METHOD FOR AUTOMATIC POWER CALIBRATION OF AN ACTIVATION SIGNAL OF AT LEAST ONE SENSOR AND DEVICE FOR IMPLEMENTING SAID 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 a pressure sensor for an electronic tire pressure monitoring 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: - determining (Sdet) the maximum transmission power Pmax of the non-activation signal of said sensor and the minimum transmission power Pmin of the activation signal of said sensor; - storing (Smem) said maximum transmission power Pmax and minimum transmission power Pmin, when a difference δ between said powers Pmax and Pmin reaches a value equal to or less than a predetermined value δ0. [Fig. 4]

Description

Title of the invention: METHOD FOR AUTOMATIC POWER CALIBRATION 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, particularly pressure sensors, in the automotive sector, and to the means 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 enabling the implementation of said method.

[0002] The present invention advantageously applies to pressure sensors located (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 motor vehicle's on-board computer, to which said sensors transmit data (for example, relating to the tire pressure and / or temperature).

[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, for example a radio frequency transmitter, to enable the transmission of data to the on-board computer. The on-board computer, receiving the data from the sensors, can then alert the vehicle user if one of the tires has punctured or if the tire is deflating, posing a safety risk.

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

[0006] When changing tires, it is indeed necessary to pair (or connect via radio link) the sensors housed in the new tires with the vehicle's on-board computer. This pairing (or establishing a radio link) is done using 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 identifier, and transmit it to the on-board computer, so that the latter detects and locates sensors housed in newly installed tires and can capture their signals, in order to warn the user if a drop in pressure is detected in one of 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 in order 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 the activation of a plurality of sensors, it is therefore necessary to calibrate the emission power of such an activation device to avoid waking up unwanted sensors.

[0009] For example, in a factory, vehicle tires or wheels may: - passing on a conveyor belt, the tires are then close enough to each other that the activation signal emitted by the activation device triggers the activation of the sensors located inside the tires adjacent to the tire being tested; - being 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, includes twin wheels.

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

[0011] Furthermore, when installing an activation device in an industrial environment, a specialized operator must be present to adjust the 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. Therefore, the activation device must be adjusted so that the signal strength received by the sensors is sufficient to activate the desired sensors, for example, sensors located at a specific distance along a production line. while limiting the exposure of operators to said activation signals.

[0012] The invention thus aims to solve at least one of the problems mentioned above and is therefore a new method for the automatic power calibration 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 a: - determination of the maximum emission power Pmax of the non-activation signal of said sensor and the minimum emission power Pmin of the activation signal of said sensor; - memorization of said maximum emission powers Pmax and minimum Pmin, when a difference ô between said powers Pmax and Pmin reaches a value equal to or less than a predetermined value ô0.

[0013] Thus, any activation signal emitted with a power less than or equal to the transmission power Pmax does not activate said sensor. Whereas any activation signal emitted with a power strictly greater than the transmission power Pmin does not activate the sensor.

[0014] According to one possible feature, the determination of the maximum power Pmax and minimum power Pmin is stopped when the difference ô between said powers Pmax and Pmin reaches a value equal to or less than a value ô0.

[0015] According to another possible characteristic, the determination of said powers Pmax and Pmin is carried out by means of a dichotomous variation of the power of the activation signal. Dichotomous variation refers to varying the activation signal power through several iterations to determine a range for 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; which corresponds to the arithmetic mean of the maximum power Pmax and the minimum power Pmin. That is to say, the transmission power P of the activation signal, when determining the maximum and minimum powers, corresponds to , where Pmin and Pmax are previously stored emission power values ​​since the maximum and minimum emission powers vary depending on the result of the previously emitted signal (and therefore on the previously stored power values).

[0017] According to another possible characteristic, the determination of said powers Pmax and Pmin is achieved 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;.

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

[0019] According to another possible feature, if there is no reception of a response signal from said at least one sensor then the power P; of the activation signal emitted is identified with the maximum power Pmax (or maximum power for which the signal does not activate said sensor). A response signal is considered not to have been received after a predetermined time Tr, said time TR being, for example, greater than 5 seconds, and preferably greater than 10 seconds. The predetermined time TR is generally a function of the type of sensor and the environment in which the activation and response signals will propagate.

[0020] According to another possible feature, there is a latency time TL between each iteration of emission of an activation signal during the process according to the invention. Indeed, without a latency time (LT), there is a risk of detecting sensor activation by an activation signal from a previous step or iteration. The previous activation at power Pu can thus be interpreted as an activation at power P, thereby skewing 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, set between 0.5 and 1.5 seconds, and preferably approximately equal to 1 second.

[0021] According to another possible feature, there is an initialization of said process, initialization during which the initial values ​​of the maximum power Pmax of the non-activation signal, of the minimum power Pmin of the activation signal and / or of the difference ô0 between said maximum and minimum powers Pmax and Pmin are predetermined. Note that the initial values ​​of the maximum power Pmax, the minimum power Pmin, and the power difference δ0 can also be default values; for example, the maximum transmission power can correspond to the maximum power at which the activation device is capable of emitting an activation signal, the minimum transmission power can correspond to the minimum power at which the activation device is capable of emitting an activation signal, while the power difference δ0 is 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 feature, 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 feature, there is memorization of the identification number of each of the sensors which emitted a signal in response to said identification activation signal.

[0024] Thus, when calibrating several sensors simultaneously, for example in the case of dual wheels, it is necessary to calibrate the activation signal strength for each sensor, even if they are located at different positions in space. To achieve this, it can be advantageous to associate a position with each sensor identifier and determine whether the sensor has been activated or not 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 (reception) power 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 signals emitted by said sensors; - a communication module with a remote electronic entity, such as the on-board computer of a motor vehicle, in order to transmit information carried by the received signals; characterized in that said device is configured, on the one hand, to determine the maximum emission power Pmax of the non-activation signal of said at least one sensor and the minimum emission power Pmin of the signal causing the activation of said at least one sensor, and on the other hand, to stop the determination of said maximum power Pmax and minimum power Pmin when the difference θ between said power Pmax and Pmin reaches a value equal to or less than a predetermined value ô0.

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

[0029] The invention will be better understood, and other objects, details, features and advantages thereof will become more apparent from the following description of particular embodiments of the invention, given solely by way of illustration and not limitation, with reference to the accompanying drawings, in which: - the [Fig.l], referenced [[Fig.l]], is a schematic representation illustrating an activation device for at least one sensor according to the invention; - [Fig.2], referenced [Fig.2], is an enlarged and partially torn view of the device in [Fig.1]; - the [Fig.3], referenced [Fig.3] is a schematic representation of a second embodiment of an activation device according to the invention; - Figure 4, referenced as [Fig. 4], is a logic diagram of the automatic power calibration process for an activation signal of at least one sensor according to the invention. - [Fig.5], referenced [Fig.5], is a flowchart of a variant implementation of the process of [Fig.4].

[0030] Fig. 1 is a very schematic representation of a sensor activation device 1 9, more particularly in the present example of a learning device for an electronic system 3 for controlling the tire pressure of a motor vehicle 5 (said device 1 can also be referred to as a "valve activator" or "valve forcer").

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

[0032] The device 1 includes a housing 13, for example made of plastic, a display device 15, a keypad 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, on the other hand, is a schematic, enlarged and partially torn-off view of the activation device 1 of Fig.1.

[0034] Said device 1 comprises as follows: - at least one sensor activation module 31, such as means or modules for generating (continuous and / or modulated) sensor activation signals, said activation module 31 including in particular the antenna 19 which allows the said generated signals to be radiated to the sensors 9; - a signal receiving module 33 from the sensors, generally including another antenna housed in the casing 13 and configured for example to capture signals in a frequency band between 300 and 500 MHz (the sensor emitting a signal in this frequency band after being 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 receiving module 33); - a communication module 37 with an on-board computer 11 of a motor vehicle to transmit 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 that includes an OBD communication management circuit 38 and the previously mentioned OBD connector 21. It should be noted that the management circuit 38 can also be integrated into the electronic unit 35. Furthermore, the device 1 also includes a battery 41 configured to power its various elements (and electronic components).

[0036] It should also be noted that the 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 handled 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 a fleet manager's premises, etc.

[0038] Unlike the device in [Fig. 1], the activation device 1' illustrated in [Fig. 3] is a device intended to be positioned in a fixed location, whereas the sensors to be activated are generally at a predetermined distance, for example on a production line 40 comprising a conveyor belt on which is placed at least one tire P equipped with a sensor Cp The activation device 1' can thus include all 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 generally does not include a screen, keypad, OBD communication module, etc. Programming and communication with said device 1' can be carried out from a third-party electronic device connected to it, for example via a communication module 37' of the device 1'.

[0040] Fig. 3, on the other hand, is a very schematic representation of a sensor 9 activation device 1' intended for industrial use.

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

[0042] Said at least sensor 7 or Cl, here a pressure sensor for an electronic tire pressure control system of a motor vehicle, includes 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 purpose, the device 1, 1' is configured to operate a method 100 for automatic calibration of the emission power of an activation signal of at least one sensor 9.

[0045] Said process 100, more particularly illustrated in [Fig. 4], comprises: - a determination Sdet of the maximum power Pmax of the non-activation signal of said sensor and of the minimum power Pmin of the activation signal of said sensor; - a memorization Smem of said maximum power Pmax and minimum power Pmin, when a difference ô between said powers Pmax and Pmin reaches a value equal to or less than a predetermined value ô0 (for example a relative difference less than or equal to 5%).

[0046] Thus, when the difference ô which is equal to Pmin - Pmax < ô0, then the values ​​of said maximum power Pmax and minimum power Pmin are recorded in a memory, for example a random or read memory of the electronic entity 35, so that the value of the minimum power Pmin is used under the nominal conditions of use of the activation device 1 or 1'.

[0047] Said method 100 also includes a preliminary initialization step Sinit, during which the initial values ​​of the maximum power Pmax of the non-activation signal, the minimum power Pmin of the activation signal and the difference ô0 between said maximum and minimum powers Pmax and Pmin are predetermined and / or entered manually.

[0048] The determination of the maximum power Pmax and minimum power Pmin is stopped when the difference ô between said powers Pmax and Pmin reaches a value equal to or less than the value of the difference ô0. It should be noted that the smaller the difference θ, the longer the process according to the invention. Furthermore, the smaller the sensor whose minimum power we are trying to determine, the longer the process according to the invention. Moreover, the smaller the sensor whose minimum power we are trying to determine, the longer the process. The activation point is located near other sensors, the lower the value of the difference θ must be to avoid activating surrounding sensors.

[0049] More particularly, the determination Sdet of the maximum power Pmax and minimum power Pmin includes several substeps which can iterate until the difference ô is less than or equal to ô0.

[0050] Once the initial values ​​of the parameters Pmin, Pmax and ô0 are fixed, there is emission of an activation signal Si of sensor having a power P; corresponding to the arithmetic mean of the values ​​of the maximum power Pmax and the minimum power Pmin, that is to say here p. _ .

[0051] For a predetermined time after the emission of the activation signal Si, there is detection or non-detection of a response signal Sc from at least one sensor (response signal emitted in response to the activation signal Si emitted). For example, we can consider that there is no reception of a response signal after a predetermined time TR, said time TR 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 Sc from at least one sensor, there is a step S2 of updating the power value Pmin, the value of the power P; of the previously emitted activation signal then becomes the new minimum power value Pmin and the value of the parameter Pmin is modified for the next emission of an activation signal Si to the sensor 9.

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

[0054] Following a change in one of the parameter values ​​Pmin or Pmax, particularly during steps S2 or S3, the difference Δ between the minimum and maximum power values ​​Pmin or Pmax is calculated. More specifically, the difference Δ = Pmin - Pmax

[0055] A comparison S5 then takes place between the difference ô thus calculated and the predetermined value ô0 of this difference (or target value of the difference). If the calculated value ô is greater than the predetermined value ô0, a new iteration of steps Si and S2 or Si and S3 is implemented. Thus, a new activation signal S; is emitted at the power P;, taking into account the modified value of one of the minimum powers Pmin or maximum powers Pmax depending on whether step S2 or S3 was implemented during the previous iteration.

[0056] The determination of said powers Pmax and Pmin is thus carried out by means of a dichotomous variation of the power P of the activation signal S, since there is iteration by variation of the powers P of the activation signal. If the variation of the powers is a function of an arithmetic mean of the minimum power Pmin and the maximum power Pmax*

[0057] More specifically, there is then an iteration of the actions performed during the steps Si to S5 previously described until the calculated value of the difference ô is less than or equal to the predetermined value ô0. When this condition is met, the values ​​of the minimum power Pmin and maximum power Pmax correspond to the optimal values ​​sought and are then stored during a step Smem.

[0058] In an embodiment of the method in [Fig. 4], particularly when there are several sensors, for example in the case of twin wheels, the emission power of an activation signal is calibrated for each of the sensors, which are generally located at different positions in space. That is to say, advantageously, each sensor is associated, in addition to its identifier, with a maximum power value Pmax and a minimum power value Pmin, as well as a predetermined value ô0.

[0059] Furthermore, since each sensor has its own identifier, it is advantageous to associate a position in space (for example, position no. 1 for the nearest sensor, position no. 2 for the second nearest sensor, etc.) with a sensor (and its identifier). The association of a sensor (and its identifier) ​​with a position is, for example, determined based on 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 carrying 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 update accordingly of the values ​​of the maximum power Pmax and minimum power Pmin. That is to say that for a given power P; of an activation signal, there is an update of the value of the maximum non-activation power Pmax when the sensor has not emitted a response signal in a predefined response time TR, while if there is a reception of a response signal, there is an update of the value of the minimum activation power Pmin.

[0061] The different steps of the process 100 are iterated, therefore activation signals are emitted until all the values ​​of the maximum power Pmax and minimum power Pmin (for each of the sensors) have been determined such that the difference between said powers Pmax and Pmin is less than or equal to the predetermined value. finished ô0 (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 according to the reception or not of a signal (carrying the identifier or identification number) of the sensor which emitted it, this at each activation signal P; (and the successive iterations of emission of activation signal).

[0063] Once the difference θ between the maximum power Pmax and the minimum power Pmin is less than or equal to a predetermined value θ0 is reached for a given sensor, the transmission power values ​​are stored and the sensor is no longer taken into account for subsequent activation signal transmission iterations. This continues until the set of differences θ between the maximum power Pmax and the minimum power Pmin is less than or equal to a predetermined value θ0 for each of the sensors is determined.

[0064] Figure 5 is a flowchart of an alternative embodiment of the process of Figure 4. The process 100' of Figure 5 has essentially the same steps as the process of Figure 4, and these steps will not necessarily be described again or exhaustively, except to specify their differences or particularities. Furthermore, when the steps are analogous or similar, the same reference numerals will be used.

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

[0066] For this, there is prior identification of a plurality of sensors for which we seek to calibrate an activation signal. Thus, after Sinit initialization, there is S6 verification of the presence in memory of the identification numbers (or identifiers) Id associated with each of the 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; for example at the maximum possible emission power at which the activation device is capable of emitting a signal.

[0068] Then, during a predetermined time, for example TR, the response signals emitted by said sensors are received S8. Since the response signals carry the identification numbers (or identifiers) of the sensors, the identification number (or identifier) ​​of each sensor that emitted a signal is then stored S9. response to the identification activation signal.

[0069] Then, there is determination Sdet of the maximum power Pmax of the non-activation signal of the sensors and of the minimum power Pmin of the activation signal of the sensors.

[0070] Unlike method 100 of [Fig. 4], after emission of an activation signal at a power P; : - if a response signal Sc is received from all the stored sensors, the value of the power P; of the previously emitted activation signal becomes (step S2) then at the new minimum power value Pmin and the value of the parameter Pmin is modified for the next emission of an activation signal Si; - if there is no reception of a response signal Sc from all the stored sensors (during the predetermined time TR), the value of the power P; of the previously emitted activation signal becomes (step S3) then the new maximum power value Pmax and the value of the parameter Pmax is modified for the next emission of an activation signal Si.

[0071] Subsequently and as before, the difference ô between the minimum power P min and maximum power Pmax is calculated S4 and is compared S5 with the predetermined value ô0.

[0072] If the calculated difference value ô is greater than the predetermined value ô0, a new iteration of steps Si and S2 or Si and S3 is implemented. Thus, a new activation signal Si of power P; is emitted, but taking into account the modified value of one of the minimum powers Pmin or maximum powers Pmax.

[0073] Otherwise, that is, when the difference ô of the powers is equal to or less than the predetermined value ô0, the determination of the emission powers is stopped, and the values ​​of said maximum power Pmax and minimum power Pmin are recorded in a memory, for example a RAM or ROM of the electronic entity 35. This is in particular so that the value of the minimum power Pmin is used under the nominal conditions of use of the activation device 1 or 1'.

[0074] It should be noted that in one embodiment of the method 100', the identification numbers can be entered manually, or sorted manually by the user after emission of an identification signal and reception of the response signals.

[0075] In another unrepresented embodiment of the processes 100 and 100', the activation signal used under normal operating conditions of the activation device 1 or 1' has an emission power corresponding to the minimum power Pmin memorized plus a predefined percentage, for example 10%, in order to guarantee the activation of the sensor(s).

Claims

Demands

1. An automatic method (100, 100') for calibrating the power (Pi) of an activation signal (Si) of at least one sensor (Ci), in particular a pressure sensor for an electronic tire pressure control system (7) of a motor vehicle (5), said sensor (Ci) having an identification number (Id) and comprising at least one data transmission and reception module, characterized in that said method (100, 100') comprises: - determining (Sdet) the maximum transmission power Pmax of the non-activation signal of said sensor and the minimum transmission power Pmin of the activation signal of said sensor; - storing (Smem) said maximum transmission power Pmax and minimum transmission power Pmin, when a difference θ between said powers Pmax and Pmin reaches a value equal to or less than a predetermined value

2. o0. Method (100, 100') according to the preceding claim, characterized in that there is a stop in the determination (Sdet) of the maximum power Pmax and minimum power Pmin when the difference ô between said power Pmax and Pmin reaches a value equal to or less than a predetermined value ô0.

3. Method (100, 100') according to the preceding claim, characterized in that the determination (Sdet) of said powers Pmax and Pmin 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 Pmax and Pmins' is carried out by the detection or non-detection of at least one response signal (Sc) from said at least one sensor as a function of the activation signal (Si) previously emitted at a power R.

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

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 (Cl) then the power P; of the activation signal (Si) emitted is identified with the maximum power Pmax.

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 Pmax of the non-activation signal, of the minimum power Pmin of the activation signal (Si) and of the difference ô0 between said maximum and minimum powers Pmax and Pmin 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; which corresponds to the arithmetic mean of the maximum power Pmax and the minimum power Pmin.

9. A 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. .T 1. Method (100, 100') according to the preceding claim, characterized in that there is memorization (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 memorization of the identification number (Id) of each of the sensors (Ci).

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 sensor signal receiving module (33); - an electronic entity (35) configured to store and / or process information carried 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 carried by the received signals;characterized in that said device is configured, on the one hand, to determine the maximum emission power Pmax of the non-activation signal of said at least one sensor and the minimum emission power Pmin of the signal causing the activation of said at least one sensor, and on the other hand, to stop the determination (Sdet) of said maximum power Pmax and minimum power Pmin when the difference ô between; said powers Pmax and Pmin reach a value equal to or less than a predetermined value ô0.

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