Method for detecting the movement of a vehicle

Abstract

The invention relates to a method for detecting a rotational movement of a body around an axis of rotation relative to a fixed structure, the body comprising a sensor intended to carry out measurements on the body and comprising a first radiofrequency transmitter / receiver intended to communicate with a second radiofrequency transmitter / receiver provided on an electronic computer mounted on the fixed structure by means of low energy Bluetooth® communication to transmit the measurements to the electronic computer, the sensor being able to emit (1) radiofrequency signals and the electronic computer being able to acknowledge receipt (2) of the radiofrequency signals by transmitting a response signal to the sensor.The method comprises a step of detecting (6) the rotational movement of the body by the sensor using the response signals transmitted by the electronic computer and a step of adapting (7) the periodicity of the radiofrequency signals emitted by the sensor as a function of the rotation or non-rotation of the body. Figure for the abstract: figure 1.

Description

Title of the invention: Method for detecting the movement of a vehicle Technical field

[0001] The present invention relates to a method for detecting the rolling of a motor vehicle by means of a system for monitoring the pressure of the tires of said vehicle. Prior art

[0002] Automotive safety legislation requires manufacturers to provide means of monitoring vehicle tire pressure.

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

[0004] As is known per se, these pressure monitoring systems, commonly referred to as "TPMS" (from the English "Tire Pressure Monitoring System"), typically comprise at least one wheel unit (comprising at least one pressure sensor) arranged inside the chamber defined by the tire and the rim of the wheel of a vehicle, and remote calculation means communicating with this wheel unit by single or two-way radio frequencies, these calculation means generally being located in the electronic computer of an on-board electronic central unit of the vehicle (commonly referred to as "ECU" for "Electronic Control Unit" in English).

[0005] Communication between the wheel unit and the ECU is performed via a radio frequency communication network. The wheel unit comprises a transmitter and the ECU comprises a receiver.

[0006] A radio frequency frame, generally called an “RF frame” is transmitted by the wheel unit and received by the ECU in order to transmit wheel pressure parameters.

[0007] Radio frequency communication is carried out using low energy Bluetooth® (commonly referred to as “BLE” for “Bluetooth Low Energy” in English) allowing the bidirectional exchange of data over short distances using UHF radio waves on the 2.4 GHz frequency band.

[0008] The advantage of Bluetooth® Low Energy over “classic” Bluetooth® is that it allows small amounts of data to be sent while consuming very little energy.

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

[0010] The tire wheel unit is typically powered by a non-rechargeable battery that may have a lifespan of ten years, for example.

[0011] It is known to use an accelerometer, a shock sensor or a terrestrial magnetic field sensor in pressure monitoring systems to detect the rolling of the vehicle. This rolling detection makes it possible to optimize the consumption of the wheel unit by limiting the number of radiofrequency frame emissions when the vehicle is stationary ("parking" mode). This makes it possible to reduce the energy consumption of the wheel unit in order to extend the battery life.

[0012] However, adding an accelerometer, shock sensor, or Earth's magnetic field sensor increases the complexity, weight, and cost of the wheel units of the pressure monitoring system.

[0013] This also results in more product references to manage. Statement 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, making it possible to reduce the complexity and weight of the wheel units of the pressure monitoring system, by reducing the number of its components.

[0015] The invention relates to a method for detecting a rotational movement of a body about an axis of rotation relative to a fixed structure. The body comprises a sensor for performing measurements on the body and comprises a first radio frequency transmitter / receiver for communicating with a second radio frequency transmitter / receiver provided on an electronic computer mounted on the fixed structure by means of low energy Bluetooth® communication to transmit the measurements to the electronic computer. The sensor is capable of transmitting radio frequency signals periodically and the electronic computer is capable of acknowledging receipt of the radio frequency signals by transmitting a radio frequency response signal to the sensor.

[0016] According to the invention, the detection method comprises a step of detecting the rotational movement of the body by the sensor using the response signals transmitted by the electronic computer and a step of adapting the periodicity of the radiofrequency signals emitted by the sensor as a function of the rotation or non-rotation of the body.

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

[0018] There are also fewer product references to manage.

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

[0020] Alternatively, during the step of adapting the periodicity of the emitted signals, the sensor emits periodic radiofrequency frames intended to be received by the electronic computer according to a first periodicity PI when the body is not rotating. The sensor emits periodic radiofrequency frames according to a second periodicity P2 when the body is rotating, P2 being strictly greater than PI.

[0021] Alternatively, during the step of detecting the rotational movement of the body, the sensor measures the intensity of the response signal emitted by the electronic computer. The body is considered to be rotating if a variation between two successive radiofrequency response signals is detected, otherwise the body is considered to be immobile.

[0022] Alternatively, the variation in intensity between two successive radiofrequency response signals is considered significant if a detection threshold taking into account a margin of error is reached.

[0023] This makes it possible to make a comparison between two successive radiofrequency response signals with a margin of error taking into account the measurement precision, the surrounding noise, a vehicle parking nearby, the fluctuation between the low energy Bluetooth channels, for example.

[0024] Alternatively, an average is taken over several measurements to filter the radiofrequency signals.

[0025] This makes it possible to take into account that in “parking” mode, two successive radiofrequency response signals may be different.

[0026] Alternatively, after detecting the rotation of the body, the sensor emits radiofrequency frames according to the second periodicity P2. The electronic computer acknowledges receipt of the radiofrequency frames of period P2 by transmitting a response signal to the sensor. The sensor measures the intensity of a succession of response signals emitted by the electronic computer to determine a shape of the signals. The rotation of the body is confirmed when the shape of the signals is periodic. Otherwise, the wheel is considered stationary if the shape of the signals is not periodic.

[0027] This makes the process more reliable and ensures that the body is rotating.

[0028] Alternatively, during the step of detecting the rotational movement of the body, the sensor emits radiofrequency frames, the rotation of the body being detected if the electronic computer acknowledges receipt of the radiofrequency frames by transmitting a response signal to the sensor. The sensor emits radiofrequency frames according to the second periodicity P2.

[0029] This variant provides a simpler method. Activation of the electronic calculator means that the body is rotating.

[0030] Alternatively, the step of detecting the rotational movement of the body is carried out with a sensor in “presence state” mode in which short periodic signals are transmitted by the sensor to authorize a connection with the electronic computer.

[0031] Alternatively, the detection method is a method for detecting the rolling of a motor vehicle comprising a pressure monitoring system intended to measure the pressure in a tire of a wheel of the vehicle. The wheel comprises a wheel unit capable of establishing low energy Bluetooth® communication to transmit pressure measurements to an electronic computer of an electronic central unit of the vehicle.

[0032] The invention also relates to a motor vehicle implementing the detection method as defined previously. Brief description of the drawings

[0033] [Fig. 1] [Fig. 1] represents a diagram of a method for detecting the rotation of a vehicle wheel, according to a first embodiment of the invention;

[0034] [Fig.2] [Fig.2] represents a diagram of a rotation detection method of a vehicle wheel, according to a second embodiment of the invention. Description of the embodiments

[0035] The invention relates to a method for detecting a rotational movement of a body around an axis of rotation relative to a fixed structure, and more particularly of a vehicle wheel to determine whether the vehicle is moving or stationary ("parking mode").

[0036] The example below is given for a pressure monitoring system associated with a wheel of a vehicle but can also be applied to other monitoring or measurement systems associated with a rotating body which uses low energy Bluetooth® communication.

[0037] The vehicle comprises a pressure monitoring system which is commonly referred to as "TPMS" (Tire Pressure Monitoring System in English), and which typically comprises at least one wheel unit, comprising a pressure sensor, arranged inside the chamber defined by the tire and the rim of the wheel of the vehicle, and remote calculation means communicating with this wheel unit by bidirectional radio frequencies, these calculation means generally being located in the electronic calculator of an on-board electronic central unit of the vehicle (commonly referred to as "ECU" for "Electronic Control Unit" in English).

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

[0039] The tire wheel unit is typically powered by a non-rechargeable battery. chargeable which can have a lifespan of ten years, for example.

[0040] Communication between the wheel unit and the electronic central unit is performed via a radio frequency communication network. The wheel unit comprises a first radio frequency transmitter / receiver assembly and the electronic central unit comprises a second radio frequency transmitter / receiver assembly.

[0041] A radio frequency frame, generally called an “RF frame” is transmitted by the wheel unit and received by the electronic central unit in order to transmit wheel pressure parameters.

[0042] Radio frequency communication is carried out using low energy Bluetooth® (commonly referred to as “BLE” for Bluetooth® Low Energy in English) allowing short-distance bidirectional data exchange using UHF radio waves on the 2.4 GHz frequency band.

[0043] The wheel unit operates according to two communication modes, including a “presence state” mode in which short-duration periodic signals are transmitted by the wheel unit to authorize a connection with the electronic central unit and a “connected” mode in which a stable connection is established between the wheel unit and the electronic central unit for the transmission of pressure measurements.

[0044] In "presence state" (or "advertising" in English) communication mode, a two-way communication is established between the wheel unit and the electronic central unit. The electronic central unit acknowledges the periodic signals by transmitting a frame of radiofrequency signals to the wheel unit. In other words, the electronic central unit confirms the correct reception of the received signal by returning a specific radiofrequency frame to the wheel unit. This operation of transmitting frames of radiofrequency signals is commonly referred to by the English term "scan-request".

[0045] The “presence state” mode is used first to try to establish a radio frequency connection with the electronic central unit and possibly switch to “connected” mode which allows pressure information to be exchanged by radio frequency frame between the wheel unit and the electronic central unit.

[0046] The “connected” mode is optional.

[0047] The transmission power of the wheel unit is fixed and high, to ensure a good radio frequency reception balance by the electronic central unit.

[0048] When the vehicle is started, the electronic central unit analyzes or scans its environment to search for the connection with the wheel unit. When the electronic central unit picks up a signal transmitted by the wheel unit, it accepts (or acknowledges) this signal and indicates it to the wheel unit. More particularly, the wheel unit sends radio frequency frames.

[0049] According to the invention, the method for detecting the rotation of the vehicle wheel comprises a step of detecting the rotational movement of the wheel by the wheel unit by means of the radiofrequency signals transmitted by the electronic central unit and received by the wheel unit and a step of adapting the periodicity of the radiofrequency signals emitted by the wheel unit as a function of the movement of the wheel, i.e. the rotation or non-rotation of the wheel.

[0050] During the step of adapting the periodicity of the emitted signals, the wheel unit emits periodic radiofrequency frames intended to be received by the electronic central unit according to a first periodicity PI when the wheel is not rotating. The wheel unit emits periodic radiofrequency frames according to a second periodicity P2 when the wheel is rotating, P2 being strictly greater than PL. 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 radiofrequency frames and the electronic central unit acknowledges receipt (or acknowledges) of the radiofrequency frames by transmitting a response signal to the wheel unit.

[0052] The wheel unit measures the intensity of the response signal emitted by the electronic central unit. The wheel on which the wheel unit is mounted is considered to be rotating if a variation in intensity is detected between two successive radiofrequency response signals, otherwise the wheel is considered to be stationary. More precisely, it is the variation in the signal strength indication (called “Received Signal Strength Indication” RSSI) which is analyzed by the wheel unit. The signal strength indication is available because it is required by the Bluetooth® low energy standard.

[0053] The wheel unit rotates, receives radio frequency response signals at different angles of the wheel, with a changing radio frequency link budget, which is not the case when the vehicle is in "parking" mode.

[0054] Thus, the wheel is considered stationary and the vehicle in “parking” mode if the variation between two successive radiofrequency response signals is not significant, that is to say if the signals have identical or almost identical intensities taking into account a margin of error. The wheel is considered rotating and the vehicle moving if the variation between two successive response signals is significant. It is in fact the intensity of the electromagnetic field of the radiofrequency signal received by the wheel unit which is measured. The wheel unit analyzes the radiofrequency power level which it receives.

[0055] To deduce that the wheel is stationary, the comparison between two successive radiofrequency response signals is carried out with a margin of error taking into account the measurement precision, the surrounding noise, a vehicle parking nearby, the fluctuation between the Bluetooth® low energy channels, for example.

[0056] A detection threshold can be applied. A variation in intensity is then detected if this detection threshold is reached, in other words if the difference between two successive radiofrequency response signals is sufficiently high, taking into account the previous parameters which can disturb and vary the radiofrequency signal.

[0057] If the variation between two successive response signals is less than this detection threshold, the wheel is considered stationary.

[0058] Alternatively, given that in “parking” mode, two successive radiofrequency response signals may be different, an average may be taken over several measurements over a determined period, i.e. over an identical wheel angle between each measurement, to enable the signal to be filtered.

[0059] According to the diagram of [Fig. 1] illustrating an example, the detection method comprises a first step 1 during which the wheel unit transmits radiofrequency frames and a second step 2 during which the electronic central unit acknowledges receipt of the radiofrequency frames by transmitting a response signal to the wheel unit, regardless of the communication mode (“presence state” mode or “connected” mode).

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

[0061] According to a first result (step referenced 4), the wheel is considered stationary and the vehicle in “parking” mode (step referenced 5) if the variation between two successive response signals is not significant taking into account the margin of error.

[0062] According to a second result (step referenced 6), the wheel is considered to be rotating and the vehicle to be rolling if the variation between two successive response signals is significant by exceeding a detection threshold.

[0063] The detection method comprises a fourth step 7 during which the wheel unit emits radiofrequency frames according to the second periodicity P2, that is to say it increases the periodicity of the radiofrequency frames.

[0064] The detection method comprises a fifth step 8 during which the electronic central unit acknowledges receipt (acknowledges) of the radiofrequency 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 intensity of a succession of response signals emitted by the electronic central unit to determine the shape of the signals. The rotation of the wheel and therefore the rolling of the vehicle are confirmed when the shape of the signals is periodic. In other words, the wheel unit analyzes the radiofrequency power level that it receives and identifies a (periodic) imprint, a signature of a relative rotation of the wheel.

[0066] Preferably, the rotation of the wheel and therefore the rolling of the vehicle are confirmed. when the shape of the signals is sinusoidal.

[0067] The rotation of the wheel and therefore the rolling of the vehicle are shown diagrammatically by result 10 of the diagram.

[0068] If the shape of the signals is not periodic, the wheel is considered stationary and the vehicle is in “parking” mode (step referenced 5).

[0069] The detection method comprises a sixth step 11 during which the electronic central unit switches to rolling mode. The internal modes of the wheel unit are modified in order to optimize in particular its electrical consumption.

[0070] A timing step 12 may be added before looping back to the first step 1.

[0071] According to a second embodiment of the invention, during the step of detecting the rotational movement of the wheel, the wheel unit transmits radiofrequency frames, the rotation of the wheel being detected if the electronic central unit acknowledges receipt of the radiofrequency frames by transmitting a response signal to the wheel unit.

[0072] If the vehicle was initially stationary, the wheel unit emitted radio frequency frames according to the first periodicity PL. The wheel unit increases the periodicity of the radio frequency frames according to the second periodicity P2 when the electronic central unit is activated.

[0073] On the contrary, if the vehicle was initially rolling, the wheel unit emitted radio frequency frames according to the second periodicity P2. The wheel unit reduces the periodicity of the radio frequency frames according to the first periodicity PI when the electronic central unit becomes inactive.

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

[0075] According to the diagram in [Fig.2], the detection method comprises a first step 13 during which the wheel unit emits radiofrequency frames according to the low periodicity PI when the vehicle is stationary (“parking” mode).

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

[0077] The wheel unit detects the response signal during a fifth step 16 and switches to rolling mode.

[0078] The periodicity of the radiofrequency frames is increased according to the second periodicity P2 during a fifth step 17.

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

Claims

Claims

1. A method of detecting a rotational movement of a body about an axis of rotation relative to a fixed structure, the body comprising a sensor for performing measurements on the body and comprising a first radio frequency transmitter / receiver for communicating with a second radio frequency transmitter / receiver provided on an electronic computer mounted on the fixed structure by means of low energy Bluetooth® communication to transmit the measurements to the electronic computer, the sensor being capable of transmitting radio frequency signals periodically and the electronic computer being capable of acknowledging receipt of the radio frequency signals by transmitting a radio frequency response signal to the sensor,characterized in that it comprises a step of detecting the rotational movement of the body by the sensor using the response signals transmitted by the electronic computer and a step of adapting the periodicity of the radiofrequency signals emitted by the sensor as a function of the rotation or non-rotation of the body.

2. Detection method according to claim 1, characterized in that during the step of adapting the periodicity of the emitted signals, the sensor emits periodic radiofrequency frames intended to be received by the electronic computer according to a first periodicity PI when the body is not rotating, the sensor emitting periodic radiofrequency frames according to a second periodicity P2 when the body is rotating, P2 being strictly greater than PI.

3. Detection method according to any one of claims 1 or 2, characterized in that during the step of detecting the rotational movement of the body, the sensor measures the intensity of the response signal emitted by the electronic computer, the body being considered to be rotating if a variation in intensity is detected between two successive radiofrequency response signals, otherwise the body being considered to be immobile.

4. Detection method according to claim 3, characterized in that the variation in intensity between two successive radiofrequency response signals is considered significant if a detection threshold taking into account a margin of error is reached.

5. Detection method according to claim 3, characterized in that an average is carried out on several measurements to filter the radiofrequency signals.

6. Detection method according to any one of claims 3 to 5, characterized in that after detection of the rotation of the body, the sensor emits radiofrequency frames according to the second periodicity P2, the electronic computer acknowledging receipt of the radiofrequency frames of period P2 by transmitting a response signal to the sensor, the sensor measuring the intensity of a succession of response signals emitted by the electronic computer to determine a shape of the signals, the rotation of the body being confirmed when the shape of the signals is periodic, otherwise, the wheel being considered stationary if the shape of the signals is not periodic.

7. Detection method according to claim 2, characterized in that during the step of detecting the rotational movement of the body, the sensor emits radiofrequency frames, the rotation of the body being detected if the electronic computer acknowledges receipt of the radiofrequency frames by transmitting a response signal to the sensor, the sensor emitting radiofrequency frames according to the second periodicity P2.

8. Detection method according to claim 7, characterized in that the step of detecting the rotational movement of the body is carried out with a sensor in “presence state” mode in which short periodic signals are transmitted by the sensor to authorize a connection with the electronic computer.

9. Detection method according to any one of claims 1 to 8, characterized in that the detection method is a method for detecting the running of a motor vehicle comprising a pressure monitoring system intended to measure the pressure in a tire of a wheel of the vehicle, the wheel comprising a wheel unit capable of establishing low energy Bluetooth® communication to transmit pressure measurements to an electronic computer of a central electronic unit of the vehicle.

10. Motor vehicle characterized in that it implements the method of detecting a rotational movement of a body as defined according to any one of claims 1 to 9.

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