Method for detecting the travel of a vehicle

Abstract

The invention relates to a method for detecting a rotational movement of a body relative to a fixed structure about an axis of rotation, the body comprising a sensor intended to perform measurements on the body and having a first radio frequency transceiver, the invention relates to a sensor comprising a first radio frequency transceiver intended to communicate with a second radio frequency transceiver provided on an electronic computer mounted on a fixed structure via a # imgabs0 # low-power communication link for transmitting measurements to the electronic computer, the sensor being capable of transmitting (1) a radio frequency signal, and the electronic computer is able to confirm the reception (2) of the radio frequency signal by transmitting the response signal to the sensor. The method comprises a step of detecting (6) a rotational movement of the body by means of the sensor by means of a response signal emitted by the electronic computer, and a step of adjusting (7) the periodicity of the radiofrequency signal emitted by the sensor as a function of rotation or non-rotation of the body.

Description

[Technical field]

[0001] The invention relates to a method for detecting the movement of a motor vehicle by means of a system for monitoring the tire pressure of the vehicle. [Background Technology]

[0002] Motor vehicle safety regulations require manufacturers to provide devices for monitoring the pressure of vehicle tires.

[0003] For this purpose, many pressure monitoring systems have been developed and put on the market in recent years.

[0004] As is well known, these pressure monitoring systems, usually denoted “TPMS” (“Tire Pressure Monitoring System”), usually comprise: at least one wheel unit (including at least one pressure sensor), which is arranged inside a chamber defined by the tire and the rim of a wheel of the vehicle; and a remote computing device, which has a unidirectional or bidirectional radio frequency communication link with the wheel unit, these computing devices usually being located in an electronic computer of an on-board central electronic unit (“Electronic Control Unit”, usually denoted “ECU”) of the vehicle.

[0005] The wheel unit and the ECU communicate via a radio frequency communication network. The wheel unit comprises a transmitter, and the ECU comprises a receiver.

[0006] Radio frequency frames (commonly referred to as "RF frames") are transmitted by the wheel units and received by the ECU in order to transmit wheel pressure parameters.

[0007] RF communication in Bluetooth Low Energy (commonly denoted "BLE") enables the short-range, two-way exchange of data using UHF radio waves in the 2.4 GHz band.

[0008] Compared to "regular" The advantage of low power consumption is that it allows very little energy to be consumed when sending small amounts of data.

[0009] The wheel unit may be secured inside the tread of the tire, or to an inflation valve of the tire which is mounted in an orifice formed in the rim.

[0010] The wheel unit of the tire is usually powered by a non-rechargeable battery, which may have a service life of, for example, ten years.

[0011] As is known, in pressure monitoring systems, accelerometers, impact sensors, or sensors sensing the Earth's magnetic field are used to detect the movement of the vehicle. This detection of the movement of the vehicle makes it possible to optimize the consumption of the wheel unit by limiting the number of radio frequency frames transmitted when the vehicle is stopped ("parking" mode). This makes it possible to reduce the energy consumption of the wheel unit and extend the service life of the battery.

[0012] However, adding accelerometers, collision sensors, or sensors for sensing the earth's magnetic field increases the complexity, weight, and cost of the wheel unit of the pressure monitoring system.

[0013] This also results in more product references to manage. [Summary of the invention]

[0014] The invention solves this problem by proposing a method for detecting the rotation of a body, in particular a wheel of a motor vehicle, which method makes it possible to reduce the complexity and weight of the wheel unit of the pressure monitoring system by reducing the number of components thereof.

[0015] The invention relates to a method for detecting a rotational movement of a body relative to a fixed structure about a rotation axis. The body comprises a sensor intended to measure the body and has a first radio frequency transceiver intended to detect a rotational movement of a body about a rotation axis. The low power communication link communicates with a second RF transceiver provided on an electronic computer mounted on the fixed structure to transmit the measurement value to the electronic computer. The sensor can periodically transmit a RF signal, and the electronic computer can confirm receipt of the RF signal by transmitting a RF response signal to the sensor.

[0016] According to the present invention, the detection method includes the steps of detecting the rotational movement of the body through the sensor with the aid of the response signals emitted by the electronic computer, and adjusting the periodicity of the radio frequency signals emitted by the sensor according to whether the body rotates or not.

[0017] The invention thus provides a method for detecting the rotation of a body, in particular a wheel of a motor vehicle, which method makes it possible to reduce the complexity and weight of a pressure monitoring system by reducing the number of its components.

[0018] There will also be fewer product references to manage.

[0019] The invention also makes it possible to reduce the energy consumption of the sensor and to extend the service life of the battery.

[0020] In a variant, during the step of adjusting the periodicity of the emitted signal, when the body is not rotating, the sensor emits periodic radio frequency frames intended to be received by the electronic computer with a first periodicity P1. When the body is rotating, the sensor emits periodic radio frequency frames with a second periodicity P2, wherein P2 is strictly greater than P1.

[0021] In a variant, during the step of detecting the rotational movement of the body, the sensor measures a response signal emitted by an electronic computer. If a change between two consecutive radio frequency response signals is detected, the body is considered to be rotating, otherwise, the body is considered to be stationary.

[0022] In a variant, a change in strength between two consecutive radio frequency response signals is considered significant if a detection threshold taking into account an error margin is reached.

[0023] This allows two consecutive RF response signals to be compared with an error margin (e.g., taking into account the accuracy of the measurement, ambient noise, nearby parked vehicles, and fluctuations between Bluetooth low energy channels).

[0024] In a variant, multiple measurements are averaged to filter these RF signals.

[0025] This makes it possible to take into account the fact that two consecutive RF response signals in “park” mode may be different.

[0026] In a variant, after detecting the rotation of the body, the sensor transmits a radio frequency frame with a second periodicity P2. The electronic computer confirms the reception of the radio frequency frame with a period of P2 by transmitting a response signal to the sensor. The sensor measures the strength of the continuous response signal transmitted by the electronic computer to determine the shape of the signal. If the shape of the signal is periodic, it is confirmed that the body is rotating. Otherwise, if the shape of the signal is not periodic, it is considered that the wheel is stationary.

[0027] This makes the method more reliable and ensures that the body is indeed rotated.

[0028] In a variant, during the step of detecting the rotational movement of the body, the sensor transmits radiofrequency frames, and if the electronic computer verifies the reception of these radiofrequency frames by transmitting a response signal to the sensor, the rotation of the body is detected. The sensor transmits radiofrequency frames with a second periodicity P2.

[0029] This variant provides a simpler method. If the electronic computer is activated, it means that the body is rotating.

[0030] In a variant, the step of detecting the rotational movement of the body is performed using a sensor in a "broadcast" mode in which a periodic signal of short duration is emitted by the sensor to allow connection to the electronic computer.

[0031] In a variant, the detection method is a method for detecting the movement of a motor vehicle comprising a pressure monitoring system intended to measure the tire pressure of a wheel of the vehicle. The wheel comprises a wheel unit capable of establishing A low power communication link is used to transmit the pressure measurements to the electronic computer of the vehicle's central electronic unit.

[0032] The invention also relates to a motor vehicle implementing the detection method as defined above. [Drawings]

[0033] Figure 1 A simplified diagram showing a method for detecting the rotation of a wheel according to a first embodiment of the present invention;

[0034] Figure 2 A simplified diagram shows a method for detecting the rotation of a wheel according to a second embodiment of the present invention. [Specific implementation method]

[0035] The invention relates to a method for detecting rotational movement of a body (and in particular a wheel) about a rotation axis relative to a fixed structure in order to determine whether the vehicle is moving or stopped ("parking mode").

[0036] The examples below are given for a pressure monitoring system associated with a wheel of a vehicle, but can also be applied to a system using Low power communication link to other monitoring or measurement systems associated with the rotating body.

[0037] The vehicle includes a pressure monitoring system, usually denoted as "TPMS" ("Tire Pressure Monitoring System"), and usually comprises: at least one wheel unit, which includes a pressure sensor and is arranged inside a chamber defined by the tire and the rim of a wheel of the vehicle; and a remote computing device, which has a two-way radio frequency communication link with the wheel unit, these computing devices are usually located in an electronic computer of an on-board central electronic unit ("Electronic Control Unit", usually denoted as "ECU") of the vehicle.

[0038] The wheel unit may be secured inside the tread of the tire, or to an inflation valve of the tire which is mounted in an orifice formed in the rim.

[0039] The wheel unit of the tire is usually powered by a non-rechargeable battery, which may have a service life of, for example, ten years.

[0040] The wheel unit and the central electronic unit communicate via a radio frequency communication network. The wheel unit comprises a first radio frequency transceiver assembly and the central electronic unit comprises a second radio frequency transceiver assembly.

[0041] Radio frequency frames (commonly referred to as "RF frames") are transmitted by the wheel units and received by the central electronic unit in order to transmit the wheel pressure parameters.

[0042] RF communication in Bluetooth Low Energy (commonly denoted "BLE") enables the short-range, two-way exchange of data using UHF radio waves in the 2.4 GHz band.

[0043] The wheel unit operates in two communication modes, namely a "broadcast" mode, in which a periodic signal of short duration is transmitted by the wheel unit to allow connection to the central electronic unit, and a "connection" mode, in which a stable connection is established between the wheel unit and the central electronic unit to transmit pressure measurements.

[0044] In the "broadcast" communication mode, a two-way communication link is established between the wheel unit and the central electronic unit. The central electronic unit confirms the receipt of the periodic signal by transmitting a radio frequency signal frame to the wheel unit. In other words, the central electronic unit confirms that the received signal has been correctly received by returning a specific radio frequency frame to the wheel unit. This operation of transmitting a radio frequency signal frame is usually denoted by the term "scan request".

[0045] The "broadcast" mode is first used to try to establish a radio frequency connection with the central electronic unit and may be changed to a "connect" mode so that pressure information can be exchanged between the wheel unit and the central electronic unit via radio frequency frames.

[0046] The "Connect" mode is optional.

[0047] The transmission power of the wheel unit is fixed and is increased to ensure successful reception of the radio frequency by the central electronic unit.

[0048] When the vehicle starts, the central electronic unit analyzes or scans its surrounding area to try to connect to the wheel unit. When the central electronic unit receives a signal transmitted by the wheel unit, the central electronic unit accepts (or confirms) the signal and notifies the wheel unit. More specifically, the wheel unit sends a radio frequency frame.

[0049] According to the present invention, a method for detecting the rotation of a wheel of a vehicle comprises: a step of detecting the rotational movement of the wheel by the wheel unit through a radio frequency signal transmitted by a central electronic unit and received by the wheel unit, and a step of adjusting the periodicity of the radio frequency signal transmitted by the wheel unit according to the movement of the wheel (i.e., the rotation or non-rotation of the wheel).

[0050] During the step of adjusting the periodicity of the transmitted signal, when the wheel is not rotating, the wheel unit transmits periodic radio frequency frames intended to be received by the central electronic unit with a first periodicity P1. When the wheel is rotating, the wheel unit transmits periodic radio frequency frames with a second periodicity P2, wherein P2 is strictly greater than P1. This makes it possible to save energy when the vehicle is parked.

[0051] According to a first embodiment of the invention, during the step of detecting the rotational movement of the wheel, the wheel unit transmits a radio frequency frame and the central electronic unit confirms the reception (or acknowledges) of the radio frequency frame by transmitting a response signal to the wheel unit.

[0052] The wheel unit measures the strength of the response signal emitted by the central electronic unit. If a change in strength between two consecutive RF response signals is detected, the wheel on which the wheel unit is mounted is considered to be rotating, otherwise, the wheel is considered to be stationary. More specifically, the change is a change in the received signal strength indication (RSSI) analyzed by the wheel unit. Since the received signal strength indication is determined by It is specified in the low power consumption standard and therefore available.

[0053] The wheel unit rotates and receives the RF response signal at different angles of the wheel, where the RF link budget varies, which does not happen when the vehicle is in "park mode".

[0054] Thus, if the variation between two consecutive RF response signals is not significant, in other words, if the two signals present the same or almost the same intensity (taking into account the error margin), the wheel is considered to be stationary and the vehicle is in "park" mode. If the variation between two consecutive RF response signals is significant, the wheel is considered to be rotating and the vehicle is moving. In fact, what is measured is the intensity of the electromagnetic field of the RF signal received by the wheel unit. The wheel unit analyses the level of RF power it receives.

[0055] To infer that the wheel is stationary, within an error margin (e.g., taking into account the accuracy of the measurement, ambient noise, nearby parked vehicles, and A comparison is performed between two consecutive RF response signals in the case of fluctuations between low-power channels).

[0056] A detection threshold may be applied. If this detection threshold is reached taking into account the above parameters capable of disturbing the RF signal and causing it to change (in other words, if the difference between two consecutive RF response signals is high enough), a strength change is detected.

[0057] If the change between two consecutive RF response signals is less than the detection threshold, the wheel is considered to be stationary.

[0058] In a variant, in the case where two consecutive RF response signals may differ when in “parking” mode, a plurality of measurements may be averaged with a determined period (that is to say with the same wheel angle between each measurement) so that the signal can be filtered.

[0059] according to Figure 1 , a simplified diagram of an example is shown, the detection method comprises: a first step 1, during which the wheel unit transmits a radio frequency frame; and a second step 2, during which the central electronic unit confirms the reception of the radio frequency frame by transmitting a response signal to the wheel unit, regardless of the communication mode ("broadcast" mode or "connection" mode).

[0060] The detection method comprises a third step 3 during which the wheel unit measures the intensity or power of the response signal emitted by the central electronic unit.

[0061] According to a first result (reference step numbered 4), if the variation between two consecutive RF response signals is not significant taking into account the error margin, it is considered that the wheel is stationary and the vehicle is in "parking" mode (reference step numbered 5).

[0062] According to the second result (reference step numbered 6), if the change between two consecutive RF response signals is significant and exceeds the detection threshold, it is considered that the wheel is rotating and the vehicle is moving.

[0063] The detection method comprises a fourth step 7 during which the wheel unit transmits radio frequency frames with a second periodicity P2, that is to say the wheel unit increases the periodicity of the radio frequency frames.

[0064] The detection method comprises a fifth step 8 during which the central electronic unit confirms (acknowledges) the reception of the radio frequency frames of period P2 by transmitting a response signal to the wheel unit.

[0065] The detection method comprises a sixth step 9 during which the wheel unit measures the strength of the continuous response signal emitted by the central electronic unit to determine the shape of the signal. In the event that the shape of the signal is periodic, it is confirmed that the wheel is rotating and therefore the vehicle is moving. In other words, the wheel unit analyses the level of radio frequency power it receives and identifies a (periodic) footprint which is a signature of the relative rotation of the wheels.

[0066] Preferably, in case the shape of the signal is sinusoidal, it is confirmed that the wheels are rotating and therefore the vehicle is moving.

[0067] exist Figure 1 In the simplified diagram of FIG. 1 , the rotation of the wheels and thus the movement of the vehicle are schematically illustrated by the result 10 .

[0068] If the shape of the signal is not periodic, the wheel is considered to be stationary and the vehicle is in "park" mode (refer to step marked 5).

[0069] The detection method comprises a seventh step 11 during which the central electronic unit switches to operating mode. The internal modes of the wheel unit are modified in order to significantly optimize its power consumption.

[0070] Before the method returns to the first step 1, a time delay step 12 may be added.

[0071] According to a second embodiment of the invention, during the step of detecting the rotational movement of the wheel, the wheel unit transmits a radio frequency frame, and if the central electronic unit confirms the reception of the radio frequency frame by transmitting a response signal to the wheel unit, the rotation of the wheel is detected.

[0072] If the vehicle is initially stationary, the wheel units transmit radio frequency frames with a first periodicity P1. When the central electronic unit is active, the wheel units increase the periodicity of the radio frequency frames to a second periodicity P2.

[0073] On the contrary, if the vehicle is initially moving, the wheel unit transmits the radio frequency frame with the second periodicity P2. When the central electronic unit is inactive, the wheel unit reduces the periodicity of the radio frequency frame to the first periodicity P1.

[0074] In fact, when the vehicle is stopped, the central electronic unit is turned off. When the vehicle starts to move, the central electronic unit is turned on and starts to respond to the wheel units. This response allows the wheel units to detect the movement of the vehicle.

[0075] according to Figure 2 , the detection method comprises a first step 13 during which, when the vehicle is stationary (“parking” mode), the wheel units transmit radio frequency frames with a low periodicity P1.

[0076] The detection method comprises a second step 14 of determining the movement of the vehicle. If the vehicle is moving, during a fourth step 15 the central electronic unit confirms the reception of the radio frequency frames from the wheel units by transmitting a response signal to the wheel units.

[0077] During a fifth step 16 , the wheel unit detects the response signal and switches to operating mode.

[0078] During a sixth step 17 , the periodicity of the radio frames is increased to a second periodicity P2 .

[0079] If the vehicle is stationary, a delay is applied during a seventh step 18 before the method loops back to the first step 13 .

Claims

1. A method for detecting a rotational movement of a body about a rotation axis relative to a fixed structure, the body comprising a sensor intended to perform measurements on the body and having a first radio frequency transceiver intended to communicate with a second radio frequency transceiver provided on an electronic computer mounted on the fixed structure via The invention relates to a method for transmitting a measurement value to the electronic computer by communicating via a low power consumption communication link, wherein the sensor is capable of periodically transmitting radio frequency signals, and the electronic computer is capable of confirming receipt of these radio frequency signals by transmitting radio frequency response signals to the sensor, characterized in that The method comprises the steps of detecting the rotational movement of the body through the sensor by means of the response signals emitted by the electronic computer, and adjusting the periodicity of the radio frequency signals emitted by the sensor according to the rotation or non-rotation of the body.

2. The detection method according to claim 1, characterized in that During the step of adjusting the periodicity of the transmitted signals, when the body is not rotating, the sensor transmits periodic radio frequency frames intended to be received by the electronic computer with a first periodicity P1, and when the body rotates, the sensor transmits periodic radio frequency frames with a second periodicity P2, wherein P2 is strictly greater than P1.

3. The detection method according to any one of claims 1 and 2, characterized in that During the step of detecting the rotational movement of the body, the sensor measures the intensity of the response signals emitted by the electronic computer and considers the body to be rotating if a change in intensity between two consecutive radio frequency response signals is detected, otherwise the body is considered to be stationary.

4. The detection method according to claim 3, characterized in that This strength change between two consecutive radio frequency response signals is considered significant if a detection threshold taking into account an error margin is reached.

5. The detection method according to claim 3, characterized in that: Multiple measurements are averaged to filter these RF signals.

6. The detection method according to any one of claims 3 to 5, characterized in that: After detecting the rotation of the body, the sensor transmits radio frequency frames with the second periodicity P2. The electronic computer confirms the reception of these radio frequency frames with a period of P2 by transmitting a response signal to the sensor. The sensor measures the strength of the continuous response signals transmitted by the electronic computer to determine the shape of these signals. When the shapes of these signals are periodic, it is confirmed that the body is rotating. Otherwise, if the shapes of these signals are not periodic, it is considered that the wheel is stationary.

7. The detection method according to claim 2, characterized in that: During the step of detecting the rotational movement of the body, the sensor transmits radio frequency frames, and if the electronic computer confirms the reception of these radio frequency frames by transmitting a response signal to the sensor, the rotation of the body is detected, the sensor transmitting radio frequency frames with the second periodicity P2.

8. The detection method according to claim 7, characterized in that The step of detecting the rotational movement of the body is performed using a sensor in a "broadcast" mode in which a periodic signal of short duration is emitted by the sensor to allow connection to the electronic computer.

9. The detection method according to any one of claims 1 to 8, characterized in that: The detection method is a method for detecting the driving of a motor vehicle, the motor vehicle comprising a pressure monitoring system, the pressure monitoring system is intended to measure the pressure of the tire of the wheel of the vehicle, the wheel comprising a wheel unit, the wheel unit being able to establish A low power communication link is used to transmit the pressure measurements to the electronic computer of the vehicle's central electronic unit.

10. A motor vehicle, characterized in that: The motor vehicle implements the method for detecting a rotational movement of a body as defined in any one of claims 1 to 9.

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