EP0918309B2 - Locking system for motor vehicles detecting approach of the user - Google Patents

Description

The present invention relates to a motor vehicle equipped with a system for detecting the approach of a user.

Such detection systems are already used in certain motor vehicles to automatically trigger the unlocking of a door lock or an authorization for opening the door, as soon as the user approaches, without the latter needing to use a key or a remote control. To perform this automatic unlocking before opening the door, there is used a system generally called "hands-free access system", which system is to activate a remote exchange of information between an identifier on the vehicle and an identifier worn by the user. 'user. When the identifier has been recognized correct by the identifier, the lock will be unlocked, allowing the user to open the door by simply pulling on the door pallet.

However, it is not possible to leave the identifier and / or the identifier permanently enabled because their power consumption is too great. On the other hand, the identifier and the identifier must be able to be activated at all times because the approach of the vehicle by the user is unpredictable. Therefore, it has already been proposed to use a system for approach detection or entry of the pallet by the user, to activate the identifier of the vehicle only when the user prepares to open the door.

It has been proposed to equip the door pallets with an electric switch to detect the start of the actuating stroke of the pallet for the opening of the door. However, this solution has the disadvantage of performing a too late detection of the user's approach, because the time required for the identifier to correctly recognize the user's identifier and to control the unlocking of the lock is generally much longer than the time required for the user to complete the actuation stroke of the pallet. In other words, the door is generally not yet unlocked when the user has completed the stroke of actuation of the pallet and it is sometimes necessary that it actuates the pallet several times before obtaining the opening of the door.

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

The document EP-A-0735219 discloses a system for detecting the user's approach to waking up the on-board interrogation device, using an antenna connected to a Doppler, volumetric, or infra-red type of waking sensor.

The document DE No. 196 17 038 discloses a motor vehicle having a first electrode integrated with a handle of a door, a second electrode on the surface of the door, a capacitive detector integrated in the door handle, the capacitive sensor being connected by an electrical connection to the unit centralized control unit, a voltage of opposite poles being applied to the two electrodes and, to produce an electric field, between the handle and the door, the 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 for the purpose of identifying the user. However, such a system requires detecting a change in the electric field generated between two electrodes, and inserting the hand between the two electrodes, which delays the detection.

In addition, all currently known solutions require additional electrical connections between the pallet and another part of the door.

The aim of the invention is to eliminate the aforementioned drawbacks and to propose a motor vehicle equipped with a new approach detection system of a user, allowing a detection, which is anticipated compared with that of a contactor pallet and whose cost is lower than that of an optical detector or ultrasound, without the need for connection by connectors or additional electrical harness with the pallet.

For this purpose, the invention relates to a motor vehicle equipped with a user approach detection system, as defined in claim 1.

This capacitance detection could be processed by an electronic module, for example, previously integrated into the lock of a vehicle door, to control various functions, such as door lock unlocking, as well as the transfer of the door lock. information on the state of a lock to other locks.

According to the invention, the aforementioned surface is part of an opening pallet of a vehicle opening, for example, a door, a gas door, a trunk, said pallet being connected to a door lock by a mechanical linkage which is electrically conductive and isolated from the mass of the vehicle to serve as an electrical connection between said surface and said 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 sheathed cable or a control rod actuating a lever for opening the lock of the opening.

According to the invention, the detector is arranged to activate an identifier on the vehicle, which identifier, in the first place, checks, when activated, whether the user has an authorized identifier and, secondly, whether the verification shows that the identifier is recognized correct, controlled at least one function of the vehicle, for example the unlocking of a sash lock.

a étant un coefficient sans dimension compris entre 0 et 1.The threshold value Cs is advantageously obtained by the following formula: $$\mathrm{cs}=\frac{\mathrm{Cmin}+\mathrm{a\; <figure-callout\; id="1"\; label="Cmax"\; filenames="imgf0001.png"\; state="\{\{state\}\}">Cmax</figure-callout>}}{1+\mathrm{at}}$$

a being a dimensionless coefficient between 0 and 1.

In a particular embodiment, the device comprises a system for performing an automatic recalibration of the aforementioned threshold value. For example, when the detected capacity value remains stably greater than the threshold value Cs for a predetermined duration, for example of the order of 30 s, the minimum capacity value Cmin then takes this new capacity value. detected. Conversely, when the detected capacitance value remains stably lower than the minimum capacitance value Cmin for a predetermined duration, for example of the order of 2 s, Cmin then takes this new capacitance value detected. 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 ratio Cmax / Cmin constant.

According to yet another characteristic of the invention, the device comprises a system for performing a series of elementary capacitance detections, each corresponding to different generated frequencies, said elementary capacitance values detected from the same series being then averaged, while spreading out. possibly the discordant values, said average value then being compared with the predetermined threshold value Cs to activate, if necessary, the identifier. If all the generated frequencies of the same series result in discordant elementary detections, the system is arranged not to activate the identifier, in order to maintain the conviction security.

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

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

According to yet another characteristic, the metal surface may be covered with an insulating over-molding to protect it from external aggression.

Of course, one could alternatively measure the capacity of the dipole according to other methods: for example, by inserting the capacitor in an oscillator circuit whose frequency is measured, by measuring the impulse response of the capacitor to a pulse emission high frequency, or by measuring the modulus 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 an electronic module integrated in the lock.

To better understand the object of the invention will now be described by way of purely illustrative and non-limiting example, 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 :

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

According to the embodiment shown in the drawing, it has been indicated by broken lines on the figure 1 , a door 1 of a motor vehicle which comprises a detector 2, an identifier 3 and a lock 4. The detector 2 is intended to detect the approach of a user 5 of the door 1, as indicated by the arrow 6. When the 5 has been detected sufficiently close to the door 1, the detector 2 will emit a signal via a line 7 to the identifier 3 to activate it. When the identifier 3 is activated, it exchanges information signals with an identifier carried by the user 5, as represented by the two arrows with opposite directions 8, 9. As soon as the identifier 3 recognizes the identifier of the user 5 as correct, it sends a control signal through the line 10 to the lock 4 to cause its unlocking. The detector 2 has been arranged to detect the approach of the user 5 early enough to allow unlocking of the lock 4 before the user 5 actuates the same lock 4 by a pallet to open the door 1, according to an action indicated by the arrow 11.

However, in the case where the unlocking has not been completed by the time the user finishes lifting the pallet, provision can be made to use, in addition, a lock making unnecessary a double action on the door handle, for example the lock described in the request French Patent No. FR2767348 . In this case, the opening of the door will be at the same time as its unlocking.

To open the door 1, the user 5 must enter a door opening pallet 12 and exert a tensile force on it to cause the opening of the lock 4, by means of a sheathed cable 13 or a control rod connecting the pallet 12 to an opening lever 14 linked to the lock 4. As visible on the figure 2 , the pallet 12 comprises a metal surface portion 15, which is electrically connected to the detector 2 via the cable 13 and the lever 14 which are electrically conductive and isolated from the vehicle mass. The surface portion 15 may also be covered with overmolding to protect it from external aggression. Alternatively, the entire pallet 12 may constitute said metal surface. By using the mechanical connection 13 between the pallet 12 and the detection module 2, additional connectivity in the door is avoided.

Referring now to the figure 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 in the lock 4. In these conditions, the pair formed by, of firstly, the vehicle V which is grounded, and secondly, the whole of the surface 15 and the cable 13, defines a radiating dipole whose equivalent impedance Z ₁ is represented on the figure 3 . This impedance Z ₁ is generally constant and consists of a small capacitance C ₁ resulting from the residual capacitance of the cable 13 and a parallel conductance g ₁ , the value of which represents the resistive leaks between the assembly (cable pallet). lock) and the mass of the vehicle, this conductance may vary depending on untimely leakage to the ground, for example, in the presence of water in the door. The value of the admittance of the dipole must be minimized to limit the effect of radiation around the vehicle. In other words, this dipole is determined so that it behaves like an antenna that is not tuned and undersized with respect to the wavelength emitted by the generator 16. The dipole furthermore comprises, in parallel, a variable capacitance capacitor C 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 capacitance 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 overmoulding 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 furthermore comprises, in series with the capacitor C, an impedance Z ₂ equivalent to the user / mass torque, this impedance Z ₂ being generally small with respect to C and consisting of a capacitor C ₂ in parallel with a conductance g ₂ .

We will now refer to the figure 4 , which represents an electronic circuit for measuring the imaginary part alone of the admittance of the dipole. The fact of measuring the imaginary part alone of the admittance has the advantage of only detecting the capacitive part of the dipole and to overcome the value of the resistance of the dipole, which resistance can vary in the presence of more or less liquid. driver and therefore may distort the measurement to be made. As the frequency used is constant, one can model the radiating dipole by the simplified equivalent electrical diagram referenced Z. On the figure 4 it can be seen that the equivalent Z impedance of the dipole comprises a conductance g equivalent to the set of conductances g ₁ and g ₂ and, in parallel, a variable capacitance C 'equivalent to the set of capacitors C ₁ , C ₂ and C of the figure 3 .

The generator 16 is a stable oscillator delivering a sinusoidal voltage signal U (t), with U (t) = Ucos (2πf ₀ .t). This voltage signal generates a current in the dipole Z, which is converted into a voltage U ₂ (t) by an amplifier A1 connected across a resistor R _m , R _m being connected on the one hand to the generator 16 and on the other hand, at the 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, and therefore to a value of zero, thanks to the capacitor 25, which connects said negative input to the mass, a resistor 26 being furthermore 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 the case may be, and generates pulses sent on a capture circuit Cp. These pulses control an electronic switch I which receives the output signal U ₂ (t) of 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, via an operational amplifier A ₂ , provides an exploitable output U _S which makes it possible to obtain the instantaneous captured value. 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 well independent of the conductance g.

The electronic circuit of the figure 4 and its operation to obtain the imaginary part alone of the admittance of the Z dipole will not be described here in more detail and reference will be made, for this purpose, to the request of French patent No. FR2768508 in the name of the plaintiff.

In a variant, instead of capturing the instantaneous value of the current at the passage through 0 of the voltage signal, it would be possible to measure the phase difference between the voltage and the current as well as the amplitude of the current, in order to obtain the value of the desired capacity regardless of the resistance, although in this case a computing unit is required.

The interest of the circuit of the figure 4 is that it can be used together with the micro-controller present in the electronic module integrated to the door lock, simply using a current acquisition interface.

Moreover, a high-frequency signal can be generated externally and can be superimposed on the measurement signals detected for various reasons, for example, by antenna effect, parasitic capacitive coupling, induction, etc. This may result amplitude and phase beats on the measured current, as well as random errors on the current measurements, for the high frequency disturbances modulated by the generator. Of course, the measurements made are not sensitive to the so-called "high frequency envelope detection" phenomena present in the non-modulated disturbances because here the measurement does not take into account the DC components.

In order to overcome measurement errors caused by a radiated field-type disturbance, a series of n elementary detections can be made, n being a predetermined integer, each detection corresponding to a different frequency f 1, with i ranging from 0 to n . From these n measurements, the average value will be taken, having previously discarded any measurements which show too much discordance with respect to the other measurements. Then this average value will be compared with the threshold capacity value Cs for the activation or not of the identifier of the vehicle.

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

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

The threshold value Cs will be obtained by the following formula: $$\mathrm{cs}=\frac{\mathrm{Cmin}+\mathrm{\alpha \; <figure-callout\; id="1"\; label="Cmax"\; filenames="imgf0001.png"\; state="\{\{state\}\}">Cmax</figure-callout>}}{1+\mathrm{\alpha }}\mathrm{with}0\left|\mathrm{\alpha }\right|1$$

The value of the coefficient α is preferably less than 1 because the capacity curve of the capacitor 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 sufficiently distant from the pallet, to allow unlocking of the lock before the user has completed the actuation stroke of the pallet, it is better to weight more the value of the minimum capacity Cmin than that of the maximum capacity Cmax. For example, the threshold capacitance value Cs will be determined so that it corresponds to a distance of about 10 cm between the hand and the pallet.

In the case of figure 3 , Cmin will be equal to C ₁ and C max will be at most equal to C ₂ + C ₁ . However, if the value of C ₁ is too high relative to C ₂ to obtain a reliable detection of the capacitance variation, it is possible to use an additional inductance L in parallel with the dipole impedance Z (see FIG. figure 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 function only of C and C ₂ , C' varying between 0 and C ₂ .

Throughout the lifetime of the system, the automatic recalibration of Cs can be kept operational, to avoid that the detection system can be stuck in a prolonged state in a state leading to the permanent activation of the identifier, this which could cause a discharge of the vehicle battery. For example, if the vehicle is parked close enough to a wall or pole, the detected capacity may increase accordingly and trigger the activation of the identifier. Therefore, it can be predicted that, if the detected capacitance value remains stably greater than the threshold value Cs for a determined duration, the minimum capacitance value Cmin is replaced by this new value, to shift the value by the same amount. of the threshold capacity Cs and thus disable the identifier. Then, when this disturbance is suppressed, the detected capacitance value becomes less than Cmin, and after a predetermined duration, the system is arranged to replace Cmin with this new value detected when it remains stable during this period. . Thus, the minimum capacity value Cmin returns to its usual reference value after a determined period.

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

Although the invention has been described in connection with a particular embodiment, it is obvious that it is not limited thereto and that it comprises all the technical equivalents of the means described and their combinations, if they These are within the scope of the invention defined by the claims.

Claims (9)

1. Motor vehicle (V) equipped with a system for detecting the approach of a user (5), comprising:

   - a metallic surface (15) which is isolated from the chassis of the vehicle (V) and is connected to a high-frequency wave generator (16), so that the pair formed by the chassis of the vehicle and the said surface define a radiating dipole with high impedance (Z₁) behaving as an untuned antenna which is underdimensioned relative to the wavelength, and

   - a capacitance-variation detector (2) which is connected to the said surface (15) and is intended to detect the variation in the capacitance of the dipole ;

   characterized in that the said dipole having a capacitance which varies as a function of the capacitance of the capacitor (C) formed by the hand/surface (15) pair whose capacitance increases when the user's hand approaches the said surface, the detector (2) is designed to activate an identifier (3) on the vehicle when it detects a capacitance greater than a predetermined threshold value Cs lying between a predetermined minimum capacitance value Cmin of the dipole, corresponding to its residual capacitance in the user's absence, and a predetermined maximum capacitance value Cmax of the dipole, corresponding to its capacitance when the hand of a user (5) is in contact with the said surface (15), and in that the aforementioned surface (15) forms part of an opening handle (12) of an opening vehicle panel (1), the said handle being connected to an opening-panel lock (4) by a mechanical link (13) which is electrically conductive and isolated from the chassis of the vehicle in order to serve as an electrical connection between the said surface and the generator (16), and in that the said identifier, firstly, checks when it is activated whether the user (5) is carrying authorized identification and, secondly, if the check shows that the identification is recognized as correct, actuates at least one function of the vehicle.
2. Vehicle according to Claim 1, characterized in that the threshold value Cs is obtained by the following formula: $$\mathrm{Cs}\mathrm{=}\frac{\mathrm{Cmin}\mathrm{+}\mathrm{a\; Cmax}}{\mathrm{1}\mathrm{+}\mathrm{a}}$$

   

   a being a dimensionless coefficient lying between 0 and 1.
3. Vehicle according to Claim 2, characterized in that it includes a system for automatically recalibrating the threshold value Cs when the detected capacitance value remains stably greater than this threshold value Cs for a predetermined period of time, the minimum capacitance value Cmin then assuming this new detected capacitance value.
4. Vehicle according to one of Claims 2 and 3, characterized in that it includes a system for automatically recalibrating the threshold value Cs when the detected capacitance value remains stably less than the minimum capacitance value Cmin for a predetermined period of time, the minimum capacitance value Cmin then assuming this new detected capacitance value.
5. Vehicle according to one of Claims 3 and 4, characterized in that it includes a system for modifying the maximum capacitance value Cmax so as to keep the ratio Cmax/Cmin constant when the minimum capacitance value Cmin is modified by automatic recalibration.
6. Vehicle according to one of the preceding claims, characterized in that it includes a system for performing a series of elementary capacitance detections, each corresponding to different generated frequencies, the said detected elementary capacitance values in a given series then being averaged, optionally discarding the spurious values, the said average value then being compared with the predetermined threshold value Cs in order to activate the identifier (3) if appropriate.
7. Vehicle according to one of the preceding claims, characterized in that the detector (2) is designed to detect only the imaginary part of the admittance of the dipole for a fixed frequency delivered by a stable oscillator serving as a high-frequency wave generator (16).
8. Vehicle according to Claim 7, characterized in that it includes an inductor (L), in parallel with the equivalent impedance (Z) of the dipole, designed to eliminate from the detected capacitance value the residual capacitance (Ci) of the dipole in the user's absence.
9. Vehicle according to one of the preceding claims, characterized in that the metallic surface (15) is covered with an insulator moulded over it.

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