measures, TXRA and TXRA_ABS, respectively as running averages of the magnitude of this current and the absolute value of the magnitude of this current, wherein the running averages are calculated over a period of, for example, 1 to 7 milliseconds, e.g. 5 milliseconds. If ThresholdRA 1 ⁇ TXRA ⁇ ThresholdRA 2 and TXRA_ABS ⁇ ThresholdRA 3 , then the current signal from the corresponding first 14 or third 64 coil is considered to be valid, and the corresponding first 14 or third 64 coil is considered to be operative.
- the safing criteria is considered to be satisfied, and this condition is latched for a period of time, for example, a predetermined period of 30 milliseconds. If the conditions on TXRA or TXRA_ABS later both become unsatisfied, then the safing condition is unlatched substantially immediately thereafter. Otherwise, if any of the other four conditions become unsatisfied, then the safing condition is unlatched after the period of time lapses, unless within that interval, all six safing conditions again become satisfied.
- step ( 232 ) if the vehicle 12 has two (or more) doors, e.g. a front 24 and rear 74 door on a particular side thereof, then in step ( 234 ), steps ( 202 ) through ( 230 ) are performed for each door 24 , 74 using the associated first 60 and second 80 magnetic sensor signals from the corresponding first 18 and second 68 magnetic sensors, so as to determine the first crash metrics M 1 B or M 1 C for each door 24 , 74 .
- a second crash metric M 2 is calculated from the combination, e.g. linear combination, of the first crash metrics M 1 B and M 1 C corresponding to different doors 24 , 74 on the same side of the vehicle 12 .
- the second crash metric M 2 is equal to the first crash metric M 1 B (for purposes of describing a general magnetic crash sensing algorithm 200 in the context of a vehicle having an arbitrary number of doors on a side—in a two-door vehicle 12 having only one door 24 on a side, there would be no need to have distinct first M 1 B and second M 2 crash metrics).
- step ( 240 ) the values of the first M 1 B,C and second M 2 crash metric are damped, so that the values of the respective resulting first ⁇ tilde over (M) ⁇ 1 B,C and second ⁇ tilde over (M) ⁇ 2 damped crash metrics are attenuated over time to insignificant levels after the event subsides provided that a side impact crash of sufficient severity to warrant actuation of the safety restraint actuator 82 does not occur, even for events for which there may have been associated metal bending resulting from the crash. Damping provides for facilitating algorithm exit in step ( 250 ) following significant crash events that were not sufficiently severe to warrant actuation of the safety restraint actuator 82 .
- the damping factor ⁇ could include an integral of the AC measure Y AC commencing with algorithm entrance, or the sample number since algorithm entrance multiplied by a constant minus the running average of the AC measure Y AC calculated using a relatively long time window, e.g. greater than 10 milliseconds.
- a threshold e.g. 0.75
- the magnetic crash sensing algorithm 200 provides for adapting a deployment threshold as a function of the door state that was detected in step ( 208 ). For example, if one of the doors 24 , 74 were partially latched rather than being fully closed, the magnitude of the second damped crash metric ⁇ tilde over (M) ⁇ 2 would likely be greater than if both doors were fully closed, and less than if both doors were partially latched.
- the deployment threshold can be adjusted to accommodate the combination of door states on a particular side of the vehicle 12 , wherein, in one embodiment, the threshold would be lowest for both doors 24 , 74 fully closed, highest for both doors 24 , 74 partially latched, and intermediate thereto if one of the doors is fully closed and the other is partially latched.
- a preset threshold scheme would be used in lieu of step ( 242 ).
- step ( 244 ) the first ⁇ tilde over (M) ⁇ 1 B,C and second ⁇ tilde over (M) ⁇ 2 damped crash metrics and the AC measure Y AC are compared with associated threshold levels (positive and negative), and, in one embodiment, if each metric or measure exceeds it respective threshold for at least a specified minimum number of consecutive iterations, then, in step ( 246 ), if the safing criteria from step ( 230 ) are also simultaneously satisfied, then in step ( 248 ) the appropriate safety restraint actuator(s) 82 is/are deployed.
- neither the satisfaction of the deployment threshold in step ( 244 ) nor the satisfaction of the safing criteria in step ( 246 ) latches TRUE, but instead, both criteria must be simultaneously TRUE in order for the safety restraint actuator(s) 82 to be actuated.
- other logical combinations of the various crash metrics and other measures are used in the actuation decision.
- the actuation decision could be governed by one or more of the various crash metrics and measures, or the satisfaction of the safing criteria could latch TRUE, so that an actuation of the safety restraint actuator(s) 82 would occur when the deployment threshold is satisfied in step ( 244 ) provided that the safing criteria had been satisfied earlier, subsequent to algorithm entrance.
- step ( 250 ) if an exit criteria is satisfied, then the core crash detection algorithm ( 214 - 250 ) is exited in step ( 252 ), and the magnetic crash sensing algorithm 200 continues with step ( 202 ), whereupon subsequent entry of step ( 206 ), the algorithm will be indicated as being inactive (i.e. not entered) until the entrance criteria is again satisfied responsive to conditions on the first filtered signal Y 1 (i), which continues to be calculated in step ( 204 ) following the acquisition of the first 18 or second 68 magnetic sensor in step ( 202 ).
- the exit criteria is satisfied if the first filtered signals Y 1 B and Y 1 C , the associated AC measures Y AC B and Y AC C , and the damped crash metric M 3 are less than associated threshold values for a specified number of iterations of the core crash detection algorithm ( 214 - 250 ), or if the time period since algorithm entrance in step ( 212 ) exceeds a time-out threshold.
- the above-described magnetic crash sensing algorithm 200 can be embodied in various ways, and can be modified within the scope of the instant invention.
- the first filtered signal Y 1 (i) and the AC measure Y AC could be processed separately, as if each were a separate crash metric. These individual metrics could then be separately damped (step ( 240 )) and used separately to compare against individual deployment thresholds (step ( 244 )). These metrics could alternatively be combined with similar metrics derived from a second magnetic sensor to create two M 2 metrics (following the example in step ( 236 )): a low frequency and a higher frequency M 2 metric. This alternative individual signal processing creates more individual metrics, making the algorithm slightly more complicated, but also providing additional flexibility in setting deployment conditions.
- additional filtered signals might be obtained from the raw data using different window running averages to produce time domain equivalents of high-pass frequency filtering, or other types of filters can be utilized, for example single or multiple pole low-pass or band-pass filters, other digital filters, e.g. FIR or IIR, or Fourier transform filters Several such filtered signals might be combined with each other or with the raw data signal to give measures associated with desired frequency bands. Such additional frequency analysis and derived measures might be necessary for a specific vehicle platform or magnetic system mounting location and method and would be based upon the associated crash data and data from non-crash “abuse events”.
- the magnetic crash sensing algorithm 200 provides a method of processing magnetic crash signals from a magnetic crash sensor so as to provide for the rapid, real time determination of both the crash severity and the associated crash type (e.g. pole crash vs. barrier crash) for a particular crash event
- the magnetic crash sensing algorithm 200 provides for the actuation of safety restraint actuator(s) 82 at a relatively early time as necessary so as to provide for protecting the occupant from the crash, while also discriminating lower severity crash events (as determined by potential occupant injury) so as to avoid inadvertent or unnecessary actuation of safety restraint actuator(s) 82 , particularly those safety restraint actuator(s) 82 which are not resetable, i.e. reusable for multiple crash events.
- the magnetic crash sensing algorithm 200 also provides for immunity to external electrical and mechanical “abuse events” including those caused by electromagnetic induction, or localized impacts with relatively low mass but high speed objects.
- the associated magnetic crash sensors 10 . 1 , 10 . 2 provide for distributed crash sensing that can be beneficially less sensitive to localized mechanical or electrical disturbances which might otherwise adversely affect a crash sensing system using more localized crash sensors.
- the polarity of the associated magnetic crash sensor signals 60 , 80 provides information that can be used for distinguishing various types of crashes. For example, in one embodiment, measured data suggests that localized impacts that cause significant intrusion into the vehicle will give a positive crash metric polarity while more broad surface impacts will give a negative polarity crash metric. Pole-like impacts might be identified as positive polarity while cart-like impacts would be identified by negative polarity. The door motion and crush will vary between crash types, potentially producing signals of opposite sign that correspond to more or less magnetic signal (magnetic flux 40 ) reaching the receiver sensors than is normally received.
- magnetic crash sensing algorithm 200 has been described herein in the context of side impact crash detection, a similar algorithm could be used to detect impacts anywhere on the vehicle using appropriate associated magnetic crash sensor hardware.
- third 10 . 3 and fourth 10 . 4 magnetic crash sensors are adapted similar to the first 10 . 1 and second 10 . 2 magnetic crash sensors illustrated in FIG. 1 , with the exception that the second 26 and fourth 76 coils at the second 20 and fourth 70 locations respectively are adapted to operate in a receiver mode and a transceiver mode so as to provide for sensing both a crash event involving a respective front 24 or rear 74 door, thereby generating the above-described first 60 and second 80 magnetic sensor signals, and to also provide for either continuously sensing the opening state of the respective front 24 or rear 74 doors, and/or for providing associated safing of the first 60 and second 80 magnetic sensor signals.
- the second coil 26 is operatively coupled to a third coil driver 34 . 3 , which is in turn operatively coupled to a third oscillator 36 . 3 , wherein an oscillatory signal from the third oscillator 36 . 3 is applied by the third coil driver 34 . 3 so as to cause an associated current in the at least one third coil 64 , responsive to which the at least one third coil 64 generates a third magnetic field 38 . 3 responsive to the reluctance of the associated magnetic circuit, and which caused eddy currents in associated proximal conductive elements which thereby influences the resulting third magnetic field 38 . 3 .
- the third oscillator 36 is operatively coupled to a third coil driver 34 . 3 , which is in turn operatively coupled to a third oscillator 36 . 3 , wherein an oscillatory signal from the third oscillator 36 . 3 is applied by the third coil driver 34 . 3 so as to cause an associated current in the at least one third coil 64 , responsive to which the at least one third
- the third magnetic field 38 . 3 is responsive to the reluctance of the associated magnetic circuit, which is affected by a crash involving the elements thereof and/or the gaps 52 therein, and which is also affected by the opening state of the front door 24 .
- a signal responsive to the third magnetic field 38 . 3 and responsive to the self-impedance of the second coil 26 is sensed within the circuitry associated with the third coil driver 34 . 3 and a resulting signal is demodulated by a third demodulator 56 .
- the fourth coil 76 is operatively coupled to a fourth coil driver 34 . 4 , which is in turn operatively coupled to a second oscillator 36 . 2 , wherein an oscillatory signal from the fourth oscillator 36 . 4 is applied by the fourth coil driver 34 . 4 so as to cause an associated current in the at least one third coil 64 , responsive to which the at least one third coil 64 generates a fourth magnetic field 38 . 4 responsive to the reluctance of the associated magnetic circuit, and which caused eddy currents in associated proximal conductive elements which thereby influences the resulting fourth magnetic field 38 . 4 .
- the fourth oscillator 36 is operatively coupled to a fourth coil driver 34 . 4 , which is in turn operatively coupled to a second oscillator 36 . 2 , wherein an oscillatory signal from the fourth oscillator 36 . 4 is applied by the fourth coil driver 34 . 4 so as to cause an associated current in the at least one third coil 64 , responsive to which the at least one
- the third magnetic field 38 . 3 is responsive to the reluctance of the associated magnetic circuit, which is affected by a crash involving the elements thereof and/or the gaps 52 therein, and which is also affected by the opening state of the rear door 74 .
- a signal responsive to the fourth magnetic field 38 . 4 and responsive to the self-impedance of the fourth coil 76 is sensed within the circuitry associated with the fourth coil driver 34 . 3 and a resulting signal is demodulated by a fourth demodulator 56 .
- the frequency of the fourth oscillator 36 . 4 is adapted so that the resulting third magnetic field 38 . 4 is sufficiently strong to provide a useful signal level of the third magnetic sensor signal 92 .
- fifth 10 . 5 and sixth 10 . 6 magnetic crash sensors are adapted similar to the third 10 . 3 and fourth 10 . 4 magnetic crash sensors illustrated in FIG. 6 , with the exception that the rolls of the first 14 and second 26 coils are reversed, and the roles of the third 64 and fourth 76 coils are reversed, wherein the second 26 and fourth 76 coils of the respective fifth 10 . 5 and sixth 10 . 6 magnetic crash sensor are each driven in both a transmit mode and a transceiver mode, and the first 14 and third 64 coils are used only in the receive mode.
- the above-illustrated combined transmitter/receiver and transceiver topology provides for enhancing the confidence in the sensing of the instant door state, which can be provided for continuously—even with the vehicle in a quiescent (i.e. key off) state—by using a low-power low duty cycle operation in the transceiver mode.
- the transceiver mode that provides for monitoring the door state can operate on a sufficiently small amount of power so as to operate comfortably in the key-off or sleep energy levels.
- This key off magnetic dome light after factory pre-set will permit the MSI microprocessor to know for certain the door status (compared to factory calibration) so the MSI can be certain as to arm and when to activate the vehicle dome light, as a function of the door position.
- One embodiment would involve a (self inductance) transmitting device at the “B” and “C” pillars and would be operated at minimum power. This approach would be activated at the factory and would require minimum power so it would be operated in key-off. The door opening inductance change is significant compared to the change due to a crash and thresholds would be set accordingly. The “B” and “C” would safe each other during an impact. An accelerometer might also be considered to support safing (impact during door ajar situation).
- the continuous detection of the door opening state provides for using the associated magnetic crash sensing system to provide for controlling a dome light in the vehicle, or for providing a door opening signal to a vehicle security system.
- a sense resistor could be added to validate the bulb to be present and illuminated (perhaps a photo receiver sensor or temperature sensor to validate light or heat present as well).
- the system can determine the instant position of the vehicle door (open versus ajar for the “B” and “C” transmitters) to permit the microprocessor to elect to illuminate the dome light or arm the MSI system for safety and security.
- the magnetic crash sensing system can be factory pre-set, i.e. tuned, to guarantee the door is closed at a specific time and calibrate the magnetic crash sensing system (place the hinge and striker signals into NV memory for future use).
- the magnetic crash sensing system can operate on low power and or low duty cycle to obtain standard automotive sleep mode energy consumption levels so the door open/closed movement can be MSI tracked at key off.
- the magnetic crash sensing system would be operated in a transmitter duty cycle mode. This specification for this mode would perhaps call for the magnetic crash sensing system to send a carrier burst once a second, and during the burst 10 to 20 cycles of the carrier would be transmitted. The 10 to 20 cycles would be enough carrier to permit the demodulator to successfully lock on to the hinge signal and test the door open status, while not demanding excessive amounts of power.
- the “B” and “C” pillars would utilized at transmitters in normal mode and in “key-off” or sleep mode would act as inductance meters, operating at very low power levels in run mode and even lower power in sleep mode as in sleep mode “B” and “C” pillars would be duty cycle pulsed.
- This system will achieve minimal operating power levels running (key-on) or asleep (key off) thus permitting unwanted intrusion monitoring (security) as well as dome light function (safety) and enhanced dome light accuracy.
- a seventh embodiment of a magnetic crash sensing system 10 . 7 incorporated in a vehicle 12 comprises a first coil 14 at a corresponding first location 16 of the vehicle 12 , and a plurality of magnetic sensors 18 . 1 , 18 . 2 at a corresponding plurality of second locations 20 . 1 , 20 . 2 of the vehicle 12 .
- the first coil 14 is located around the striker 22 of the door latch assembly 24 of the front door 24 , and the magnetic sensors 18 . 1 , 18 .
- the first coil 14 is operatively coupled to a coil driver 44 , which is in turn operatively coupled to an oscillator 46 , wherein an oscillatory signal from the oscillator 46 is applied by the coil driver 44 so as to cause an associated current in the first coil 14 , responsive to which the first coil 14 generates a magnetic field 48 comprising magnetic flux 40 in associated first 52 . 1 and second 52 . 2 magnetic circuits.
- the second 28 and third 32 coils surround metallic elements of the associated first 52 . 1 and second 52 . 2 magnetic circuits, and the magnetic flux 40 propagates within the associated magnetically permeable material of the first 52 . 1 and second 52 . 2 magnetic circuits and flows through the second 28 and third 32 coils surrounding the associated magnetically permeable material.
- the second 28 and third 32 coils generate voltage signals responsive to the oscillating magnetic flux 40 , or component thereof, directed along the axis of the second 28 and third 32 coils respectively, in accordance with Faraday's law of magnetic induction.
- the doors 24 , 38 are isolated from the remainder of the vehicle 12 , e.g. the frame, by the gaps 54 therebetween, except where the hinges 30 and door latch assemblies 24 , 36 provide relatively lower reluctance paths therebetween.
- the oscillator 46 generates a oscillating signal, for example, having either a sinusoidal, square wave, triangular or other waveform shape, of a single frequency, or a plurality of frequencies that are either stepped, continuously swept or simultaneous.
- the frequency is adapted so that the resulting magnetic field 48 is conducted through the first 52 . 1 and second 52 . 2 magnetic circuits with sufficient strength so as to provide a useful signal level from the associated magnetic sensors 18 . 1 , 18 . 2 that cooperate therewith.
- the oscillation frequency would typically be less than about 50 KHz for a steel structure, e.g. 10 to 20 KHz in one embodiment.
- the magnetic field 48 is responsive to the reluctance of the associated first 52 . 1 and second 52 . 2 magnetic circuits, which is affected by a crash involving the elements thereof and/or the gaps 54 therein.
- the magnetic field 48 is sensed by the magnetic sensors 18 . 1 , 18 . 2 , and a signal therefrom is conditioned by associated signal preprocessors 56 . 1 , 56 . 2 which are operatively coupled to a processor 58 .
- each signal preprocessor 56 . 1 , 56 . 2 demodulates the signal from the associated magnetic sensor 18 . 1 , 18 . 2 with an associated demodulator, and converts from analog to digital form with an associated analog-to-digital converter which is sampled and input to the processor 58 .
- the signal preprocessors 56 . 1 , 56 . 2 may also provide for amplification. Changes to the magnetic field 48 at a particular location in the first 52 . 1 and second 52 .
- the magnetic field 48 sensed by the magnetic sensors 18 . 1 , 18 . 2 contains information about the nature of the remainder of the magnetic circuit, including the front 26 and rear 38 doors and the adjacent A-pillar 44 , B-pillar 32 and C-pillar 78 , any of which could be involved in, or affected by, a side-impact crash.
- the seventh embodiment of the magnetic crash sensing system 10 . 7 can operate in a variety of modes, for example, as disclosed in U.S. Pat. Nos. 6,777,927, 6,586,926, or 6,407,660; or U.S. application Ser. Nos. 10/666,165 or 10/946,151; each of which is incorporated in its entirety by reference herein.
- the magnetic crash sensing system 10 . 7 provides for controlling a safety restraint actuator 82 , e.g. side air bag system, responsive to the detection of a crash, and/or provides for activating an indicator 84 , e.g. warning lamp, warning message, or audible alarm, e.g. responsive to a door open or partially latched condition, or a prediction of an impending crash responsive to the interaction of an approaching vehicle with a proximity field of the magnetic crash sensing system 10 . 7 .
- a safety restraint actuator 82 e.g. side air bag system
- an indicator 84 e.g. warning lamp
- the arrangement of the first coil 14 as a transmitter coil 66 at a central location, e.g. proximate to the B-pillar 32 , and the plurality of magnetic sensors 18 . 1 , 18 . 2 , e.g. receiver coils 68 , in cooperation therewith at relatively distal locations relative thereto, e.g. proximate to the A-pillar 44 and C-pillar 78 respectively, provides for a magnetic crash sensing system 10 . 7 that is responsive to disturbances affecting either the front 26 or rear 38 doors on a side of the vehicle, but requiring only a single transmitter coil 66 , e.g. the first coil 14 as presently illustrated in FIG. 8 .
- the magnetic crash sensing system 10 . 7 could be adapted so that either the second 28 or third 32 coils acted as the transmitting coil 62 , with the remaining coils acting as associated magnetic sensors 18 . 1 , 18 . 2 .
- a eighth embodiment of a magnetic crash sensing system 10 . 8 incorporates all of the features of the seventh embodiment 10 . 7 described hereinabove, and further comprises at least one additional magnetic sensor 18 . 3 within a gap 54 between the fixed body structure and a door, e.g. the front door 24 .
- FIG. 9 illustrates the additional magnetic sensor 18 . 3 located between the front edge 70 of the front door 24 and an adjacent edge 72 of the A-pillar 44
- the additional magnetic sensor 18 . 3 could be located elsewhere in the gap 54 between either the front 26 or rear 38 door and the fixed body structure of the vehicle 12 .
- the additional magnetic sensor 18 . 3 is operatively coupled to an associated signal preprocessor 56 . 3 which is in turn operatively coupled to the processor 58 , so as to provide a signal that can be used either for safing or as a primary crash sensing signal.
- the mechanical components of the first 52 . 1 and second 52 . 2 magnetic circuits in which the transmitter 66 and receiver 68 coils are placed are constructed for other functions.
- the hinges 30 and strikers 22 , 34 are designed with primary functions, e.g. to facilitate occupant entrance, exit and vehicle locking, which components are generally constructed according to associated specifications that govern strength, geometry, material and design constraints. Accordingly, configuring the transmitter 66 or receiver 68 coils, that would encircle the magnetically permeable members, can be otherwise challenging and subject to constraints on coil shape, turn count, connector access and wire gauge that might otherwise limit the optimization of the transmitter 66 or receiver 68 coils for their primary function to generate or sense time varying magnetic fields.
- the fragmentary view 300 of the A-pillar 44 and front door 24 from FIG. 9 is illustrated in greater detail, illustrating several embodiments of the additional magnetic sensor 18 . 3 , 18 . 3 ′, 18 . 3 ′′ in greater detail, each comprising a gap coil 74 that is sufficiently small to be located within the gap 54 between the A-pillar 44 and the front door 24 .
- the gap coil 74 of the additional magnetic sensor 18 . 3 , 18 . 3 ′, 18 . 3 ′′ is not necessarily constrained to surround existing magnetic permeable components of the first 52 . 1 or second 52 .
- the gap coil 74 is wound around an associated spool 76 which is fastened to the fixed structure of the vehicle, e.g. the edge 72 of the A-pillar 44 facing the front edge 70 of the front door 24 .
- the gap coil 74 can be used as either a transmitter coil 66 or a receiver coil 68 , although in the eighth embodiment of a magnetic crash sensing system 10 . 8 , the gap coil 74 is used as a receiver coil 68 responsive to the magnetic flux 40 within the gap 54 , e.g.
- the gap coil 74 can be oriented so as to optimize the signal-to-noise ratio of the signal generated thereby responsive to a crash or other disturbance to be monitored.
- the axis 78 of the gap coil 74 is substantially perpendicular to the edge 72 of the A-pillar 44 and to the front edge 70 of the front door 24 when the front door 24 is closed.
- the first magnetic sensor 18 . 3 ′ is attached to the A-pillar 44 with a fastener 80 through the associated spool 76 , e.g. a socket head screw 80 . 1 through a counterbore in the spool 76 .
- the magnetic permeability of the fastener 80 can be adapted in accordance with the sensing or field generating requirements of the associated gap coil 74 .
- the fastener 80 associated with the first magnetic sensor 18 can be adapted in accordance with the sensing or field generating requirements of the associated gap coil 74 .
- 3 ′ is substantially aligned with the axis 78 of the gap coil 74 , so that a fastener 80 of a material with a relatively high permeability, e.g. carbon steel or electrical steel, will tend to concentrate the magnetic flux 40 through the gap coil 74 , whereas a fastener 80 of a material with a relatively low permeability, e.g. stainless steel, aluminum or brass, will tend to emulate an air core so that the magnetic sensor 18 . 3 ′ has less of a tendency to perturb the associated first 52 . 1 or second 52 . 2 magnetic circuit.
- a fastener 80 of a material with a relatively high permeability e.g. carbon steel or electrical steel
- a fastener 80 of a material with a relatively low permeability e.g. stainless steel, aluminum or brass
- the axis 78 of the gap coil 74 is substantially parallel to the edge 72 of the A-pillar 44 and to the front edge 70 of the front door 24 , so as to be substantially aligned with the length of the associated gap 54 .
- the second magnetic sensor 18 . 3 ′ is shown attached to the A-pillar 44 with a fastener 80 through a flange that depends from the associated spool 76 .
- FIG. 10 also illustrates the second coil 26 around a hinge 22 of the front door 24 .
- the second coil 26 can be located at various second locations 20 . 1 ′, 20 . 1 ′′, 20 . 1 ′′′ relative to the hinge 22 .
- the second location 20 . 1 ′ is on around a portion of the hinge plate 30 . 1 that attaches to the fixed vehicle structure, e.g. the A-pillar 44 or B-pillar 32 , at a location between the A-pillar 44 or B-pillar 32 and the hinge joint 30 . 2 .
- the second location 20 . 1 ′′ is on around a portion of the hinge plate 30 .
- the second location 20 . 1 ′′′ is on around a portion of the hinge plate 30 . 3 that attaches to the front 26 or rear 38 door, at a location between the front edge 70 of the front 26 or rear 38 door and the hinge joint 30 . 2 .
- a gap coil 74 may be mounted on the B-pillar 32 or C-pillar 78 on an outward facing surface 82 in the gap 54 between the outward facing surface 82 and a corresponding proximate inward facing surface 84 of the front 26 or rear 38 door respectively.
- the gap coil 74 is secured to the outward facing surface 82 with a flat head screw 80 . 2 through the spool 76 around which the coil is wound.
- the gap coil 74 illustrated in FIG. 12 is responsive to changes in reluctance of the associated first 52 . 1 or second 52 . 2 magnetic circuit responsive to the door opening state of the associated front 26 or rear 38 door and accordingly can be used to generate a signal indicative thereof, e.g. so as to provide for discriminating between a closed door, a partially latched door and an open door.
- a gap coil assembly 86 comprises a gap coil 74 wound around a spool 76 , both of which are encapsulated in an encapsulant 88 , e.g. a silicone potting compound, so as mitigate against environmentally induced degradation.
- the gap coil 74 for example, is wound of wire, e.g. 20 to 50 gauge enamel coated conductive wire, e.g. copper or aluminum.
- the spool 76 is, for example, made of a relatively rigid material such as plastic or aluminum.
- the gap coil assembly 86 can further comprise a core 90 of a material having relatively high magnetic permeability such as ferrite, mu-metal, or amorphous metal, e.g. METGLAS®.
- a material having relatively high magnetic permeability such as ferrite, mu-metal, or amorphous metal, e.g. METGLAS®.
- the gap coil assemblies 86 illustrated in FIGS. 13 and 14 can be mounted, for example, by bonding or clamping. Referring to FIG. 15 , the gap coil assembly 86 is mounted with a fastener 80 , e.g. a cap screw 80 . 3 and washer 92 , through a central mounting hole 94 in the spool 76 .
- the material and dimensions of the fastener 80 would be selected according to the particular application.
- a material having relatively high magnetic permeability such as carbon steel or electrical steel could be used to concentrate the associated magnetic flux 40 through the gap coil 74
- a material of relatively low magnetic permeability such as aluminum, brass or stainless steel could be used to emulate an air core, thereby having less influence on the inherent flow of magnetic flux 40 across the associated gap 54 within which the gap coil assembly 86 is located.
- the gap coil assembly 86 is mounted with a fastener 80 , e.g. a socket head screw 80 . 1 , and further incorporates a magnetically permeable core 96 comprising a shouldered sleeve 98 that is recessed within the central mounting hole 94 in the spool 76 .
- the magnetically permeable core 96 can comprise either carbon steel, electrical steel, mu-metal, ferrite, or amorphous metal, e.g. METGLAS®.
- the length of the shouldered sleeve 98 can be adjusted in relation to the associated gap 54 in which the gap coil assembly 86 is mounted depending upon the extent of associated magnetic focusing required.
- a multi-axis gap coil assembly 100 comprises a plurality of gap coils 74 arranged on a central hub 102 wherein the axis 78 of each gap coil 74 is oriented in a different direction so as to provide for sensitivity to a corresponding component of the magnetic field 48 in that direction.
- the multi-axis gap coil assembly 100 is mounted with a fastener 80 , e.g. a socket head screw 80 . 1 , recessed in a spool 76 of one of the gap coils 74 and through the central hub 102 .
- the individual gap coils 74 can be either preassembled and attached to the central hub 102 , or wound around corresponding spool portions 104 that are attached to, or an integral part of, the central hub 102 .
- the central hub 102 and associated spool portions 104 could be plastic injection molded as a single part.
- the material used to construct the central hub 102 can be of relatively low magnetic permeability, e.g. plastic or aluminum, in applications for which the associated magnetic flux 40 need not be concentrated, and of a material of relatively higher magnetic permeability, e.g. ferrite, carbon steel, electrical steel or mu-metal, in applications for which it is beneficial to concentrate the associated magnetic flux 40 proximate to the associated gap coils 74 .
- the multi-axis gap coil assembly 100 is illustrated with six gap coils 74 , three oriented in orthogonal relation to one another, and the remaining three oriented obliquely relative thereto. It should be understood that this arrangement of gap coils 74 is principally to illustrate a variety of possible arrangements, and should not be taken to mean that the multi-axis gap coil assembly 100 must have that number of gap coils 74 , or gap coils 74 arranged as so illustrated. More particularly, the multi-axis gap coil assembly 100 would have at least two gap coils 74 oriented with associated axes 78 thereof in different directions, so as to provide for multi-axis magnetic field sensitivity within a gap 54 between body elements of the vehicle 12 .
- the shape, size, gauge, and number of turns of a gap coil 74 is not limiting, but can instead be adapted or optimized for a particular application or configuration, e.g. the gap coil 74 can adapted to resonate at a particular frequency, to fit within a particular gap 54 , or to influence the reluctance of the associated magnetic circuit 52 . 1 , 52 . 2 in a particular way. For example, it has been beneficial to operate the gap coil 74 away from resonance so as to provide for a relatively flat frequency response thereof.
- the gap coil 74 can be developed and manufactured in accordance with any of a wide range of known coil design and manufacturing processes, and can be made small with any of a wide range of known connector and mounting configurations that would be selected or adapted for a particular mounting position and location in a given vehicle platform.
- a plurality of individual gap coils 74 can be connected with a common cable harness that is adapted to provide for the placement of the individual gap coils 74 at the respective magnetic sensor locations with separation therebetween so as to provide for improved sensing coverage area and magnetic flux discrimination, thereby providing for safing, redundancy, and/or improved event discrimination at comparable or reduced cost relative to coils that must otherwise be adapted to conform to existing vehicle hardware, e.g. hinges 30 or strikers 22 , 34 .
- the gap coils 74 are beneficially small, self contained, easily mounted, and provide some level of redundancy in the associated magnetic crash sensing system.
- the gap coils 74 can be adapted to include proximate electrical components—e.g. resistors, capacitors, reference inductors, IC, amplifiers, A/D, etc.—if necessary to improve the function thereof.
- a nineth embodiment of a magnetic crash sensing system 10 . 9 is the same as the seventh embodiment 10 . 7 except for the magnetic sensors 18 . 1 , 18 . 2 , which in the nineth embodiment 10 . 9 are first 28 ′ and second 32 ′ gap coils located at corresponding second locations 20 . 1 ′′′′, 20 . 2 ′′′′ in the respective gaps 54 between the A-pillar 44 and the front door 24 , and between the rear door 38 and the C-pillar 78 respectively, wherein the first 28 ′ and second 32 ′ gap coils are each in accordance with the gap coils 74 , gap coil assemblies 86 or multi-axis gap coil assembly 100 as disclosed herein.
- a tenth embodiment of a magnetic crash sensing system 10 . 10 is the same as the nineth embodiment 10 . 9 except that the first coil 14 is replaced with a corresponding first coil 14 ′ located at corresponding first location 16 ′ in the respective gap 54 between the front door 24 and the B-pillar 32 , wherein the first coil 14 ′ is accordance with the gap coils 74 , gap coil assemblies 86 or multi-axis gap coil assembly 100 as disclosed herein. Accordingly, the tenth embodiment of a magnetic crash sensing system 10 . 10 incorporates gap coils 74 throughout, the location of which in the associated gaps 54 is not otherwise constrained by existing vehicle hardware. The tenth embodiment of a magnetic crash sensing system 10 .
- the coil driver 44 provides a measure of voltage across, current through, and/or power absorbed by the first coil 14 ′, which is operatively coupled through a signal preprocessor 56 . 3 to the processor 58 , for example, either so as to provide for magnetic crash sensing responsive to the self-inductance of the first coil 14 ′, e.g. in accordance with the teachings of U.S. Pat. No. 6,587,048; or so as to provide for magnetic crash sensing using a time domain reflectometry technique, e.g. in accordance with the teachings of U.S. Pat. No. 6,583,616; each of which above referenced patents are incorporated in its entirety by reference herein.
- a toroidal helical coil 108 provides for generating a voltage signal V responsive to the associated oscillating circumferential magnetic field B E in accordance with Faraday's Law, responsive to which an associated current signal I is generated when the toroidal helical coil 108 is connected to an associated circuit, e.g. a signal preprocessor 56 . 1 , 56 . 2 , 56 . 3 .
- the toroidal helical coil 108 comprises a conductive path 110 , e.g. a winding of conductive wire 110 . 1 , e.g. copper or aluminum wire, around a toroidal core 112 .
- the toroidal core 112 is illustrated in FIGS. 21 and 22 as having a circular shape ( FIG.
- the toroidal core 112 can have any closed shape with any cross-sectional shape, either uniform or not.
- the toroidal core 112 could have a rectangular cross-section, similar to that of a washer.
- the toroidal core 112 comprises a major axis M and a minor axis m, wherein the conductive path 110 makes at least one turn around the minor axis m, and at least one turn around the major axis M.
- the conductive path 110 makes a plurality of turns around the minor axis m, and a single turn around the major axis M.
- the at least one turn around the minor axis m provides for generating a component of the voltage signal V responsive to an oscillating circumferential magnetic field B E
- the at least one turn around the major axis M provides for generating a component of the voltage signal V responsive to an oscillating axial magnetic field B C , the latter of which is illustrated in FIGS. 20 a and 20 b .
- the toroidal helical coil 108 can be used to sense both axial B C and circumferential B E magnetic fields.
- 21 and 22 comprises a major radius , a minor radius r, and an associated outside b and inside a radii and a minor diameter 2r, and may be constructed of either a ferromagnetic or a non-ferromagnetic material, depending upon the application, i.e. whether or not it is necessary to concentrate circumferential magnetic flux within the toroidal core 112 .
- Any of the above described magnetic sensors 18 . 1 , 18 . 2 , 18 . 3 , 18 . 3 ′, 18 . 3 ′′ may incorporate a toroidal helical coil 108 instead of or in addition to the associated coil 28 , 32 , 68 , 74 .
- a toroidal helical coil assembly 114 comprises a toroidal helical coil 108 encapsulated in an encapsulant 88 about a central mounting hole 94 adapted to receive an associated fastener 80 , e.g. a cap screw 80 . 3 .
- the modeling and testing done with a toroidal helical coil 108 suggests that the eddy currents I E (and therefore the associated circumferential magnetic field B E ) are substantially enhanced when the steel core 106 associated with the toroidal helical coil 108 is electrically connected to the front 26 or rear 38 doors and/or the vehicle frame, whereby an electrical connection to both, e.g. via a hinge 22 , is beneficial. Tests have indicated that a stronger signal may be obtained when using a toroidal helical coil 108 instead of a circular wound gap coil 74 at a location otherwise suitable for a gap coil assembly 86 .
Abstract
Description
- The instant application is a continuation-in-part of U.S. application Ser. No. 10/946,151 filed on Sep. 20, 2004, now U.S. Pat. No. 7,113,874, which claims the benefit of prior U.S. Provisional Application Ser. No. 60/503,906 filed on Sep. 19, 2003. The instant application is also a continuation-in-part of U.S. application Ser. No. 10/905,219 filed on Dec. 21, 2004, which claims the benefit of prior U.S. Provisional Application Ser. No. 60/481,821 filed on Dec. 21, 2003. The instant application is also related in subject matter to U.S. application Ser. No. 11/530,492 filed on Sep. 11, 2006. Each of the above-identified applications is incorporated by reference in its entirety.
- In the accompanying drawings:
-
FIG. 1 illustrates a schematic block diagram of a magnetic crash sensor in a vehicle; -
FIG. 2 illustrates a flow chart of a magnetic crash sensing algorithm; -
FIG. 3 illustrates a plot of a signal from a magnetic sensor of a magnetic crash sensor associated with a front door of a vehicle responsive to a relatively high speed slam of the front door; -
FIG. 4 illustrates a plot of a signal from a magnetic sensor of a magnetic crash sensor associated with a front door of a vehicle responsive to a relatively high speed slam of the front door, for various opening angles of the associated rear door; -
FIG. 5 illustrates a plot of a signal from a magnetic sensor of a magnetic crash sensor associated with a rear door of a vehicle responsive to a relatively high speed slam of the rear door, for various opening angles of the associated front door; -
FIG. 6 illustrates a schematic block diagram of a magnetic crash sensor in a vehicle; -
FIG. 7 illustrates a schematic block diagram of a magnetic crash sensor in a vehicle; -
FIG. 8 illustrates a schematic block diagram of a seventh embodiment of a magnetic crash sensing system in a vehicle; -
FIG. 9 illustrates a schematic block diagram of a eighth embodiment of a magnetic crash sensing system in a vehicle; -
FIG. 10 illustrates a detailed view of several coils from the eighth embodiment illustrated inFIG. 9 , and illustrates several coil embodiments; -
FIG. 11 illustrates various locations for a coil around a door hinge; -
FIG. 12 illustrates a coil mounted so as to provide for sensing a door opening condition; -
FIG. 13 illustrates an encapsulated coil assembly; -
FIG. 14 illustrates a portion of a coil assembly incorporating a magnetically permeable core; -
FIG. 15 illustrates a portion of a coil assembly adapted for mounting with a fastener; -
FIG. 16 illustrates a portion of a coil assembly adapted for mounting with a fastener, further comprising a magnetically permeable core; -
FIG. 17 illustrates a coil assembly comprising a plurality of coils arranged in a variety of orientations; -
FIG. 18 illustrates a schematic block diagram of a nineth embodiment of a magnetic crash sensing system in a vehicle; -
FIG. 19 illustrates a schematic block diagram of a tenth embodiment of a magnetic crash sensing system in a vehicle; -
FIGS. 20 a and 20 b illustrate eddy currents, associated magnetic fields and axial magnetic fields in various ferromagnetic elements; -
FIG. 21 illustrates a toroidal helical coil; and -
FIG. 22 illustrates a toroidal helical coil assembly. - Referring to
FIG. 1 , a first magnetic crash sensor 10.1 incorporated in avehicle 12 comprises at least onefirst coil 14 at a corresponding at least onefirst location 16 of thevehicle 12, and an associated at least one firstmagnetic sensor 18 at a corresponding at least onesecond location 20 of thevehicle 12. For example, in the embodiment illustrated inFIG. 1 , afirst coil 14 is located around an upper hinge 22.1 of afront door 24 of thevehicle 12, and the at least one firstmagnetic sensor 18 comprises asecond coil 26 around the striker 28.1 of the door latch assembly 30.1 of thefront door 24, wherein the striker 28.1 is operatively coupled to the B-pillar 32 of thevehicle 12 and thesecond coil 26 is proximate thereto. The at least onefirst coil 14 is operatively coupled to a first coil driver 34.1, which is in turn operatively coupled to a first oscillator 36.1, wherein an oscillatory signal from the first oscillator 36.1 is applied by the first coil driver 34.1 to cause an associated current in the at least onefirst coil 14, responsive to which the at least onefirst coil 14 generates a first magnetic field 38.1 comprisingmagnetic flux 40 in an associated first magnetic circuit 42.1 comprising theA-pillar 44,front door 24, B-pillar 32, and the body 46, frame 48 orpowertrain 50 of thevehicle 12. The first oscillator 36.1 generates an oscillating signal, for example, having either a sinusoidal, square wave, triangular or other waveform shape, of a single frequency, or a plurality of frequencies that, for example, are either stepped, continuously swept or simultaneous. The frequency is adapted so that the resulting first magnetic field 38.1 is conducted through the first magnetic circuit 42.1 with sufficient strength so as to provide a useful signal level from the firstmagnetic sensor 18 that cooperates therewith. For example, the oscillation frequency would typically be less than about 100 KHz for a steel structure, e.g. 20 to 30 KHz in one embodiment. An oscillation frequency in the audio range, e.g. 10 to 20 KHz, can also be used for crash sensing, however, such frequencies may cause an audible hum to be generated by the associated magnetic circuit. The first magnetic field 38.1 is responsive to the reluctance of the associated first magnetic circuit 42.1, which is affected by a crash involving the elements thereof and/or thegaps 52 therein. The first magnetic field 38.1 is sensed by the at least one firstmagnetic sensor 18, and the signal therefrom is conditioned by an associated first signal conditioner 54.1, demodulated by a first demodulator 56.1, converted from analog to digital form by a first analog-to-digital converter 58.1, and input as a firstmagnetic sensor signal 60 to aprocessor 62, which processes the signal as described more fully hereinbelow. The first signal conditioner 54.1 may incorporate buffering, amplification, high-pass, low-pass, or band-pass filtering, The first demodulator 56.1, for example, may provide amplitude demodulation, constant sampling relative to the phase of the first oscillator 36.1, or constant sampling relative to the phase of the signal sensed by the firstmagnetic sensor 18. For example, any envelope detection or phase or frequency demodulation technique could be used to obtain the demodulated signal. Since various demodulation techniques could be used to extract the crash information from the signal from the firstmagnetic sensor 18, the particular demodulation method will, for example, depend upon the particular implementation and the cost of the components used to perform this function. In another embodiment, the analog-to-digital conversion function and the demodulation function are combined a single process. It should be understood that the first demodulator 56.1 may also provide for amplification, and that the first analog-to-digital converter 58.1 would incorporate an associated sampler. Changes to the first magnetic field 38.1 at a particular location in the first magnetic circuit 42.1 propagate within the associated first magnetic circuit 42.1 at the speed of light and are seen throughout the first magnetic circuit 42.1. Accordingly, the first magnetic field 38.1 sensed by the at least one firstmagnetic sensor 18 contains information about the nature of the remainder of the magnetic circuit, including thefront door 24 andadjacent A-pillar 44 and B-pillar 32, any of which could be involved in and affected by a side-impact crash. - In the embodiment illustrated in
FIG. 1 , thevehicle 12 further incorporates a second magnetic crash sensor 10.2 comprising at least one third coil 64 at a corresponding at least onethird location 66 of thevehicle 12, and an associated at least one secondmagnetic sensor 68 at a corresponding at least onefourth location 70 of thevehicle 12. For example, in the embodiment illustrated inFIG. 1 , a third coil 64 is located around an upper hinge 72.1 of arear door 74 of thevehicle 12, and the at least one secondmagnetic sensor 68 comprises afourth coil 76 around the striker 28.2 of the door latch assembly 30.2 of therear door 74, wherein the striker 28.2 is operatively coupled to the C-pillar 78 of thevehicle 12 and thefourth coil 76 is proximate thereto. The at least one third coil 64 is operatively coupled to a second coil driver 34.2, which is in turn operatively coupled to a second oscillator 36.2, wherein an oscillatory signal from the second oscillator 36.2 is applied by the second coil driver 34.2 so as to cause an associated current in the at least one third coil 64, responsive to which the at least one third coil 64 generates a second magnetic field 38.2 comprisingmagnetic flux 40 in the associated second magnetic circuit 42.2 comprising the B-pillar 32,rear door 74, C-pillar 78, and the body 46, frame 48 orpowertrain 50 of thevehicle 12. The second oscillator 36.2 generates a oscillating signal, for example, having either a sinusoidal, square wave, triangular or other waveform shape, or a single frequency or a plurality of frequencies that, for example, are either stepped, continuously swept or simultaneous. The frequency is adapted so that the resulting second magnetic field 38.2 is conducted through the second magnetic circuit 42.2 with sufficient strength so as to provide a useful signal level from the secondmagnetic sensor 68, which cooperates therewith. The second magnetic field 38.2 is responsive to the reluctance of the associated second magnetic circuit 42.2, which is affected by a crash involving the elements thereof and/or thegaps 52 therein. The second magnetic field 38.2 is sensed by the at least one secondmagnetic sensor 68, and a signal therefrom is conditioned by an associated second signal conditioner 54.2, demodulated by a second demodulator 56.2, converted from analog to digital form by a second analog-to-digital converter 58.2 and input as a secondmagnetic sensor signal 80 to theprocessor 62, which processes the signal as described more fully hereinbelow. The second signal conditioner 54.2 may incorporate buffering, amplification, high-pass, low-pass, or band-pass filtering. The second demodulator 56.2, for example, may provide amplitude demodulation, constant sampling relative to the phase of the second oscillator 36.2, or constant sampling relative to the phase of the signal sensed by the secondmagnetic sensor 68. For example, any envelope detection or phase or frequency demodulation technique could be used to obtain the demodulated signal. Since various demodulation techniques could be used to extract the crash information from the signal from the secondmagnetic sensor 68, the particular demodulation method will, for example, depend upon the particular implementation and the cost of the components used to perform this function. In another embodiment, the analog-to-digital conversion function and the demodulation function are combined a single process. It should be understood that the second demodulator 56.2 may also provide for amplification, and that the second analog-to-digital converter 58.2 would incorporate an associated sampler. Changes to the second magnetic field 38.2 at a particular location in the second magnetic circuit 42.2 propagate within the associated second magnetic circuit 42.2 at the speed of light and are seen throughout the second magnetic circuit 42.2. Accordingly, the second magnetic field 38.2 sensed by the at least one secondmagnetic sensor 68 contains information about the nature of the remainder of the magnetic circuit, including therear door 74 and adjacent B-pillar 32 and C-pillar 78, any of which could be involved in and affected by a side-impact crash. - Alternatively, as suggested by
FIG. 1 , thefirst coil 14 could be located around the lower hinge 22.2 of thefront door 24; the at least onefirst coil 14, could comprise first coils 14.1, 14.2 around the upper 22.1 and lower 22.2 hinges respectively; the third coil 64 could be located around the lower hinge 22.2 of therear door 74; or the at least one third coil 64, could comprise third coils 64.1, 64.2 around the upper 72.1 and lower 72.2 hinges respectively. Furthermore, the first 36.1 and second 36.2 oscillators could be one and the same, or could be separate, operating at the same or different frequencies with the same type or different types of waveforms. Other arrangements of themagnetic sensor 10 can be used to provide the first 60 or second 80 magnetic sensor signals—for example, as described in U.S. Pat. Nos. 6,407,660 (ASL-250), 6,433,688 (ASL-249), 6,587,048 (ASL-243), 6,777,927 (ASL-241), which are incorporated herein by reference. - For example, in another embodiment, the
magnetic sensor door door gap 52 between thedoor - As another example, in yet another embodiment, the first 36.1 and/or second 32.2 oscillators may be replaced with pulse sources, whereby the pulse amplitude may be adapted to provide for sufficient signal-to-noise ratio and the pulse width may be adapted to provide for reduced power consumption.
- As yet another example, in yet another embodiment, the first 10.1 and/or second 10.2 magnetic crash sensors need not necessarily incorporate associated first 36.1 or second 36.2 oscillators, or first 56.1 or second 56.2 demodulators, but instead the associated first 60 and second 80 magnetic sensor signals could be responsive to magnetostriction signals, magnetic coil pair signals, ferromagnetic shock signals, or other time varying magnetic signals that do not have a carrier from which the information must be extracted prior to analysis.
- The first
magnetic sensor signal 60 from the first magnetic crash sensor 10.1—for avehicle 12 with onemagnetic crash sensor 10 on a particular side of thevehicle 12,—or the first 60 and second 80 magnetic sensor signals from the first 10.1 and second 10.2 magnetic crash sensors—for avehicle 12 with twomagnetic crash sensors 10 on a particular side of thevehicle 12,—are processed, for example, in accordance with a magneticcrash sensing algorithm 200 as illustrated by the flow chart ofFIG. 2 , which is executed separately for each side ofvehicle 12. - Referring to
FIG. 2 , beginning with step (202), theprocessor 62 samples the ith sample of the first 60 or second 80 magnetic sensor signal responsive to the associatedmagnetic flux 40 at the location of the associated first 18 or second 68 magnetic sensor. For example, a sampling rate of about 6 KHz in one embodiment provides for medium-to-high frequency content in the raw sampled signal. For purposes of illustration, this signal is designated as Y0(i), which corresponds to the sampling of either the first 60 or second 80 magnetic sensor signal, depending upon which is being processed. - Then, in step (204) the sampled signal Y0(i) is filtered with a first filter to remove noise from the raw magnetic signal, using a relatively lower frequency filter, for example, a running average filter with a sufficiently wide associated time window. The filter is adapted to balance between providing for noise reduction, maintaining a relatively fast step response, and providing for relatively fast computation. For example, in one embodiment, the first filter incorporates a window of about 6 milliseconds, which corresponds to a low-pass cutoff frequency of about 100 Hz. A second embodiment of this filter could be a band-pass filter set produce a signal with relatively lower frequency content, for example from 50 Hz to 250 Hz. The output of the first filter is a first filtered signal Y1(i).
- Then, in step (206), if the core crash detection algorithm (214-250) has been previously entered following step (212) and not subsequently exited at step (252), the process continues with step (216). Otherwise, in step (208), the opening state of the door is detected from the first filtered signal Y1(i), or another similar relatively longer time constant/lower frequency signal derived from the sampled signal Y0(i) (e.g. about a 1 Hz low-passed signal). The relatively slow motion of the
doors 24, 74 (or of one of thedoors 24 in a two-door vehicle 12) can be tracked from the magnitude of the associated first filtered signals Y1(i). As adoor magnetic flux 40 interacting with themagnetic sensor door vehicle 12, the amount that thedoor 24 is open (i.e. degrees of rotation open) may be determined by comparison with calibration data comprising predetermined signal magnitudes known as a function of door angle. For a four-door vehicle 12, the amount thatdoor vehicle 12 can be estimated by comparing the first 60 and second 80 magnetic sensor signals from a particular side of thevehicle 12 with the associated calibration data to determine the associated door state of the associateddoor coil 14, 64 located inside thedoor vehicle 12, wherein the associated first 60 or second 80 magnetic sensor signal was responsive to the self-inductance of thecoil 14, 64, and if thiscoil 14, 64 was not substantially responsive to the position of the associateddoor vehicle 12, then steps (208) and (210) of the magneticcrash sensing algorithm 200 would be omitted when processing that first 60 or second 80 magnetic sensor signal. - Generally, for each combination of these possible door states, the interpretation of the first 60 and second 80 magnetic sensor signals can be adjusted to avoid inadvertent deployments, alter deployment thresholds, or temporarily disable the
safety restraint actuator 82, in accordance with the vehicle manufacturer's specifications. Recognition of the door state of thedoor doors magnetic flux 40 that cannot be attributed to one of the possible door states can be indicative of a system failure or a change in the properties or geometry of thedoor magnetic flux 40, theprocessor 62 can use anindicator 84, or an alarm, to alert an occupant of the vehicle of a potential system failure. Such recognition is possible within a relatively short period of time—e.g. within seconds—after occurrence and the monitoring for such a failure can occur continuously while the system is active. - Generally, if a
door safety restraint actuator 82 cannot operate properly to protect an associated occupant, and therefore typically should be disabled until thedoor door coil 14, 64 operated in a self-inductance mode were located inside thedoor 24, 74). For example,FIG. 3 illustrates a firstmagnetic sensor signal 60 generated responsive to afront door 24 being slammed shut by a hydraulic robot in accordance with a less than worse case condition, wherein the magnitude of the resulting firstmagnetic sensor signal 60 approaches an associated crash detection threshold. Accordingly, in one embodiment, if eitherdoor vehicle 12, then the crash detection algorithm would prevent asafety restraint actuator 82, e.g. side air bag inflator, associated with that side of thevehicle 12 from actuating, so as to prevent an inadvertent deployment thereof. The responsiveness of the first 60 and second 80 magnetic sensor signals to the position of thedoor door vehicle 12 was not turned on if the magnetic field were applied at a low duty cycle to conserve power. - If the
door door safety restraint actuator 82 responsive to a significant, non-crash event (also known as an “abuse event”), as described more fully hereinbelow. The magnitude of the impact response of acoil 14, 64 operated in a self-inductance mode and located inside thedoor door 24, 74 (i.e fully latched or partially latched). - Referring to
FIG. 4 , the firstmagnetic sensor signal 60 from the firstmagnetic sensor 18 proximate to the B-pillar 32 is responsive to the angle of thefront door 24 and is nearly independent of the angle of therear door 74. Accordingly, it is possible to estimate the angle of thefront door 24 from the magnitude of the firstmagnetic sensor signal 60, particularly the associated first filtered signal Y1(i), using calibration data, for example, as illustrated inFIG. 4 . The sensitivity of the firstmagnetic sensor signal 60 is greater for smaller door angles than larger door angles, and for angles less than about 15 degrees, the door angle can be estimated relatively accurately. It is preferable that relatively short term signal offsets caused by effects other than door angle, such as temperature or recent mechanical changes to thefront door 24, be maintained to less than an equivalent of about ±1 degree, in order to estimate the associated door state of thefront door 24 sufficiently accurately Longer term signal offsets caused by effects such as door droop or accumulated damage can be characterized by monitoring the offset over time, and compensated by subtracting the offset from the signal. Another way to adjust for changes in door alignment over time is to compare the voltage applied to the at least onefirst coil 14 with the corresponding resulting current passing therethrough. Faraday's Law can be used to derive a relationship between the inductance L of the at least onefirst coil 14, which is influenced by the proximity to nearby metal (i.e. the local gap between thedoor 24 and thefirst location 16 of the at least one first coil 14), and the voltage (V) across and current (I) through the at least one first coil 14 (i.e. V=L*dI/dt). The measure of coil inductance derived from the known current (I) and voltage (V) in the at least onefirst coil 14 can provide for adapting the expected response of the first magnetic crash sensor 10.1 as a function of door angle. - Referring to
FIG. 5 , the secondmagnetic sensor signal 80 from the secondmagnetic sensor 68 proximate to the C-pillar 78 is a strong function of the angle of therear door 74 and is also a function of the angle of thefront door 24. Accordingly, because the secondmagnetic sensor signal 80 has significant response to the angle of thefront door 24, the angle and associated door state of thefront door 24 is determined first, and then used in the determination of the angle of therear door 74. If the door state of thefront door 24 is open, e.g. having an angle greater than about three degrees, then the door state of therear door 74 need not be determined because, in that case, thesafety restraint actuator 82 on that side of thevehicle 12 would be disabled anyway. If the door state of thefront door 24 is either fully closed or partially latched, then the angle of therear door 74 can be determined from the offset of the secondmagnetic sensor signal 80 using calibration data, for example as illustrated inFIG. 5 . As with thefront door 24, it is preferable that relatively short term signal offsets in the secondmagnetic sensor signal 80 caused by effects other than door angle, such as temperature or recent mechanical changes to therear door 74, be maintained to less than an equivalent of about ±1 degree, in order to estimate the associated door state of therear door 74 sufficiently accurately. Longer term signal offsets caused by effects such as door droop or accumulated damage can be characterized by monitoring the offset over time, and compensating by subtracting the offset from the signal. - Returning to
FIG. 2 , following the estimation in step (208) of the door state of the front 24 and rear 74 doors, in step (210), if a front 24 or rear 74 door is detected as being either open or slammed, the core crash detection algorithm (214-250) is not entered, but instead, the process repeats with step (202). For example, in one embodiment, a potential adverse affect of a door slam condition can be avoided by delaying the confirmation of a partially latched or closed door state for a brief period of time following the initial detection thereof. - Otherwise, if the front 24 and rear 74 doors are either partially latched or fully closed, then in step (212), if criteria for commencing the core crash detection algorithm (214-250), i.e. entrance criteria, are satisfied, then the core crash detection algorithm (214-250) is entered commencing with step (214). For example, the first filtered signal Y1(i) is compared with one or more previous values thereof for each
door door magnetic flux 40 reaching themagnetic sensor rear door 74 exceeds a threshold of about 0.6 volts, then the entrance criteria is satisfied. Although the magneticcrash sensing algorithm 200 ofFIG. 2 illustrates a single step (212) at which the entrance criteria is tested, it is anticipated that there may be a plurality of different entrance criteria for associated different portions of the overall magneticcrash sensing algorithm 200, whereby there would be more than one associated step at which it would be determined if the associated entrance criteria satisfied the corresponding criteria necessary to commence that particular portion of the magneticcrash sensing algorithm 200. Upon entrance, the core crash detection algorithm (214-250) and associated steps (202) and (204) continue to be executed in sequence until either thesafety restraint actuator 82 is actuated in step (248), or until the core crash detection algorithm (214-250) exits with step (252) because of either damped-out values of the associated discrimination metrics or because of a time-out condition. - Upon entrance of the core crash detection algorithm (214-250), in step (214), associated variables of the magnetic
crash sensing algorithm 200 are initialized. Then in step (216), the sampled signal Y0(i) is filtered, for example, with a second low-pass filter with a relatively higher cut-off frequency, so as to extract relatively higher frequency information from the raw magnetic signal, for example, by using a running average filter with a relatively narrower associated time window. For example, in one embodiment, the first filter incorporates a window of about 1.1 millisecond which provides information in the range from DC to 250 Hz. The output of the second filter is a second filtered signal Y2(i). - Then, in step (218), an AC measure YAC is calculated so as to provide a measure of mid-to-high frequency information from the magnetic signal on the impact side of the
vehicle 12, for example, by calculating a running average of the difference between the sampled signal Y0(i) and the second filtered signal Y2(i), as follows:
For example, in one embodiment, K1 is set so that the width of the running average window is about 5 milliseconds. Measurements have shown that an integration of the AC content of the magnetic signal is, in general, related to, e.g. proportional to, the impact energy or crash severity. The AC measure YAC is a running average of the difference between the raw data and the mid-frequency low-pass filtered data that provides a measure of the fluctuation (AC) content of the magnetic signal, which is related to the door gap velocity, vibration, and crushing energy being transferred to thedoor - Stated in another way, for at least one first frequency less than at least one second frequency, the magnitude of a component of the relatively lower frequency first filtered signal Y1(i) at the at least one first frequency is greater than the corresponding magnitude of a component of the relatively higher frequency second filtered signal Y2(i) or the AC measure YAC at the same at least one first frequency; and the magnitude of a component of the relatively lower frequency first filtered signal Y1(i) at the at least one second frequency is less than the corresponding magnitude of a component of the relatively higher frequency second filtered signal Y2(i) or the AC measure YAC at the same at least one second frequency. Depending upon the particular application, the frequency ranges of the filters associated with the relatively lower frequency first filtered signal Y1(i), and the relatively higher frequency second filtered signal Y2(i) or the AC measure YAC may be separated from one another, or may partially overlap, depending upon the nature of the particular vehicle, as necessary to provide for adequate discrimination of various crash and non-crash events from one another, and as necessary to provide for adequate detection speed. For example, data can be collected for a variety of impacts, e.g. pole, soft-bumper, ECE cart,
FMVSS 214 barrier, and non-crash events, of various severities, and the associated filter types and cut-off frequencies may be adjusted, along with other parameters of the magneticcrash sensing algorithm 200, so as to provide for generating a timely safety restraint actuation signal when necessary, and so as to not generation a safety restraint actuation signal when not necessary. - Then, from step (220), if the magnitude of the first filtered signal Y1(i) exceeds a threshold, in steps (222)-(226) the relatively higher frequency AC measure YAC is combined, e.g. linearly, with the relatively lower frequency first filtered signal Y1(i) to form first crash metric M1 B or M1 C, corresponding to the front 24 or rear 74 door respectively. Otherwise, in step (228), the first crash metric M1 B or M1 C is set to the value of the corresponding first filtered signal Y1(i). The requirement of step (220) lessens the possibility of high frequency noise (which is not expected to have significant DC content) falsely enhancing the first crash metric M1 B or M1 C during non-crash conditions.
- More particularly, in step (222), the values of coefficients a and b are determined. These coefficients are used in step (226) to calculate the first crash metric M1 B or M1 C as follows:
M 1 B,C =α·Y 1 +β·b·Y AC (2)
where β is a transition-smoothing factor determined in step (224) in accordance with a transition-smoothing algorithm. The coefficients a and b associated with the linear combination are specific to the particular type ofvehicle 12, and would be determined from associated crash and non-crash data associated with “abuse events”. The coefficients a and b determine the relative weighting or contribution of the relatively lower frequency first filtered signal Y1(i) and the relatively higher frequency AC measure YAC in the first crash metric M1 B or M1 C. For example, for a particular vehicle application, if the higher frequency components of the sampled signal Y0(i) provide a more reliable and repeatable indication of crash severity, the value of b might be set greater than that of a so as to relatively emphasize the higher frequency information in the first crash metric M1 B or M1 C. In one embodiment, the coefficients a and b may be constants. In other embodiments, the sign and or magnitude of coefficients a and b may be a dynamic function of time of the sign or value of the second filtered signal Y2(i). - For example, in one embodiment of steps (220)-(228), if the magnitude of the first filtered signal Y1(i) associated with the
rear door 74 is less than or equal to a threshold, then in step (226), the first crash metric M1 B or M1 C is set equal to the corresponding first filtered signal Y1(i). Otherwise, in step (222), a=1 and b=1 for thefront door 24, and a=1 and b=−1 for therear door 74, wherein the threshold level is the same as for the entrance criteria of step (212). Stated in another way,
If |Y1 C|≦DC_Threshold (3.0)
Then M1 B=Y1 B and M1 C=Y1 C (3.1)
Otherwise (4.0)
M 1 B =Y 1 B +Y AC B and M 1 C =Y 1 C −Y AC C (4.1) - In accordance with another embodiment, additional conditions are provided as follows:
If Y1 C<ThresholdC OR Y1 B<ThresholdB (5.0)
Then Equations (3.0-3.1) and (4.0-4.1) (5.1)
Otherwise If Y1 C>ThresholdC Then (6.0)
If Y1 C≦DC_Threshold Then Equation (4.1) (6.1)
Otherwise If Y1 C≦−DC_Threshold
Then M1 B=Y1 B −Y AC B and M 1 C =Y 1 C +Y AC C (6.2)
Otherwise Equation (3.1) (6.3)
wherein, in one embodiment, ThresholdB is about −2.3 volts and ThresholdC is between −1 and +1 volt. - In step (224), the transition-smoothing algorithm provides for smoothing the effect of a transition between an inclusion of the AC measure YAC in the first crash metric M1 B or M1 C, in step (226), and the exclusion thereof in the first crash metric M1 B or M1 C, in step (228). More particularly, the transition smoothing algorithm provides for determining a value for the transition smoothing factor β in equation (2) a) has a value that is bounded between 0.0 and 1.0; b) is initialized to 0.0; c) is incremented by a factor, for example, between 0.04 and 1.0 (i.e. no smoothing), e.g. 0.09 (i.e. 9%), for each iteration for which the result of step (220) is affirmative; and d) is decremented by that factor each iteration for which the result of step (220) is negative.
- Then, in step (230), a safing criteria is evaluated so as to provide an independent basis for determining whether or not to enable actuation of the associated
safety restraint actuator 82. Although the particular safing strategy would depend upon the requirements of the vehicle manufacturer, in accordance with one embodiment, the safing strategy is adapted so as to prevent a single point failure from causing an inadvertent actuation of the associatedsafety restraint actuator 82. The evaluation of the safing criteria may be performed by an independent processor so as to preclude the prospect of a failure of theprocessor 62 causing an inadvertent deployment. In accordance with one embodiment, the safing strategy is adapted so the first 60 and second 80 magnetic sensor signals are used to safe one another. - Furthermore, signals—e.g. associated current and voltage—from the first 34.1 and second 34.2 coil drivers are also monitored to verify the operation of the associated first 14 and third 64 coils, e.g. to verify the fidelity and operativeness of the coils and associated signals and to monitor the associated noise level. For example, referring to
FIG. 1 , one or more signals—e.g. a measure of current through the at least onefirst coil 14 and/or the associated voltage thereacross—from the first coil driver 34.1 are operatively coupled to at least one associated third demodulator 86.1, the output(s) of which is/are operatively coupled to an associated at least one third analog-to-digital converter 88.1, the output(s) of which is/are operatively coupled to theprocessor 62, so as to provide the signals necessary to verify the operation of the at least onefirst coil 14. Similarly one or more signals—e.g. a measure of current through the at least one third coil 64 and/or the associated voltage thereacross—from the second coil driver 34.2 are operatively coupled to at least one associated fourth demodulator 86.2, the output(s) of which is/are operatively coupled to an associated at least one fourth analog-to-digital converter 88.2, the output(s) of which is/are operatively coupled to theprocessor 62, so as to provide the signals necessary to verify the operation of the at least one third coil 64. - In accordance with one embodiment, the safing criteria are satisfied for a particular magnetic crash sensor 10.1, 10.2 if the associated coil driver 34.1, 34.2 generates a substantially noise-free signal at the proper amplitude and frequency, and both the first 60 and second 80 magnetic sensor signals exhibit substantial nominal signal levels and variation over time.
- In accordance with another embodiment, the current though the first 14 or third 64 coil is processed to calculate two measures, TXRA and TXRA_ABS, respectively as running averages of the magnitude of this current and the absolute value of the magnitude of this current, wherein the running averages are calculated over a period of, for example, 1 to 7 milliseconds, e.g. 5 milliseconds. If ThresholdRA1<TXRA<ThresholdRA2 and TXRA_ABS<ThresholdRA3, then the current signal from the corresponding first 14 or third 64 coil is considered to be valid, and the corresponding first 14 or third 64 coil is considered to be operative. Also, substantially simultaneously, if |Y1|>Threshold_Y1 B,C and |YAC|>Threshold_YAC B,C for both the first 60 and second 80 magnetic sensor signals, then the safing criteria is considered to be satisfied, and this condition is latched for a period of time, for example, a predetermined period of 30 milliseconds. If the conditions on TXRA or TXRA_ABS later both become unsatisfied, then the safing condition is unlatched substantially immediately thereafter. Otherwise, if any of the other four conditions become unsatisfied, then the safing condition is unlatched after the period of time lapses, unless within that interval, all six safing conditions again become satisfied.
- Then, in step (232), if the
vehicle 12 has two (or more) doors, e.g. a front 24 and rear 74 door on a particular side thereof, then in step (234), steps (202) through (230) are performed for eachdoor door - Then, in step (236), if the
vehicle 12 has two (or more) doors, a second crash metric M2 is calculated from the combination, e.g. linear combination, of the first crash metrics M1 B and M1 C corresponding todifferent doors vehicle 12. For example, in one embodiment, the second crash metric M2 is given by:
M 2 =c·M 1 B +d·M 1 C (7)
where c and d are coefficients that are specific to a particular type ofvehicle 12. For example, in one embodiment, c=−1 and d=1. If the vehicle has only onedoor 24, then, from step (232), in step (238), the second crash metric M2 is equal to the first crash metric M1 B (for purposes of describing a general magneticcrash sensing algorithm 200 in the context of a vehicle having an arbitrary number of doors on a side—in a two-door vehicle 12 having only onedoor 24 on a side, there would be no need to have distinct first M1 B and second M2 crash metrics). - Then, from either step (236) or (238), in step (240), the values of the first M1 B,C and second M2 crash metric are damped, so that the values of the respective resulting first {tilde over (M)}1 B,C and second {tilde over (M)}2 damped crash metrics are attenuated over time to insignificant levels after the event subsides provided that a side impact crash of sufficient severity to warrant actuation of the
safety restraint actuator 82 does not occur, even for events for which there may have been associated metal bending resulting from the crash. Damping provides for facilitating algorithm exit in step (250) following significant crash events that were not sufficiently severe to warrant actuation of thesafety restraint actuator 82. - For example, in one embodiment, a damping factor α would be given by the summation of the absolute value of the first filtered signal Y1(i) commencing with algorithm entrance, and a corresponding crash metric M would be given by the product of that damping factor α times the first filtered signal Y1(i), as follows:
where C1 and C2 are constants. - As another example, in another embodiment, the damping factor α could include an integral of the AC measure YAC commencing with algorithm entrance, or the sample number since algorithm entrance multiplied by a constant minus the running average of the AC measure YAC calculated using a relatively long time window, e.g. greater than 10 milliseconds.
- As yet another example, following algorithm entrance, the damping process commences if the absolute value of the first filtered signal Y1 C(i) from the second
magnetic sensor signal 80 associated with therear door 74 exceeds a threshold, e.g. 0.75, at which time a summation value σ(0) is initialized to an initial value σ0, for example, σ0=300. Then, for each subsequent iteration, the second damped crash metric {tilde over (M)}2 is calculated as follows:
where γ is a damping modification factor, e.g. having a value of 0.7 for the particular embodiment, and Y1 B(i) is the value of the first filtered signal Y1(i) based on the firstmagnetic sensor signal 60. - Then, in step (242), the magnetic
crash sensing algorithm 200 provides for adapting a deployment threshold as a function of the door state that was detected in step (208). For example, if one of thedoors vehicle 12, wherein, in one embodiment, the threshold would be lowest for bothdoors doors coil 14, 64 operated in a self-inductance mode and located inside thedoor - Then, in step (244), the first {tilde over (M)}1 B,C and second {tilde over (M)}2 damped crash metrics and the AC measure YAC are compared with associated threshold levels (positive and negative), and, in one embodiment, if each metric or measure exceeds it respective threshold for at least a specified minimum number of consecutive iterations, then, in step (246), if the safing criteria from step (230) are also simultaneously satisfied, then in step (248) the appropriate safety restraint actuator(s) 82 is/are deployed. In one embodiment, neither the satisfaction of the deployment threshold in step (244) nor the satisfaction of the safing criteria in step (246) latches TRUE, but instead, both criteria must be simultaneously TRUE in order for the safety restraint actuator(s) 82 to be actuated. In another embodiment, other logical combinations of the various crash metrics and other measures are used in the actuation decision. For example, in another embodiment, the actuation decision could be governed by one or more of the various crash metrics and measures, or the satisfaction of the safing criteria could latch TRUE, so that an actuation of the safety restraint actuator(s) 82 would occur when the deployment threshold is satisfied in step (244) provided that the safing criteria had been satisfied earlier, subsequent to algorithm entrance.
- Otherwise, from either step (244) or step (246), in step (250), if an exit criteria is satisfied, then the core crash detection algorithm (214-250) is exited in step (252), and the magnetic
crash sensing algorithm 200 continues with step (202), whereupon subsequent entry of step (206), the algorithm will be indicated as being inactive (i.e. not entered) until the entrance criteria is again satisfied responsive to conditions on the first filtered signal Y1(i), which continues to be calculated in step (204) following the acquisition of the first 18 or second 68 magnetic sensor in step (202). For example, in accordance with one embodiment, the exit criteria is satisfied if the first filtered signals Y1 B and Y1 C, the associated AC measures YAC B and YAC C, and the damped crash metric M3 are less than associated threshold values for a specified number of iterations of the core crash detection algorithm (214-250), or if the time period since algorithm entrance in step (212) exceeds a time-out threshold. - The above-described magnetic
crash sensing algorithm 200 can be embodied in various ways, and can be modified within the scope of the instant invention. - For example, the first filtered signal Y1(i) and the AC measure YAC could be processed separately, as if each were a separate crash metric. These individual metrics could then be separately damped (step (240)) and used separately to compare against individual deployment thresholds (step (244)). These metrics could alternatively be combined with similar metrics derived from a second magnetic sensor to create two M2 metrics (following the example in step (236)): a low frequency and a higher frequency M2 metric. This alternative individual signal processing creates more individual metrics, making the algorithm slightly more complicated, but also providing additional flexibility in setting deployment conditions.
- As another example, additional filtered signals might be obtained from the raw data using different window running averages to produce time domain equivalents of high-pass frequency filtering, or other types of filters can be utilized, for example single or multiple pole low-pass or band-pass filters, other digital filters, e.g. FIR or IIR, or Fourier transform filters Several such filtered signals might be combined with each other or with the raw data signal to give measures associated with desired frequency bands. Such additional frequency analysis and derived measures might be necessary for a specific vehicle platform or magnetic system mounting location and method and would be based upon the associated crash data and data from non-crash “abuse events”.
- The magnetic
crash sensing algorithm 200 provides a method of processing magnetic crash signals from a magnetic crash sensor so as to provide for the rapid, real time determination of both the crash severity and the associated crash type (e.g. pole crash vs. barrier crash) for a particular crash event The magneticcrash sensing algorithm 200 provides for the actuation of safety restraint actuator(s) 82 at a relatively early time as necessary so as to provide for protecting the occupant from the crash, while also discriminating lower severity crash events (as determined by potential occupant injury) so as to avoid inadvertent or unnecessary actuation of safety restraint actuator(s) 82, particularly those safety restraint actuator(s) 82 which are not resetable, i.e. reusable for multiple crash events. The magneticcrash sensing algorithm 200 also provides for immunity to external electrical and mechanical “abuse events” including those caused by electromagnetic induction, or localized impacts with relatively low mass but high speed objects. The associated magnetic crash sensors 10.1, 10.2 provide for distributed crash sensing that can be beneficially less sensitive to localized mechanical or electrical disturbances which might otherwise adversely affect a crash sensing system using more localized crash sensors. - The polarity of the associated magnetic crash sensor signals 60, 80 provides information that can be used for distinguishing various types of crashes. For example, in one embodiment, measured data suggests that localized impacts that cause significant intrusion into the vehicle will give a positive crash metric polarity while more broad surface impacts will give a negative polarity crash metric. Pole-like impacts might be identified as positive polarity while cart-like impacts would be identified by negative polarity. The door motion and crush will vary between crash types, potentially producing signals of opposite sign that correspond to more or less magnetic signal (magnetic flux 40) reaching the receiver sensors than is normally received.
- Although the magnetic
crash sensing algorithm 200 has been described herein in the context of side impact crash detection, a similar algorithm could be used to detect impacts anywhere on the vehicle using appropriate associated magnetic crash sensor hardware. - Referring to
FIG. 6 , third 10.3 and fourth 10.4 magnetic crash sensors are adapted similar to the first 10.1 and second 10.2 magnetic crash sensors illustrated inFIG. 1 , with the exception that the second 26 and fourth 76 coils at the second 20 and fourth 70 locations respectively are adapted to operate in a receiver mode and a transceiver mode so as to provide for sensing both a crash event involving arespective front 24 or rear 74 door, thereby generating the above-described first 60 and second 80 magnetic sensor signals, and to also provide for either continuously sensing the opening state of therespective front 24 or rear 74 doors, and/or for providing associated safing of the first 60 and second 80 magnetic sensor signals. - The
second coil 26 is operatively coupled to a third coil driver 34.3, which is in turn operatively coupled to a third oscillator 36.3, wherein an oscillatory signal from the third oscillator 36.3 is applied by the third coil driver 34.3 so as to cause an associated current in the at least one third coil 64, responsive to which the at least one third coil 64 generates a third magnetic field 38.3 responsive to the reluctance of the associated magnetic circuit, and which caused eddy currents in associated proximal conductive elements which thereby influences the resulting third magnetic field 38.3. The third oscillator 36.3 generates a oscillating signal, for example, having either a sinusoidal, square wave, triangular or other waveform shape, or a single frequency or a plurality of frequencies that, for example, are either stepped, continuously swept or simultaneous. The third magnetic field 38.3 is responsive to the reluctance of the associated magnetic circuit, which is affected by a crash involving the elements thereof and/or thegaps 52 therein, and which is also affected by the opening state of thefront door 24. A signal responsive to the third magnetic field 38.3 and responsive to the self-impedance of thesecond coil 26 is sensed within the circuitry associated with the third coil driver 34.3 and a resulting signal is demodulated by a third demodulator 56.3, converted from analog to digital form by a third analog-to-digital converter 58.3 and input as a thirdmagnetic sensor signal 90 to theprocessor 62 for example, in accordance with the teachings of U.S. application Ser. No. 11/530,492 which is incorporated herein by reference. The frequency of the third oscillator 36.3 is adapted so that the resulting third magnetic field 38.3 is sufficiently strong to provide a useful signal level of the thirdmagnetic sensor signal 90. - The
fourth coil 76 is operatively coupled to a fourth coil driver 34.4, which is in turn operatively coupled to a second oscillator 36.2, wherein an oscillatory signal from the fourth oscillator 36.4 is applied by the fourth coil driver 34.4 so as to cause an associated current in the at least one third coil 64, responsive to which the at least one third coil 64 generates a fourth magnetic field 38.4 responsive to the reluctance of the associated magnetic circuit, and which caused eddy currents in associated proximal conductive elements which thereby influences the resulting fourth magnetic field 38.4. The fourth oscillator 36.4 generates a oscillating signal, for example, having either a sinusoidal, square wave, triangular or other waveform shape, or a single frequency or a plurality of frequencies that, for example, are either stepped, continuously swept or simultaneous. The third magnetic field 38.3 is responsive to the reluctance of the associated magnetic circuit, which is affected by a crash involving the elements thereof and/or thegaps 52 therein, and which is also affected by the opening state of therear door 74. A signal responsive to the fourth magnetic field 38.4 and responsive to the self-impedance of thefourth coil 76 is sensed within the circuitry associated with the fourth coil driver 34.3 and a resulting signal is demodulated by a fourth demodulator 56.3, converted from analog to digital form by a fourth analog-to-digital converter 58.3 and input as a fourthmagnetic sensor signal 92 to theprocessor 62 for example, in accordance with the teachings of U.S. application Ser. No. 11/530,492 which is incorporated herein by reference. The frequency of the fourth oscillator 36.4 is adapted so that the resulting third magnetic field 38.4 is sufficiently strong to provide a useful signal level of the thirdmagnetic sensor signal 92. - Referring to
FIG. 7 , fifth 10.5 and sixth 10.6 magnetic crash sensors are adapted similar to the third 10.3 and fourth 10.4 magnetic crash sensors illustrated inFIG. 6 , with the exception that the rolls of the first 14 and second 26 coils are reversed, and the roles of the third 64 and fourth 76 coils are reversed, wherein the second 26 and fourth 76 coils of the respective fifth 10.5 and sixth 10.6 magnetic crash sensor are each driven in both a transmit mode and a transceiver mode, and the first 14 and third 64 coils are used only in the receive mode. - The above-illustrated combined transmitter/receiver and transceiver topology provides for enhancing the confidence in the sensing of the instant door state, which can be provided for continuously—even with the vehicle in a quiescent (i.e. key off) state—by using a low-power low duty cycle operation in the transceiver mode. The transceiver mode that provides for monitoring the door state can operate on a sufficiently small amount of power so as to operate comfortably in the key-off or sleep energy levels. This key off magnetic dome light, after factory pre-set will permit the MSI microprocessor to know for certain the door status (compared to factory calibration) so the MSI can be certain as to arm and when to activate the vehicle dome light, as a function of the door position.
- One embodiment would involve a (self inductance) transmitting device at the “B” and “C” pillars and would be operated at minimum power. This approach would be activated at the factory and would require minimum power so it would be operated in key-off. The door opening inductance change is significant compared to the change due to a crash and thresholds would be set accordingly. The “B” and “C” would safe each other during an impact. An accelerometer might also be considered to support safing (impact during door ajar situation).
- This topology would expect the vehicle cross talk to be minimized, reducing the overall cost of electronics. As the system is continuously monitoring the strikers, production scatter and temperature drift would be normalized out of the monitoring device. Production scatter is one time and the value is stored in EEPROM. The temperature slew rate would be measured and the sleep timer (update rate) would be set accordingly.
- This approach will recognize door open and closed over time and detect an impact. On a two-door vehicle, a safing accelerometer or additional “button” coil (near the striker) could safe.
- The continuous detection of the door opening state provides for using the associated magnetic crash sensing system to provide for controlling a dome light in the vehicle, or for providing a door opening signal to a vehicle security system.
- When using the magnetic crash sensing system to control the dome light, a sense resistor could be added to validate the bulb to be present and illuminated (perhaps a photo receiver sensor or temperature sensor to validate light or heat present as well).
- The system can determine the instant position of the vehicle door (open versus ajar for the “B” and “C” transmitters) to permit the microprocessor to elect to illuminate the dome light or arm the MSI system for safety and security.
- The magnetic crash sensing system can be factory pre-set, i.e. tuned, to guarantee the door is closed at a specific time and calibrate the magnetic crash sensing system (place the hinge and striker signals into NV memory for future use).
- The magnetic crash sensing system can operate on low power and or low duty cycle to obtain standard automotive sleep mode energy consumption levels so the door open/closed movement can be MSI tracked at key off.
- To obtain the lowest power performance (for key-off), the magnetic crash sensing system would be operated in a transmitter duty cycle mode. This specification for this mode would perhaps call for the magnetic crash sensing system to send a carrier burst once a second, and during the
burst 10 to 20 cycles of the carrier would be transmitted. The 10 to 20 cycles would be enough carrier to permit the demodulator to successfully lock on to the hinge signal and test the door open status, while not demanding excessive amounts of power. - At 20,000 Hz the 10 cycles would require 50 microseconds per cycle, or 50*10=500 microseconds. This total time 500 micro-seconds divided by the 1 second repetition rate leads us to a duty cycle of 500/1,000,000=0.0005 or 0.05% on time. A 1-watt system at this duty would be (on the average) a 0.05-watt system.
- In another embodiment (perhaps preferred for the lowest expected power consumption) the “B” and “C” pillars would utilized at transmitters in normal mode and in “key-off” or sleep mode would act as inductance meters, operating at very low power levels in run mode and even lower power in sleep mode as in sleep mode “B” and “C” pillars would be duty cycle pulsed.
- During an impact the inductance (current and voltage) would modulate.
- This system will achieve minimal operating power levels running (key-on) or asleep (key off) thus permitting unwanted intrusion monitoring (security) as well as dome light function (safety) and enhanced dome light accuracy.
- Referring to
FIG. 8 , a seventh embodiment of a magnetic crash sensing system 10.7 incorporated in avehicle 12 comprises afirst coil 14 at a correspondingfirst location 16 of thevehicle 12, and a plurality of magnetic sensors 18.1, 18.2 at a corresponding plurality of second locations 20.1, 20.2 of thevehicle 12. For example, in the seventh embodiment illustrated inFIG. 8 , thefirst coil 14 is located around thestriker 22 of thedoor latch assembly 24 of thefront door 24, and the magnetic sensors 18.1, 18.2 comprise asecond coil 26 around ahinge 22 of thefront door 24, and athird coil 32 around a striker 34 of the door latch assembly 36 of the rear door 38, wherein thestriker 22 of thedoor latch assembly 24 of thefront door 24 is operatively coupled to the B-pillar 32 of thevehicle 12, and the striker 34 of the door latch assembly 36 of the rear door 38 is operatively coupled to the C-pillar 78 of thevehicle 12. Thefirst coil 14 is operatively coupled to acoil driver 44, which is in turn operatively coupled to an oscillator 46, wherein an oscillatory signal from the oscillator 46 is applied by thecoil driver 44 so as to cause an associated current in thefirst coil 14, responsive to which thefirst coil 14 generates a magnetic field 48 comprisingmagnetic flux 40 in associated first 52.1 and second 52.2 magnetic circuits. The second 28 and third 32 coils surround metallic elements of the associated first 52.1 and second 52.2 magnetic circuits, and themagnetic flux 40 propagates within the associated magnetically permeable material of the first 52.1 and second 52.2 magnetic circuits and flows through the second 28 and third 32 coils surrounding the associated magnetically permeable material. The second 28 and third 32 coils generate voltage signals responsive to the oscillatingmagnetic flux 40, or component thereof, directed along the axis of the second 28 and third 32 coils respectively, in accordance with Faraday's law of magnetic induction. Thedoors 24, 38 are isolated from the remainder of thevehicle 12, e.g. the frame, by the gaps 54 therebetween, except where thehinges 30 anddoor latch assemblies 24, 36 provide relatively lower reluctance paths therebetween. - The oscillator 46 generates a oscillating signal, for example, having either a sinusoidal, square wave, triangular or other waveform shape, of a single frequency, or a plurality of frequencies that are either stepped, continuously swept or simultaneous. The frequency is adapted so that the resulting magnetic field 48 is conducted through the first 52.1 and second 52.2 magnetic circuits with sufficient strength so as to provide a useful signal level from the associated magnetic sensors 18.1, 18.2 that cooperate therewith. For example, the oscillation frequency would typically be less than about 50 KHz for a steel structure, e.g. 10 to 20 KHz in one embodiment. The magnetic field 48 is responsive to the reluctance of the associated first 52.1 and second 52.2 magnetic circuits, which is affected by a crash involving the elements thereof and/or the gaps 54 therein.
- The magnetic field 48 is sensed by the magnetic sensors 18.1, 18.2, and a signal therefrom is conditioned by associated signal preprocessors 56.1, 56.2 which are operatively coupled to a processor 58. For example, each signal preprocessor 56.1, 56.2 demodulates the signal from the associated magnetic sensor 18.1, 18.2 with an associated demodulator, and converts from analog to digital form with an associated analog-to-digital converter which is sampled and input to the processor 58. The signal preprocessors 56.1, 56.2 may also provide for amplification. Changes to the magnetic field 48 at a particular location in the first 52.1 and second 52.2 magnetic circuits propagate therewithin at the speed of light and are seen therethroughout. Accordingly, the magnetic field 48 sensed by the magnetic sensors 18.1, 18.2 contains information about the nature of the remainder of the magnetic circuit, including the front 26 and rear 38 doors and the adjacent A-pillar 44, B-
pillar 32 and C-pillar 78, any of which could be involved in, or affected by, a side-impact crash. - The seventh embodiment of the magnetic crash sensing system 10.7 can operate in a variety of modes, for example, as disclosed in U.S. Pat. Nos. 6,777,927, 6,586,926, or 6,407,660; or U.S. application Ser. Nos. 10/666,165 or 10/946,151; each of which is incorporated in its entirety by reference herein. Accordingly, the magnetic crash sensing system 10.7 provides for controlling a
safety restraint actuator 82, e.g. side air bag system, responsive to the detection of a crash, and/or provides for activating anindicator 84, e.g. warning lamp, warning message, or audible alarm, e.g. responsive to a door open or partially latched condition, or a prediction of an impending crash responsive to the interaction of an approaching vehicle with a proximity field of the magnetic crash sensing system 10.7. - The arrangement of the
first coil 14 as atransmitter coil 66 at a central location, e.g. proximate to the B-pillar 32, and the plurality of magnetic sensors 18.1, 18.2, e.g. receiver coils 68, in cooperation therewith at relatively distal locations relative thereto, e.g. proximate to the A-pillar 44 and C-pillar 78 respectively, provides for a magnetic crash sensing system 10.7 that is responsive to disturbances affecting either the front 26 or rear 38 doors on a side of the vehicle, but requiring only asingle transmitter coil 66, e.g. thefirst coil 14 as presently illustrated inFIG. 8 . Alternatively the magnetic crash sensing system 10.7 could be adapted so that either the second 28 or third 32 coils acted as the transmittingcoil 62, with the remaining coils acting as associated magnetic sensors 18.1, 18.2. - Referring to
FIG. 9 , a eighth embodiment of a magnetic crash sensing system 10.8 incorporates all of the features of the seventh embodiment 10.7 described hereinabove, and further comprises at least one additional magnetic sensor 18.3 within a gap 54 between the fixed body structure and a door, e.g. thefront door 24. AlthoughFIG. 9 illustrates the additional magnetic sensor 18.3 located between thefront edge 70 of thefront door 24 and an adjacent edge 72 of the A-pillar 44, the additional magnetic sensor 18.3 could be located elsewhere in the gap 54 between either the front 26 or rear 38 door and the fixed body structure of thevehicle 12. The additional magnetic sensor 18.3 is operatively coupled to an associated signal preprocessor 56.3 which is in turn operatively coupled to the processor 58, so as to provide a signal that can be used either for safing or as a primary crash sensing signal. - Generally, the mechanical components of the first 52.1 and second 52.2 magnetic circuits in which the
transmitter 66 andreceiver 68 coils are placed are constructed for other functions. For example, thehinges 30 andstrikers 22, 34 are designed with primary functions, e.g. to facilitate occupant entrance, exit and vehicle locking, which components are generally constructed according to associated specifications that govern strength, geometry, material and design constraints. Accordingly, configuring thetransmitter 66 orreceiver 68 coils, that would encircle the magnetically permeable members, can be otherwise challenging and subject to constraints on coil shape, turn count, connector access and wire gauge that might otherwise limit the optimization of thetransmitter 66 orreceiver 68 coils for their primary function to generate or sense time varying magnetic fields. Also, given a wide range ofhinge 22 andstriker 22, 34 designs, it may be difficult to standardize thetransmitter 66 orreceiver 68 coils for a wide range of vehicle platforms if thetransmitter 66 orreceiver 68 coils are to encircle metal, which can increase the cost of these and associated components for a given vehicle platform. Furthermore, coils intended to be assembled around existing components may need to be installed prior to the final assembly of that component in the vehicle which necessitates close cooperation with the supplier of that component so as to provide for the integration of the coil therewith. For example, formany hinges 30, inclusion of a coil thereon would require that the coil undergo an E-coat process along with thehinge 22. - Referring to
FIG. 10 , the fragmentary view 300 of the A-pillar 44 andfront door 24 fromFIG. 9 is illustrated in greater detail, illustrating several embodiments of the additional magnetic sensor 18.3, 18.3′, 18.3″ in greater detail, each comprising agap coil 74 that is sufficiently small to be located within the gap 54 between the A-pillar 44 and thefront door 24. Thegap coil 74 of the additional magnetic sensor 18.3, 18.3′, 18.3″ is not necessarily constrained to surround existing magnetic permeable components of the first 52.1 or second 52.2 magnetic circuits, so as to provide for placement of thegap coil 74 in locations without being adversely constrained by the geometries or functions of proximate elements of thevehicle 12. Thegap coil 74 is wound around an associatedspool 76 which is fastened to the fixed structure of the vehicle, e.g. the edge 72 of the A-pillar 44 facing thefront edge 70 of thefront door 24. Generally, thegap coil 74 can be used as either atransmitter coil 66 or areceiver coil 68, although in the eighth embodiment of a magnetic crash sensing system 10.8, thegap coil 74 is used as areceiver coil 68 responsive to themagnetic flux 40 within the gap 54, e.g. resulting from changes in the proximity field ofmagnetic flux 40 and/or to eddy currents that propagate through the surrounding metal structures. Thegap coil 74 can be oriented so as to optimize the signal-to-noise ratio of the signal generated thereby responsive to a crash or other disturbance to be monitored. - For example, in a first magnetic sensor 18.3′, the
axis 78 of thegap coil 74 is substantially perpendicular to the edge 72 of the A-pillar 44 and to thefront edge 70 of thefront door 24 when thefront door 24 is closed. The first magnetic sensor 18.3′ is attached to the A-pillar 44 with afastener 80 through the associatedspool 76, e.g. a socket head screw 80.1 through a counterbore in thespool 76. The magnetic permeability of thefastener 80 can be adapted in accordance with the sensing or field generating requirements of the associatedgap coil 74. For example, thefastener 80 associated with the first magnetic sensor 18.3′ is substantially aligned with theaxis 78 of thegap coil 74, so that afastener 80 of a material with a relatively high permeability, e.g. carbon steel or electrical steel, will tend to concentrate themagnetic flux 40 through thegap coil 74, whereas afastener 80 of a material with a relatively low permeability, e.g. stainless steel, aluminum or brass, will tend to emulate an air core so that the magnetic sensor 18.3′ has less of a tendency to perturb the associated first 52.1 or second 52.2 magnetic circuit. As another example, in a second magnetic sensor 18.3″, theaxis 78 of thegap coil 74 is substantially parallel to the edge 72 of the A-pillar 44 and to thefront edge 70 of thefront door 24, so as to be substantially aligned with the length of the associated gap 54. The second magnetic sensor 18.3′ is shown attached to the A-pillar 44 with afastener 80 through a flange that depends from the associatedspool 76. -
FIG. 10 also illustrates thesecond coil 26 around ahinge 22 of thefront door 24. Referring toFIG. 11 , thesecond coil 26 can be located at various second locations 20.1′, 20.1″, 20.1′″ relative to thehinge 22. For example, in one embodiment, the second location 20.1′ is on around a portion of the hinge plate 30.1 that attaches to the fixed vehicle structure, e.g. the A-pillar 44 or B-pillar 32, at a location between the A-pillar 44 or B-pillar 32 and the hinge joint 30.2. In another embodiment, the second location 20.1″ is on around a portion of the hinge plate 30.1 that attaches to the fixed vehicle structure, e.g. the A-pillar 44 or B-pillar 32, at a location where the hinge plate 30.1 is bolted to the A-pillar 44 or B-pillar 32. In yet another embodiment, the second location 20.1′″ is on around a portion of the hinge plate 30.3 that attaches to the front 26 or rear 38 door, at a location between thefront edge 70 of the front 26 or rear 38 door and the hinge joint 30.2. - Referring to
FIG. 12 , agap coil 74 may be mounted on the B-pillar 32 or C-pillar 78 on an outward facingsurface 82 in the gap 54 between the outward facingsurface 82 and a corresponding proximate inward facingsurface 84 of the front 26 or rear 38 door respectively. In the embodiment illustrated inFIG. 12 , thegap coil 74 is secured to the outward facingsurface 82 with a flat head screw 80.2 through thespool 76 around which the coil is wound. Thegap coil 74 illustrated inFIG. 12 is responsive to changes in reluctance of the associated first 52.1 or second 52.2 magnetic circuit responsive to the door opening state of the associatedfront 26 or rear 38 door and accordingly can be used to generate a signal indicative thereof, e.g. so as to provide for discriminating between a closed door, a partially latched door and an open door. - Referring to
FIG. 13 , a gap coil assembly 86 comprises agap coil 74 wound around aspool 76, both of which are encapsulated in an encapsulant 88, e.g. a silicone potting compound, so as mitigate against environmentally induced degradation. Thegap coil 74 for example, is wound of wire, e.g. 20 to 50 gauge enamel coated conductive wire, e.g. copper or aluminum. Thespool 76 is, for example, made of a relatively rigid material such as plastic or aluminum. - Referring to
FIG. 14 , the gap coil assembly 86 can further comprise acore 90 of a material having relatively high magnetic permeability such as ferrite, mu-metal, or amorphous metal, e.g. METGLAS®. - The gap coil assemblies 86 illustrated in
FIGS. 13 and 14 can be mounted, for example, by bonding or clamping. Referring toFIG. 15 , the gap coil assembly 86 is mounted with afastener 80, e.g. a cap screw 80.3 andwasher 92, through a central mounting hole 94 in thespool 76. The material and dimensions of thefastener 80 would be selected according to the particular application. A material having relatively high magnetic permeability such as carbon steel or electrical steel could be used to concentrate the associatedmagnetic flux 40 through thegap coil 74, whereas a material of relatively low magnetic permeability such as aluminum, brass or stainless steel could be used to emulate an air core, thereby having less influence on the inherent flow ofmagnetic flux 40 across the associated gap 54 within which the gap coil assembly 86 is located. - Referring to
FIG. 16 , the gap coil assembly 86 is mounted with afastener 80, e.g. a socket head screw 80.1, and further incorporates a magnetically permeable core 96 comprising a shouldered sleeve 98 that is recessed within the central mounting hole 94 in thespool 76. For example, the magnetically permeable core 96 can comprise either carbon steel, electrical steel, mu-metal, ferrite, or amorphous metal, e.g. METGLAS®. The length of the shouldered sleeve 98 can be adjusted in relation to the associated gap 54 in which the gap coil assembly 86 is mounted depending upon the extent of associated magnetic focusing required. - Referring to
FIG. 17 , a multi-axis gap coil assembly 100 comprises a plurality of gap coils 74 arranged on a central hub 102 wherein theaxis 78 of eachgap coil 74 is oriented in a different direction so as to provide for sensitivity to a corresponding component of the magnetic field 48 in that direction. The multi-axis gap coil assembly 100 is mounted with afastener 80, e.g. a socket head screw 80.1, recessed in aspool 76 of one of the gap coils 74 and through the central hub 102. The individual gap coils 74 can be either preassembled and attached to the central hub 102, or wound around corresponding spool portions 104 that are attached to, or an integral part of, the central hub 102. For example, the central hub 102 and associated spool portions 104 could be plastic injection molded as a single part. The material used to construct the central hub 102 can be of relatively low magnetic permeability, e.g. plastic or aluminum, in applications for which the associatedmagnetic flux 40 need not be concentrated, and of a material of relatively higher magnetic permeability, e.g. ferrite, carbon steel, electrical steel or mu-metal, in applications for which it is beneficial to concentrate the associatedmagnetic flux 40 proximate to the associated gap coils 74. The multi-axis gap coil assembly 100 is illustrated with six gap coils 74, three oriented in orthogonal relation to one another, and the remaining three oriented obliquely relative thereto. It should be understood that this arrangement of gap coils 74 is principally to illustrate a variety of possible arrangements, and should not be taken to mean that the multi-axis gap coil assembly 100 must have that number of gap coils 74, or gap coils 74 arranged as so illustrated. More particularly, the multi-axis gap coil assembly 100 would have at least two gap coils 74 oriented with associatedaxes 78 thereof in different directions, so as to provide for multi-axis magnetic field sensitivity within a gap 54 between body elements of thevehicle 12. - Generally, the shape, size, gauge, and number of turns of a
gap coil 74 is not limiting, but can instead be adapted or optimized for a particular application or configuration, e.g. thegap coil 74 can adapted to resonate at a particular frequency, to fit within a particular gap 54, or to influence the reluctance of the associated magnetic circuit 52.1, 52.2 in a particular way. For example, it has been beneficial to operate thegap coil 74 away from resonance so as to provide for a relatively flat frequency response thereof. Thegap coil 74 can be developed and manufactured in accordance with any of a wide range of known coil design and manufacturing processes, and can be made small with any of a wide range of known connector and mounting configurations that would be selected or adapted for a particular mounting position and location in a given vehicle platform. - A plurality of individual gap coils 74 can be connected with a common cable harness that is adapted to provide for the placement of the individual gap coils 74 at the respective magnetic sensor locations with separation therebetween so as to provide for improved sensing coverage area and magnetic flux discrimination, thereby providing for safing, redundancy, and/or improved event discrimination at comparable or reduced cost relative to coils that must otherwise be adapted to conform to existing vehicle hardware, e.g. hinges 30 or
strikers 22, 34. The gap coils 74 are beneficially small, self contained, easily mounted, and provide some level of redundancy in the associated magnetic crash sensing system. The gap coils 74 can be adapted to include proximate electrical components—e.g. resistors, capacitors, reference inductors, IC, amplifiers, A/D, etc.—if necessary to improve the function thereof. - Referring to
FIG. 18 , a nineth embodiment of a magnetic crash sensing system 10.9 is the same as the seventh embodiment 10.7 except for the magnetic sensors 18.1, 18.2, which in the nineth embodiment 10.9 are first 28′ and second 32′ gap coils located at corresponding second locations 20.1″″, 20.2″″ in the respective gaps 54 between the A-pillar 44 and thefront door 24, and between the rear door 38 and the C-pillar 78 respectively, wherein the first 28′ and second 32′ gap coils are each in accordance with the gap coils 74, gap coil assemblies 86 or multi-axis gap coil assembly 100 as disclosed herein. - Referring to
FIG. 19 , a tenth embodiment of a magnetic crash sensing system 10.10 is the same as the nineth embodiment 10.9 except that thefirst coil 14 is replaced with a correspondingfirst coil 14′ located at correspondingfirst location 16′ in the respective gap 54 between thefront door 24 and the B-pillar 32, wherein thefirst coil 14′ is accordance with the gap coils 74, gap coil assemblies 86 or multi-axis gap coil assembly 100 as disclosed herein. Accordingly, the tenth embodiment of a magnetic crash sensing system 10.10 incorporates gap coils 74 throughout, the location of which in the associated gaps 54 is not otherwise constrained by existing vehicle hardware. The tenth embodiment of a magnetic crash sensing system 10.10 may be further adapted so that thecoil driver 44 provides a measure of voltage across, current through, and/or power absorbed by thefirst coil 14′, which is operatively coupled through a signal preprocessor 56.3 to the processor 58, for example, either so as to provide for magnetic crash sensing responsive to the self-inductance of thefirst coil 14′, e.g. in accordance with the teachings of U.S. Pat. No. 6,587,048; or so as to provide for magnetic crash sensing using a time domain reflectometry technique, e.g. in accordance with the teachings of U.S. Pat. No. 6,583,616; each of which above referenced patents are incorporated in its entirety by reference herein. - Referring to
FIGS. 20 a and 20 b, modeling and test results suggest that eddy currents IE are produced on the surface of steel pins orfasteners 80,strikers 22, 34, and hinges 30, wherein the eddy currents IE oscillate longitudinally along the associated steel core 106, producing an associated circumferential magnetic field BE surrounding the axes of the associated steel core 106. Referring toFIGS. 21 and 22 , a toroidal helical coil 108 provides for generating a voltage signal V responsive to the associated oscillating circumferential magnetic field BE in accordance with Faraday's Law, responsive to which an associated current signal I is generated when the toroidal helical coil 108 is connected to an associated circuit, e.g. a signal preprocessor 56.1, 56.2, 56.3. The toroidal helical coil 108 comprises a conductive path 110, e.g. a winding of conductive wire 110.1, e.g. copper or aluminum wire, around a toroidal core 112. Although the toroidal core 112 is illustrated inFIGS. 21 and 22 as having a circular shape (FIG. 21 ) and a uniform circular cross section (FIG. 22 )—i.e doughnut shaped—, in general the, the toroidal core 112 can have any closed shape with any cross-sectional shape, either uniform or not. For example, the toroidal core 112 could have a rectangular cross-section, similar to that of a washer. The toroidal core 112 comprises a major axis M and a minor axis m, wherein the conductive path 110 makes at least one turn around the minor axis m, and at least one turn around the major axis M. For example, in the embodiment illustrated inFIG. 21 , the conductive path 110 makes a plurality of turns around the minor axis m, and a single turn around the major axis M. The at least one turn around the minor axis m provides for generating a component of the voltage signal V responsive to an oscillating circumferential magnetic field BE, and the at least one turn around the major axis M provides for generating a component of the voltage signal V responsive to an oscillating axial magnetic field BC, the latter of which is illustrated inFIGS. 20 a and 20 b. Accordingly, the toroidal helical coil 108 can be used to sense both axial BC and circumferential BE magnetic fields. The doughnut-shaped toroidal core 112 illustrated inFIGS. 21 and 22 comprises a major radius , a minor radius r, and an associated outside b and inside a radii and a minor diameter 2r, and may be constructed of either a ferromagnetic or a non-ferromagnetic material, depending upon the application, i.e. whether or not it is necessary to concentrate circumferential magnetic flux within the toroidal core 112. Any of the above described magnetic sensors 18.1, 18.2, 18.3, 18.3′, 18.3″ may incorporate a toroidal helical coil 108 instead of or in addition to the associatedcoil FIG. 22 , a toroidal helical coil assembly 114 comprises a toroidal helical coil 108 encapsulated in an encapsulant 88 about a central mounting hole 94 adapted to receive an associatedfastener 80, e.g. a cap screw 80.3. The modeling and testing done with a toroidal helical coil 108 suggests that the eddy currents IE (and therefore the associated circumferential magnetic field BE) are substantially enhanced when the steel core 106 associated with the toroidal helical coil 108 is electrically connected to the front 26 or rear 38 doors and/or the vehicle frame, whereby an electrical connection to both, e.g. via ahinge 22, is beneficial. Tests have indicated that a stronger signal may be obtained when using a toroidal helical coil 108 instead of a circularwound gap coil 74 at a location otherwise suitable for a gap coil assembly 86. - While specific embodiments have been described in detail, those with ordinary skill in the art will appreciate that various modifications and alternatives to those details could be developed in light of the overall teachings of the disclosure. Accordingly, the particular arrangements disclosed are meant to be illustrative only and not limiting as to the scope of the invention, which is to be given the full breadth of the appended claims and any and all equivalents thereof.
Claims (21)
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WO2008039878A3 (en) | 2009-04-23 |
US20070118312A1 (en) | 2007-05-24 |
US7463987B2 (en) | 2008-12-09 |
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