WO2010049091A1

WO2010049091A1 - Method and system for locating the position of wheels on a vehicle

Info

Publication number: WO2010049091A1
Application number: PCT/EP2009/007566
Authority: WO
Inventors: Youri Vassilieff
Original assignee: Continental Automotive France
Priority date: 2008-10-29
Filing date: 2009-10-22
Publication date: 2010-05-06
Also published as: FR2937772A1; FR2937772B1

Abstract

According to the invention, a vehicle (2) comprises a radiofrequency transmitter (13, 14, 15, 16, 17) combined with each wheel (3, 4, 5, 6, 7), each transmitter generating at least one radiofrequency carrier during transmission, and a signal processing member (18) provided with at least one radiofrequency reception output (20, 22). The method for locating the position of the wheels on a vehicle comprises the following steps: detecting (202) for each transmitter (13, 14, 15, 16, 17), and in response to at least one transmitted carrier, at least a first and a second reception carrier different from each other and subjected to different propagation conditions between said transmitter (13, 14, 15, 16, 17) and at least one reception input (32; 46, 48); and determining from the signals of said first and second reception carriers, a multidimensional model curve of the signal generated by each transmitter based on the position on the vehicle of the wheel with which it is combined.

Description

Method and system for locating the position of the wheels on a vehicle

The invention relates to a method and a system for locating the position of the wheels on a vehicle. More particularly, the vehicle is equipped with a tire pressure monitoring system and comprises a plurality of wheels each equipped with an RF radiofrequency signal transmitter generating at least one radiofrequency carrier, as well as a signal processing member having at least one least one RF reception input of said carrier.

Conventionally, it is known during assembly of a factory vehicle to introduce in the processing member the identity (identifier code) of each wheel mounted on the vehicle and their position thereon. It is thus possible for the processor to identify the position of a wheel, because it transmits through its radiofrequency transmitter a signal that contains its identity. However, if the position of the wheels is changed, for example during a rotation of the wheels intended to equalize the wear of the tires, the treatment unit (which is not kept informed of the modification of the position wheels), continues to display the position of a wheel by reference to its identity (as it was initially stored) so that the position information displayed in the event of an anomaly on the wheel does not correspond to the actual position of the wheel on the vehicle.

To remedy this drawback, the document EP 0 931 679 proposes a method of locating the position of the wheels on a vehicle, in which, the wheels each equipped with a detection module emit a detection signal representative of a state of wheel. The vehicle is further equipped with a wheel detection signal processing member. The method of locating the wheels, according to this document, consists in determining from an envelope of the detection signal (as received by the processing unit) a signature of the detection signal of each wheel as a function of its location on the vehicle and to memorize this signature and the corresponding location of the wheel in the treatment unit.

EP 0 931 679 briefly describes the determination of the signature from the envelope of the detection signal, the envelope having a periodic shape with a period equal to the current rotation period of the wheel. Such a determination mode has the disadvantage of depending on a time reference and therefore the speed of the vehicle since the period of the envelope is a function of the speed of rotation of the wheel.

It is therefore necessary during the signature determination step to provide a synchronous auxiliary time reference of wheel rotation and wheel speed. The object of the invention is to overcome the provision of an auxiliary time reference, synchronous with the rotation of the wheels and the speed of the wheel.

To this end, the subject of the invention is a method for locating the position of wheels on a vehicle, the vehicle comprising: one or more wheels each equipped with a radiofrequency signal transmitter generating at least one radiofrequency transmission carrier defined by an emission frequency, and

a signal processing element having at least one radio frequency reception input for said carrier. The method according to the invention is characterized in that it comprises the steps of:

detecting for each transmitter, in response to at least one transmitted carrier, at least first and second reception carriers, which are distinct from one another, and subjected to different propagation conditions between said transmitter and at least one reception entrance,

determining from the signals of said first and second reception carriers a multidimensional model curve of the signal emitted by each transmitter as a function of the position on the vehicle of the wheel with which it is associated, and

storing the multidimensional model curve and the corresponding position of the wheel in the treatment unit.

Thus by using a combination of several signals received from a single transmitter it is possible to obtain a model curve independent of the speed of rotation of the wheel and specific to the position of the transmitter on the vehicle and therefore significant position on the vehicle of the wheel that emitted the signals. According to particular embodiments, the location method comprises one or more of the following characteristics:

for each transmitter, the signal generated is a signal modulated according to a type modulation included in the set formed by the digital amplitude, frequency and phase modulations. the sum of the number of radiofrequency transmit carriers and the number of radiofrequency reception inputs is at least equal to three.

for each transmitter, the number of radiofrequency transmit carriers is equal to two and the number of radiofrequency reception inputs is equal to one. In this case the method according to the invention further comprises the steps consisting, for each transmitter, in:

Filtering the first and second reception carriers separate from one another in a first and second filtered signal, • generating by amplitude demodulation from the first and the second filtered signal respectively a first model curve of the first carrier in reception and a second model curve of the second carrier in reception. the number of radiofrequency transmit carriers is equal to one and the signal processing member comprises two radiofrequency reception inputs arranged to receive a first and a second carrier which are distinct by their response to different propagation conditions between said transmitter and the transmitter; respective receiving input. In this case the method according to the invention comprises for each transmitter the steps of

Detecting, respectively at the first input and the second reception input, said first and second reception carriers distinct from one another, and

• Generating by amplitude demodulation respectively from the first and the second carrier in reception a first model curve of the first carrier in reception and a second model curve of the second carrier in reception.

the multidimensional model curve of the signal emitted by each emitter as a function of the position on the vehicle of the wheel with which it is associated, is a two-dimensional model curve able to be represented by a set of points marked by two coordinates.

Advantageously, the method according to the invention also consists in reducing the multidimensional model curve to a so-called reduced model curve consisting of at least one characteristic section of said model curve. The invention also relates to a system for locating the position of the wheels on a vehicle comprising:

a plurality of wheels each equipped with a radiofrequency signal transmitter generating at least one radiofrequency transmission carrier defined by a transmission frequency, and a signal processing element having at least one radiofrequency reception input.

According to the invention this location system is characterized in that it comprises:

for each transmitter, means for generating, in response to at least one transmission carrier, at least a first and a second reception carrier that are distinct from each other and subjected to different propagation conditions between said transmitter and minus a receipt input, and means for determining from the signals of said first and second reception carriers a multidimensional model curve of the signal emitted by each transmitter as a function of the position on the vehicle of the wheel with which it is associated, and means for memorizing the multidimensional model curve and the corresponding position of the wheel in the treatment organ.

According to particular embodiments, the location system comprises one or more of the following characteristics:

each transmitter is adapted to transmit a carrier on each of two different frequencies and in that it comprises a single reception antenna and at least two different filters tuned respectively to said frequencies.

- Each transmitter is adapted to emit a carrier at a single frequency and in that it comprises at least two directional receiving antennas arranged at the processing member in two different positions. The invention will be better understood on reading the description of two embodiments which follow, given solely by way of example and with reference to the drawings in which:

1 is a schematic view of a system for locating the position of the wheels on a vehicle according to a first embodiment of the invention; FIG. 2 is a schematic view of a position-locating system; wheels on a vehicle according to a second embodiment of the invention,

FIG. 3 is a graphical view illustrating two two-dimensional models associated with two different transmitters mounted on two different wheels,

FIG. 4 is a generic flow diagram of the method for locating the position of the wheels, according to the invention,

FIGS. 5 and 6 are flow charts of particular examples of the location method of FIG. 4.

With reference to FIGS. 1 and 2, the method for locating the position of a wheel is intended to be implemented on a vehicle 2 having a plurality of wheels 3, 4, 5, 6, 7 each equipped with a signal transmitter identical radio frequency RF 13, 14, 15, 16, 17 respectively generating at least one radiofrequency carrier in the UHF band (referred to as Ultra High Frequency).

A radiofrequency transmission carrier is defined by its transmission frequency. The expression "several wheels" means at least two wheels, or all the wheels as shown in FIGS. 1 and 2, the left front wheel 3 being associated with the transmitter 13, the right front wheel 4 being associated with the transmitter 14, both left and right rear wheels 5 and 6 and the spare wheel 7 being each associated with a respective transmitter 15, 16, 17.

The vehicle comprises a processing member 18, mounted at the rear of the vehicle and in front of the spare wheel 7. This processing member is provided with at least one receiving inlet 20 (FIG. 1), (20, 22 ) (Figure 2).

The vehicle comprises a set of obstacles 24 constituted in particular by elements of the vehicle structure (not shown) and the engine block 26.

The set of obstacles 24 is able to modify in a different way the propagation of the radio frequency signals coming from the emitters 13, 14, 15, 16, 17 as a function of the position of these emitters on the vehicle, the rotational position of each transmitter relative to the wheel with which it is associated, the transmission frequency of at least one carrier of each transmitter and the position of at least one reception input.

The processing unit 18 comprises means 28 for determining directly and independently of the speed of the vehicle, from the signals received from a single transmitter, a multidimensional model curve of the transmitted signal. Thus, each transmitter has a model curve as a function of its position on the vehicle, and this independently of the speed of rotation of the wheel, as will be explained below.

The processing member 18 also comprises means 30 for storing a multidimensional model curve and the corresponding position of the wheel.

According to the first embodiment of the locating system represented in FIG. 1, each transmitter 13, 14, 15, 16, 17 is able to generate a signal on two carriers: the first at a frequency F1 and the second at a frequency frequency F2.

The spacing between the frequencies F1 and F2 guarantees different propagation conditions between the same transmitter, for example the transmitter 13, and the same reception input 20 located on the processing unit 18, for each of these frequencies. According to the first embodiment of the locating system represented in FIG. 1, the processing unit 18 thus comprises:

a single receiving antenna 32. This antenna is connected to the single reception point of entry 20 for the two carriers at frequencies F1 and F2. The signal picked up by the single antenna 32 is thus a frequency multiplex signal of the two carriers at frequencies F1 and F2.

a signal divider 34 with an input and two outputs whose input is connected to the reception input 20, two filter / demodulator assemblies 38, 40. The filter 38a of the first set 38 is selective at F1 and connected at the input to a first output of the divider 34, the filter 40a of the second set 40 being selective at F2 and connected at input to a second output of the divider 34. The amplitude demodulator 38b following the filter 38a of the first set 38, respectively the demodulator 40a in amplitude according to the filter 40b of the second set 40 is connected at the output to a first input 42, respectively a second input 44 of the means of determination 28.

- the means of determination 28 and

the means 30 for storing the multidimensional model curves and the corresponding positions of the wheels on the vehicle.

Thus, the two carriers at frequencies F1 and F2 received at the reception input

20, are separated at the output of the two filters 38a, 38b and demodulated in amplitude so as to input two determination means 28 (analog values) of said first and second received carriers F1 and F2, synchronous with one another and likewise periodicity, namely the periodicity of the rotation of the wheel on which the transmitter is mounted.

According to a second embodiment of the location system illustrated in FIG. 2, each transmitter is able to generate a signal on a single carrier at a frequency F3. In this case, the processing unit 18 comprises two directional receiving antennas 46, 48, each being respectively connected to a different receiving input respectively 20, 22 and oriented in a different direction. Here, the two directions are mutually orthogonal.

The distance separating the two reception inputs 20, 22 and / or the orientation difference of the antennas 46, 48 are fixed so as to guarantee different propagation conditions across the set of obstacles 24 between the same transmitter and the two receiving inlets 20, 22 located at the processing member 18.

The processing unit 18 also comprises, (as in the first embodiment) two demodulators 50, 52 in amplitude, the first demodulator 50 (respectively the second 52) being connected at the input to the reception input 20,

(respectively at the reception input 22).

The amplitude demodulator 50 (respectively the amplitude demodulator

52) is connected at the output to the first input 42, (respectively the second input

44) determining means 28. Thus, when for example the transmitter 13 generates a signal on a single carrier at a frequency F3, a first carrier is received at the frequency F3 at the input of 20 while at the same time a second carrier at the same frequency F3 is received at the reception input 22 distinct from the input 20.

The first and second carriers respectively received at the reception inputs 20 and 22 are amplitude modulated according to the same rotation period of the wheel 3 but with a different waveform due to the different propagation conditions.

The first and second carriers received are demodulated in amplitude by their associated demodulator 50, 52 so as to provide input means 28 for determining the first and second carriers received at the same frequency F3 but at different reception inputs. The received signals are synchronous with each other and of the same periodicity, namely the periodicity of the rotation of the wheel 3 on which the transmitter 13 is mounted.

With reference to FIGS. 1 and 2, the determination means 28 are able to provide a two-dimensional model curve associated with a transmitter (and especially its position on the vehicle).

The two-dimensional model curve is a curve, continuous or in pieces, contained in a plane, described as a function of time, each point at a given moment t having for first coordinate the amplitude of the signal of the first carrier received demodulated at the instant t and for second coordinate the amplitude of the signal of the second carrier received demodulated at the same time t.

In practice, the signals of the first and second received carriers are sampled and the respective samples of the two signals taken at the same time are associated in the form of a two-dimensional vector to achieve the model curve of a specific transmitter. To simplify the drawing of Figure 3, only two two-dimensional model curves provided by the determining means 28 are shown.

It is assumed here that the sampling frequency of the received carrier signals is significantly greater than the rotational speed of the wheels.

A first model curve 60, shown in solid lines, is in the form of a first continuous closed curve, it corresponds to the two amplitudes of the carriers received from the same transmitter defined according to any one of the illustrated embodiments. in Figures 1 and 2.

A first amplitude of the first carrier received by the processing unit

18, is encoded along an axis X1 and a second amplitude of the second received carrier is encoded along an axis X2. It is assumed here that the first model curve is determined when the transmitter 13 is transmitting and the remaining transmitters 14,

15, 16 and 17 are silent. A second pattern curve 62, shown in broken lines, for convenience, to distinguish it from the first signature 60, is in the form of a second closed curve, continuous in reality. It corresponds to the two amplitudes of the received carriers defined according to any one of the embodiments of FIGS. 1 and 2, a first amplitude being reported along the axis X1 and a second amplitude being reported along the axis X2. It is assumed here that the second model curve is determined when only the transmitter 14 is then transmitting and the remaining transmitters 13, 15, 16 and 17 are silent.

The closing of each model curve 60 and 62 results from the periodicity of rotation of each emitter with the associated wheel, and the value of the period of rotation of the wheel has no influence on the shape of each curve, since it translated only by the speed at which a point set by a current time describes the curve. These model curves are therefore independent of the period of rotation of the wheel and have a characteristic shape of the position of the wheel which emitted the signals from which they were formed.

The model curves are thus obtained from the amplitudes of the signals of the received carriers, that is to say by a simple representation in a conventional coordinate system, and independently of the speed of rotation of the wheels and consequently of the vehicle speed. Thus, obtaining the model curves 60 and 62 requires no assistance from an auxiliary speed signal of the wheel.

It should be noted that the transmission moments of the transmitters 13, 14, 15, 16 and 17 can be coordinated in a strictly deterministic manner by an exchange of coordination information of the transmission times between the transmitters, which requires the use of a common communication resource.

However, in practice, the transmit moments of the transmitters are programmed according to a law of distribution of the transmission moments defined so as to minimize the risk that the emission by a transmitter of a location signal is scrambled by a transmission other issuers. This transmission technique and its variants in a radio-frequency broadcasting type network (called broadcasting) are conventional and will not be detailed here.

It should also be noted that the two-dimensional model curve of an emitter, for example the model curve 60 of the emitter 13, is reducible to a reduced model curve 64 distinct from the two-dimensional model curves of the other emitters, for example the model curve 62. of the transmitter 14. The reduced model curve 64 comprises a set of one or more sections of the two-dimensional model curve 60, each section being distinct from the other model curves of the other emitters.

For example, the reduced model curve 64 of the model curve 60 comprises one or more sections 66, 68, 70, 72.

The sections 66 and 68 are parts of two protuberances of the model curve 60 which are outside and farthest from the model curve 62.

The sections 70 and 72 are parts of the model curve 60 which are internal to and farthest from the model curve 62. According to FIG. 4, a generic method 200 implemented by one of the position locating systems of the wheels described in FIGS. 1 and 2 comprises the following sequence of steps:

in a first step 201, each radiofrequency signal transmitter 13, 14, 15, 16, 17 generates at least one radiofrequency transmission carrier characterized by a transmission frequency.

in a second step 202, the set of obstacles 24 generates, for each transmitter 13, 14, 15, 16, 17 in response to at least one transmitted carrier, at least a first and a second receiver carrier, each of which is distinct. on the other, and subject to different propagation conditions between said transmitter and at least one reception input.

in a following step 204, the processing unit 18 determines from the signals of said first and second reception carriers a multidimensional model curve of the signal emitted by each transmitter as a function of the position on the vehicle 2 of the wheel to which it is associated. and then, in a step 206, the processing unit 18 stores the multidimensional model curve and the position (on the vehicle) of the transmitter that gave this curve.

Thus, an association is made between a model curve and a wheel position on the vehicle. Subsequently, each time a transmitter creates a model curve similar to that memorized it is deduced that the position of this transmitter on the vehicle is that which has been memorized for this model curve (whatever the identity of the wheel ). This makes it possible to quickly find the position of a wheel on the vehicle, without having to take into account the speed of rotation of the wheel. A permutation of the wheels can therefore be performed without this disturbing the determination of the position of each wheel since this determination is independent of the identity (identification code of each wheel).

According to FIG. 5, the location method 207 implemented by the location system described in FIG. 1 is more particularly detailed. This method 207 comprises the same steps as those described in FIG. 4 and these same steps carry the same references 201, 202, 204, 206.

A step 208 followed by a step 210 succeeds the step 202 and precedes the step 204. In step 208, the first and second reception carriers, distinct from each other, by the frequency as well as by their response to different propagation conditions between said transmitter and the reception input are filtered into a first and second filtered signal,

Then, in step 210, a first model curve of the first carrier in reception and a second model curve of the second carrier in reception are obtained by an amplitude demodulation from respectively the first and second filtered signal.

According to FIG. 6, the location method 211 implemented by the location system described in FIG. 2 is more particularly detailed. This method 211 comprises the same steps as those described in FIG. 4 and these same steps carry the same references 201, 202, 204, 206.

A step 212 followed by a step 214 succeeds to the step 202 and precedes the step 204.

In step 212, a first and second reception carrier are detected respectively at the first input 46 and the second reception input 48, which are distinct from one another by their response to different propagation conditions between the transmitter and the receiver. the corresponding receiving input.

Then, in step 214, a first model curve of the first receiver carrier and a second model curve of the second receiver carrier are generated by amplitude demodulation from the first and second receiver carriers, respectively.

As a variant, the transmission frequency of the radio frequency localization signal is located in the Very High Frequency (VHF) band.

Claims

A method of locating the position of wheels on a vehicle (2), the vehicle comprising:

one or more wheels (3, 4, 5, 6, 7) each equipped with a radiofrequency signal transmitter (13, 14, 15, 16, 17) generating at least one radiofrequency transmission carrier defined by a frequency of issue, and

a signal processing element (18) having at least one radiofrequency reception input (20, 22) for said carrier, said method being characterized in that it comprises the steps of:

detecting (202) for each transmitter (13, 14, 15, 16, 17), in response to at least one transmitted carrier, at least first and second reception carriers, distinct from one another, and subjected to different propagation conditions between said transmitter (13, 14, 15, 16, 17) and at least one receiving input (20, 22),

determining (204) from the signals of said first and second reception carriers a multidimensional model curve (60, 62) of the signal emitted by each transmitter as a function of the position on the vehicle (2) of the wheel with which it is associated , and

- Store (206) the multidimensional model curve (60, 62) and the corresponding position of the wheel in the treatment member (18).

2. A method of locating according to claim 1, characterized in that for each transmitter (13, 14, 15, 16, 17) the signal generated is a signal modulated according to a type modulation included in the set formed by the digital modulations amplitude, frequency and phase.

3. The locating method according to one of claims 1 and 2, characterized in that the sum of the number of radiofrequency transmit carriers and the number of radiofrequency reception inputs is at least equal to three.

4. Method of location according to one of claims 1 to 3, characterized in that for each transmitter the number of radio frequency transmitters is equal to two and the number of radio frequency reception inputs is equal to one.

5. Location method according to claim 4, characterized in that it further comprises the steps consisting, for each transmitter, in:

filtering (208) the first and second reception carriers separate from one another in a first and second filtered signal,

- Generating (210) by an amplitude demodulation from the first and the second filtered signal respectively a first model curve of the first carrier in reception and a second model curve of the second carrier in reception.

6. Location method according to one of claims 1 to 3, characterized in that the number of radiofrequency transmit carriers is equal to one and the signal processing member (18) comprises two radiofrequency reception inputs arranged to receive a first and a second carrier separated by their response to different propagation conditions between said transmitter (13, 14, 15, 16, 17) and the respective reception input.

7. Location method according to claim 6, characterized in that it comprises for each transmitter the steps of

detecting (212) respectively at the first input (20) and the second input (22) receiving said first and second reception carriers separate from each other, and

- Generating (214) by an amplitude demodulation respectively from the first and the second carrier in reception a first model curve of the first carrier in reception and a second model curve of the second carrier in reception.

8. Location method according to one of claims 1 to 7, characterized in that the multidimensional model curve (60, 62) of the signal emitted by each transmitter (12, 14) as a function of the position on the vehicle (2) of the wheel (3, 4, 5, 6, 7) with which it is associated, is a two-dimensional model curve able to be represented by a set of points marked by two coordinates.

9. Location method according to one of claims 1 to 8, characterized in that it comprises the step consisting, for each transmitter, in

- reducing the multidimensional model curve (60) to a reduced multidimensional model curve (64) consisting of at least one characteristic section of said model curve.

A system for locating the position of the wheels on a vehicle (2) comprising:

a plurality of wheels (3, 4, 5, 6, 7) each equipped with a radiofrequency signal transmitter (13, 14, 15, 16, 17) generating at least one radiofrequency transmission carrier defined by an emission frequency, and

a signal processor (18) having at least one radiofrequency reception input (20, 22), said system being characterized in that it comprises:

for each transmitter, means (24) for generating, in response to at least one transmission carrier, at least a first and a second reception carrier that are distinct from one another and subjected to different propagation conditions between said transmitter and at least one receiving input (32; 46, 48), and means (28) for determining from the signals of said first and second reception carriers a multidimensional model curve (60, 62) of the signal emitted by each transmitter as a function of the position on the vehicle (2) of the wheel to which it is associated, and - means (30) for storing the multidimensional model curve and the corresponding position of the wheel in the processing member (18).

Positioning system according to claim 10, characterized in that each transmitter (13, 14, 15, 16, 17) is adapted to transmit a carrier on each of two different frequencies (F1, F2) and in that comprises a single receiving antenna (32) and at least two different filters (38, 40) tuned respectively to said frequencies (F1, F2).

Location system according to claim 10, characterized in that each transmitter (13, 14, 15, 15, 17) is adapted to transmit a carrier at a single frequency (F3) and in that it comprises at least two directional receiving antennas (46, 48) arranged at the processing member in two different positions.