WO2002061447A2 - Apparatus and method for measuring vehicle speed and/or acceleration - Google Patents
Apparatus and method for measuring vehicle speed and/or acceleration Download PDFInfo
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- WO2002061447A2 WO2002061447A2 PCT/US2001/050518 US0150518W WO02061447A2 WO 2002061447 A2 WO2002061447 A2 WO 2002061447A2 US 0150518 W US0150518 W US 0150518W WO 02061447 A2 WO02061447 A2 WO 02061447A2
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- vehicle path
- radiation
- vehicle
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- bar
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Classifications
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- G—PHYSICS
- G01—MEASURING; TESTING
- G01P—MEASURING LINEAR OR ANGULAR SPEED, ACCELERATION, DECELERATION, OR SHOCK; INDICATING PRESENCE, ABSENCE, OR DIRECTION, OF MOVEMENT
- G01P3/00—Measuring linear or angular speed; Measuring differences of linear or angular speeds
- G01P3/64—Devices characterised by the determination of the time taken to traverse a fixed distance
- G01P3/68—Devices characterised by the determination of the time taken to traverse a fixed distance using optical means, i.e. using infrared, visible, or ultraviolet light
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- G—PHYSICS
- G08—SIGNALLING
- G08G—TRAFFIC CONTROL SYSTEMS
- G08G1/00—Traffic control systems for road vehicles
- G08G1/01—Detecting movement of traffic to be counted or controlled
- G08G1/052—Detecting movement of traffic to be counted or controlled with provision for determining speed or overspeed
Definitions
- the present invention relates generally to an apparatus and method for measuring the speed and/or acceleration of a vehicle. More particularly, the invention relates to the use of a projected radiation beam that is blocked by passing vehicles.
- One such device uses radiation sources on one side of the roadway, projecting a beam across the roadway to be received by a respective detector.
- the detectors are on the opposite side of the roadway from the radiation sources.
- the detectors detect when the beam is blocked by a tire of the vehicle.
- a calculating circuit determines the speed and/or acceleration of the vehicle based on information from the detectors.
- a disadvantage of this known arrangement is that the radiation sources and detectors must be placed on opposite sides of the roadway from each other. Since both the detectors and radiation sources require power to operate, this means that a separate power supply must be provided on each side of the roadway.
- Another disadvantage of the known arrangement is that it is difficult to align the sources and detectors so that the beam hits the detector.
- Still another disadvantage of the known arrangement is that there is no means for approximating the size and/or mass of the passing vehicle, information useful in the calculation of the Specific Power generated by the vehicle.
- Specific Power is crucial to correlating on- road in-use emissions from vehicles to stationary loaded-mode tests when the embodiment of this invention is applied to on-road in-use emissions testing.
- the present invention provides a system and method that can form more than one beam crossing a vehicle path using one radiation emitter.
- the invention provides an embodiment having an apparatus for measuring at least one of a speed and acceleration of a vehicle travelling on a vehicle path, the apparatus comprises a first radiation source arranged on a first side of the vehicle path that emits a radiation beam towards a second, opposite side of the vehicle path; a first reflector arranged on the second side of the vehicle path from the first radiation source that receives the beam from the first radiation source and reflects the beam in a direction generally parallel to the vehicle path; a second reflector arranged on the second side of the vehicle path that receives the reflected radiation from the first reflector, and reflects its towards the first side of the vehicle path; and a first radiation detector arranged at the first side of the vehicle path that receives the reflected radiation from the second reflector.
- the invention provides in an embodiment an apparatus for measuring at least one of a speed and acceleration of a vehicle travelling on a vehicle path, the apparatus that comprises a first radiation source arranged at a first side of the vehicle path that emits radiation; a beam splitter arranged at the first side of the vehicle path that receives the radiation from the first radiation source and splits the received beam into two partial beams, with one partial beam directed across the vehicle path towards a second side of the vehicle path opposite the first side of the vehicle path, and a second partial beam; and a first reflector mounted on the first side of the vehicle path that directs the second partial beam towards the second side of the vehicle path; a first detector on the second side of the vehicle path that receives the first partial beam from the beam splitter; and a second detector on the second side of the vehicle path that receives the second beam from the first reflector.
- the invention provides in an embodiment a method for measuring at least one of the speed and/or acceleration of the vehicle, the method comprising the steps of: projecting a beam from a first side of the vehicle path towards a second, opposite side of the vehicle path; reflecting the beam, at the second side of the vehicle path, generally in a direction along the vehicle path; reflecting the beam from the second side of the vehicle path towards the first side of the vehicle path, and detecting the reflected beam at the first side of the vehicle path.
- the invention provides a method for measuring at least one of the speed and/or acceleration of the vehicle, the method comprising the steps of: projecting a radiation beam at a first side of the vehicle path; splitting the radiation beam into two partial radiation beams; reflecting one of the two partial radiation beams across the vehicle path; reflecting the other of the two partial radiation beams across the vehicle path; detecting the first reflected partial radiation beam; and detecting the second partial reflected radiation beam.
- the invention provides an apparatus and method that detects the mass of a passing vehicle.
- FIG. 1 is a schematic diagram of the hardware utilized in the present invention.
- FIG. 2 is a top plan view of a source/detector (S/D) unit according to a preferred embodiment of the invention.
- FIG. 3 is a front view of the S/D unit shown in FIG. 2.
- FIG. 4 is a top plan view of a reflector unit according to the present invention.
- FIG. 5 is a front view of the reflector unit shown in FIG. 4.
- FIG. 6 is a side view of the S/D unit of FIG. 2 and also represents a side view of the reflector unit of FIG. 4.
- FIG. 7 is a top plan view of an alternative embodiment of the present invention.
- FIG. 8 is a top plan view of another alternative embodiment of the present invention.
- FIG. 9 is a top plan view of another alternative embodiment of the present invention.
- two or more laser/photo-detector modules also referred to as source/detector (S/D) units
- S/D source/detector
- the beam is reflected back by the retro-reflective element and detected by the S/D unit.
- the timing of the interruption of the beams is used to calculate an indication of speed and/or acceleration of the vehicle.
- the present invention provides a system and method for measuring the speed and/or acceleration of a vehicle. Referring to FIG.
- a preferred embodiment of the system 10 includes a plurality of integral source/detector ("S/D") units 12 arranged on opposite sides of the vehicle path from retro-reflector matrix units 14.
- the S/D units 12 each have a radiation beam output and a detector.
- the S/D units 12 and/or retro-reflector matrix units 14 can be positioned by being attached to bar units 16, 18 of known length to fixedly separate the distance D between the units in the direction of travel being measured.
- the S/D units 12 each project a radiation beam, such as a laser beam, generally pe ⁇ endicularly across the roadway or path of vehicle travel toward the other side of the roadway.
- Each retro-reflector matrix unit 14 is positioned on the other side of the roadway and receives and reflects the beam back to the respective S/D unit 12.
- the S/D unit 12 receives the reflected beam.
- the retro-reflector matrix units 14 can be provided by employment of commercially available reflector items. These retro-reflectors reflect at least a portion of a received light beam back in the direction from which the light beam hit the retro-reflector. Even if the beam does not hit the reflector pe ⁇ endicular to the reflector, the retro-reflector matrix 14 will reflect a sufficient amount of light back towards the origin of the beam to be detected. Thus, the retro-reflector matrix units 14 will reflect a sufficient amount of a received beam back to the respective S/D unit 12 for detection. This provides a significant advantage of the invention, whereby the retro-reflector matrix 14 does not need to be aligned to be directly pe ⁇ endicular with the direction of the beam. This feature greatly simplifies installation and set up of the system 10.
- FIG. 1 further schematically depicts the arrangement of the S/D units 12 and the retro- reflector matrix units 14, with the S/D units 12 mounted to S/D bar units 16, and the retro- reflector matrix units 14 mounted to reflector bar units 18.
- the S D bar units 16 each include at least two S/D units, S/D 1 and S/D 2, but may include any number greater than two, that is S/D N units.
- FIG. 1 also schematically illustrates that more than one S/D bar 16 and more than one reflector bar unit 18 maybe used. Mounting the S/D units, S/D 1 and S/D 2, on S/D bar unit 16 provides a fixed distance between the S/D units that are mounted on the S/D bar unit 16.
- the S/D bar unit 16 may also include a speed and acceleration microcontroller 20 which includes electronics that respond to the sensed interruptions of the beams.
- a speed and acceleration microcontroller 20 which includes electronics that respond to the sensed interruptions of the beams.
- more than one S/D bar unit 16 may be used, with the bars cascaded ("daisy chained") together, and each bar having at least two S D units 12.
- the S/D bar units 16 can be configured so that they can cascaded simply by connecting the end of one S D bar unit 16 to the beginning of the next S/D bar unit 16.
- the reflector bars 18 can be cascaded in corresponding fashion.
- a single external computer system 22 receives signals from the microcontrollers 20 of each bar 16 in use via an interface such as an RS232 interface, and can calculate the vehicle's speed and/or acceleration.
- the computer system 22 can also supply power to the S/D bar unit(s) 16.
- the S/D unit(s) 16 also include a tilt sensor 24.
- the computer 22 can be a personal computer or a personal digital assistant or other suitable device.
- the following list depicts a sequence of events for a single speed and acceleration bar with " ⁇ /" S/D units: 1.
- the system reads road slope from the tilt sensor. A road slope with an incline
- the vehicle begins by driving through a speed and acceleration system which is a single bar of " ⁇ " S/D laser and retro-reflective matrixes with "D" distance between them.
- the vehicle's front tires blocks the 1 st laser beam that traverses the roadway.
- the system records the Time F1B ⁇ 0c of the block. 5.
- the vehicle's front tires exit the 1 st laser beam that traverses the roadway.
- the system records the TimeF n b i o c of the unblock.
- the vehicle's front tires blocks the 2 nd laser beam that traverses the roadway.
- the system records the Timep 2 Bi o c of the block.
- the vehicles front tires exit the 2 nd laser beam that traverses the roadway.
- the system records the TimeF 2 un ioc of the unblock.
- the system reads relative vehicle mass from magnetometer sensor. Nehicle type is determined from magnetic signature ⁇ e.g. small vehicle up to a semi tractor/trailer ⁇ .
- the vehicle's rear tires block the 1 st laser beam that traverses the roadway. 13.
- the system records the TimemBi o c of the block.
- the vehicle's rear tires exit the 1 st laser beam that traverses the roadway.
- the system records the Time R1 un b ioc of the unblock.
- the vehicle's rear tires blocks the 2 nd laser beam that traverses the roadway.
- the system records the of the block. 18.
- the vehicle's rear tires exit the 2 nd laser beam that traverses the roadway.
- the system calculates the Nehicle's Speed and Acceleration based on 1 st and 2 nd lasers:
- Speed! D/(Time F2 Bioc - Time F1B ⁇ 0 c)
- Speed 2 D/(Time F2U nb_oc - Time F1Unbloc )
- the vehicle's front tires blocks the 3 rd laser beam that traverses the roadway.
- the system records the TimeF 3 Bi oc of the block.
- the vehicle's front tires exit the 3 rd laser beam that traverses the roadway.
- the system records the Time F3 u n bioc of the unblock.
- the vehicle's rear tires blocks the 3 rd laser beam that traverses the roadway.
- the system records the Time 3B i 0C of the block.
- the system records the Time 3 u n bioc of the unblock.
- the system calculates the Vehicle's Speed and Acceleration based on 2 nd and 3 rd lasers:
- Speeds D/(Time F3B ⁇ 00 - Time F2B ioc)
- Speed 6 D/(Time F3UnbIoc - Time F2Unb!oc )
- Speedy D/(Time R3B)oc -
- Accel 3 (Speedy - SpeedsyCTimemBioc - Time F2B ⁇ 0C )
- Accel 4 (Speed8 - Speed 6 )/(Time R3Unb ⁇ 0C - Time F2Unb]oc ).
- the system further calculates the Vehicle's Speed and Acceleration based on the 1 st and 3 rd lasers:
- Speed 9 2*D/(Time F3Bloc - Time F ⁇ B ⁇ oc )
- Speedy 2*D/(Time F3Unb ⁇ 0C - Time F ⁇ j nb ⁇ 0C )
- Speed ⁇ 2*D/(Time R3Bloc - Time R ⁇ B )C
- Speedy 2*D/(Time R3unb ⁇ 0C - Time R1Unbloc )
- Accel 5 (Speed ⁇ - Speed 9 )/(Time R3Unb ⁇ 0C - Time F ⁇ B ⁇ 0C )
- Accelg (Speed 12 - Speed ⁇ 0 )/(TimeR3Unbioc - Time F1UnbIoc ).
- the vehicle's rear tire blocks the lSf h laser beam that traverses the roadway.
- the system records the TimepjV B ioc of the block.
- the vehicle's rear tire exit the N" 1 laser beam that traverses the roadway.
- the system records the Timep M J nb i o c of the unblock.
- the system calculates the average speed and acceleration:
- the system saves the vehicle's Speed avg and Accel avg .
- Nehicle specific power is calculated either using measured relative vehicle mass, or utilizing an equation that discounts the mass of the vehicle. SP can be calculated so that an on-road in-use measurement of a vehicle's emissions can be correlated to a treadmill test such as IM240 or other loaded mode treadmill test where SP can be calculated. USEPA uses a formula for calculating SP that is: 2 * speed * acceleration, though this does not take into account an adjustment for acceleration, as can be done with this system, for those vehicles sampled on an inclined/declined roadway. Measured acceleration is adjusted for the effect acceleration due to gravity (a g ) has on the vehicle.
- the effect of a g is calculated by multiplying the SINE of the road slope (measured in degrees angle relative to the horizon) by the factor 21.82.
- a road slope expressed in Percent Grade is multiplied directly to the 21.82 factor (e.g. 6% grade is 0.06 * 21.82).
- the vehicle For an inclined (uphill) road slope, the vehicle must overcome acceleration due to gravity that works against the vehicle moving uphill. Therefore a g is added to the measured acceleration from the system, and a g is subtracted from the measured acceleration when a vehicle is traveling downhill. Both measured and adjusted acceleration can be reported by the system.
- the number "N" of lasers is typically between two to four lasers and the distance “D” is typically between 1.44 feet (0.43 meters) to 4.0 feet (1.22 meters).
- the sequence of events described above for performing calculations based on the sensed beam information represents a presently preferred embodiment. However, any other suitable calculations may be performed based on the sensed interruptions of the light beams, and also various steps such as, for example, calculation of specific power can be omitted in some embodiments if desired.
- the S/D units 12 can be provided by an off-the-shelf system having a class 2 visible laser diode light source and an appropriate detector.
- any suitable radiation beam can be employed.
- the projected beam is a modulated laser beam.
- Employing a modulated beam rather than a constant beam minimizes reflective noise, and thereby provides improved performance.
- the modulation is preferably fast enough to permit measurements having a desired accuracy.
- the beam can be modulated at approximately a 20 kHz rate. Higher radiation rates of over 200 kHz can also be employed.
- the S/D units 12 in some applications are battery powered via the external computer 22 being battery powered.
- the S/D units 12 may also be powered by a temporary or permanent corded connection or other suitable power connection.
- an operator can align the units and observe that proper alignment has been achieved, all from one side of the roadway. That is, the operator can first set the retro-reflector units 14 on the far side of the roadway, and then can place the S/D units 12 on the near side of the roadway, and manipulate the S/D units 12 until proper alignment is observed by observing an indication of the detection of the beam by the S/D units 12. Set up of the assembly is described in more detail below.
- the S/D units 12 are mounted on bar units 16 which may be rigid metal bars, the S/D units 12 may also be deployed individually. Similarly, the retro-reflective units 14 may be deployed individually instead of on reflector bars 18.
- the S/D units 12 and/or retro-reflective matrixes 14 can be mounted in other fashions, and for example might be permanently mounted in a curb or roadway wall structure.
- the bar units 16 and/or 18 may be designed to be cascaded touching end to end, or may be designed to be spaced from each other by a predetermined distance.
- the S/D bar units 16 can be adjusted to position the height of the laser beam above the vehicle path surface, such as a roadway, and also to orient the beam to be at least substantially parallel to the surface.
- the bar units 16 maybe provided with adjustable legs 24, 26, 28 that support the bar units 16, 18 as shown in FIGS. 2-6.
- the bar unit 16 includes a first rectangular tubular portion 30 connected in line with a second rectangular tubular segment 32.
- the two rectangular tubular segments 30, 32 are detachably mated together via a connecting piece 34 that slides into suitable tubes welded into at the respective ends of the segments 30 and 32.
- the connecting piece 34 has two holes drilled therethrough and receives removable pins 36.
- a L-shaped rear plate 38 is attached to the back side of the segments 30 and 32 via attachment screws 40.
- the rear plate 38 may be provided with a stiffening flange 52 as shown.
- the rear plate 38 has a vertical housing at its rear corner for receiving an adjustable leg 24.
- the adjustable leg 24, as can be best seen in the side view of FIG. 6, has a number of holes drilled therethrough one inch (2.54 cm) apart and a releasable pin 42 can be inserted though the housing and a respective hole in the leg 24 in order to provide one inch (2.54 cm) height adjustment for the leg 24 relative to the rear plate 38 and bar assembly 30, 32.
- the bar segment 30 has a leg 26 that is similarly height adjustable by a pin 44.
- the bar segment 32 also has a leg 28 that is height adjustable by a pin 46.
- each of the legs 24, 26 and 28 can be independently height adjusted to effect coarse adjustment. It is also possible in the preferred embodiment to effect a more fine adjustment on each leg 24, 26, and 28 by the lower portion of each leg having a threaded foot 50 that can be rotated to raise or lower the foot 50 by fine amounts relative to its respective leg 24, 26, and 28.
- the foot 50 is designated by the reference numeral 50 throughout, because the threaded insertion of the foot into the respective legs 24, 26 and 28 is the same for each leg.
- the arrangement of the legs 24, 26 and 28 permits the S/D bar 16 including the L-shaped rear portion 38 to be adjusted for use on a flat surface, or on a curbed or uneven surface.
- the rear leg 24 is in a primarily upward position so that it can rest in the top of a curb, while the front legs 26 and 28 can rest on a pavement surface below the curb.
- the rear leg 24 could be lowered into a fully lowered state, in which the feet of the legs 24, 26 and 28 would be generally in the same horizontal plate, and could rest on a roadway surface.
- the adjustment of the legs 24, 26 and 28, including both fine and coarse adjustments in the preferred embodiment, also permits the S/D bar 16 to be used on a crowned or otherwise inclined road surface, and still permit a generally horizontal beam.
- the S/D bar 16 also includes three S/D units 12 in the location shown.
- the S/D units 12 are mounted in apertures in the front wall of the bar segments 30 or 32, and rest generally flush with the front surface of those segments.
- the S/D bar 16 also includes the microcontroller 20 mounted internally of the bar 16 at the location shown.
- An indicator such as three holes having LED's 54 mounted therein is provided on the front surface of the bar unit 32.
- the LED's indicate when the entire arrangement including the bars 16 and 18 are in alignment as discussed in more detail below.
- the end 56 of the S/D bar 16 may have an attachment arrangement that corresponds to the other end 58 of the bars, so that the bars may be cascaded or daisy chained together. Connections 56 and 58 may also include connections for power and/or data transmission. When one bar is used alone, or in the case of the end bar of the daisy chained combination, the connector 56 may be connected directly to external computer 22 via a RS232 interface 24.
- FIGS. 4 and 5 illustrate a preferred embodiment of the reflector bar 18.
- Like elements as in FIGS. 2 and 3 are indicated by like reference numerals throughout.
- the principal differences between the reflector bar 18 and the S/D bar 16 is that the reflector bar 18 has retro-reflector matrix elements 16 mounted in the positions shown, rather than the S/D units 12.
- the retro-reflector matrixes 16 are mounted substantially flush onto the front face of the segments 30 and 32.
- the reflector unit 18 does not require the supply of power, or any supply or transmission of data. Therefore, the end connections 62 and 64 which maybe provided for cascading the reflector bars do not need to include power and/or data transmission.
- each S/D bar 16 there are three S/D units 12 on each S/D bar 16, equally spaced from each other, and there are three retro-reflector matrixes 60 on each reflector bar 18, also equally spaced from each other.
- the number of units and their spacing may be modified as desired in other embodiments.
- the user To set up the bars for operation, in a example of the usage of a single bar, the user first sets up the S/D bar 16 so that it is projecting a beam generally across the roadway surface. The user then crosses the vehicle path and sets up the reflector bar 18, so that it will receive and reflect the projected beams. The user can manipulate the reflector bar 18 until proper alignment has occurred, which will be indicated by the LED's 54 on the front face of the S/D bar 16.
- the construction described above also permits for ready disassembly of the bars. For example, when not in use, the S/D bar 16 can be separated by pulling out the pins 36 and undoing the screws 40.
- the legs 24, 26 and 28 can also be removed from their respective housings.
- the S/D bar 16 may include a tilt and/or mass sending arrangement 70.
- the sensor 70 includes a tilt sensor that can detect the degree of tilt from horizontal, along the lengthwise axis of the S/D bar 16. Signals from the tilt sensor may be provided to the controller 20 for use in the adjustment of measured acceleration for the acceleration of gravity pulling with/against the vehicle being measured. Calculation of Specific Power of the measured vehicle includes the adjusting of measured acceleration for the acceleration on the vehicle due to the Earth's gravity.
- the sensor 70 can include a mass sensor such as a magnetometer in addition to, or instead of, a mass sensor.
- a magnetometer can be used to detect the mass of the vehicle, and this data can be used in the calculation of Specific Power.
- FIG. 7 is a top view of two alternative arrangements for beam projecting and receiving that can be implemented with the present invention.
- the items 74 and 76 are not present.
- FIG. 7 illustrates a first bar 62, which in some embodiments includes a radiation beam projector 66 and a radiation beam receiver 68.
- the beam P 3 is projected by the radiation source 66 towards a second bar 64.
- the second bar 64 includes a first mirror 70 and a second mirror 72 as shown.
- the beam P 3 is projected from the radiation source 66 towards the first mirror 70, which then reflects the beam longitudinally along the second bar 64 towards the second mirror 72.
- the second mirror 72 reflects the beam Pi toward a detector 68.
- the arrangement just described thereby causes the beam to form two beam passes that cross the roadway P 3 between items 66 and 70, and P ⁇ between items 72 and 68.
- This arrangement provides for a single beam path that forms two effective beams P 3 and Pi that will each be blocked by a vehicle's tires as it passes on a trajectory 60 through the paths Pi, P , and P .
- the distance between source and detector is preferably greater than the longest tire length of the vehicles to be measured taken at height two to eight inches from the road surface.
- the spacing be less than the smallest axle spacing (vehicle wheelbase) expected from passing vehicles. For most vehicles, a proper spacing can be determined and implemented so that that the front wheel will first block the rear beam Pi, and then block the front beam P , followed by another wheel of the vehicle blocking the rear beam Pi and then the front beam
- FIG. 7 also illustrates a second embodiment, where a half-reflective mirror (or beam splitter) 74 is placed on the second bar 64 as shown, and a detector 76 is placed on the first bar 62.
- the beam splitter 74 reflects a portion of the beam P towards the detector 76, while permitting some of the beam to continue on to the second mirror 72.
- the mirrors 70 and 72 can be conventional mirrors angled at 45 degrees. To facilitate alignment of the multiple mirror arrangement, the mirrors can be two-part mirrors having a suitable included angle between each, which facilitates the ability of the mirror to react to partial misalignment caused by noise, vibration, and/or skew of the bars 62 & 64 relative to each other.
- This second embodiment of FIG. 7 provides for a total of three beam paths Pi, P 2 , and
- FIG. 8 illustrates another alternative embodiment for the beam path.
- a radiation projector 92 on a first bar 84 projects the beam as shown.
- the first bar 84 has a half-reflective mirror (or beam splitter) 94 and a second mirror 96 as shown.
- a partial beam P 2 is reflected to a sensor 86 on the second bar 82 and also a second partial beam Pi is reflected to a detector 98 on the second bar 82.
- This embodiment thus also provides two detectable beam paths Pi, and P 2 resulting from one radiation projector 92. It is possible to calculate the vehicle speed and acceleration traveling on trajectory 80 through the system of beam paths, and to place the beams at a proper spacing using the spacing considerations discussed with regard to the embodiments of FIG. 7.
- the beam splitters discussed above can be partially silvered mirrors or can be produced by using polarizing lens(es) and appropriate polarization on the sensors 68, 76 of FIG. 7, and 86, 98 of FIG. 8. They can be embodied as any suitable form of beam splitter.
- the embodiment of FIG. 9 illustrates another variation of speed and acceleration detection.
- the embodiment of FIG. 9 is a single-detector, multi-source arrangement.
- the detector 118 is an analog detector as opposed to the digital on/off types of detectors used in the embodiments described above.
- multiple radiation sources 110 and 120, along with an analog detector 118 are attached to a common structure 102 such as a bar, or implanted into a curb alongside of a typical roadway.
- a common structure (104) such as a bar, or implanted into a curb.
- a beam is generated from radiation source 110 and travels across the roadway to a mirror 112, forming pathway P 3 .
- the beam continues down a path roughly parallel to the path of travel for a vehicle 100, passes through a beam splitter 114, and then is passed back across the roadway by another mirror 116, forming pathway Pi.
- the beam then reaches a detector 118.
- the beam splitter 114 has a bias between its pass- through and reflective amounts of light. This allows the detector 118 to be able to distinguish which beam path across the road has been broken by a tire of a vehicle.
- One example of an embodiment that uses two sources 110 and 120 and a 30/70 bias beam splitter 114 yields the following inte ⁇ retation algorithm.
- V D Vpi + V P2
- V D is voltage at the detector resulting from all light passing through the system;
- V P I is voltage at the detector resulting from electromagnetic radiation passing though PI optical circuit only;
- Vp 2 is voltage at the detector resulting from electromagnetic radiation passing through P2 optical circuit only.
- the voltage measured at the detector 118 would be only the 3.5 volts being received from the P 2 beam path.
- the P 3 beam path is reestablished, but the P 2 beam path is eventually closed off. Under this condition, the voltage measured at the detector 118 is now 1.5 volts.
- no voltage is measured, except some potentially marginal voltage due to stray light.
- a computerized algorithm is applied to determine the time taken for a vehicle to pass through each of the optical circuit, thereby yielding the speed of the vehicle and the change in speed (acceleration).
- this is an example of using two sources with a single detector; however, it is possible to apply the logic of this example to one, two, three, or more sources in conjunction with a single detector.
- This embodiment allows a flexibility to use several cheaper source components in place of having several expensive detector/sensor pairs, one pair for each beam path. Furthermore, this embodiment allows all devices that require power to be on the same side of the roadway, much like the features shown in FIG. 7 and FIG.
Abstract
Description
Claims
Priority Applications (1)
Application Number | Priority Date | Filing Date | Title |
---|---|---|---|
AU2002246861A AU2002246861A1 (en) | 2000-12-29 | 2001-12-28 | Apparatus and method for measuring vehicle speed and/or acceleration |
Applications Claiming Priority (8)
Application Number | Priority Date | Filing Date | Title |
---|---|---|---|
US25856100P | 2000-12-29 | 2000-12-29 | |
US60/258,561 | 2000-12-29 | ||
US09/846,247 | 2001-05-02 | ||
US09/846,375 | 2001-05-02 | ||
US09/846,247 US6561027B2 (en) | 2000-12-29 | 2001-05-02 | Support structure for system for measuring vehicle speed and/or acceleration |
US09/846,375 US6750444B2 (en) | 2000-12-29 | 2001-05-02 | Apparatus and method for measuring vehicle speed and/or acceleration |
US09/985,296 | 2001-11-02 | ||
US09/985,296 US6781110B2 (en) | 2000-12-29 | 2001-11-02 | Apparatus and method for measuring vehicle speed and/or acceleration |
Publications (2)
Publication Number | Publication Date |
---|---|
WO2002061447A2 true WO2002061447A2 (en) | 2002-08-08 |
WO2002061447A3 WO2002061447A3 (en) | 2003-02-13 |
Family
ID=27500622
Family Applications (1)
Application Number | Title | Priority Date | Filing Date |
---|---|---|---|
PCT/US2001/050518 WO2002061447A2 (en) | 2000-12-29 | 2001-12-28 | Apparatus and method for measuring vehicle speed and/or acceleration |
Country Status (2)
Country | Link |
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AU (1) | AU2002246861A1 (en) |
WO (1) | WO2002061447A2 (en) |
Cited By (3)
Publication number | Priority date | Publication date | Assignee | Title |
---|---|---|---|---|
DE10146639A1 (en) * | 2001-09-21 | 2003-04-10 | Sick Ag | Light grid with beam splitter |
DE102009009386B4 (en) * | 2009-02-18 | 2011-01-27 | Leuze Electronic Gmbh & Co Kg | Optoelectronic device |
CN104504905A (en) * | 2015-01-12 | 2015-04-08 | 重庆交通大学 | Vehicle track and speed identification method |
Citations (3)
Publication number | Priority date | Publication date | Assignee | Title |
---|---|---|---|---|
US5343043A (en) * | 1993-04-13 | 1994-08-30 | Envirotest Syst. Corp. | Remote sensor device for monitoring motor vehicle exhaust systems with high speed sampling |
US5812249A (en) * | 1996-09-26 | 1998-09-22 | Envirotest Systems Corporation | Speed and acceleration monitoring device using visible laser beams |
US5910929A (en) * | 1998-07-10 | 1999-06-08 | Sonic Systems Corporation | Audio railway crossing detector |
-
2001
- 2001-12-28 AU AU2002246861A patent/AU2002246861A1/en not_active Abandoned
- 2001-12-28 WO PCT/US2001/050518 patent/WO2002061447A2/en not_active Application Discontinuation
Patent Citations (3)
Publication number | Priority date | Publication date | Assignee | Title |
---|---|---|---|---|
US5343043A (en) * | 1993-04-13 | 1994-08-30 | Envirotest Syst. Corp. | Remote sensor device for monitoring motor vehicle exhaust systems with high speed sampling |
US5812249A (en) * | 1996-09-26 | 1998-09-22 | Envirotest Systems Corporation | Speed and acceleration monitoring device using visible laser beams |
US5910929A (en) * | 1998-07-10 | 1999-06-08 | Sonic Systems Corporation | Audio railway crossing detector |
Cited By (3)
Publication number | Priority date | Publication date | Assignee | Title |
---|---|---|---|---|
DE10146639A1 (en) * | 2001-09-21 | 2003-04-10 | Sick Ag | Light grid with beam splitter |
DE102009009386B4 (en) * | 2009-02-18 | 2011-01-27 | Leuze Electronic Gmbh & Co Kg | Optoelectronic device |
CN104504905A (en) * | 2015-01-12 | 2015-04-08 | 重庆交通大学 | Vehicle track and speed identification method |
Also Published As
Publication number | Publication date |
---|---|
AU2002246861A1 (en) | 2002-08-12 |
WO2002061447A3 (en) | 2003-02-13 |
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