Method for positioning a wheel of a motor vehicle

Abstract

The invention relates to a method for positioning a wheel of a motor vehicle (10) comprising at least one central processing unit (12) comprising an ultra-wideband radiofrequency primary transceiver (24) and a plurality of wheel units (14a, 14b, 14c, 14d) each comprising an ultra-wideband radiofrequency secondary transceiver (26a, 26b, 26c, 26d) adapted to communicate with the primary transceiver (24), characterized in that it comprises at least one step of measuring the distance between the primary transceiver (24) and a secondary transceiver (26a, 26b, 26c, 26d) to be positioned by analyzing the propagation time of exchanged messages, and a step of positioning the wheel unit (14a, 14b, 14c, 14d) associated with the secondary transceiver (26a, 26b, 26c, 26d) to be positioned based on the distance measured in the measuring step.

Description

TECHNICAL FIELD

[0001] The present patent application relates to a method for positioning the wheels of a motor vehicle, which method is particularly applied in the field of tire monitoring systems for motor vehicles. BACKGROUND

[0002] For safety purposes, motor vehicles are known to be equipped with monitoring systems known by the acronym "TPMS" (Tire Pressure Monitoring System).

[0003] Such monitoring systems generally have a central processing unit, a wheel unit, each wheel unit being equipped with an associated wheel of the vehicle, and a radio frequency communication assembly adapted to ensure communication between each wheel unit and the central processing unit.

[0004] The central unit has an electronic processor known by the acronym "ECU" (Electronic Control Unit).

[0005] Each wheel unit comprises an electronic assembly of sensors in order to detect, among other things, abnormal situations of the wheel. For example, these sensors can be tire inflation pressure sensors, temperature sensors and wheel acceleration sensors.

[0006] In addition, each wheel unit has a battery and a memory.

[0007] In order to exploit the data transmitted by the wheel units, it is essential to know the position of each wheel unit. More particularly, the position information is necessary in order to know the recommended pressure threshold to be applied (depending on the question of whether it is a front wheel or a rear wheel) and also in order to display the current pressure value at the associated wheel.

[0008] This position constraint remains present throughout the life of the vehicle, in particular after the wheels have been replaced or the positions of these wheels have been swapped.

[0009] A method for positioning the wheels of a vehicle by angular correlation is known, for example from EP-0806306, EP-0895879 and FR-2974033, the principle of which is based on the correlation between a signal transmitted by an angle sensor mounted on a wheel and a signal transmitted by a speed sensor mounted on the vehicle in the vicinity of this wheel.

[0010] Generally, such a method using angular correlation is applied to a signal transmitted by a speed sensor of an active safety system such as an anti-lock braking system (ABS) and an electronic stability program (ESP).

[0011] TECHNICAL PROBLEM TO BE SOLVED

[0012] The state of the art, in particular through the detection methods by angular correlation, requires complex architectures and synchronization of the radiofrequency messages. SUMMARY

[0013] The object of the present invention is to solve these drawbacks, in particular by proposing a method for locating a wheel of a motor vehicle, which is fast and does not require angular measurements made by the active safety system.

[0014] This object and other objects, which will become apparent hereafter, are achieved by a method for locating a wheel of a motor vehicle, said vehicle having at least:

[0015] - a central processing unit comprising an ultra-wideband radiofrequency main transceiver, and

[0016] - a plurality of wheel units each comprising an electronic assembly of sensors and an ultra-wideband radiofrequency transceiver for communicating with the main transceiver, each wheel unit being mounted on a wheel of the motor vehicle,

[0017] said method comprising at least:

[0018] - an exchange step of at least one message exchanged between the main transceiver and a secondary transceiver to be located among said wheel units, the main transceiver sending a dated output message to the secondary transceiver to be located, the secondary transceiver to be located responding by sending a return message to the main transceiver, and thereafter, in a measurement step, the central unit analyzing the propagation times of the output message and the return message in order to measure the distance between the main transceiver and the secondary transceiver to be located,

[0019] - a measurement step of the distance between the main transceiver and the secondary transceiver to be located by analyzing the propagation times of said exchanged messages, and

[0020] - a locating step of said wheel unit associated with the secondary transceiver to be located in the motor vehicle based on the distance measured in the measurement step,

[0021] The method is remarkable in that the secondary transceiver to be located sends an initial message comprising data characterizing the operating parameters of the associated wheel, and that this initial message initiates the exchange step between the main transceiver and the secondary transceiver to be located.

[0022] Thus, the method according to the invention provides an effective solution for locating a wheel with limited technical resources.

[0023] Other optional features, taken separately or in combination, according to the method of the invention:

[0024] - a method applied to a motor vehicle comprising a main transceiver centred on the central longitudinal axis of the motor vehicle and a plurality of wheel units, each wheel unit being equipped with an accelerometer, said positioning step comprising a phase of discriminating the wheels, which comprises analysing the data transmitted by the accelerometers to discriminate the direction of rotation of the associated wheel and to discriminate the wheels laterally opposite on either side of the central longitudinal axis of the motor vehicle;

[0025] - a method applied to a motor vehicle comprising a main transceiver which is déporté, arranged in the motor vehicle such that the distances between said main transceiver and each secondary transceiver are not all identical. Thanks to this feature, it is possible to dispense with the use of accelerometers;

[0026] - during the positioning step, the distances measured in the second measurement step are compared with a preset standard distance in order to associate each measured distance with at least one secondary transceiver, thus locating said associated wheel.

[0027] The invention also relates to a motor vehicle comprising at least:

[0028] - a central processing unit comprising an ultra-wideband radiofrequency main transceiver, and

[0029] - a plurality of wheel units, each wheel unit comprising an electronic assembly of sensors and an ultra-wideband radiofrequency secondary transceiver for communicating with the main transceiver, each wheel unit being mounted on a wheel of the motor vehicle,

[0030] and which is remarkable in that said central unit and / or said wheel units are suitably programmed to implement the method described above. BRIEF DESCRIPTION OF DRAWINGS

[0031] Other features and advantages of the invention will become apparent on reading the following description, given with reference to the attached drawings, in which:

[0032] Figure 1 is a schematic view of a motor vehicle equipped with wheel units and a central unit centred on the central longitudinal axis of the vehicle, to which a method according to a first embodiment of the invention is applied;

[0033] Figure 2 is a schematic view similar to Figure 1 , in which the central unit is déporté, to which a method according to a second embodiment of the invention is applied.

[0034] For greater clarity, in all the figures, identical or similar elements are denoted by the same or similar references. DETAILED DESCRIPTION

[0035] Figure 1A motor vehicle 10 is depicted, equipped with a central processing unit 12 and four wheel units 14a, 14b, 14c, 14d, each wheel unit being mounted on an associated wheel 16a, 16b, 16c, 16d.

[0036] The four wheels 16a, 16b, 16c, 16d comprise a left front wheel, designated 16a, a right front wheel, designated 16b, a right rear wheel, designated 16c, and a left rear wheel, designated 16d, the pair of left wheels 16a, 16d being laterally opposite the pair of right wheels 16b, 16c about a central longitudinal axis A.

[0037] The central unit 12 has, inter alia, an electronic processor, abbreviated as "ECU" (Electronic Control Unit), and a memory.

[0038] Furthermore, the central unit 12 comprises a radiofrequency primary transceiver 24.

[0039] Each wheel unit 14a, 14b, 14c, 14d, as part of a "TPMS" type monitoring system, comprises an electronic housing containing a sensor assembly dedicated to measuring parameters such as the pressure and temperature of the tyre with which the associated wheel 16a, 16b, 16c, 16d is equipped. Each wheel unit 14a, 14b, 14c, 14d also has a battery and a memory (which are not shown).

[0040] Each wheel unit 14a, 14b, 14c, 14d is also equipped with a secondary transceiver 26a, 26b, 26c, 26d suitable for communicating and transmitting messages with the primary transceiver 24.

[0041] The messages exchanged between the primary transceiver 24 and each secondary transceiver 26a, 26b, 26c, 26d comprise, inter alia, data characterising the operating parameters of each associated wheel 16a, 16b, 16c, 16d and an identification code for each associated wheel unit 14a, 14b, 14c, 14d.

[0042] The communication is carried out according to a communication protocol using ultra- wideband radiofrequency radiation allowing bidirectional exchange of data.

[0043] The method according to the invention comprises a first exchange step comprising exchanging messages or signals between the primary transceiver 24 and each secondary transceiver 26a, 26b, 26c, 26d to be positioned subsequently.

[0044] More specifically, in the exchange step, the primary transceiver 24 sends a dated output message to the secondary transceiver 26a, 26b, 26c, 26d to be positioned, for example the secondary transceiver 26a associated with the front left wheel unit 14a, and the secondary transceiver 26a to be positioned subsequently responds by sending a return message to the primary transceiver 24.

[0045] According to a preferred embodiment of the application, the secondary transceiver 26a to be positioned sends an initial message comprising data characterizing the operating parameters of the associated wheel 16a and which initiates the exchange step between the primary transceiver 24 and the secondary transceiver 26a to be positioned. This is because, in the case of a TPMS type monitoring system, it is usual for each secondary transceiver 26a, 26b, 26c, 26d to send a message to the primary transceiver 24 at regular intervals or when an event occurs, in order to transmit the operating parameters of the associated wheel 16a, 16b, 16c, 16d to the central unit 12.

[0046] The first exchange step is repeated for each secondary transceiver 26a, 26b, 26c, 26d of each wheel unit 14a, 14b, 14c, 14d, and is followed by a second measurement step of measuring the distance between the primary transceiver 24 and the secondary transceiver 26a to be positioned.

[0047] The second step of distance measurement comprises analyzing the propagation times of the output message and the return message in order to measure the distance between the primary transceiver 24 and the secondary transceiver 26a to be positioned.

[0048] The distance between the primary transceiver 24 and the secondary transceiver 26a to be positioned is calculated, for example, by multiplying the propagation times of the output message and the return message by the speed of light and then dividing the result by 2, taking into account the response latency of the secondary transceiver 26a to be positioned, which is known. This is because electromagnetic radiation propagates at the speed of light in a vacuum, regardless of its frequency. The signals sent by the transceivers are physically electromagnetic waves radiated by antennas and therefore propagate at the speed of light.

[0049] The calculation of the distance based on the propagation time or time of flight of ultra- wideband radio frequency messages is known in the prior art and will therefore not be described again.

[0050] The second measurement step is repeated for each secondary transceiver 26a, 26b, 26c, 26d of each associated wheel unit 14a, 14b, 14c, 14d.

[0051] After the second measurement step, the method comprises a third positioning step of positioning the wheel unit 14a or wheel 16a associated with the secondary transceiver 26a to be positioned in the motor vehicle 10, based on the distance measured in the previous second measurement step.

[0052] According to a first embodiment of the method according to the application, as shown in Figure 1 The main transceiver 24 is centered on the central longitudinal axis A of the motor vehicle 10.

[0053] Thanks to the central position of the main transceiver 24, the front left wheel unit 14a and the front right wheel unit 14b are equidistant from the main transceiver 24. Similarly, the rear right wheel unit 14c and the rear left wheel unit 14d are equidistant from the main transceiver 24.

[0054] In order to distinguish between the two equidistant wheel units 14a, 14b, 14c, 14d, it is necessary to determine their respective direction of rotation, or more precisely, the direction of rotation of the associated wheels 16a, 16b, 16c, 16d.

[0055] This is because the wheels arranged on the left of the central axis A of the motor vehicle 10 and the opposite wheels arranged on the right of the central axis A of the motor vehicle 10 rotate in opposite directions of rotation.

[0056] To this end, still with reference to the first embodiment, each wheel unit 14a, 14b, 14c, 14d is equipped with an accelerometer (not shown) adapted to transmit to the central unit 12 a signal characterizing the direction of rotation of the associated wheel 16a, 16b, 16c, 16d.

[0057] The positioning step also comprises a phase of distinguishing between the wheels 16a, 16b, 16c, 16d, with the aim of distinguishing between the direction of rotation, and thus the lateral position, of the wheels 16a, 16b, 16c, 16d by analyzing the radial acceleration values transmitted by the associated accelerometer.

[0058] The phase of distinguishing between the wheels 16a, 16b, 16c, 16d also makes it possible to distinguish between two double wheels on the same axle. Double wheels of this type are mainly installed on heavy goods vehicles.

[0059] According to a second embodiment of the method according to the application, as shown in Figure 2 The main transceiver 24 is offset with respect to the central longitudinal axis A of the motor vehicle 10; that is to say, the main transceiver 24 is arranged in the motor vehicle 10 such that the distances between the main transceiver 24 and each of the secondary transceivers 26a, 26b, 26c, 26d are mutually different.

[0060] According to the second embodiment, therefore, in a third positioning step, the distances measured in the second measuring step are compared with a preset standard distance, in order to associate each measured distance with the appropriate secondary transceiver 26a, 26b, 26c, 26d, thus positioning each wheel unit 14a, 14b, 14c, 14d, and therefore each wheel 16a, 16b, 16c, 16d.

[0061] To this end, a preset standard distance of each secondary transceiver 26a, 26b, 26c, 26d from the primary transceiver 24 is recorded in a calibration table, which is stored in the memory of the central unit 12.

[0062] It will be apparent that the method according to the second embodiment can advantageously be applied to a motor vehicle 10 which does not have an accelerometer.

Claims

1. A method for positioning a wheel of a motor vehicle (10), said vehicle comprising at least: - a central processing unit (12) comprising an ultra-wideband radio frequency primary transceiver (24), and - a plurality of wheel units (14a, 14b, 14c, 14d) each comprising an electronic assembly of sensors and an ultra-wideband radio frequency secondary transceiver (26a, 26b, 26c, 26d) for communicating with the primary transceiver (24), each wheel unit (14a, 14b, 14c, 14d) being mounted on a wheel (16a, 16b, 16c, 16d) of the motor vehicle (10), said method comprising at least: - an exchange step of at least one message exchanged between the primary transceiver (24) and a secondary transceiver (26a, 26b, 26c, 26d) to be positioned among the wheel units, the primary transceiver (24) sending a dated output message to the secondary transceiver (26a, 26b, 26c, 26d) to be positioned, the secondary transceiver (26a, 26b, 26c, 26d) to be positioned responding by sending a return message to the primary transceiver (24), and thereafter, in a measurement step, the central processing unit (12) analyzing the propagation times of the output message and of the return message in order to measure the distance between the primary transceiver (24) and the secondary transceiver (26a, 26b, 26c, 26d) to be positioned, - a measurement step of the distance between the primary transceiver (24) and the secondary transceiver (26a, 26b, 26c, 26d) to be positioned by analyzing the propagation times of the exchanged messages, and - a positioning step of the wheel unit (14a, 14b, 14c, 14d) associated with the secondary transceiver (26a, 26b, 26c, 26d) to be positioned in the motor vehicle (10) based on the distance measured in the measurement step, said method being characterized in that the secondary transceiver (26a, 26b, 26c, 26d) to be positioned sends an initial message comprising data characterizing operating parameters of the associated wheel (16a, 16b, 16c, 16d), and in that the initial message initiates the exchange step between the primary transceiver (24) and the secondary transceiver (26a, 26b, 26c, 26d) to be positioned.

2. The method according to claim 1, applied to a motor vehicle (10), said motor vehicle comprising: the primary transceiver (24) being centered on a central longitudinal axis (A) of the motor vehicle, and a plurality of wheel units (14a, 14b, 14c, 14d), each equipped with an accelerometer, said positioning step comprising a phase of discriminating said wheels (16a, 16b, 16c, 16d), said phase comprising an analysis of the data transmitted by said accelerometers to discriminate the direction of rotation of the associated wheel (16a, 16b, 16c, 16d) and to discriminate the laterally opposite wheels (16a, 16b, 16c, 16d) on either side of said central longitudinal axis (A) of the motor vehicle (10).

3. The method according to claim 1 or 2, applied to a motor vehicle (10) comprising a main transceiver (24) eccentrically arranged in said motor vehicle (10) so that the distances between said main transceiver (24) and each secondary transceiver (26a, 26b, 26c, 26d) are mutually different.

4. The method according to any of the preceding claims, characterized in that, In said positioning step, the distances measured in the second measuring step are compared with preset standard distances in order to associate each measured distance with at least one secondary transceiver (26a, 26b, 26c, 26d), thus locating the associated wheel (16a, 16b, 16c, 16d).

5. A motor vehicle (10) comprising at least: - a central processing unit (12) comprising an ultra-wideband radiofrequency main transceiver (24), and - a plurality of wheel units (14a, 14b, 14c, 14d), each comprising an electronic assembly of sensors and an ultra-wideband secondary transceiver (26a, 26b, 26c, 26d) for communicating with said main transceiver (24), each wheel unit (14a, 14b, 14c, 14d) being mounted on a wheel (16a, 16b, 16c, 16d) of said motor vehicle (10), characterized in that said central processing unit (12) and / or said wheel units (14a, 14b, 14c, 14d) are suitably programmed to implement the method according to any one of claims 1 to 4.

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