Method for detecting foreign objects below motor vehicle

Abstract

The invention relates to a method for detecting foreign objects beneath a vehicle (10) equipped with a tire pressure monitoring system comprising at least two wheel units (16a, 16b) and a central unit (12) comprising a communication device (24) for communicating with each of said wheel units, characterized in that the communication device (24) communicates with the wheel units (16a, 16b). The method comprises a detection step and an analysis step, the detection step comprising a transmission phase comprising transmitting at least one detection signal from a first wheel unit (16a) to a second wheel unit (16b) via a transmission channel (C1), the analysis step comprises comparing and measuring a property difference between the probe signal received by the second wheel unit (16b) and a previously defined reference signal, and determining whether the measured difference is characterised by the presence of a foreign object in the transmission channel employed by the probe signal.

Description

[Technical field]

[0001] The present patent application relates to a method for detecting foreign objects beneath a motor vehicle equipped with a tire pressure monitoring system. [Background Technology]

[0002] For safety purposes, it is known to equip motor vehicles with a monitoring system referred to as “TPMS” (Tire Pressure Monitoring System).

[0003] Such a monitoring system, such as that described in document FR3045498, generally comprises a central processing unit mounted on the vehicle, and wheel units each fitted to an associated wheel of the vehicle.

[0004] The central unit includes an electronic computer referred to as ECU (Electronic Control Unit).

[0005] The vehicle's central unit is also equipped with a radio receiver designed to communicate with each wheel unit.

[0006] Each wheel unit is responsible for periodically acquiring a physical quantity representative of an operating parameter of the associated wheel, in particular for detecting anomalies in the associated wheel.

[0007] Each wheel unit also sends messages to the central unit of the vehicle, these messages comprising data relating to the pressure, temperature and acceleration of the associated wheel, as well as the identification code of the transmitting wheel unit.

[0008] To this end, each wheel unit includes a tire inflation pressure sensor, a temperature sensor, an accelerometer and a radio transmitter.

[0009] Furthermore, each wheel unit is equipped with a battery for power supply and a microcontroller and a microprocessor including a memory for storing data.

[0010] When the vehicle's central unit receives these data, in the event of a significant difference in pressure from that recommended by the manufacturer, the TPMS system will inform the vehicle driver that one of the wheels is underinflated, via a warning message displayed, for example, on the vehicle's dashboard.

[0011] A technical problem that remains is detecting the presence of foreign objects underneath a motor vehicle.

[0012] The foreign object is, for example, a living being, and more particularly, an animal, which gets under the vehicle before or after the driver sits in the driver's seat.

[0013] However, when starting a motor vehicle, the driver has no way of knowing whether there is a foreign object under the car.

[0014] Even if the driver performs a visual check, this is not sufficient because there is a delay between the moment the check is performed and the moment the vehicle is started, during which time an animal may get under the vehicle.

[0015] Likewise, with regard to electric motor vehicles equipped with induction charging batteries, the presence of foreign objects under the vehicle should also be avoided, thereby avoiding damage to the object if the foreign object is a living thing.

[0016] In particular, exposure to electromagnetic fields may produce undesirable biological effects on organisms.

[0017] It is also necessary to avoid placing foreign objects underneath the electric vehicle, interposing the foreign objects between the inductive charger and the vehicle, so as to avoid interfering with the inductive charging of the vehicle. [Summary of the invention]

[0018] The object of the present invention is to solve the problem of detecting the presence of a foreign object under a motor vehicle, in particular at the moment of starting the vehicle or at the moment of inductive charging of the vehicle.

[0019] This and other objects, which will become apparent from reading the following description, are achieved by a method for detecting a foreign object beneath a motor vehicle equipped with a tire pressure monitoring system, said system comprising at least:

[0020] a first wheel unit, which is fitted to a first wheel of the motor vehicle and comprises a first radio communication device comprising a transmitter and a receiver,

[0021] a second wheel unit fitted to a second wheel of the motor vehicle and comprising a second communication device comprising a transmitter and a radio receiver, and

[0022] a central unit comprising a computer and a communication device designed to communicate with each of said wheel units,

[0023] The method is characterized in that:

[0024] a detection step comprising, in sequence, a transmission phase comprising transmitting at least one detection signal from the first wheel unit to the second wheel unit via a transmission channel extending between the first wheel unit and the second wheel unit, followed by a phase in which the detection signal is received by the second wheel unit, and

[0025] an analysis step consisting in comparing and measuring a difference in properties between said detection signal received by the second wheel unit and a previously defined reference signal, and determining whether said measured difference characterizes the presence of a foreign object on said transmission channel adopted by said detection signal.

[0026] The invention thus makes it possible to detect the presence of a foreign object under a vehicle without having to perform a visual inspection under the vehicle.

[0027] According to other optional features of the present invention used alone or in combination:

[0028] - the properties measured during the analysis step are related to the variation of power with frequency of the detection signal;

[0029] - the properties measured during the analysis step are related to the variation of phase with frequency of the detection signal;

[0030] - the method comprises a step of determining the reference signal, which step is performed at least once before the detection step and comprises, in succession, a transmission phase consisting in transmitting the detection signal from the first wheel unit to the second wheel unit via the transmission channel, and then a phase of receiving the detection signal received by the second wheel unit and storing the detection signal as the reference signal;

[0031] - The communication device of each wheel unit and the central unit is based on Standard operation. Specifically, The standard allows for bidirectional exchanges between two peripheral devices;

[0032] In a minimum exemplary embodiment of the invention, the first wheel unit and the second wheel unit are arranged diagonally to one another on the motor vehicle, so that the transmission channel separating the wheel units passes through the center of the vehicle;

[0033] the motor vehicle comprises four wheel units, each of which is fitted to a wheel of the vehicle, the emission phase of the detection step comprising the emission of at least one detection signal from each wheel unit to each of the three other wheel units, and the analysis step comprising the comparison and measurement of a difference in properties between the detection signal received by each wheel unit and an associated reference signal previously defined, and determining whether said measured difference characterizes the presence of a foreign object on the transmission channel adopted by the detection signal in question;

[0034] - the method is executed by the motor vehicle when a start sequence of said vehicle is detected;

[0035] The motor vehicle is an electric motor vehicle powered by a battery, the method being carried out when an inductive charging process of the battery is detected.

[0036] The invention also relates to a motor vehicle comprising at least a central unit and two wheel units, which are suitably programmed to implement the method described above. [Brief Description of the Drawings]

[0037] Other features, objects and advantages of the present invention will become apparent from reading the following detailed description, and for an understanding of these other features, objects and advantages, reference should be made to the accompanying drawings, in which:

[0038] [ Figure 1 ] Figure 1 is a schematic top view of a motor vehicle equipped with a central unit and four wheel units, which are suitably programmed to implement the method according to the invention;

[0039] [ Figure 2 ] Figure 2 is a graph in which the axis of abscissa shows the communication channel in megahertz (MHz) and the axis of ordinate shows decibels (dB), the graph representing a variation in power with the frequency of a reference signal received by the second wheel unit and transmitted by the first wheel unit;

[0040] [ Figure 3 ] Figure 3 is similar to Figure 2 a graph showing a variation of power with frequency of a detection signal received by the second wheel unit and transmitted by the first wheel unit;

[0041] [ Figure 4 ] Figure 4 is a graph in which the axis of abscissa shows the communication channel in megahertz (MHz) and the axis of ordinate is in angle (°), the graph representing a change in phase with the frequency of a reference signal received by the second wheel unit and transmitted by the first wheel unit;

[0042] [ Figure 5 ] Figure 5 is similar to Figure 4 a graph showing a phase variation with the frequency of a detection signal received by the second wheel unit and transmitted by the first wheel unit;

[0043] [ Figure 6 ] Figure 6 is a flow chart illustrating the sequence of steps of the method according to the present invention.

[0044] Throughout the drawings, the same or similar elements are denoted by the same or similar reference numerals. [Specific implementation method]

[0045] Figure 1 A motor vehicle 10 according to the invention is schematically shown, comprising a central unit 12 and four wheels 14a, 14b, 14c, 14d, each wheel being equipped with a respective wheel unit 16a, 16b, 16c, 16d.

[0046] In order to avoid a lengthy description, only the first wheel unit 16a is described below, wherein the four wheel units 16a, 16b, 16c, 16d have similar designs and operations.

[0047] The wheel unit 16 a belongs to a tire pressure monitoring system, also referred to as “TPMS” for short.

[0048] The wheel unit 16a comprises a housing enclosing a microcontroller equipped with a processor, a battery, a memory and a set of sensors dedicated to measuring operating parameters of the wheel unit 16a.

[0049] The set of sensors comprises, for example, a temperature sensor and a pressure sensor capable of measuring the inflation pressure of the tire of the associated wheel 14 a .

[0050] The measurement values ​​obtained by the sensors can be sent to a central unit 12 of the motor vehicle 10 .

[0051] For this purpose, the wheel unit 16 a comprises a radio communication device 18 which comprises a transmitter 20 and a receiver 22 .

[0052] Likewise, the central unit 12 comprises a radio communication device 24 which is designed to communicate with each of the wheel units 16 a , 16 b , 16 c , 16 d and comprises a transmitter 26 and a receiver 28 .

[0053] According to an exemplary embodiment, the communication device 18 of each wheel unit 16a, 16b, 16c, 16d and the communication device 24 of the central unit 12 are arranged according to a protocol that allows short-range bidirectional data exchange using radio waves. Standard operation.

[0054] Furthermore, the central unit 12 of the motor vehicle 10 comprises an electronic computer 30 and a memory 32 .

[0055] In this exemplary embodiment of the invention, motor vehicle 10 is an electric motor vehicle powered by a battery (not shown).

[0056] The present invention relates to a method for detecting a foreign object located beneath a motor vehicle 10 , Figure 6 The sequence of steps of this method is shown in .

[0057] "Foreign objects" will be understood to mean both living things (such as animals) and inanimate objects.

[0058] The method according to the invention comprises a first detection step E1 comprising, in succession, a transmission phase and a reception phase.

[0059] The transmission phase comprises sequentially transmitting a detection signal from each wheel unit 16a, 16b, 16c, 16d to each of the other three wheel units 16a, 16b, 16c, 16d.

[0060] The receiving phase includes each of the other three wheel units 16a, 16b, 16c, 16d receiving the detection signal transmitted by each wheel unit 16a, 16b, 16c, 16d in sequence.

[0061] The wheel units 16a, 16b, 16c, 16d are connected in pairs via transmission channels over which signals are transmitted.

[0062] The term "transmission channel" refers to the route along which data is transmitted between a transmitter and a receiver.

[0063] In the present invention In the context of a type of communication, a transmission channel is the path along which radio signals are passed between the connected wheel units 16a, 16b, 16c, 16d.

[0064] As in Figure 1 As can be seen in the figure, the first channel C1 extends between the first wheel unit 16a and the second wheel unit 16b, the second channel C2 extends between the first wheel unit 16a and the third wheel unit 16c, the third channel C3 extends between the first wheel unit 16a and the fourth wheel unit 16d, the fourth channel C4 extends between the second wheel unit 16b and the fourth wheel unit 16d, the fifth channel C5 extends between the second wheel unit 16b and the third wheel unit 16c, and the sixth channel C6 extends between the third wheel unit 16c and the fourth wheel unit 16d.

[0065] According to a preferred exemplary embodiment of the present invention, the first detection step E1 comprises executing a dedicated The "channel detection" function of the technology.

[0066] A "channel sounding" function is usually implemented to measure the quality and condition of the transmission channel, in particular interference, noise and other parameters.

[0067] The first detection step E1 is followed by a second analysis step E2 consisting in comparing and measuring differences in properties between the detection signal received by each wheel unit 16a, 16b, 16c, 16d and a previously defined reference signal associated with each receiving wheel unit 16a, 16b, 16c, 16d.

[0068] This second analysis step E2 is performed by the computer 30 of the central unit 12 .

[0069] For this purpose, the probe signal to be analyzed is transmitted by radio communication to the central unit 12 , which analyzes it using a corresponding reference signal stored in the memory 32 of the central unit 12 .

[0070] For example, the probe signal received by the second wheel unit 16b and sent from the first wheel unit 16a via the first transmission channel C1 is compared with a reference signal associated with the pair of wheel units 16a, 16b and the associated channel C1.

[0071] Each reference signal is a signal representative of a "null" transmission between a transmitter of a wheel unit 16a, 16b, 16c, 16d and a receiver of another wheel unit 16a, 16b, 16c, 16d, that is to say a signal when the transmission channel employed by the signal is not disturbed by the presence of foreign objects.

[0072] Specifically, the transmission channel may be affected by various factors, such as radio interference, electromagnetic noise, and physical obstacles.

[0073] The analysis step E2 makes it possible to determine whether a measured difference between the detection signal received by the relevant wheel unit 16a, 16b, 16c, 16d and the associated reference signal characterizes the presence of a foreign object on the employed transmission channel.

[0074] According to an exemplary embodiment of the invention, the properties measured during the analysis step E2 relate to the variation of the power as a function of the frequency of the probe signal upon reception.

[0075] By way of example, Figure 2 A graph is shown which represents the variation of the power as a function of the frequency of the reference signal received by the second wheel unit 16b and transmitted by the first wheel unit 16a.

[0076] Figure 3 It also shows something like Figure 2 Graph showing the power as a function of the frequency of the detection signal received by the second wheel unit 16b and transmitted by the first wheel unit 16a.

[0077] It can be observed Figure 2 and Figure 3 These differences characterize the presence of foreign objects on the adopted transmission channel C1.

[0078] These properties measured during the analysis step E2 are also related to the variation of the phase with the frequency of the detection signal upon reception; this is called the phase signature.

[0079] By way of example, Figure 4 A graph is shown which represents the phase variation as a function of the frequency of a reference signal received by the second wheel unit 16b and transmitted by the first wheel unit 16a.

[0080] in other words, Figure 4 The graph of φ shows the phase characteristic of the reference signal received by the second wheel unit 16b.

[0081] In this exemplary embodiment, Communications use an 80 MHz frequency band, covering the range from 2402 to 2480 MHz, ie, forty channels, each spaced two MHz apart.

[0082] In a non-limiting manner, it should be noted that the communication devices 18 , 24 may operate according to other technologies that may have information about the transmission channel in terms of amplitude and phase, such as Wifi or Ultra Wideband UWB.

[0083] Figure 5 It also shows something like Figure 4 , which shows a graph showing a change in phase as a function of frequency of a detection signal received by the second wheel unit 16b and transmitted by the first wheel unit 16a.

[0084] It can be observed Figure 4 and Figure 5 These differences characterize the presence of foreign objects on the adopted transmission channel C1.

[0085] Preferably, the method according to the invention is executed by the motor vehicle 10 when a start procedure of the vehicle is detected.

[0086] Thus, if a foreign object is detected during the analysis step E2 , the starting of the motor vehicle 10 is prevented and / or a warning message is displayed on the dashboard of the vehicle.

[0087] Likewise, the method according to the invention may be carried out by the motor vehicle 10 when an inductive charging procedure of the vehicle battery is detected or during an inductive charging procedure.

[0088] If a foreign object is detected during the analysis step E2 , charging of the motor vehicle 10 is blocked or suspended and / or a warning message is displayed on the dashboard of the vehicle.

[0089] Finally, the method according to the invention comprises a step of determining a reference signal E0 , performed before the detection step E1 .

[0090] For example, the step of determining the reference signal E0 is performed in the factory when the motor vehicle 10 is equipped with its four wheel units 16 a , 16 b , 16 c , 16 d .

[0091] However, the step of determining the reference signal E0 may be performed during the service life of the motor vehicle 10 , for example when one or more wheel units 16 a , 16 b , 16 c , 16 d are replaced.

[0092] The step of determining the reference signal E0 comprises a transmission phase consisting of sequentially transmitting a detection signal from each wheel unit 16a, 16b, 16c, 16d to each of the other three wheel units 16a, 16b, 16c, 16d.

[0093] The step of determining the reference signal E0 also comprises a reception phase comprising each of the other three wheel units 16a, 16b, 16c, 16d receiving a detection signal sequentially transmitted by each wheel unit 16a, 16b, 16c, 16d.

[0094] This reception phase is followed by a phase of storing the received probe signals as reference signals and associating the reference signals with the pair of wheel units in question.

[0095] Of course, the step of determining the reference signal E0 is performed when no foreign object is present beneath the motor vehicle 10 .

[0096] Therefore, the method according to the present invention can detect the presence of a foreign object under the motor vehicle 10 by scanning a wide area included between these four wheel units 16a, 16b, 16c, 16d.

[0097] In a non-limiting manner, in a minimal configuration of the method according to the invention, the method is performed only between two wheel units 16a, 16b which are arranged diagonally to one another so that the transmission channel C1 separating the two wheel units passes through the center of the motor vehicle 10.

[0098] Of course, the present invention has been described in the foregoing text by way of example, and it should be understood that those skilled in the art can produce various variant embodiments of the present invention without thereby departing from the scope of the present invention.

Claims

1. A method for detecting a foreign object beneath a motor vehicle (10), the motor vehicle being equipped with a tire pressure monitoring system, said system comprising at least: a first wheel unit (16a) which is fitted to a first wheel (14a) of the motor vehicle (10) and comprises a first radio communication device (18) comprising a transmitter (20) and a receiver (22), a second wheel unit (16b) fitted to a second wheel (14b) of the motor vehicle (10) and comprising a second communication device comprising a transmitter and a radio receiver, and a central unit (12) comprising a computer (30) and a communication device (24) designed to communicate with each of said wheel units (16a, 16b), The method is characterized in that: a detection step (E1) comprising, in sequence: a transmission phase comprising transmitting at least one detection signal from the first wheel unit (16a) to the second wheel unit (16b) via a transmission channel (C1), the transmission channel extending between the first wheel unit (16a) and the second wheel unit (16b), followed by a phase in which the detection signal is received by the second wheel unit (16b), and An analysis step (E2) consisting in comparing and measuring a difference in properties between said detection signal received by the second wheel unit (16b) and a previously defined reference signal, and determining whether said measured difference characterizes the presence of a foreign object on said transmission channel (C1) adopted by said detection signal.

2. The method for detecting foreign objects according to claim 1, wherein: The properties measured during the analysis step (E2) are related to the variation of power with frequency of the detection signal.

3. The method for detecting foreign objects according to claim 1 , wherein: The properties measured during the analysis step (E2) are related to the variation of the phase with the frequency of the detection signal.

4. The method for detecting foreign objects according to claim 1, wherein: The method comprises a step (E0) of determining the reference signal, which is performed at least once before the detection step (E1) and sequentially comprises a transmission phase, which comprises transmitting the detection signal from the first wheel unit (16a) to the second wheel unit (16b) via the transmission channel (C1), and then comprises a phase of receiving the detection signal received by the second wheel unit (16b) and storing the detection signal as the reference signal.

5. The method for detecting foreign objects according to any one of the preceding claims, characterized in that The communication device (18) of each wheel unit (16a, 16b) and the central unit (12) is based on Standard operation.

6. The method for detecting foreign objects according to any one of the preceding claims, characterized in that The first wheel unit (16a) and the second wheel unit (16b) are arranged diagonally to one another on the motor vehicle (10) so that the transmission channel (C1) separating the wheel units passes through the center of the vehicle.

7. The method for detecting foreign objects according to any one of the preceding claims, characterized in that The motor vehicle (10) comprises four wheel units (16a, 16b, 16c, 16d), each of which is fitted to a wheel (14a, 14b, 14c, 14d) of the vehicle, the transmission phase of the detection step (E1) comprising transmitting at least one detection signal from each wheel unit (16a, 16b, 16c, 16d) to each of the three other wheel units, and the analysis step (E2) comprising comparing and measuring a difference in properties between the detection signal received by each wheel unit (16a, 16b, 16c, 16d) and a previously defined associated reference signal, and determining whether the measured difference characterizes the presence of a foreign object on the transmission channel (C1, C2, C3, C4, C5, C6) adopted by the detection signal in question.

8. The method for detecting foreign objects according to any one of the preceding claims, characterized in that The method is performed by the motor vehicle (10) when a start-up procedure of said vehicle is detected.

9. The method for detecting foreign objects according to any one of the preceding claims, characterized in that The motor vehicle (10) is an electric motor vehicle powered by a battery, and the method is performed when an inductive charging process of the battery is detected.

10. A motor vehicle (10) comprising at least a central unit (12) and two wheel units (16a, 16b), which are suitably programmed to implement the method according to any one of claims 1 to 9.

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