METHOD OF LOCATING THE POSITION OF WHEELS OF AN AUTOMOTIVE VEHICLE

Abstract

Disclosed is a method of locating the position of wheels of a vehicle equipped with an electronic unit for measuring operating parameters of each wheel, involving, for the purpose of locating the position of a wheel, the ordering of the transmission, by the electronic unit outfitting that wheel, of n RFi signals transmitted at times t.sub.1 to t.sub.n for angular positions .sub.1 to .sub.n of the electronic unit, to a central unit additionally connected to speed sensors that are each positioned in proximity to a wheel and able to furnish data .sub.1 representative of the orientation of the wheel.

Claims

1. A method of locating the position of wheels (1-4) of a vehicle (V) comprising: r wheels (1-4) equipped with an electronic unit (5-8) integrating means of measuring (9) the angular position of said electronic unit and a transmitter (10) designed to transmit signals containing data representative of operating parameters of each wheel and an identification code of said electronic unit, positioned on the vehicle (V) in proximity to each of the wheels (1-4), a wheel speed sensor (13-16) able to furnish data representative of the orientation of the wheel (1-4), and, integrated in the vehicle (V), a central unit (11), that is, provided with a receiver (12) for the receiving of the signals coming from the electronic units (5-8), and that is also connected to the different wheel speed sensors (13-16), said method of locating involving, for the purpose of locating the position of a wheel (1-4): for the electronic unit (5-8) equipping said wheel, the furnishing to the central unit (11), at successive times t.sub.1 . . . t.sub.n, of n signals RF1 . . . RFn transmitted for at least one angular position .sub.1 . . . .sub.n of said electronic unit, each of the n signals RF1 . . . RFn containing the identification code of the electronic unit (5-8) and data representative of the angular position .sub.1 . . . .sub.n of transmission, for the central unit (11): the gathering of the values B1 . . . Bn measured by each of the r wheel speed sensors (13-16), for each of the successive times t.sub.1 to t.sub.n, and the determining of so-called compensated values .sub.1 to .sub.n, determined in relation to a fixed unique reference position, by a compensation of each measured value B1 . . . Bn as a function of the data representative of the angular position 74 .sub.1 . . . .sub.n of transmission of the associated signal RF1 . . . RFn, the calculating, for each series of compensated values .sub.1 to .sub.n associated with a wheel speed sensor (13-16), of a characteristic value V.sub.n1, V.sub.n2 . . . V.sub.nr representative of the dispersion of said series of values, and the assigning of the identification code of the electronic unit (5-8) to the position of the wheel (1-4) situated in proximity to the wheel speed sensor (13-16) at the origin of the most clustered series of angular values .sub.1-.sub.n, and said method involving, in a preliminary phase, the determining of an angular value dmax corresponding to an angular tolerance of precision allowable for the angular position i of transmission of each signal RFi, and the determining of a corresponding compensated value .sub.max and then for each electronic unit: upon the receipt of each RFi signal furnished by said electronic unit, with i3, a value is calculated that is representative of the mean X(i) of the i compensated values .sub.1 to .sub.i obtained for each of the r wheel speed sensors (13-16), upon receipt of each RF(i+1) signal, with i3, the compensated value (.sub.i+1) obtained for each of the r wheel speed sensors (13-16) is measured, for each compensated value (.sub.i+1) a so-called comparison angular value .sub.com is calculated, such that:
.sub.com=.sub.(i+1)X(i), and the RF(i+1) signal is eliminated when all the calculated values .sub.com, each of which corresponds to a wheel speed sensor (13-16), are such that: .sub.com.sub.max.

2. The method of location as claimed in claim 1 wherein the assigning of an identification code of an electronic unit (5-8) to a wheel position (1-4) involves, starting with the receipt of the third signal RFi, selecting the two characteristic values V.sub.n1, V.sub.n2 of the lowest value, with V.sub.n2>V.sub.n1, and then when the ratio V.sub.n2/V.sub.n1 is greater than a predetermined threshold assigning the identification code to the wheel (1-4) situated in proximity to the wheel speed sensor (13-16) at the origin of the series of angular values having the characteristic value V.sub.n1, said method of location being wherein: one calculates only the angular comparison value .sub.com of the at least one of the two series of compensated values .sub.1 to .sub.i corresponding to the characteristic values V.sub.n1, V.sub.n2, one eliminates the signal Rfi when each calculated value .sub.com is such that: .sub.com.sub.max.

3. The method of location as claimed in claim 1, wherein, upon reception of a signal RFi, with i3, coming from an electronic unit (5-8): one takes into account, for the purpose of the determination of the new characteristic value of each dispersion, the selected value .sub.i such that the angular distance d between the value .sub.i and the mean X(i1) of the (i1) compensated values .sub.1-.sub.i1 is equal to min(d1, d2), where d1 and d2 represent the two complementary angular sectors delimited by the values .sub.i and X(i1) situated on a circular circumference, one calculates characteristic values V.sub.i of the dispersion of i angular values such that:
V.sub.i=V.sub.i1(i1)/i+d.sup.2(i1)/i.sup.2 with d=min(d1, d2).

4. The method of location as claimed in claim 3 wherein: one transforms the value .sub.max corresponding to the angular tolerance of precision dmax allowable for the angular position i of transmission of each signal RFi, into values Max(V.sub.i-V.sub.i1) expressed in terms of maximum variation value of variances, and such that, for each characteristic value V.sub.i1, V.sub.i2 . . . V.sub.ir:
Max (V.sub.i-V.sub.i1)=((i1)/i.sup.2)(dmax).sup.2(V.sub.i1)/i, one transforms each comparison value .sub.com into a value (V.sub.i-V.sub.i1) expressed in terms of a variation of variances, and one eliminates the signals RFi when each calculated value (V.sub.i-V.sub.i1) corresponding to a wheel speed sensor (13-16) is greater than or equal to the corresponding value Max(V.sub.i-V.sub.i1) calculated for this wheel speed sensor (13-16).

5. The method of location as claimed in claim 1, wherein one increments the number of signals RFi eliminated, and one proceeds with an overall reinitialization of the location procedure when the number of signals eliminated exceeds a predetermined threshold.

6. The method of location as claimed in claim 1, further comprising, for each electronic unit (5-8), after the receipt of the first three signals RF1-RF3 furnished by said electronic unit: calculating the maximum angular deviation between the 3 compensated values .sub.1 to .sub.3 obtained for each of the r wheel speed sensors (13-16), eliminating the group of the first three signals RF1-RF3, and ordering an overall reinitialization of the location procedure when for all the wheel speed sensors (13-16) the maximum deviation between the 3 compensated values .sub.1 to .sub.3 is greater than a predetermined compensated value .sub.max which is lower in value than the value .sub.max.

7. The method of location as claimed in claim 6 further comprising, for each electronic unit (5-8), after the receipt of the first two signals RF1-RF2 furnished by said electronic unit: calculating the maximum angular deviation between the 2 compensated values .sub.1 to .sub.2 obtained for each of the r wheel speed sensors (13-16), eliminating the first two signals RF1, RF2, and ordering an overall reinitialization of the location procedure when for all the wheel speed sensors (13-16) the deviation between the 2 compensated values .sub.1 to .sub.2 is greater than a predetermined value 2.sub.max which is lower in value than the value 3.sub.max.

8. The method of location as claimed in claim 2, wherein, upon reception of a signal RFi, with i3, coming from an electronic unit (5-8): one takes into account, for the purpose of the determination of the new characteristic value of each dispersion, the selected value .sub.i such that the angular distance d between the value .sub.i and the mean X(i1) of the (i1) compensated values .sub.1-.sub.i1 is equal to min(d1, d2), where d1 and d2 represent the two complementary angular sectors delimited by the values .sub.i and X(i1) situated on a circular circumference, one calculates characteristic values V.sub.i of the dispersion of i angular values such that:
V.sub.i=V.sub.i1(i1)/i+d.sup.2(i1)/i.sup.2 with d=min (d1, d2).

9. The method of location as claimed in claim 2, wherein one increments the number of signals RFi eliminated, and one proceeds with an overall reinitialization of the location procedure when the number of signals eliminated exceeds a predetermined threshold.

10. The method of location as claimed in claim 3, wherein one increments the number of signals RFi eliminated, and one proceeds with an overall reinitialization of the location procedure when the number of signals eliminated exceeds a predetermined threshold.

11. The method of location as claimed in claim 4, wherein one increments the number of signals RFi eliminated, and one proceeds with an overall reinitialization of the location procedure when the number of signals eliminated exceeds a predetermined threshold.

12. The method of location as claimed in claim 2, further comprising, for each electronic unit (5-8), after the receipt of the first three signals RF1-RF3 furnished by said electronic unit: calculating the maximum angular deviation between the 3 compensated values .sub.1 to .sub.3 obtained for each of the r wheel speed sensors (13-16), eliminating the group of the first three signals RF1-RF3, and ordering an overall reinitialization of the location procedure when for all the wheel speed sensors (13-16) the maximum deviation between the 3 compensated values .sub.1 to .sub.3 is greater than a predetermined compensated value 3.sub.max which is lower in value than the value .sub.max.

13. The method of location as claimed in claim 3, further comprising, for each electronic unit (5-8), after the receipt of the first three signals RF1-RF3 furnished by said electronic unit: calculating the maximum angular deviation between the 3 compensated values .sub.1 to .sub.3 obtained for each of the r wheel speed sensors (13-16), eliminating the group of the first three signals RF1-RF3, and ordering an overall reinitialization of the location procedure when for all the wheel speed sensors (13-16) the maximum deviation between the 3 compensated values .sub.1 to .sub.3 is greater than a predetermined compensated value 3.sub.max which is lower in value than the value .sub.max.

14. The method of location as claimed in claim 4, further comprising, for each electronic unit (5-8), after the receipt of the first three signals RF1-RF3 furnished by said electronic unit: calculating the maximum angular deviation between the 3 compensated values .sub.1 to .sub.3 obtained for each of the r wheel speed sensors (13-16), eliminating the group of the first three signals RF1-RF3, and ordering an overall reinitialization of the location procedure when for all the wheel speed sensors (13-16) the maximum deviation between the 3 compensated values .sub.1 to .sub.3 is greater than a predetermined compensated value 3.sub.max which is lower in value than the value .sub.max.

15. The method of location as claimed in claim 5, further comprising, for each electronic unit (5-8), after the receipt of the first three signals RF1-RF3 furnished by said electronic unit: calculating the maximum angular deviation between the 3 compensated values .sub.1 to .sub.3 obtained for each of the r wheel speed sensors (13-16), eliminating the group of the first three signals RF1-RF3, and ordering an overall reinitialization of the location procedure when for all the wheel speed sensors (13-16) the maximum deviation between the 3 compensated values .sub.1 to .sub.3 is greater than a predetermined compensated value 3.sub.max which is lower in value than the value .sub.max.

16. The method of location as claimed in claim 8, further comprising, for each electronic unit (5-8), after the receipt of the first three signals RF1-RF3 furnished by said electronic unit: calculating the maximum angular deviation between the 3 compensated values .sub.1 to .sub.3 obtained for each of the r wheel speed sensors (13-16), eliminating the group of the first three signals RF1-RF3, and ordering an overall reinitialization of the location procedure when for all the wheel speed sensors (13-16) the maximum deviation between the 3 compensated values .sub.1 to .sub.3 is greater than a predetermined compensated value 3.sub.max which is lower in value than the value .sub.max.

17. The method of location as claimed in claim 9, further comprising, for each electronic unit (5-8), after the receipt of the first three signals RF1-RF3 furnished by said electronic unit: calculating the maximum angular deviation between the 3 compensated values .sub.1 to .sub.3 obtained for each of the r wheel speed sensors (13-16), eliminating the group of the first three signals RF1-RF3, and ordering an overall reinitialization of the location procedure when for all the wheel speed sensors (13-16) the maximum deviation between the 3 compensated values .sub.1 to .sub.3 is greater than a predetermined compensated value 3.sub.max which is lower in value than the value .sub.max.

18. The method of location as claimed in claim 10, further comprising, for each electronic unit (5-8), after the receipt of the first three signals RF1-RF3 furnished by said electronic unit: calculating the maximum angular deviation between the 3 compensated values .sub.1 to .sub.3 obtained for each of the r wheel speed sensors (13-16), eliminating the group of the first three signals RF1-RF3, and ordering an overall reinitialization of the location procedure when for all the wheel speed sensors (13-16) the maximum deviation between the 3 compensated values .sub.1 to .sub.3 is greater than a predetermined compensated value 3.sub.max which is lower in value than the value .sub.max.

19. The method of location as claimed in claim 11, further comprising, for each electronic unit (5-8), after the receipt of the first three signals RF1-RF3 furnished by said electronic unit: calculating the maximum angular deviation between the 3 compensated values .sub.1 to .sub.3 obtained for each of the r wheel speed sensors (13-16), eliminating the group of the first three signals RF1-RF3, and ordering an overall reinitialization of the location procedure when for all the wheel speed sensors (13-16) the maximum deviation between the 3 compensated values .sub.1 to .sub.3 is greater than a predetermined compensated value 3.sub.max which is lower in value than the value .sub.max.

20. The method of location as claimed in claim 8, wherein one increments the number of signals RFi eliminated, and one proceeds with an overall reinitialization of the location procedure when the number of signals eliminated exceeds a predetermined threshold.

Description

[0056] Other characteristics, purposes and advantages of the invention will emerge from the following detailed description making reference to the appended drawings, which represent a nonlimiting preferred sample embodiment. In these drawings:

[0057] FIG. 1 is a schematic top view of a vehicle having a monitoring system and an active safety system enabling an implementing of the method according to the invention for locating the position of the wheels of said vehicle,

[0058] FIGS. 2a to 2d consist of four diagrams each representing, during the locating of a wheel, dispersions of values obtained from measurements performed by one of the wheel speed sensors,

[0059] and FIG. 3 is a diagram explaining the principle of determination of the angular distance d upon receiving a new signal of order n coming from an electronic unit.

[0060] The method according to the invention is adapted to being implemented for the purpose of locating the position of wheels of a vehicle V, as represented in FIG. 1, outfitted with four wheels 1-4 and equipped with a system for monitoring of parameters of tires, such as pressure or temperature, and an active safety system such as an ABS antilock wheel system or ESP dynamic stability control system.

[0061] Usually, the monitoring system typically comprises, in the first place, an electronic unit 5-8 associated with each wheel 1-4, for example one joined to the rim of said wheel so as to be positioned inside the casing of the tire.

[0062] Each of these electronic units 5-8 integrates sensors dedicated to the measuring of the parameters of the tires, being connected to a microprocessor computing unit which is connected to a transmitter 10.

[0063] Each of these electronic units 5-8 likewise integrates, in a classical manner, means 9 of measuring the angular position of said electronic unit. Such measurement means may advantageously consist of an accelerometer able to furnish modulated signals representative of values of gravity and thus of the angular position of the electronic unit, whose frequency, being equal to the frequency of rotation of the wheels, furthermore allows calculating of the speed of rotation of said wheels.

[0064] The monitoring system likewise comprises a central unit 11 situated in the vehicle V, comprising a microprocessor and integrating a receiver 12 able to receive the signals sent by the transmitters 10 of each of the four electronic units 5-8.

[0065] The vehicle V is likewise equipped with an active safety system such as an ABS antilock wheel system or ESP dynamic stability control system, comprising four wheel speed sensors 13-16 positioned on the vehicle V, each in proximity to a wheel 1-4, and adapted to furnish, in the form of values convertible into angular values, data representative of the orientation of said wheel.

[0066] Moreover, this active safety system comprises an ABS or ESP computer 17 connected to the various wheel speed sensors 13-16, so as to receive the wheel speed information measured by said sensors, and programmed to anticipate the adjustments designed to prevent locking of the wheels 1-4.

[0067] Usually, the wheel speed sensors 13-16 consist of inductive, magnetoresistive, or Hall effect sensors, which are adapted to measure the conditions of each wheel 1-4 on a toothed or magnetic wheel.

[0068] For the purpose of the locating of each wheel 1-4 of the vehicle V, the method according to the invention consists in using the data furnished by the accelerometers 9 and the sensors 13-16, according to the method described below.

[0069] In the first place, the electronic unit 5-8 equipping the wheel 1-4 to be located furnishes a plurality of signals RF1, RF2 . . . RFn transmitted at successive times t.sub.1, t.sub.2 . . . t.sub.n for angular positions respectively .sub.1, .sub.2 . . . .sub.n of said electronic unit. Each of these n signals RF1 . . . RFn in particular comprises, in a usual manner, the identification code of the electronic unit 5-8 and representative data for the angular position of transmission.

[0070] In parallel, each sensor 13-16 furnishes to the computer 17 the measured values B1 . . . Bn representative, for each successive time t.sub.1 to t.sub.n, of the orientation of the wheel 1-4 located opposite said measurement sensor.

[0071] The implementing of the location procedure according to the invention requires, first of all, a determining and memorizing of an angular value dmax, for example equal to 45, corresponding to an angular tolerance of precision allowable for the angular position Oi of transmission of each signal Rfi.

[0072] For the purpose of this implementation, the central unit 11 of the monitoring system is programmed, first of all, for each electronic unit 5-8:

[0073] to gather the values B1 . . . Bn measured for each of the r wheel speed sensors 13-16, for each of the successive times t.sub.1 to t.sub.n of transmission, by said electronic unit, of then signals RF1 . . . RFn,

[0074] to determine so-called compensated values .sub.1 to .sub.n, determined with respect to a fixed unique reference position, by a compensation of each measured value B1 . . . Bn as a function of representative data of the angular position .sub.1 . . . .sub.n of transmission of the associated signal RF1 . . . RFn.

[0075] The processing of these compensated values .sub.1 to .sub.n involves, first of all, after receipt of the first two signals RF1-RF2 furnished by an electronic unit 5-8:

[0076] calculating the maximum angular deviation between the 2 compensated values .sub.1, .sub.2 obtained for each of the r wheel speed sensors 13-16,

[0077] eliminating the first two signals RF1-RF2,

[0078] and ordering an overall reinitialization of the location procedure when, for all the wheel speed sensors 13-16, the maximum deviation between the 2 compensated values .sub.1, .sub.2 is greater than a predetermined compensated value .sub.max corresponding to an angular value d2max less than dmax, and for example equal to 18 for a value dmax=45.

[0079] The next step, carried out after validation of the first two signals RF1-RF2 furnished by an electronic unit 5-8, involves, after receipt of the third signal RF3 furnished by said electronic unit:

[0080] calculating the maximum angular deviation between the 3 compensated values .sub.1 to .sub.3 obtained for each of the r wheel speed sensors 13-16,

[0081] eliminating all three first signals RF1-RF3,

[0082] and ordering an overall reinitialization of the location procedure when, for all the wheel speed sensors 13-16, the maximum deviation between the 3 compensated values .sub.1 to .sub.3 is greater than a predetermined compensated value 3.sub.max corresponding to an angular value d3max greater than d2max and less than dmax, and for example equal to 30 for a value d2max=18 and a value dmax=45.

[0083] The processing of the compensated values .sub.1 to .sub.n then involves, after validation of the first three signals RF1-RF3 to be calculated for each signal RFi coming from an electronic unit 5-8, calculating for each series of compensated values .sub.1 to .sub.i associated with a wheel speed sensor 13-16 a characteristic value V.sub.n1, V.sub.n2 . . . V.sub.nr, in the example, the variance representative of the dispersion of said series of values.

[0084] For this purpose, according to the invention one calculates first of all, after validation of the third signal RF3, the variances V.sub.31, V.sub.32 . . . V.sub.3r of the series of compensated values .sub.1 to .sub.3, and then, upon receiving each following signal RFi, with i>3, coming from an electronic unit 5-8, one takes into account, for the purpose of the determination of the characteristic value V.sub.i of each dispersion, the value .sub.i selected such that the angular distance d between the value .sub.i and the mean X(i1) of the (i1) values .sub.1-.sub.i1 is equal to min(d1, d2), where d1 and d2 represent, as shown in FIG. 3, the two complementary angular sectors delimited by the values .sub.i and X(i1) situated on a circular circumference, and:

[0085] one calculates the variances V.sub.i of the dispersion of the i angular values by means of the formula:

V.sub.i=V.sub.i1(i1)/i+d.sup.2(i1)/i.sup.2 with d=min(d1, d2)

[0086] one selects the two characteristic values V.sub.i1, V.sub.i2 of lowest value, with V.sub.i2>V.sub.i1 (values of the dispersions represented in FIGS. 2b and 2d which correspond to the dispersions obtained for a number n of signals RFi),

[0087] one compares the ratio V.sub.i2/V.sub.i1 to a predetermined decision threshold, and: [0088] one assigns the identification code to the wheel 1-4 situated in proximity to the wheel speed sensor 13-16 at the origin of the series of angular values having the variance V.sub.i1, when the ratio V.sub.i2/V.sub.i1 is greater than the decision threshold, [0089] one continues the location procedure when the ratio V.sub.i2/V.sub.i1 is less than the decision threshold.

[0090] Moreover, the decision threshold advantageously has a value inversely proportional to the number of signals transmitted by the electronic unit 5-8. Thus, as an example, such as is described in the patent application WO 2012/139711, this decision threshold may vary between a maximum value equal to 8 for a number of signals transmitted by the electronic unit 5-8 equal to ten, and a minimum value equal to 2 for a number of signals transmitted equal to or greater than twenty.

[0091] Moreover, according to the invention, upon receiving each signal RFi coming from an electronic unit 5-8, and for at least one of the two characteristic values V.sub.i1, V.sub.i2 of lowest value, but preferably for these two values:

[0092] one calculates, for each calculated value Vi corresponding to a wheel speed sensor 13-16, a value Max(V.sub.i-V.sub.i1) expressing a maximum allowable value as the variation of the variances, and such that:

Max(V.sub.i-V.sub.i1)=((i1)/(dmax).sup.2(V.sub.i1)/i,

[0093] one eliminates the signals RFi when each calculated value (V.sub.i-V.sub.i1), each of which corresponds to a wheel speed sensor 13-16, is greater than or equal to the corresponding value Max(V.sub.i-V.sub.i1) calculated for this wheel speed sensor 13-16.

[0094] Furthermore, one increments the number of signals RFi eliminated, and one proceeds with an overall reinitialization of the location procedure when the number of signals eliminated exceeds a predetermined threshold.

[0095] As an example, the number of signals eliminated and resulting in an overall reinitialization is chosen equal to 5.

[0096] The method of location according to the invention as described above has the advantage of being a high-performance method in terms of responsiveness and reliability, furthermore not being susceptible to being affected by the transmission of aberrant data by the electronic units.