Method for detecting a change in position of a wheel of a motor vehicle

Abstract

The present invention relates to a method for detecting positional changes of wheels (16a, 16b, 16c, 16d) of a motor vehicle (10), the vehicle including at least one central processing unit (12), at least two wheel units (14a, 14b, 14c, 14d) and at least one bidirectional communication component (18), each of the at least two wheel units including electronic components of a sensor and each of the at least two wheel units being mounted on one of the wheels (16a, 16b, 16c, 16d), the method comprising: a monitoring step, during which, while the vehicle is stationary, establishing a first pattern characterizing the position of the wheel units (14a, 14b, 14c, 14d); and an evaluation step, during which, measuring a possible first change in each of the first patterns (M1) to estimate whether the position of the wheel has changed.

Description

Technical Field

[0001] This patent application relates to a method for detecting changes in the position of the wheels of a motor vehicle, particularly applicable to the field of motor vehicle equipment. Background Technology

[0002] For safety purposes, a monitoring system known as "TPMS" (Tire Pressure Monitoring System) is equipped on motor vehicles.

[0003] Such a monitoring system typically includes: a central processing unit; wheel units, each equipped with an associated wheel of the vehicle; and a radio frequency communication component suitable for ensuring communication between each wheel unit and the central processing unit.

[0004] The central unit has an electronic processor abbreviated as "ECU" (Electronic Control Unit).

[0005] Each wheel unit includes electronic components for sensors to detect abnormal conditions in the wheel, in particular. These sensors may include tire pressure sensors, temperature sensors, and wheel acceleration sensors.

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

[0007] The communication component can exchange messages or signals bidirectionally between the central unit and / or the mobile terminal and each wheel unit. These messages specifically include data characterizing the operating parameters of each wheel and an identification code for each wheel unit.

[0008] Communication is conducted according to a communication protocol that uses ultra-high frequency (UHF) or "UHF" radio waves for short-range, two-way data exchange, for example, according to... Type of communication protocol.

[0009] To utilize the data transmitted by the wheel units, it is essential to know the position of each wheel unit on the various wheels of the vehicle. More specifically, position information is necessary to determine what recommended pressure threshold must be applied (depending on whether it is a front or rear wheel issue), and also to display the current pressure value at the associated wheel.

[0010] The position of the wheel unit relative to the position of the wheel in the vehicle is usually verified at the beginning of a new driving cycle, and according to the prior art, it is necessary to periodically send messages from the wheel unit to the central unit to synchronize with the determined angular position.

[0011] For this purpose, document WO 2012 / 139711 is known in particular, which describes a method for determining the position of the wheels of a motor vehicle by means of synchronized messages.

[0012] The energy required to send a message from each wheel unit is provided by the battery associated with the sending wheel unit.

[0013] However, the battery in each wheel unit has a limited lifespan and is not designed to be recharged. Therefore, energy consumption must be limited to optimize the lifespan of the battery in each wheel unit.

[0014] Furthermore, it should be noted that when verifying the wheel unit position at the beginning of each driving cycle, this yields an unchanged wheel unit position most of the time. This is because wheels are only replaced or rotated once or twice a year on average, especially when rotating between winter and summer tires, which represents less than one percent of the effective wheel unit position change in the wheel unit alignment procedure.

[0015] Also known is a method for verifying positional changes of wheel units, described in document US 2011 / 0304451, which queries each wheel unit when the engine is started in order to determine whether the position of the wheel unit has changed since the last engine start.

[0016] While this method allows for the restriction of the procedure used to verify the position of the wheel unit, it is complex to implement and requires auxiliary components such as a dedicated low-frequency antenna, a low-frequency controller, and dedicated wiring for each wheel unit.

[0017] Existing technologies do not provide a simple and reliable solution to ensure the detection of positional changes of wheel units with low energy consumption. Summary of the Invention

[0018] The present invention aims to address these shortcomings.

[0019] This and other objectives will become apparent from the following description, achieved by a method for detecting changes in the position of the wheels of a motor vehicle, the vehicle having:

[0020] -At least one central processing unit

[0021] - At least two wheel units, each wheel unit including electronic components of a sensor, and each wheel unit being mounted on one of the wheels of a motor vehicle, and

[0022] - At least one bidirectional radio frequency communication component, designed to ensure communication between the wheel unit and the central unit.

[0023] The method is characterized by comprising at least:

[0024] - Monitoring step: During this step, when the vehicle is stationary, each wheel unit sends a series of messages to the central unit via a communication component at a determined transmission rate. The central unit then establishes and records a first pattern for each wheel unit by measuring the power of the received messages. This first pattern represents the position of the wheel unit within the vehicle.

[0025] - An evaluation step, during which the central unit measures a possible first change in each first pattern, and the central unit compares the first change with a first predetermined threshold. If the measured first change is greater than the first predetermined threshold, the position of the wheel in question is estimated to have changed.

[0026] - A positioning step, which aims to determine the position of the wheels on the motor vehicle, and is performed if the position of at least two wheels was estimated to have changed during a previous evaluation step.

[0027] Other optional features employed individually or in combination in the method according to the invention:

[0028] The rate at which a series of messages are sent from each wheel unit is adjusted based on instantaneous changes in the first pattern of the wheel unit in question, measured during the evaluation step. This feature allows for limiting the number of messages sent, thereby limiting the battery stress on each wheel unit.

[0029] - The transmission rate of a series of messages sent by each wheel unit is determined by the central unit and transmitted to each wheel unit via the communication component;

[0030] - In response to received messages, the central unit sends a series of messages to each wheel unit via a communication component. Each wheel unit establishes and records a second pattern by measuring the power of the received messages. This second pattern characterizes the wheel unit's position within the motor vehicle. During this evaluation step, each wheel unit measures a possible second change in the associated second pattern and compares this second change to a second predetermined threshold. If the measured second change is greater than the second predetermined threshold, the position of the wheel in question is estimated to have changed. This feature makes the method more reliable by doubling the number of messages sent.

[0031] - The transmission rate of a series of messages sent by each wheel unit is adjusted according to the instantaneous changes in the second pattern of the wheel unit in question;

[0032] - This method is applied to a motor vehicle with four wheels, each wheel being associated with a wheel unit, the wheels forming a first lateral pair and an opposing second lateral pair, and also forming a first front pair and an opposing second rear pair. If the changes in measurements in each pattern of the two wheel units of the same pair of wheels are simultaneous, the position of the wheel is estimated to be unchanged.

[0033] -The motor vehicle has multiple central processing units, each of which is designed to communicate with each wheel unit via a two-way communication component;

[0034] - Each pattern is constructed by measuring the power of the received messages.

[0035] The present invention also relates to a motor vehicle comprising at least one central processing unit, at least two wheel units and at least one bidirectional radio frequency communication component, each wheel unit comprising electronic components of a sensor, and each wheel unit being mounted on one of the wheels of the motor vehicle, the bidirectional radio frequency communication component being designed to ensure communication between the wheel units and the central processing unit, characterized in that the central processing unit and / or the wheel units and / or the communication component are appropriately programmed to implement the above-described method. Attached Figure Description

[0036] Referring to the accompanying drawings, other features and advantages of the invention will become apparent from the following description, wherein:

[0037] [ Figure 1 [This diagram shows a motor vehicle equipped with wheel units and communication components, to which the method according to the invention is applied;]

[0038] [ Figure 2 ]: The first pattern M1, representing the position of one of the wheel units, is depicted in the form of a diagram.

[0039] [ Figure 3 ]: The second pattern M2, which represents the position of one of the wheel units, is depicted in the form of a diagram.

[0040] For clarity, in all the accompanying drawings, the same or similar elements are indicated by the same or similar reference numerals. Detailed Implementation

[0041] Figure 1A motor vehicle 10 is depicted, equipped with: a central processing unit 12; four wheel units 14a, 14b, 14c, and 14d, each wheel unit mounted on associated wheels 16a, 16b, 16c, and 16d; and a two-way communication component 18. The four wheels 16a, 16b, 16c, and 16d form a first lateral pair of wheels on the left side, labeled 16a and 16d, and a second lateral pair of wheels on the opposite right side, labeled 16b and 16c; and a first front pair of wheels, labeled 16a and 16b, and a second rear pair of wheels, labeled 16c and 16d.

[0042] The central unit 12 features an electronic processor and memory, abbreviated as "ECU" (Electronic Control Unit).

[0043] Each wheel unit 14a, 14b, 14c, 14d, as part of a “TPMS” type monitoring system, includes an electronic housing containing sensor components dedicated to measuring parameters such as pressure and temperature of the tires fitted to the associated wheels 16a, 16b, 16c, 16d. Each wheel unit 14a, 14b, 14c, 14d also has a battery and memory (not shown).

[0044] The communication component 18 allows for bidirectional exchange of messages or signals between the central unit 12 and each wheel unit 14a, 14b, 14c, 14d.

[0045] For this purpose, the communication component 18 has a transmitter-receiver 24 associated with the central unit 12 and four transmitter-receivers 26a, 26b, 26c, 26d each associated with a wheel unit 14a, 14b, 14c, 14d.

[0046] The messages exchanged between the central unit 12 and each wheel unit 14a, 14b, 14c, 14d specifically include data characterizing the operating parameters of each wheel 16a, 16b, 16c, 16d and the identification code of each wheel unit 14a, 14b, 14c, 14d.

[0047] Communication is conducted according to a communication protocol that uses ultra-high frequency (UHF) or "UHF" radio waves for short-range, two-way data exchange. Preferably, the method according to the invention employs... A type of communication protocol that allows a message called a "scan request" to be sent immediately in response to a received message, which is called a "broadcast".

[0048] According to a first embodiment of the present invention, the method includes a monitoring step during which each wheel unit 14a, 14b, 14c, 14d sends a series of messages to the central unit 12 via the communication component 18 at a determined transmission rate.

[0049] For example, the sending rate of this series of messages is thirty seconds, meaning that a series of messages is sent every thirty seconds.

[0050] Another scenario involves performing monitoring procedures while the vehicle 10 is stationary, continuing until the start of the next operating cycle of the vehicle 10. It should be noted that message transmission from wheel units 14a, 14b, 14c, and 14d is typical behavior within the scope of a "TPMS" type monitoring system, particularly for transmitting information to the user's mobile terminal.

[0051] Upon receiving the message, the central unit 12 creates and records a first pattern M1 in its memory for each wheel unit 14a, 14b, 14c, 14d. The first pattern M1 represents the position of the wheel units 14a, 14b, 14c, 14d in the motor vehicle 10. The initial assumption is that the position of each wheel 16a, 16b, 16c, 16d is known and correct when the first pattern M1 is created.

[0052] Each first pattern M1 is established by the central unit 12 by measuring the power of the messages received by the wheel units 14a, 14b, 14c, and 14d.

[0053] In telecommunications, the power of a received message is known as the acronym RSSI, which stands for Received Signal Strength Indication. It is a measurement of the power of the received signal at the time of reception, providing an indication of the signal strength. This power measurement is expressed in "dBm," which is an abbreviation for the power ratio (in decibels) between the measured power and 1 milliwatt.

[0054] Therefore, a “pattern” refers to the distinctive features of a message or signal transmitted and / or received by the wheel units 14a, 14b, 14c, 14d or by the central unit 12 via the communication component 18. Each pattern represents the position of the associated wheel unit 14a, 14b, 14c, 14d in the motor vehicle 10 for transmitting or receiving these messages.

[0055] from Figure 2As can be seen, for example, the first pattern M1 associated with the first left front wheel unit 14a is depicted in the form of a coordinate graph, where the horizontal axis indicates the number of received messages “Nbm”, and the vertical axis indicates the power of the message measured in “dBm”. Curve C1 shows the power measurement result of the received message, and curve C2 of the first pattern M1 is shown to be a smooth curve of the average value of the power measurement result of the received message.

[0056] Furthermore, the method according to the invention includes an evaluation step during which the central unit 12 measures possible first variations in each first pattern Ml.

[0057] The central unit 12 also compares the first change with a first predetermined threshold. If the measured first change is greater than the first predetermined threshold, the position of the wheels 16a, 16b, 16c, and 16d in question is estimated to have changed. The predetermined threshold is, for example, 5 dBm. It should be noted that the change is an average value over time to avoid taking unwanted unknown factors into account. For example, the change is averaged over a period of three to five minutes.

[0058] Finally, the method includes a positioning step, which aims to determine the position of wheels 16a, 16b, 16c, and 16d on the motor vehicle 10. This positioning step, known from the prior art, is not central to the present invention and will therefore not be described in more detail.

[0059] According to a preferred exemplary embodiment, if the measured changes in the first pattern M1 of the two wheel units 14a, 14b, 14c, 14d of the same pair of wheels are simultaneous, the positions of the wheels 16a, 16b, 16c, 16d are estimated to be unchanged. For example, assuming that the wheel units 14a, 14d of the left-side first lateral pair of wheels 16a, 16d have measured simultaneous changes in their associated first pattern M1, the positioning step will not be performed. This feature of the invention covers situations where adjacent vehicles are parked to the side, in front of, or behind the motor vehicle 10, and the two wheels 16a, 16b, 16c, 16d of the same pair change simultaneously due to the reflection effect of radio waves.

[0060] However, without limitation, if the positions of at least two wheels 16a, 16b, 16c, 16d are estimated to have changed during the evaluation step, regardless of the pair of wheels in question, then it is conceivable to implement a positioning step.

[0061] According to another aspect of the invention, the transmission rate of a series of messages transmitted from each wheel unit 14a, 14b, 14c, 14d via the communication component 18 is adjusted based on instantaneous changes in the first pattern M1 of the wheel units 14a, 14b, 14c, 14d measured during the evaluation step. For example, the nominal transmission period of this series of messages is ten to thirty seconds. When a change in the first pattern M1 of one of the wheel units 14a, 14b, 14c, 14d is observed, for example, 2.5 dBm, the transmission frequency of the wheel units 14a, 14b, 14c, 14d is doubled, or even quadrupled. If no gradient greater than 2.5 dBm is observed within five minutes, the transmission period returns to the nominal period.

[0062] The transmission rate of a series of messages from each wheel unit 14a, 14b, 14c, 14d is determined by the central unit 12 and transmitted to each wheel unit 14a, 14b, 14c, 14d via the communication component 18.

[0063] According to a second embodiment of the present invention, in response to a received message, the central unit 12 sends a series of messages to each wheel unit 14a, 14b, 14c, 14d via the communication component 18, and each wheel unit 14a, 14b, 14c, 14d establishes and records a second pattern M2 (e.g., ...) by measuring the power of the messages received from the central unit 12. Figure 3 As shown), the second drawing M2 represents the position of the wheel units 14a, 14b, 14c, and 14d in the motor vehicle 10.

[0064] like Figure 3 As can be seen, the second pattern M2 is depicted in the form of a coordinate graph. The horizontal axis represents the number of received message measurements "Nbm", and the vertical axis indicates the message power measured in "dBm". Curve C1 shows the power measurement results of the received messages, and curve C2 of the second pattern M2 is a smoothed curve representing the average value of the power measurement results of the received messages.

[0065] According to this second embodiment of the invention, during the evaluation step, each wheel unit 14a, 14b, 14c, 14d measures a possible second change in the associated second pattern M2 and compares the second change with a second predetermined threshold. If the measured second change is greater than the second predetermined threshold, the position of the wheels in question 16a, 16b, 16c, 16d is estimated to have changed.

[0066] As with the first embodiment of the invention, the transmission rate of a series of messages sent by each wheel unit 14a, 14b, 14c, 14d is adjusted according to the instantaneous changes in the second pattern M2 of the wheel units 14a, 14b, 14c, 14d under discussion.

[0067] According to a variation of the embodiments common to the two embodiments described above, the motor vehicle 10 has a plurality of central processing units 12, each central unit 12 being designed to communicate with each wheel unit 14a, 14b, 14c, 14d via a bidirectional communication component 18.

[0068] Therefore, during the monitoring step, each wheel unit 14a, 14b, 14c, 14d sends a series of messages to each central unit 12, and during the evaluation step, each central unit 12 measures a possible first change M1 in each first pattern. The use of multiple central processing units 12 improves the reliability and robustness of the method according to the invention.

Claims

1. A method for detecting positional changes of wheels (16a, 16b, 16c, 16d) of a motor vehicle (10), said vehicle having: -At least one central processing unit (12), - At least two wheel units (14a, 14b, 14c, 14d), each wheel unit including electronic components of a sensor and each wheel unit mounted on one of the wheels (16a, 16b, 16c, 16d) of the motor vehicle (10), and - At least one bidirectional radio frequency communication component (18) is designed to ensure communication between the wheel units (14a, 14b, 14c, 14d) and the central processing unit (12). Its features are, The method includes at least: - Monitoring step, during which, when the motor vehicle (10) is stationary, each wheel unit (14a, 14b, 14c, 14d) sends a series of messages to the central processing unit (12) via the communication component (18) at a determined transmission rate, and the central processing unit (12) establishes and records a first pattern (M1) for each wheel unit (14a, 14b, 14c, 14d) by measuring the power of the received messages. The first pattern represents the position of the wheel unit (14a, 14b, 14c, 14d) in the motor vehicle (10). - An evaluation step, during which the central processing unit (12) measures a possible first change in each first pattern (M1), and the central processing unit (12) compares the first change with a first predetermined threshold. If the measured first change is greater than the first predetermined threshold, the position of the wheels in question (16a, 16b, 16c, 16d) is estimated to have changed. - A positioning step, which is designed to determine the position of the wheels (16a, 16b, 16c, 16d) on the motor vehicle (10), and is performed if the position of at least two wheels (16a, 16b, 16c, 16d) was estimated to have changed during a previous evaluation step.

2. The method according to claim 1, characterized in that, The transmission rate of a series of messages from each wheel unit (14a, 14b, 14c, 14d) is adjusted based on the instantaneous changes in the first pattern (M1) of the wheel unit (14a, 14b, 14c, 14d) in question, as measured during the evaluation step.

3. The method according to claim 2, characterized in that, The transmission rate of a series of messages sent by each wheel unit (14a, 14b, 14c, 14d) is determined by the central processing unit (12) and transmitted to each wheel unit (14a, 14b, 14c, 14d) via the communication component (18).

4. The method according to any one of claims 1 to 3, characterized in that, In response to the received messages, the central processing unit (12) sends a series of messages to each wheel unit (14a, 14b, 14c, 14d) via the communication component (18), and each wheel unit (14a, 14b, 14c, 14d) establishes and records a second pattern (M2) by measuring the power of the received messages. The second pattern represents the position of the wheel unit (14a, 14b, 14c, 14d) in the motor vehicle (10). During the evaluation step, each wheel unit (14a, 14b, 14c, 14d) measures a possible second change in the associated second pattern (M2) and compares the second change with a second predetermined threshold. If the measured second change is greater than the second predetermined threshold, the position of the wheel (16a, 16b, 16c, 16d) in question is estimated to have changed.

5. The method according to claim 4, characterized in that, The transmission rate of a series of messages sent by each wheel unit (14a, 14b, 14c, 14d) is adjusted according to the instantaneous changes in the second pattern (M2) of the wheel unit (14a, 14b, 14c, 14d) in question.

6. The method according to any one of claims 1 to 3, characterized in that, It is applied to motor vehicles with four wheels (16a, 16b, 16c, 16d), each wheel being associated with a wheel unit (14a, 14b, 14c, 14d), the wheels forming a first lateral pair (14a, 14d) and an opposing second lateral pair (14b, 14c), and also forming a first front pair (14a, 14b) and an opposing second rear pair (14c, 14d), the position of the wheel (16a, 16b, 16c, 16d) is estimated to be unchanged if the changes in measurements in each pattern (M1, M2) of the two wheel units (14a, 14b, 14c, 14d) of the same pair of wheels are simultaneous.

7. The method according to any one of claims 1 to 3, characterized in that, The motor vehicle (10) has multiple central processing units (12), each central processing unit (12) being designed to communicate with each wheel unit (14a, 14b, 14c, 14d) via the bidirectional radio frequency communication component (18).

8. The method according to any one of claims 1 to 3, characterized in that, Each pattern (M1, M2) is constructed by measuring the power of the received message.

9. A motor vehicle (10) comprising at least one central processing unit (12), at least two wheel units (14a, 14b, 14c, 14d), and at least one bidirectional radio frequency communication assembly (18), each wheel unit comprising electronic components of a sensor and each wheel unit mounted on one of the wheels (16a, 16b, 16c, 16d) of the motor vehicle (10), the bidirectional radio frequency communication assembly being designed to ensure communication between the wheel units (14a, 14b, 14c, 14d) and the central processing unit (12), characterized in that, The central processing unit (12) and / or the wheel units (14a, 14b, 14c, 14d) and / or the communication component (18) are appropriately programmed to implement the method as described in any one of claims 1 to 8.

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