EP0918309A1 - Locking system for motor vehicles detecting approach of the user - Google Patents

Abstract

A metallic plate (15), electrically isolated from the vehicle is driven by a high frequency generator (16). The plate and the vehicle (V) together form a dipole, the capacitance of which is sensitive to neighboring objects. A module that detects variation in capacitance is attached to this dipole and triggers when a person is close. This in turn initiates the vehicle automatic security system which verifies the identity of the person before unlocking the vehicle.

Description

The present invention relates to a motor vehicle equipped a user approach detection system.

Such detection systems are already used in some motor vehicles to automatically trigger the unlocking a door lock or authorization door opening, as soon as the user approaches, without the user need to use a key or remote control. To do this automatic unlocking before opening the door, a system generally called "hands-free access system", which system is to enable a remote exchange of information between an identifier on the vehicle and an identifier carried by the user. When the identifier has been recognized as correct by the identifier, the lock will be unlocked, allowing the user to open the door by simple pull on the door pallet.

However, it is not possible to leave it constantly activated the identifier and / or the identifier because their electrical consumption is too important. On the other hand, the identifier and the identifier must be able to be activated at any time because approaching the vehicle by the user is unpredictable. Therefore, it has already been proposed to use a approach detection system or pallet entry by the user, to activate the vehicle identifier only when the user prepares to open the door.

It has thus been proposed to equip the door pallets with a electrical switch to detect the start of the actuation stroke of the pallet for opening the door. However, this solution has as a disadvantage of carrying out a too late detection of user approach because the time it takes for the identifier correctly recognizes the user identifier and commands unlocking the lock is generally fine greater than the time required for the user to complete the race actuation of the pallet. In other words, the door is not generally not unlocked when the user has finished the pallet actuation stroke and it is sometimes necessary that it operate the paddle several times before obtaining the opening of the door.

It is also known to use optical detection systems or ultrasounds, but their cost is generally too high.

Document DE n ° 196 17 038 describes a motor vehicle comprising a first electrode integrated into a handle of a door, a second electrode on the door surface, a capacitive sensor integrated in the door handle, the sensor capacitive being connected by an electrical connection to the control unit centralized, a voltage of opposite poles being applied to both electrodes and, to produce an electric field, between the handle and the door, insertion of the user's hand between the two electrodes modifying the electric field, this modification being measured by the capacitive detector which can thus trigger the interrogation with a view to user identification. However, such a system requires detect a change in the electric field generated between two electrodes, and insert your hand between the two electrodes, which delays detection.

In addition, all currently known solutions require additional electrical connections between the pallet and a other element of the door.

The object of the invention is to eliminate the aforementioned drawbacks and to offer a motor vehicle equipped with a new user approach detection, enabling detection, which is anticipated compared to that of a pallet contactor and whose price cost is lower than that of an optical or ultrasonic detector, without requiring connection by connectors or electrical harness additional with the pallet.

• une surface métallique isolée de la masse du véhicule et connectée à un générateur d'ondes haute fréquence, de façon que le couple formé par la masse du véhicule et ladite surface définissent un dipôle rayonnant à impédance élevée se comportant comme une antenne non accordée et sous-dimensionnée par rapport à la longueur d'ondes, et
• un détecteur de variation de capacité connecté à ladite surface et destiné à détecter la variation de la capacité du dipôle, ledit dipôle ayant une capacité qui varie en fonction de la capacité du condensateur formé par le couple (main/surface) dont la capacité augmente lorsque la main de l'utilisateur s'approche de ladite surface. Cette détection de variation de capacité pourrait être traitée par un module électronique, par exemple, préalablement intégré dans la serrure d'une portière de véhicule, pour commander diverses fonctions, telles que la décondamnation de serrure de portières, ainsi que le transfert de l'information sur l'état d'une serrure aux autres serrures.

To this end, the subject of the invention is a motor vehicle equipped with a system for detecting the approach of a user, characterized in that it comprises:

• a metal surface isolated from the vehicle mass and connected to a high frequency wave generator, so that the torque formed by the vehicle mass and said surface define a high impedance radiating dipole behaving like an antenna not tuned and under -sized relative to the wavelength, and
• a capacity variation detector connected to said surface and intended to detect the variation in the capacity of the dipole, said dipole having a capacity which varies as a function of the capacity of the capacitor formed by the pair (hand / surface) whose capacity increases when the user's hand approaches said surface. This detection of variation in capacity could be processed by an electronic module, for example, previously integrated in the lock of a vehicle door, to control various functions, such as unlocking the door lock, as well as transferring the information on the state of a lock to other locks.

In a particular embodiment, the aforementioned surface makes part of a window opening pallet, for example, a door, a fuel door, a trunk, said pallet being connected to a door lock by a mechanical connection which is electrically conductive and isolated from vehicle ground to serve electrical connection between said surface and the aforementioned generator. In this case, the aforementioned dipole is formed, on the one hand, by the mass of the vehicle and, on the other hand, by the whole of said surface and the mechanical connection, which can be constituted, for example, by a cable sheathed or a control rod actuating an opening lever the door lock.

Advantageously, the detector is arranged to activate a identifier on the vehicle in response to the detection of a variation of capacity, which identifier, first of all, checks, when it is activated, if the user has an authorized identifier and, secondly, if verification shows that the identifier is recognized as correct, order at least one function of the vehicle, for example unlocking of a door lock.

According to another characteristic, the detector is arranged to activate the identifier when it detects a capacity greater than a predetermined threshold value Cs comprised between a predetermined minimum capacity value Cmin of the dipole, corresponding for example to its residual capacity in l absence of the user, and a predetermined maximum capacity value Cmax of the dipole, corresponding for example to its capacity when the hand of a user is in contact with the pallet. The threshold value Cs is advantageously obtained by the following formula: Cs = Cmin + α Cmax 1 + α α being a dimensionless coefficient between 0 and 1.

In a particular embodiment, the device comprises a system to perform automatic recalibration of the threshold value cited above. For example, when the detected capacity value remains stably higher than the threshold value Cs during a predetermined duration, for example of the order of 30 s, the value of minimum capacity Cmin then takes this new capacity value detected. Conversely, when the detected capacity value remains stably lower than the minimum capacity value Cmin for a predetermined duration, for example, of the order of 2 s, Cmin then takes this new detected capacity value. In the case of automatic recalibration, when the minimum capacity value Cmin is modified, the maximum capacity value Cmax is also modified so as to keep the Cmax / Cmin ratio constant.

According to yet another characteristic of the invention, the device has a system for performing a series of detections elementary capacitors, each corresponding to frequencies generated different, said elementary capacity values detected of the same series then being averaged, possibly excluding the discordant values, said mean value then being compared with the predetermined threshold value Cs to activate, if necessary, the identifier. If all the frequencies generated in the same series result in discordant elementary detections, the system is arranged not to activate the identifier, in order to maintain security of condemnation.

In an advantageous embodiment, the detector is arranged to detect the imaginary part alone of the admittance of the dipole for a fixed frequency delivered by a stable oscillator serving as high frequency wave generator, to make detection insensitive to the presence of more or less conductive liquid, for example, salt water in contact with the pallet. In this case, we can even consider correct operation of the immersion system total of the pallet.

Advantageously, an inductor can be provided in parallel with the equivalent impedance of the dipole and determined to eliminate from the detected capacity value, the value of the residual capacity of the dipole in the absence of the user.

According to yet another characteristic, the metal surface can be covered with an insulating overmold to protect it from attack external.

Of course, we could also alternatively measure the capacity of the dipole according to other methods: for example, by insertion of the capacitor in an oscillator circuit whose frequency is measured, by measuring the impulse response of the capacitor to a high frequency pulse emission, or by measurement of the module of the capacitor admittance for a fixed frequency delivered by a stable oscillator.

The stable frequency generator can be obtained from a signal linked to the clock of a microcontroller or from the microcontroller itself, this microcontroller can be part of a electronic module integrated into the lock.

To better understand the object of the invention, we will now describe as a purely illustrative example and not limiting, an embodiment shown in the accompanying drawing.

• la figure 1 est un schéma synoptique fonctionnel d'un véhicule automobile selon l'invention ;
• la figure 2 est une vue schématique d'une portière d'un véhicule selon l'invention ;
• la figure 3 est un schéma électrique de principe du système de détection d'un véhicule selon l'invention ;
• la figure 4 est un schéma électrique illustrant de manière plus détaillée le système de détection d'un véhicule selon l'invention ;
• la figure 5 représente le schéma électrique simplifié d'une variante de la figure 3.

On this drawing :

• Figure 1 is a functional block diagram of a motor vehicle according to the invention;
• Figure 2 is a schematic view of a door of a vehicle according to the invention;
• Figure 3 is an electrical block diagram of the detection system of a vehicle according to the invention;
• Figure 4 is an electrical diagram illustrating in more detail the detection system of a vehicle according to the invention;
• FIG. 5 represents the simplified electrical diagram of a variant of FIG. 3.

According to the embodiment shown in the drawing, we have indicated, by dashed lines in Figure 1, a door 1 of motor vehicle which includes a detector 2, an identifier 3 and a lock 4. The detector 2 is intended to detect the approach of a user 5 of door 1, as indicated by arrow 6. When user 5 will have been detected close enough to door 1, the detector 2 will send a signal via line 7 to identifier 3 to activate it. When identifier 3 is activated, it exchanges information signals with an identifier carried by the user 5, as represented by the two opposing arrows 8, 9. As soon as identifier 3 recognizes user identifier 5 as correct, it sends a command signal by line 10 to the lock 4 to cause its unlocking. Detector 2 will have been arranged so as to detect the approach of user 5 early enough to allow unlocking of lock 4 before user 5 does not operate this same lock 4 by a pallet to open the door 1, according to an action indicated by arrow 11.

However, if the unlocking has not been completed when the user finishes lifting the pallet, you can plan to use, in addition, a lock making unnecessary a double action on the door handle, for example the lock described in the French patent application no. 97-12539. In this case, opening the door will be done at the same time as its unlocking.

To open door 1, user 5 must enter a pallet opening the door 12 and exerting a tractive effort thereon to cause the opening of lock 4, by means of a sheathed cable 13 or a control rod connecting the pallet 12 to a opening lever 14 linked to the lock 4. As visible in FIG. 2, the pallet 12 has a metal surface portion 15, which is electrically connected to the detector 2 via the cable 13 and lever 14 which are electrically conductive and isolated from ground of the vehicle. The surface portion 15 can also be covered overmolding to protect it from external aggressions. Alternatively, the entire pallet 12 can constitute said metal surface. In using the mechanical connection 13 between the pallet 12 and the module detection 2, an additional connection is avoided in the door.

Referring now to FIG. 3, it can be seen that this surface 15 is supplied with current by a high-frequency wave generator 16, which generator 16 may already be present in an electronic module M integrated into the lock 4. Under these conditions , the torque formed by, on the one hand, the vehicle V which is grounded, and on the other hand, the whole of the surface 15 and of the cable 13, defines a radiating dipole whose equivalent impedance Z ₁ is shown in Figure 3. This impedance Z ₁ is generally constant and made up of a low capacity C ₁ resulting from the residual capacity of the cable 13 and a parallel conductance g ₁ , the value of which represents the resistive leaks between l 'assembly (pallet-cable-lock) and the mass of the vehicle, this conductance can vary depending on untimely leaks to the mass, for example, in the presence of water in the door. The dipole admittance value must be minimized to limit the radiation effect around the vehicle. In other words, this dipole is determined so that it behaves like an antenna which is not tuned and undersized with respect to the wavelength emitted by the generator 16. The dipole also comprises in parallel a capacitor C with variable capacity which is defined between the aforementioned surface 15 and the hand of the user 5. This variable capacitance C increases as the hand approaches the surface 15. When the hand of the user comes into contact with the surface 15, the capacity becoming infinite, the capacitor C disappears and the user then acts as a radiating strand of antenna, which has the effect of lengthening the antenna and transmitting more high waves -frequency. On the other hand, if an insulating overmolding is provided on the surface 15, there can never be direct contact between the surface 15 and the hand of the user 5. The aforementioned dipole further comprises, in series with the capacitor C, an impedance Z ₂ equivalent to the user / mass couple, this impedance Z ₂ being generally low compared to C and consisting of a capacitor C ₂ in parallel with a conductance g ₂ .

We will now refer to FIG. 4, which represents an electronic circuit for measuring the imaginary part alone of the admittance of the dipole. Measuring the imaginary part of the admittance alone has the advantage of only detecting the capacitive part of the dipole and avoiding the value of the resistance of the dipole, which resistance can vary in the presence of liquid more or less conductor and therefore may distort the measurement to be made. As the frequency used is constant, we can model the radiating dipole by the simplified equivalent electrical diagram referenced Z. In FIG. 4, we see that the equivalent impedance Z of the dipole has a conductance g equivalent to all of the conductances g ₁ and g ₂ and, in parallel, a variable capacity C ′ equivalent to the set of capacities C ₁ , C ₂ and C in FIG. 3.

The generator 16 is a stable oscillator delivering a sinusoidal signal of voltage U (t), with U (t) = Ucos (2πf ₀ .t). This voltage signal generates in the dipole Z a current, which is converted into a voltage U ₂ (t) by an amplifier A1 connected to the terminals of a resistor R _m , R _m being connected on the one hand, to the generator 16 and on the other hand, at dipole Z.

The voltage U (t) is also applied to the positive input of a comparator A ₀ whose negative input is at the average value of the signal, therefore at a zero value, thanks to the capacitor 25, which connects said negative input to the earth, a resistor 26 being, moreover, disposed between the two inputs of the comparator A ₀ . This comparator A ₀ makes it possible to detect the zero crossings of the voltage U (t) and emits a slot at each of these passages. A monostable flip-flop T detects the rising or falling edges of the output signal of A ₀ as appropriate, and generates pulses sent to a capture circuit Cp. These pulses control an electronic switch I which receives the output signal U ₂ (t) from the operational amplifier A ₁ . A capture of the voltage U ₂ (t) is thus carried out by sampling / blocking and a voltage is obtained which provides, via an operational amplifier A ₂ , an exploitable output U _S which makes it possible to obtain the instantaneous captured value of current i (to) at time t _o such that U (t _o ) = 0. We have (to) = 2.π.fo.C'.U, where C 'is the capacitance of the equivalent capacitor, U the peak amplitude of U (t) and f ₀ the frequency of U (t); the current value i (to) is independent of the conductance g.

The electronic circuit of Figure 4 and its operation for get the imaginary part alone of the admittance of the dipole Z will not not described here in more detail and we will refer, for this purpose, to the request French Patent No. 97-11480 in the name of the Applicant, which is incorporated here by reference.

Alternatively, instead of capturing the instantaneous value of the current when the voltage signal passes through 0, we could measure the phase shift between voltage and current as well as the amplitude of the current, for get the desired capacity value regardless of resistance, although in this case a calculation unit is necessary.

The advantage of the circuit of Figure 4 is that it can be used together with the microcontroller present in the electronic module integrated in the door lock, simply using an interface current acquisition.

In addition, a high frequency signal can be generated at the exterior and come to superimpose the detected measurement signals for different reasons, for example, by antenna effect, capacitive coupling parasite, induction, etc ... It can result in amplitude beats and phase on the measured current, as well as random errors on current measurements; for high frequency disturbances modulated by the generator. Of course, the measurements made do not are not sensitive to untimely phenomena called "detection" high frequency envelope "present in unmodulated disturbances because here the measurement does not take into account the components continue.

To overcome measurement errors caused by a radiated field type disturbance, it is possible to carry out a series of n elementary detections, n being a predetermined integer, each detection corresponding to a different frequency f _i , with i between 0 and not. From these n measurements, we will take the average value, having previously discarded all measurements having too great a discrepancy with respect to the other measurements. Then this average value will be compared with the threshold capacity value Cs for activating or not the vehicle identifier.

If all frequencies result in detections discordant, in the case of an extreme and very wide disturbance spectrum or deterioration of part of the system worth average cannot be reliably obtained and the system will be arranged to be placed "by default" in a state now the locking the lock.

The threshold capacity value Cs is acquired during assembly of the system on the vehicle, by self-learning the capacity values minimum Cmin and maximum Cmax which correspond respectively to a state of non-approach and maximum approach to the surface 15 by the user.

The threshold value Cs will be obtained by the following formula: Cs = Cmin + α Cmax 1 + α with 0 | α | 1

The value of the coefficient α is taken, preferably, less than 1 because the capacitance capacity curve as a function of the distance between the surface and the hand is of the exponential type. Therefore, in order to have a detection of the approach of the hand when it is still far enough away from the pallet, to allow a unlocking the lock before the user completes the pallet actuating stroke, it is better to weight more the value of the minimum capacity Cmin than that of the maximum capacity Cmax. For example, the threshold capacity value Cs will be determined so that it corresponds to a distance about 10 cm between the hand and the palette.

In the case of Figure 3, Cmin will be equal to C ₁ and Cmax will be at most equal to C ₂ + C ₁ . However, if the value of C ₁ is too high compared to C ₂ to obtain a reliable detection of the variation in capacitance, an additional inductance L can be used in parallel with the impedance Z of the dipole (see FIG. 5) to eliminate the detection of C ₁ . For example, we choose LC ₁ . (2 π fo) ² equivalent to 1 to eliminate C ₁ from the value detected by the module M and C 'then becomes a function only of C and C ₂ , C' varying between 0 and C ₂ .

Throughout the life of the system, recalibration automatic Cs can be kept operational, to prevent the detection system may become blocked for a prolonged period in a state leading to permanent activation of the identifier, this which could cause the vehicle battery to discharge. Through example, if the vehicle is parked close enough to a wall or of a pole, the detected capacity may increase accordingly and trigger the activation of the identifier. Therefore, we can predict that, if the detected capacity value remains stably higher during a period determined at the threshold value Cs, the value of minimum capacity Cmin is replaced by this new value, for shift the value of the threshold capacity Cs by as much and thus deactivate the identifier. Then, when this disturbance is removed, the detected capacity value becomes less than Cmin, and at the end of a predetermined duration, the system is arranged to replace Cmin by this new value detected when it remains stable during of this duration. Thus, the minimum capacity value Cmin returns to its usual reference value after a fixed period.

It is also better to change the value accordingly maximum capacity Cmax, so as to maintain the same ratio Cmax / Cmin.

Although the invention has been described in connection with a mode of particular achievement, it is obvious that it is by no means there limited and that it includes all the technical equivalents of the means described as well as their combinations, if these fall within the scope of the invention.

Claims (12)

Motor vehicle (V) equipped with a system for detecting the approach of a user (5), characterized in that it comprises: a metal surface (15) isolated from the vehicle mass (V) and connected to a high frequency wave generator (16), so that the torque formed by the vehicle mass and said surface define a high impedance radiating dipole (Z ₁ ) behaving like an antenna which is not tuned and which is undersized with respect to the wavelength, and a capacitance variation detector (2) connected to said surface (15) and intended to detect the variation of the capacitance of the dipole, said dipole having a capacitance which varies as a function of the capacitance of the capacitor (C) formed by the pair ( hand / surface (15)) whose capacity increases when the user's hand approaches said surface. Vehicle according to claim 1, characterized in that the the aforementioned surface (15) is part of a pallet (12) opening a opening (1) of a vehicle, said pallet being connected to a lock opening (4) by a mechanical connection (13), which is electrically conductive and isolated from vehicle ground to serve as a connection electric between said surface and the generator (16). Vehicle according to one of claims 1 or 2, characterized by the fact that the detector (2) is arranged to activate an identifier (3) on the vehicle in response to the detection of a variation in capacity, which identifier, first of all, checks, when activated, whether the user (5) carries an authorized identifier, and, secondly, if the verification shows that the identifier is recognized as correct, order at minus a function of the vehicle. Vehicle according to claim 3, characterized in that the detector (2) is arranged to activate the identifier when it detects a capacity greater than a predetermined threshold value Cs between a predetermined minimum capacity value Cmin of the dipole, corresponding to its residual capacity in the absence of the user, and a predetermined maximum capacity value Cmax dipole, corresponding to its capacity when a user's hand (5) is in contact with said surface (15). Vehicle according to claim 4, characterized in that the threshold value Cs is obtained by the following formula: Cs = Cmin + α Cmax 1 + α α being a dimensionless coefficient between 0 and 1. Vehicle according to claim 5, characterized in that it includes a system to perform automatic recalibration of the threshold value Cs when the detected capacity value remains stably higher than this threshold value Cs during a predetermined duration, the minimum capacity value Cmin taking then this new capacity value detected. Vehicle according to one of claims 5 or 6, characterized by the fact that it has a system to perform a recalibration automatic threshold value Cs when the capacity value detected remains stably below the capacity value minimum Cmin for a predetermined period, the capacity value minimum Cmin then taking this new detected capacity value. Vehicle according to one of claims 6 or 7, characterized by the fact that it has a system to change the capacity value maximum Cmax so as to keep the ratio Cmax / Cmin constant, when the minimum capacity value Cmin is changed by automatic recalibration. Vehicle according to one of Claims 1 to 8, characterized by the fact that it has a system for performing a series of detections elementary capacitors, each corresponding to frequencies generated different, said elementary capacity values detected of the same series then being averaged, possibly excluding the discordant values, said mean value then being compared with the predetermined threshold value Cs to activate, if necessary, the identifier (3). Vehicle according to one of Claims 1 to 9, characterized by the fact that the detector (2) is arranged to detect the imaginary part only of the admittance of the dipole for a fixed frequency delivered by a stable oscillator serving as a high frequency wave generator (16). Vehicle according to claim 10, characterized in that it comprises an inductance (L), parallel to the equivalent impedance (Z) of the dipole, determined to eliminate from the value of the detected capacity the residual capacity (C ₁ ) of the dipole in the absence of the user. Vehicle according to one of claims 1 to 11, characterized by the fact that the metal surface (15) is covered with a insulating overmolding.

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