Method for automatically calibrating the power of an activation signal of at least one sensor and device for implementing the method

Abstract

The present invention relates to an automatic method (100, 100') for calibrating the power (Pi) of an activation signal (Si) of at least one sensor (C1), in particular of a pressure sensor for an electronic tyre pressure control system (7) for a motor vehicle (5), the sensor (C1) having an identification number (Id) and comprising at least one module for transmitting and receiving data, characterised in that the method (100, 100') comprises: - determining (Sdet) the maximum transmission power Pmax of the non-activation signal of the sensor and the minimum transmission power Pmin of the activation signal of the sensor; - storing (Smem) the maximum Pmax and minimum Pmin transmission powers when a difference δ between the powers Pmax and Pmin reaches a value equal to or less than a predetermined value δ0.

Description

Description Title of the invention: METHOD FOR AUTOMATICALLY CALIBRATE THE POWER OF AN ACTIVATION SIGNAL OF AT LEAST ONE SENSOR AND DEVICE FOR IMPLEMENTING SAID METHOD

[0001] The present invention relates to the field of sensors, in particular pressure sensors, in the automotive sector, and to the manner of activating such sensors and communicating with them. The invention relates more particularly to a method for automatically calibrating the power of an activation signal of said sensors, as well as to the activation devices allowing the implementation of said method.

[0002] The present invention advantageously applies to pressure sensors arranged (or housed) or intended to be housed in motor vehicle tires (for example at the rim and / or the inflation valve). These pressure sensors are generally paired with the on-board computer of the motor vehicle to which said sensors transmit data (for example relating to the pressure level and / or temperature of the tire).

[0003] The sensor-on-board computer assembly is thus designated under the term "electronic tire pressure monitoring system" (or in English "Tire Pressure Monitoring System" with the associated acronym "TPMS").

[0004] Each pressure sensor is typically equipped with a transmitter, such as a radio frequency transmitter, to enable data transmission to the on-board computer. The on-board computer, receiving data from the sensors, can then alert the vehicle user if one of the tires has a puncture or if the tire is about to deflate, posing a safety risk.

[0005] However, the pressure sensor located inside a tire is usually not removable, so changing a wheel involves changing the sensor, the new sensor is then not directly detected by the vehicle's on-board computer.

[0006] It is indeed necessary, when changing tires, to pair (or associate by radio connection) the sensors housed in the new tires with the vehicle's on-board computer. This pairing (or establishment of a radio connection) is done by means of a dedicated activation device (generally referred to in English as a "TPMS tool"), said device being configured to activate the sensors, retrieve and record the relevant data emitted by the sensor, such as the sensor ID, and transmit it to the on-board computer, so that the latter detects and locates the sensors housed in the newly installed tires and can capture their signals, in order to warn the user if a drop in pressure is detected in one of the said tires.

[0007] Sensor activation devices can also be used in an industrial setting, i.e. in manufacturing plants: of sensors, of tires when said sensors are installed there, or of motor vehicles equipped with such tires. In an industrial setting, it is therefore necessary to activate the sensors to test them, identify them (for example for quality monitoring), configure them and / or pair them with the on-board computer of a vehicle.

[0008] However, factory production lines are often very close to each other, and an activation signal emitted by a suitable activation device can cause a plurality of sensors to be activated, so it is necessary to calibrate the transmission power of such an activation device to avoid waking up unwanted sensors.

[0009] For example, in a factory, vehicle tires or wheels may: - move along a conveyor belt, the tires are then close enough to each other for the activation signal emitted by the activation device to trigger the activation of the sensors located inside the tires adjacent to the tire under test; - be mounted on a vehicle, the wheels are therefore relatively close to each other, and there is a risk of activation of several sensors located inside the different wheels of the vehicle, a risk that is all the greater if the vehicle, such as a truck, has twin wheels.

[0010] Furthermore, the activation signals emitted by said activation devices are electromagnetic signals, continuous or modulated, whose frequency is generally 125 kHz. Since these electromagnetic signals can potentially present risks to human health, it is important to minimize their transmission power (i.e. the energy radiated by the antenna transmitting the radio signal). To do this, it is necessary to find a balance between a transmission power value that guarantees the activation of the sensors and minimizing the risks for operators working near said activation devices.

[0011] Furthermore, when installing an activation device in an industrial environment, it is necessary for a specialized operator to travel to adjust the said device. The effectiveness and propagation of an activation signal are highly dependent on the environment (obstacles, echoes, etc.) in which the activation device is installed. It is therefore necessary to adjust the activation device so that the signal power received by the sensors is sufficient to activate the desired sensors, for example, sensors located at a specific distance on a production line, while limiting the exposure of operators to said activation signals.

[0012] The invention thus aims to resolve at least one of the problems mentioned above and is thus a new method for automatically calibrating the power of an activation signal of at least one sensor, in particular a pressure sensor for an electronic tire pressure control system of a motor vehicle, said sensor having an identification number and comprising at least one data transmission and reception module, characterized in that said method comprises: - determination of the maximum transmission power P max of the non-activation signal of said sensor and the minimum transmission power P min of the activation signal of said sensor; - storage of said maximum transmission powers P max and minimal P min , when a difference δ between said powers P max and P min reaches a value equal to or less than a predetermined value δ0.

[0013] Thus, any activation signal emitted with a power less than or equal to the transmission power P max does not activate said sensor. While any activation signal emitted with a power strictly greater than the transmission power P min does not activate the sensor.

[0014] According to a possible characteristic, there is a stoppage of the determination of the maximum powers P max and minimal P min when the difference δ between the said powers P max and P min reaches a value equal to or less than a value δ0.

[0015] According to another possible characteristic, the determination of said powers P max and P minis carried out by means of a dichotomous variation of the power of the activation signal. Dichotomous variation means varying, by means of several iterations, the power of the activation signal to determine a framework of the optimal power value to activate one or more sensors under nominal operating conditions.

[0016] According to another possible characteristic, the emitted activation signal has a power P i which corresponds to the arithmetic mean of the maximum power P max and the minimum power P min . That is to say that the transmission power P i of the activation signal, when determining the maximum and minimum powers, corresponds to , where P min and P maxare values ​​of the previously stored transmission powers since the maximum and minimum transmission powers vary depending on the result of the previously emitted signal (and therefore the previously stored power values).

[0017] According to another possible characteristic, the determination of said powers P max And P min is carried out by detecting or not detecting at least one response signal from said at least one sensor (i.e. emitted by said sensor) as a function of the activation signal previously emitted, for example by said activation device, at a power P i .

[0018] According to another possible characteristic, if there is reception of a response signal from said at least one sensor then the power P i of the activation signal having activated said sensor is identified with the minimum power P min(or minimum transmission power of the activation signal for which the signal activates said sensor).

[0019] According to another possible characteristic, if there is no reception of a response signal from said at least one sensor then the power P i of the emitted activation signal is identified with the maximum power P max (or maximum power for which the signal does not activate the said sensor). It is considered that there is no reception of a response signal after a predetermined time T R , said time T R being for example greater than 5 seconds, and preferably greater than 10 seconds. The predetermined time T R is generally a function of the sensor type and the environment in which the activation and response signals will propagate.

[0020] According to another possible characteristic, there is a latency time T Lbetween each iteration of emission of an activation signal during the method according to the invention. Indeed without latency time T L , there is a risk of detecting the activation of the sensor by an activation signal from a previous step or iteration. The previous activation to the power P i-1 can thus be interpreted as an activation to the power P i , thus distorting all the results. Advantageously, the latency time is configurable and depends on the type of sensor and the environment in which the sensor is located, this latency time is for example fixed between 0.5 and 1.5 sec, and preferably substantially equal to 1 second.

[0021] According to another possible characteristic, there is an initialization of said process, initialization during which the initial values ​​of the maximum power P max of the non-activation signal, of the minimum power P minof the activation signal and / or the difference δ0 between said maximum and minimum powers P max and P min are predetermined. Note that the initial values ​​of the maximum power P max , of the minimum power P min , and the difference of the powers δ0can also have default values, for example, the maximum transmission power can correspond to the maximum power at which the activation device is capable of transmitting an activation signal, the minimum transmission power can correspond to the minimum power at which the activation device is capable of transmitting an activation signal, while the difference of the powers δ0is equal to 5% (i.e. the relative difference between the powers at which the activation device is capable of emitting a minimum and maximum signal is equal to 5%).

[0022] According to another possible characteristic, there is prior identification of said sensors by emission of an activation signal at a determined power, for example the maximum emission power at which the activation device is capable of emitting a signal.

[0023] According to another possible characteristic, there is memorization of the identification number of each of the sensors having emitted a signal in response to said identification activation signal.

[0024] Thus, when calibrating several sensors at once, for example in the case of twin wheels, it is necessary to calibrate the power of the activation signal for each of the sensors, therefore for sensors located at different positions in space. To do this, it may be advantageous to associate a position with each sensor identifier and to determine whether or not the sensor has been activated based on whether or not a signal has been received from the sensor (following the emission of an activation signal by the activation device).

[0025] According to another possible characteristic, there is an association of a sensor (and its identifier), with a position, determined for example according to the power (of reception) of the response signal following an activation signal.

[0026] According to another possible feature, there is prior manual memorization of the identification number of each of the sensors.

[0027] The invention also relates to a device for activating at least one sensor, in particular pressure sensors for an electronic tire pressure control system of a motor vehicle, said device comprising: - at least one sensor activation module; - a module for receiving signals from the sensors; - an electronic entity configured to store and / or process information conveyed by the signals emitted by said sensors; - a module for communication with a remote electronic entity, such as the on-board computer of a motor vehicle, in order to transmit information conveyed by the signals received; characterized in that said device is configured, on the one hand, to determine the maximum transmission power P maxof the non-activation signal of said at least one sensor and of the minimum transmission power P min of the signal causing the activation of said at least one sensor, and on the other hand, to stop the determination of said maximum powers P max and minimal P min when the difference δ between the said powers P max and P min reaches a value equal to or less than a predetermined value δ0.

[0028] According to another possible characteristic, said sensors are pressure and / or temperature sensors housed in the tires of motor vehicles.

[0029] The invention will be better understood, and other aims, details, characteristics and advantages thereof will appear more clearly during the following description of particular embodiments of the invention, given solely for illustrative and non-limiting purposes, with reference to the appended drawings, in which: - [Fig. 1], referenced [[Fig. 1]], is a schematic representation illustrating a device for activating at least one sensor according to the invention; - [Fig. 2], referenced [Fig. 2], is an enlarged and partially broken away view of the device of [Fig. 1]; - [Fig. 3], referenced [Fig. 3] is a schematic representation of a second embodiment of an activation device according to the invention; - [Fig. 4], referenced [Fig. 4], is a flowchart of the automatic method for calibrating the power of an activation signal of at least one sensor according to the invention; - [Fig.5], referenced [Fig.5], is a flowchart of a variant embodiment of the method of [Fig.4].

[0030] [Fig. 1] is a very schematic representation of a device 1 for activating sensors 9, more particularly in the present example a learning device for an electronic system 3 for controlling the tire pressure of a motor vehicle 5 (said device 1 can also be designated by the terms “valve activator” or “valve forcer”).

[0031] The motor vehicle 5, on the one hand, is equipped with tires 7 in which the sensors 9 are housed, such as pressure sensors, and on the other hand, comprises an on-board computer 11 (also called electronic control unit and generally designated by the acronym “ECU”).

[0032] The device 1 comprises a housing 13, for example made of plastic, a display device 15, a keyboard 17 and an antenna 19 for transmitting a sensor activation signal, as well as an OBD socket 21. Said OBD socket 21 is configured to allow, for example, the connection of the device 1 to the on-board computer 11 of a vehicle, in particular via an OBD cable or using a wireless dongle (for example Bluetooth).

[0033] [Fig.2], for its part, is a schematic, enlarged and partially torn away view of the activation device 1 of [Fig.1].

[0034] Said device 1 thus comprises: - at least one sensor activation module 31, such as means or modules making it possible to generate (continuous and / or modulated) sensor activation signals, said activation module 31 comprising in particular the antenna 19 which makes it possible to radiate said generated signals to the sensors 9; - a module 33 for receiving signals from the sensors, generally comprising another antenna housed in the housing 13 and configured for example to pick up signals in a frequency band between 300 and 500 MHz (the sensor emitting a signal in this frequency band after having been activated by said activation module 31); - an electronic entity 35 configured to store and / or process information conveyed by the signals emitted by said sensors 9 (and received via the reception module 33); - a communication module 37 with an on-board computer 11 of a motor vehicle for transmitting information from at least one of said sensors 9, information received via signals from said sensors 9.

[0035] The communication module 37 is for example an OBD module which comprises a management circuit 38 for the OBD communication and the previously mentioned OBD socket 21. It will be noted that the management circuit 38 can also be integrated into the electronic entity 35. In addition, the device 1 also comprises a battery 41 configured to power its various elements (and electronic components).

[0036] It will also be noted that said activation signals (emitted by the activation devices) are electromagnetic signals, continuous or modulated, emitted by the activation module 31, which have, for example, a frequency of 125 kHz.

[0037] As illustrated in [Fig.1] and [Fig.2], the activation device 1 is a portable device (in particular one that can be manipulated by hand by an operator), but such a device can also be in the form of a fixed or transportable device, intended to be placed in a factory, in particular next to a production line, a garage, or at the premises of a vehicle fleet manager, etc.

[0038] Unlike the device of [Fig. 1], the activation device 1' illustrated in [Fig. 3] is a device intended to be positioned at a fixed location, while the sensors to be activated are generally at a determined distance, for example on a production line 40 comprising a conveyor belt on which is arranged at least one tire P equipped with a sensor C1. The activation device 1' can thus comprise all of the elements previously mentioned for the activation device of [Fig. 1].

[0039] However, unlike the activation device 1 of [Fig. 1], said activation device 1' intended for industrial applications does not generally include a screen, keyboard, OBD communication module, etc. Programming and dialogue with said device 1' can be carried out from a third-party electronic device connecting to it, for example via a communication module 37' of the device 1'.

[0040] [Fig.3], for its part, is a very schematic representation of an activation device 1' of sensors 9 intended for the industrial environment.

[0041] The activation devices 1 or 1' are configured to emit an activation signal, for example, towards at least one sensor 9 or C1, housed or not in a tire 7 or P. The sensor 7 or C1, when activated by the activation signal, emits in return one or more signals in response.

[0042] Said at least one sensor 7 or C1, here a pressure sensor for an electronic tire pressure control system of a motor vehicle, comprises at least one data transmission and reception module, as well as an identification number.

[0043] Whatever the application, it may be advantageous to calibrate the power of the activation signal emitted by said activation device 1, 1', in order to limit the operator's exposure to electromagnetic waves and to optimize the electrical consumption of said device 1, 1'.

[0044] For this, the device 1, 1' is configured to operate a method 100 for automatic calibration of the transmission power of an activation signal of at least one sensor 9.

[0045] Said method 100, more particularly illustrated in [Fig.4], comprises: - a determination S det of the maximum power P maxof the non-activation signal of said sensor and the minimum power P min of the activation signal of said sensor; - a storage S mem of said maximum powers P max and minimal P min , when a difference δ between said powers P max and P min reaches a value equal to or less than a predetermined value δ0 (for example a relative difference less than or equal to 5%).

[0046] So when the difference δ which is equal to P min – P max ≤ δ0, then the values ​​of said maximum powers P max and minimal P min are recorded in a memory, for example a RAM or ROM of the electronic entity 35, so that the value of the minimum power P min is used under the nominal conditions of use of the activation device 1 or 1'.

[0047] Said method 100 also comprises a prior initialization step Sinit , stage during which the initial values ​​of the maximum power P max of the non-activation signal, of the minimum power P min of the activation signal and the difference δ0 between said maximum and minimum powers P max and P min are predetermined and / or entered manually.

[0048] The determination of the maximum powers P is stopped. max and minimal P min when the difference δ between the said powers P max and P min reaches a value equal to or lower than the value of the difference δ0. It will be noted that the lower the difference δ, the longer the method according to the invention takes. Furthermore, the more the sensor whose minimum power is to be determined activation sensor is located close to other sensors, the lower the value of the difference δ must be to avoid activation of surrounding sensors.

[0049] More specifically, the determination S det maximum powers P max and minimal P min includes several substeps that can iterate until the difference δ is less than or equal to δ0.

[0050] Once the initial values ​​of the parameters P min , P max and δ0 are fixed, there is emission of an activation signal S i of sensor having a power P i corresponding to the arithmetic mean of the values ​​of the maximum power P max and the minimum power P min , that's to say .

[0051] During a time of the activation signal S i , there is detection or non-detection of a response signal S C from at least one sensor (response signal emitted in response to the activation signal S i emitted). For example, we can consider that there is no reception of a response signal after a predetermined time TR , said time T R being for example greater than 5 seconds, and preferably between 5 and 10 seconds.

[0052] Thus, if the activation device 1, 1' detects the reception of a response signal S C from at least one sensor, there is a step S2 for updating the power value P min , the value of the power P i of the previously emitted activation signal then becomes the new minimum power value P min and the value of the parameter P min is modified for the next emission of an activation signal S i to sensor 9.

[0053] Whereas if the activation device 1, 1' does not detect the reception of a response signal S C from at least one sensor (during the predetermined time T R ), the value of the power P iof the previously emitted activation signal then becomes (step S3) the new value of the maximum power P max and the value of the parameter P max is modified for the next emission of an activation signal S i to sensor 9.

[0054] Following the modification of one of the values ​​of the P parameters min or P max , in particular during steps S2 or S3, there is then a calculation of the difference δ between the values ​​of the minimum and maximum powers P min or P max . More specifically, the difference .

[0055] There is then a comparison S5 of the difference δ thus calculated with the predetermined value δ0 of this difference (or target value of the difference). If the calculated value δ is greater than the predetermined value δ0, a new iteration of steps S1 and S2 or S1 and S3 is implemented. Thus, a new activation signal S i is emitted to the power P i, taking into account the modified value of one of the minimum powers P m in or maximum P max depending on whether step S2 or S3 was implemented during the previous iteration.

[0056] The determination of said powers P max and P min is thus carried out by means of a dichotomous variation of the power P i of the activation signal S i , because there is iteration by variation of the powers P i of the activation signal S i the variation of the powers being a function of an arithmetic mean of the minimum powers P min and maximum P max .

[0057] More specifically, there is then iteration of the actions carried out during the steps S1 to S5 previously described until the calculated value of the difference δ is less than or equal to the predetermined value δ0. When this condition is met, the values ​​of the minimum powers P minand maximum P max correspond to the optimal values ​​sought and are then stored during a step S mem .

[0058] In an alternative embodiment of the method of [Fig. 4], in particular when there are several sensors, for example in the case of twin wheels, there is calibration of the transmission power of an activation signal for each of the sensors, which are generally located at different positions in space. That is to say that each sensor is advantageously associated, in addition to its identifier, with a value of the maximum power P max and a value of the minimum power P min , as well as a predetermined value δ0.

[0059] In addition, each sensor having its own identifier, there is advantageously an association of a position in space (for example position no. 1 for the closest sensor, position no. 2 for the second closest sensor, etc.) with a sensor (and its identifier). The association of a sensor (and its identifier) ​​with a position is for example determined as a function of the (reception) power of the response signal emitted in response to the reception of an activation signal.

[0060] Thus, unlike the method 100, there is reception or not of all the response signals emitted by the different sensors, each response signal conveying the identifier of the sensor which emitted it in response to the reception of an activation signal emitted by the activation device 1, 1', and updating accordingly of the values ​​of the maximum powers P max and minimal P min . That is to say that for a given power P iof an activation signal, there is an update of the value of the maximum non-activation power P max when the sensor has not emitted a response signal within a response time T R predefined, while if a response signal is received, the value of the minimum activation power P is updated min .

[0061] There is iteration of the different stages of the process 100, therefore emission of activation signals as long as there has not been determination of all the values ​​of the maximum powers P max and minimal P min (for each of the sensors) so that the difference of said powers P max and P min is less than or equal to the prede- terminated δ0 (for each of said sensors).

[0062] Thus, for each of the sensors, there is successive determination of the activation or non-activation of each of the sensors depending on the reception or not of a signal (conveying the identifier or identification number) from the sensor which emitted it, this at each activation signal P i (and successive iterations of activation signal emission).

[0063] Once the difference δ between maximum powers P max and minimal P min is less than or equal to a predetermined value δ0 is reached for a given sensor, the transmission power values ​​are stored and the sensor is no longer taken into account for the following iterations of activation signal transmission. This is until all the differences δ between maximum powers P max and minimal P min is less than or equal to a predetermined value δ0 for each of the sensors is determined.

[0064] [Fig. 5], for its part, is a flowchart of an alternative embodiment of the method of [Fig. 4]. The method 100' of [Fig. 5] presents substantially the same steps as the method of [Fig. 4] and these will not necessarily be described again or exhaustively, except to specify the differences or specificities. Furthermore, when the steps are analogous or similar, the same references will be used.

[0065] Thus, unlike method 100, method 100' of [Fig.5] includes after initialization S init , detection S id sensors to be activated. Indeed, the method according to the invention is also intended for the calibration of an activation signal for a plurality of sensors C m. Since said sensors may be located at different distances from the activation device 1, 1', it is necessary to find an activation signal of a power suitable for nominal and standard operating conditions of the activation device.

[0066] To do this, there is prior identification of a plurality of sensors for which we seek to calibrate an activation signal. There is thus, after initialization S init , verification S6 of the presence in memory of the identification numbers (or identifiers) Id associated with each of said sensors.

[0067] If no sensor identifier is stored in memory, then there is emission S7 of an activation signal, called identification, of a power P i, for example, at the maximum possible transmission power at which the activation device is capable of transmitting a signal.

[0068] Then, for a predetermined time, for example T R, there is reception S8 of the response signals emitted by said sensors. The response signals conveying the identification numbers (or identifiers) of the sensors, there is then storage S9 of the identification number (or identifier) ​​of each of the sensors having emitted a signal in response to said identification activation signal.

[0069] Then there is determination S det of the maximum power P max of the non-activation signal of the sensors and the minimum power P min of the sensor activation signal.

[0070] Unlike method 100 of [Fig.4], after emitting an activation signal at a power P i : - if there is reception of a response signal S c from all the stored sensors, the value of the power P i of the previously emitted activation signal then becomes (step S2) at the new minimum power value P minand the value of the parameter P min is modified for the next transmission of an activation signal Si; - if there is no reception of a response signal S C from all the stored sensors (during the predetermined time T R ), the value of the power P i of the previously emitted activation signal then becomes (step S3) the new maximum power value P max and the value of the parameter P max is modified for the next emission of an activation signal S i .

[0071] Subsequently and as previously, the difference δ between the minimum powers P m in and maximum P max is calculated S4 and is compared S5 with the predetermined value δ0.

[0072] If the calculated difference value δ is greater than the predetermined value δ0, a new iteration of steps S1 and S2 or S1 and S3 is implemented. Thus a new activation signal S iof power P i is emitted, but taking into account the modified value of one of the minimum powers P min or maximum P max .

[0073] Otherwise, that is to say when the difference δ of the powers is equal to or less than the predetermined value δ0, the determination of the transmission powers is stopped, and the values ​​of said maximum powers P max and minimum P m in are recorded in a memory, for example a RAM or ROM of the electronic entity 35. This is particularly so that the value of the minimum power P m in is used under the nominal conditions of use of the activation device 1 or 1'.

[0074] It will be noted that in an alternative embodiment of the method 100', the identification numbers can be entered manually, or can be sorted manually by the user after transmitting an identification signal and receiving the response signals.

[0075] In another variant embodiment not shown of the methods 100 and 100', the activation signal used during normal conditions of use of the activation device 1 or 1' has a transmission power corresponding to the minimum power P min stored plus a predefined percentage, for example 10%, in order to guarantee activation of the sensor(s).

Claims

Claims

1. Automatic method (100, 100') for calibrating the power (Pi) of an activation signal (Si) of at least one sensor (C1), in particular a pressure sensor for an electronic tire pressure control system (7) of a motor vehicle (5), said sensor (C1) having an identification number (Id) and comprising at least one data transmission and reception module, characterized in that said method (100, 100') comprises: - determination (Sdet) of the maximum transmission power P max of the non-activation signal of said sensor and the minimum transmission power P min of the activation signal of said sensor; - storage (Smem) of said maximum transmission powers P max and minimal P min , when a difference δ between said powers P max and P minreaches a value equal to or less than a predetermined value δ0.

2. Method (100, 100') according to the preceding claim, characterized in that the determination (Sdet) of the maximum powers P is stopped max and minimal P min when the difference δ between the said powers P max and P min reaches a value equal to or less than a predetermined value δ0.

3. Method (100, 100') according to the preceding claim, characterized in that the determination (Sdet) of said powers P max and P min is carried out by means of a dichotomous variation of the power (Pi) of the activation signal (Si).

4. Method (100, 100') according to any one of the preceding claims, characterized in that the determination (Sdet) of said powers P max and P minis carried out by the detection or non-detection of at least one response signal (Sc) coming from said at least one sensor as a function of the activation signal (Si) previously emitted at a power P i .

5. Method (100, 100') according to the preceding claim, characterized in that if there is reception of a response signal (Sc) from said at least one sensor (C1) then the power P i of the activation signal (Si) having activated said sensor (C1) is identified with the minimum power P min .

6. Method (100, 100') according to claim 4 or 5, characterized in that if there is no reception of a response signal (Sc) from said at least one sensor (C1) then the power P i of the activation signal (Si) emitted is identified with the maximum power P max .

7. Method (100, 100') according to any one of the preceding claims, characterized in that there is an initialization (Sinit) of said method, initialization during which the initial values ​​of the maximum power P max of the non-activation signal, of the minimum power P m in of the activation signal (Si) and the difference δ0 between said maximum and minimum powers P max and P min are predetermined.

8. Method (100, 100') according to any one of the preceding claims, characterized in that the activation signal (Si) emitted has a power P i which corresponds to the arithmetic mean of the maximum power P max and the minimum power P min.

9. Method (100, 100') according to any one of the preceding claims, characterized in that there is prior identification of said sensors by emission (S7) of an activation signal (Si) at a power Pi.

10. Method (100, 100') according to the preceding claim, characterized in that there is storage (S9) of the identification number (Id) of each of the sensors having emitted a signal in response to said identification activation signal.

11. Method (100, 100') according to any one of the preceding claims, characterized in that there is prior manual storage of the identification number (Id) of each of the sensors (C1).

12. Device (1; 1') for activating at least one sensor, in particular pressure sensors for an electronic tire pressure control system (7) of a motor vehicle (5), said device comprising: - at least one sensor activation module (31); - a module (33) for receiving signals from the sensors; - an electronic entity (35) configured to store and / or process information conveyed by the signals emitted by said sensors (9); - a communication module (37; 37') with a remote electronic entity, such as the on-board computer (11) of a motor vehicle (5), in order to transmit information conveyed by the received signals; characterized in that said device is configured, on the one hand, to determine the maximum transmission power P. max of the non-activation signal of said at least one sensor and the minimum transmission power P minof the signal causing the activation of said at least one sensor, and on the other hand, to stop the determination (Sdet) of said maximum powers P max and minimal P min when the difference δ between the said powers P max and P min reaches a value equal to or less than a predetermined value δ0.

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