Transmission of sequences of values representative of measurements from sensors associated with a tire to a remote receiving member

Abstract

The invention relates to a method for communicating values measured by at least one sensor (21, 22, 23) of a device (20) associated with a tire (11) to a remote receiving member (30), the method comprising steps of: - acquiring (S1) measurements via the at least one sensor; - sampling (S2) and storing (S3) the measurements to form an ordered series; - determining (S4) a sequence of values from the ordered series; - transmitting (S5) a frame (40) to the remote receiving member (30), the frame comprising a unique identifier (441) of the device, an increment indicator (442), a format indicator (444) indicating the format of the sequence of values, and this sequence of values (443), this sequence of values (443) comprising at least one reference value and a set of representations of other values in the form of a deviation relative to the reference value.

Description

DESCRIPTION Transmission of sequences of representative values ​​from sensor measurements associated with a pneumatic system to a remote receiving device TECHNICAL FIELD

[0001] This description relates to the transmission of measurement data between a device associated with a mounted assembly comprising a tire and a wheel, and a remote receiving unit. It applies particularly to devices incorporating sensors, such as temperature and pressure sensors, that measure the condition of the tire.

[0002] It is already known that vehicles have sensors on their tires, such as TPMS (Tire Pressure Monitoring System) devices, which are tire pressure monitoring systems. These systems use sensors installed inside or outside the tires to measure pressure; these measurements are then transmitted wirelessly to an electronic component of the vehicle to warn the driver in case of a pressure problem.

[0003] More recently, more complex systems have emerged for tire management, the TMS (Tire Mounted System) systems which aim to multiply the sensors and provide advanced functionalities through the measured data.

[0004] However, due in particular to the increasing number of sensors and the growing volume of data to be transmitted, various technical challenges arise. These challenges are primarily related to the energy consumption of these electronic devices, and also to radio transmission issues between them and the remote receiving device.

[0005] Each transmission of a frame to the remote component generates energy consumption. However, for the most efficient possible management of the pneumatic system, it is important to have a significant amount of data available to the receiving component, possibly of different types (pressure, temperature, etc.). The increase in the amount of data necessarily leads to an increase in the number of frames to be transmitted and therefore in the energy consumption of the electronic device.

[0006] However, the electronic device is integrated with a tire and cannot be wired to the vehicle in industrial mode. It must therefore be electrically powered by a battery. Its operating time thus depends primarily on the battery's capacity and power consumption. Furthermore, the electronic device may be difficult to access, or even completely inaccessible if it is located inside a tire, making battery replacement either impossible or undesirable.

[0007] Therefore, there is a need to improve current state-of-the-art proposals in order to minimize the energy consumption of the electronic device. DESCRIPTION OF THE INVENTION

[0008] The proposals described therefore aim to improve the situation compared to the state of the art, and in particular, to reduce the energy consumption of the device associated with the tire.

[0009] To this end, according to a first aspect, a method is proposed for communicating values ​​measured by at least one sensor of a device associated with a pneumatic system to a remote receiving unit, comprising the steps of: acquiring measurements by said at least one sensor; sampling and storing said measurements to constitute an ordered series; determining a sequence of values ​​from said ordered series; and transmitting a frame to said remote receiving unit, comprising a unique identifier of said device, an increment indicator, incremented during each transmission, an indicator of the format of said sequence of values, and said sequence of values, said sequence of values ​​comprising at least one reference value and a set of representations of other values ​​in the form of a deviation relative to said reference value.

[0010] In preferred embodiments, the method comprises one or more of the following features, which may be used separately, partially, or in full combination: the value sequence is determined to partially overlap a previous sequence; each element of the value sequence representation set corresponds to the absolute value of a relative deviation multiplied by a multiple of two, to which the value of one has been added to or subtracted from the smallest unit of representation of said relative deviation, according to one of the two possible signs for said relative deviation; the value sequence comprises values ​​from different sensors and / or corresponding to different sampling periods; the device is positioned on an inner surface of said tire, on a rim associated with said tire, or on a valve associated with said tire.said frame is transmitted according to the BLE protocol, specifically in an announcement channel.

[0011] Another aspect concerns a device suitable for use with a pneumatic tube, comprising: circuits adapted for sampling measurements acquired by sensors; a memory for storing said measurements to form an ordered series, said circuits being further adapted to determine a sequence of values ​​from said ordered series and, in conjunction with a radio frequency interface, to transmit a frame to a remote receiving device, comprising a unique identifier of said device, an increment indicator, incremented during each transmission, a format indicator for said sequence of values, and said sequence of values, said sequence of values ​​comprising at least one reference value and a set of representations of other values ​​in the form of a deviation relative to said reference value

[0012] Another aspect concerns an assembled unit, or wheel, comprising at least one device as previously described.

[0013] Another aspect concerns a computer program capable of being implemented on a device, the program comprising code instructions which, when executed by a processor, carries out the steps of the process as previously defined.

[0014] Another aspect concerns a data carrier on which at least one series of program code instructions for the execution of a process as previously defined has been stored. BRIEF DESCRIPTION OF THE DRAWINGS

[0015] Other aspects, objectives, advantages, and features of the invention will become clearer upon reading the following detailed description of preferred embodiments thereof, given by way of non-limiting example, and made with reference to the accompanying drawings in which: Figure 1 represents a context for the implementation of the process and devices described. Figure 2 schematically represents the architecture of a device according to one embodiment. Figure 3 illustrates a flowchart illustrating a process according to one embodiment. Figure 4 illustrates an example of a frame transmitted between a device and a remote receiving organ, according to embodiments. Figure 5 illustrates an example of a payload of a frame transmitted between a device and a remote receiving organ, according to embodiments. Figure 6 illustrates a concrete example of a succession of frames transmitted by a device, according to one embodiment. DETAILED DESCRIPTION OF SPECIFIC METHODS OF IMPLEMENTATION

[0016] Figure 1 shows a mounted assembly, or wheel, 10 comprising a tire 11 and a rim 12. The wheel is intended to be mounted on a motor vehicle.

[0017] A device 20 is associated with the tire 11, that is, adapted to provide information on the condition of this tire by means of sensors. This device is an electronic device. For example, it could be a TPMS or TMS device, or any other device of the same type with similar functionalities.

[0018] The device 20 can be positioned directly on or within the tire 11. In particular, this device can be positioned and fixed to an inner surface of the tire. The device 20 can also be positioned on the rim 12, or on a valve associated with the tire. Generally, the device 20 is attached to the mounted assembly 10.

[0019] This device is suitable for communicating measurements acquired by the sensors to a remote receiving organ 30.

[0020] This remote receiver 30 can be located within the motor vehicle. For example, it could be one of the circuits that make up the vehicle's instrument panel. It can then be designed to display data from these measurements on an interface of this instrument panel, in the form of numerical values, indicator lights in case of alarms (triggered by exceeding thresholds, for example), etc.

[0021] The remote receiving unit 30 can also be located outside the vehicle. For example, it can be located in a station where the motor vehicle may be parked periodically. This could be a regular parking area for the vehicle, or a maintenance area, for example.

[0022] The measurements can be communicated by transmitting a data frame 40 to this remote receiving device. This frame 40 includes, in particular, representative values ​​of these measurements, adapted for processing by the remote receiving device 30.

[0023] Figure 2 schematically illustrates a possible architecture of such a device 20.

[0024] In this embodiment, sensors 21, 22, and 23 are integrated into the device's structure. Other embodiments may involve sensors located outside the device itself, capable of communicating with it via wired or wireless means, for example, using near-field communication (NFC). This example shows three sensors, but it is obviously possible to use fewer or more.

[0025] The device also includes processing means 24, or electronic circuits, typically comprising a microcontroller, or processor, and a memory 25.

[0026] The device 20 also includes a radio frequency interface 26 adapted to transmit frames 40 to the remote receiving device 30. This radio interface 26 can conform to various radio communication mechanisms and protocols. In particular, it can conform to short-range radio communication protocols such as Wi-Fi or Wi-Fi Direct, Zigbee, Z-Wave, Bluetooth, or BLE.

[0027] In cases where the transmission itself needs to minimize the energy consumption of the transmitting device, the BLE protocol can be chosen.

[0028] The Bluetooth Low Energy (BLE) protocol is a version of the Bluetooth protocol designed to provide low-power wireless communications. BLE is standardized in the IEEE 802.15.1 standard and is part of the Bluetooth specifications adopted by the Bluetooth Special Interest Group (Bluetooth SIG).

[0029] The BLE protocol uses 2.4 GHz frequency bands and 40 channels distributed between 2402 and 2480 MHz and with a width of 2 MHz.

[0030] According to this protocol, three advertising channels are defined. These are specific channels used for broadcasting advertising messages or frames, particularly for the purpose of establishing a connection: devices listening on these channels can receive advertisements, allowing a device to initiate a connection. They can also be used to announce their presence (discovery mechanism) or for beacon-type signaling. (English). Data is exchanged between participants after a connection is established, in frames transmitted over other channels.

[0031] Advertisement frames, transmitted through advertising channels, are thus opposed to data frames transmitted through other channels.

[0032] The advertising channels are channels 37 (2402 MHz), 38 (2426 MHz) and 39 (2480 MHz). These three channels are strategically located within the frequency band to minimize interference with other technologies using the same band (such as Wi-Fi, which also operates in the 2.4 GHz band).

[0033] Establishing a connection between two parties in a BLE communication poses an energy consumption problem, particularly due to the synchronizations to be carried out between them and the multiple frequency hops to be made to transmit and listen in the correct channels.

[0034] Also, according to an embodiment based on this BLE protocol, it is chosen not to establish a connection between the device 20 and the remote receiving organ 30. In particular, the frames 40 are transmitted on an advertisement channel.

[0035] Figure 3 illustrates a flowchart of the described process, according to one embodiment. This flowchart shows a breakdown into steps given for guidance purposes; it may be necessary to subdivide certain steps, combine others, or use a different breakdown that achieves the same final functionality.

[0036] According to this embodiment, a step SI consists of acquiring measurements by the sensor(s) 21, 22, 23. A preliminary step may consist of setting up the measuring device within the assembled unit.

[0037] These sensors may include a pressure sensor. They may also include a temperature sensor, an accelerometer, a rotation sensor, etc. The proposed method is independent of the number and type of sensors considered.

[0038] In step S2, these measurements are sampled. The sampling process depends in particular on the format of the measurements acquired by the sensors. The sampling frequency is variable; it may depend, in particular, on the type of measurements and their estimated rate of change. These sampling rates can be set during a parameterization phase of device 20. According to one embodiment, it can It is planned that the device 20 is adapted to receive a parameter message (for example emitted by the remote receiving organ 30, which would then also be a transmitter) specifying these sampling rates.

[0039] These sampled measurements are then stored, in a step S3, in a memory 25 of the device 20, by the processing circuits 24. This forms an ordered series in which each measurement corresponds to a time, or date, according to the sampling chosen.

[0040] In a step S4, a sequence of values ​​is determined from the stored ordered series, for transmission, in a step S5 within the frame 40 to the distant receiving organ 30.

[0041] Since this frame is of limited size, it is necessary to define an encoding of the measurements so that the transmitted values ​​allow for the transmission of a larger number of measurements.

[0042] In the case of an implementation where frames are transmitted over BLE protocol advertising channels, as illustrated in Figure 4, this frame 40 comprises a one-byte preamble 41, a four-byte address field 42, a two-byte header 43, and a payload 44 (or PDU for Protocol Data Unit). The frame also includes a three-byte error correction code (CRC) 45.

[0043] Preamble 41 is a synchronization field used to indicate the start of the frame.

[0044] For advertisement frames, address field 42 is fixed and has the value 0x8E89BED6. For data frames, this address is unique to the current connection between two devices.

[0045] Header 43 indicates the frame type: for example, a "connectionless communication" type for an advertisement frame. For such a frame, it also indicates the length of the payload 44, which can be between 0 and 37 bytes.

[0046] Also, the transmission of the sequence of values ​​is constrained in this payload to a maximum of 37 bytes.

[0047] As illustrated in Figure 5, part of this payload 44 is also used for other information as will be seen later: an identifier 441 of the device 20, an increment indicator 442 and a format indicator 444. The sequence of values ​​then occupies only a part 443 of the payload 44.

[0048] This device identifier 441 is a unique identifier, meaning that it allows device 20 to be identified in a unique way.

[0049] The order of the fields is illustrative.

[0050] Furthermore, transmission on an advertising channel assumes that the remote receiving device 30 is listening to that channel. If this device is a general-purpose device, it must listen to all channels of the BLE protocol and can only receive a portion of the frames transmitted on the advertising channels.

[0051] Furthermore, the environment of the devices 20 causes interference with radio communications: frequency band occupation by other networks (Wi-Fi in particular), presence of the metal parts of the rim 12, rotation of the assembled unit 10, etc. Consequently, a large number of frames 40 are not received by the remote receiving device 30.

[0052] However, since a two-way connection is avoided, the radio link between device 20 and the remote transmitting unit 30 is unidirectional. Therefore, the latter cannot alert device 20 that it has not received certain frames 40. Furthermore, such a request and its repetition would be detrimental, as they would generate an increased load on device 20 and thus an increase in energy consumption, which is precisely what we are trying to avoid.

[0053] It is therefore proposed that the sequence of values ​​transmitted in the frames constitutes a history of the measurements. The remote receiving device 30, receiving such a frame, can thus access measurements corresponding to several dates and thereby determine the evolution over time of the measured quantity (pressure, temperature, etc.).

[0054] As mentioned previously, it may be possible to maximize the number of measurements represented by the sequence of transmitted values, so that a single frame brings a large amount of information to the distant receiving organ 30.

[0055] To do this, different encoding methods can be used.

[0056] Preferably, measurements are converted into a unit that minimizes the number of digits needed to represent them.

[0057] In particular, for pressure, a representation in bars will be preferred rather than in millibars or pascals, for example.

[0058] According to one embodiment, the measurements are encoded so that a sequence of values ​​includes at least one reference value and a set of representations of other values ​​in the form of a deviation relative to that reference value.

[0059] This implementation method is based on the fact that the measured quantities change slowly and that the relative differences are therefore small. Their representation can thus be encoded in a small number of bytes.

[0060] For example, the reference value can be encoded using 2 bytes and each relative deviation using 4 bits. Thus, if the sequence of values ​​is encoded using 18 bytes, a sequence of 33 values ​​can be encoded. This can be compared to a conventional encoding in which each measurement would be represented by a value encoded using 2 bytes, which would only allow for 9 values / measurements.

[0061] According to one embodiment, the encoding of relative deviations can be optimized by a method called zigzag encoding. This encoding method avoids using a bit just for the sign of the relative deviation.

[0062] This method consists of, for each element of the set of representations of the sequence of values, taking the absolute value of a relative deviation multiplied by a multiple of two, then adding or subtracting the value "1" to the smallest unit of representations of this relative deviation, according to one of the two possible signs of the relative deviation.

[0063] For example, we add or subtract "1" for the negative sign: negative relative deviations are thus transformed into odd values, while positive relative deviations, due to multiplication by a multiple of "2", are transformed into even values.

[0064] The smallest unit of representation can also be called the last significant digit or last non-zero digit, whether this relative difference is an integer or a decimal number.

[0065] In other words, this method consists of performing the following manipulation on the relative deviation: if the relative deviation is positive, it is multiplied by two (or another multiple of two); if the deviation is negative, its absolute value is multiplied by two (or another multiple of two) and one is added (or one is subtracted) to the smallest unit of representation of the value.

[0066] Thus, for the distant receptor organ 30, it can test the parity of the encoded gap to determine if it is positive or negative, and perform the inverse operation to recover the relative gap; that is: if the number is even, the relative gap is obtained by dividing by 2 (or another multiple of two); if the number is odd, the relative gap is obtained by subtracting (or adding) the value 1 to the smallest unit representing the value, then dividing by 2 (or another multiple of two). The relative gap is the opposite of the value thus obtained.

[0067] For example, the value 3.14 is positive, so we can just multiply it by two for its encoding, which gives 6.28.

[0068] Since the value -3.14 is negative, we multiply its absolute value (6.28) by two and add 1 to the smallest unit of representation, or last digit (here 8): we thus obtain 6.29. As this value is odd, the receiver will be able to determine that it is a negative relative difference.

[0069] This allows us to gain encoding space to allow the value sequence to transmit more measurements and / or to improve the accuracy of each measurement represented (i.e., a number of useful bits per value).

[0070] As mentioned previously, maximizing the number of measurements represented by the sequence of transmitted values ​​allows the distant receiving organ 30 to obtain a large amount of information on the history of measurements.

[0071] Furthermore, it can be anticipated that the sequence of values ​​will be determined to partially overlap a previous sequence. Typically, the sequence of values ​​partially overlaps the immediately preceding sequence. In other words, according to In this embodiment, each frame 40 can include values ​​representing measurements already represented in a previous frame.

[0072] This method of implementation makes it possible to reconstruct a more complete history even in the event of the loss of a frame 40, by taking advantage of this redundancy.

[0073] To do this, frames 40 can include an increment flag 442.

[0074] This increment indicator allows a frame 40 to be uniquely identified, modulo the size of this field 442, but which is designed so that two frames cannot have the same increment indicator within a sufficiently long time interval to generate ambiguity.

[0075] The increment indicator can be generated by means of a simple counter implemented by the circuits 24 of the device 20. During each transmission of a frame 40, this counter is incremented by one unit (it can be incremented before the transmission or after the transmission, according to operational choices).

[0076] Thus, the remote receiving organ 30 can use the increment indicator to position the received frames relative to each other, that is to say, to order them.

[0077] This increment number also makes it easy to determine which frames were not received.

[0078] Thus, the content of an unreceived frame can be reconstructed, at least partially, by the remote receiving organ 30, using the contents of the immediately preceding and following frames.

[0079] For example, we assume that 33 measurements are represented by the value sequences of each frame 40. We assume an overlap rate of 33%. We can then consider that a T1 frame comprises a sequence of values ​​corresponding to measurements ml to m33, a T2 frame comprises a sequence of values ​​corresponding to measurements m22 to m55, a T3 frame comprises a sequence of values ​​corresponding to measurements m44 to m66.

[0080] If frame T2 is not received by the remote receiving device 30, it can nevertheless reconstruct a history from frames T1 and T3: [ml-m33 ; m44-m66]. The effect of the loss of frame T2 is thus minimized (interval [m33-m44]) due both to the redundancy of information transmission between several frames, and to the identification of frames that can be ordered upon reception for the increment indicator 442.

[0081] Furthermore, as previously discussed, a device can include several sensors. The measurements from these different sensors must therefore be transmitted to the remote receiving unit 30.

[0082] According to one embodiment, a frame 40 transmits a sequence of values ​​corresponding to a single sensor, i.e. representing only pressure or temperature measurements, etc.

[0083] In another embodiment, the value sequence can include values ​​from different sensors. Thus, the value sequence is subdivided into subsequences, each corresponding to a sensor 21, 22, 23. For example, the 18-byte field 443 can be divided into 3 subfields, not necessarily of equal size, each corresponding to one of these sensors.

[0084] Furthermore, according to one embodiment, the sequence of values ​​can correspond to different sampling periods.

[0085] The variety of sampling periods makes it possible both to help reconstruct a measurement history in case of frame losses, and to address distinct problems.

[0086] Therefore, it is useful to have a history of pressure and / or temperature measurements at short intervals to estimate load behavior at the coupling, but also at longer time scales (for example, one pressure measurement over 8 hours or 24 hours) to enable the detection of a slow leak, or even on an even longer scale (for example one measurement per day over 8 days or a month) in order to monitor the behavior and condition of a tire on a vehicle returning from a mission to the depot.

[0087] As with the different sensors, these different samples can be distributed in specific frames or within the same frame.

[0088] Thus, a sequence of values ​​may include a first part relating to a first sampling period and a second part relating to a second sampling period, for example. Other parts and sampling periods may also be added.

[0089] For example, a sequence of values ​​could include The first 4 values ​​correspond to a one-hour sample. The following 4 values ​​correspond to a 4-hour sampling; The following 4 values ​​correspond to a 16-hour interval.

[0090] Thus, if the remote receiving device 30 receives a frame 40 every hour, containing 16 values, it can reconstruct a 64-hour history with hourly accuracy.

[0091] It can be envisaged that devices 20 can transmit frames according to one or more of the modalities described above.

[0092] In the latter case, a format indicator 444 (which may form part of the 443 field corresponding to the sequence of values) allows the frame type to be indicated and a format to be defined for this sequence of values ​​to be defined.

[0093] In particular, this format indicator can specify: the type of measurement: pressure, temperature, acceleration, etc.; the unit of encoding of these measurements: pascals, hectopascals, bars..., degrees Celsius, Fahrenheit...; the type of encoding: each measurement on a fixed number of bits, or encoding with reference value and relative deviations; one or more sampling periods, and the corresponding subdivision of the sequence of values ​​according to these sampling periods, etc.

[0094] For example, a given value for this field can refer to a catalog of possible formats, which is shared by the device 20 and the remote receiving organ 30. In this way, by considering this format indicator 444, the latter can decode the entire sequence of values, so as to recover the encoded measurements.

[0095] The frame 40 thus prepared is then transmitted to the remote receiving device 30. As previously described, it can be transmitted in a BLE protocol advertising channel. However, other protocols are also conceivable, including future developments of this protocol, or other protocols based on the same principles.

[0096] Figure 6 illustrates a concrete example of a succession of T1, T2...T8 frames transmitted by a device 20.

[0097] The x-axis shows an ordered series of measurements (the numbers 1 to 28 representing an order of measurements, 28 representing the oldest measurement in time).

[0098] Frames T1 to T8 are transmitted successively, in that temporal order. Frame T1 is the oldest transmitted frame.

[0099] Each frame corresponds to the same format (identical format identifier 444) which corresponds to 3 different sampling periods: a period of 1 for a duration of 5 measurements, then a period of 3, then a period of 6. Thus, frame Tl includes measurements 8, 9, 10, 11, 12 (period of 1), 15, 18 and 21 (period of 3), and 27 (period of 6).

[0100] It is assumed that the T3 and T7 frames are lost (i.e. not received by the distant receiving organ 30).

[0101] The redundancy of the data present in each frame allows for the reconstruction of most of the data, especially the most recent data. In this case, only measurement 19 would be missing because it is (in this example) transmitted only by frame T3. Of course, other frames before frame T1 or after frame T8 could also allow for the reconstruction of measurement 19, despite the missing data from frames T3 and T7.

[0102] More generally, these proposals are not limited to the examples and embodiments described and illustrated. They are particularly susceptible to numerous variations accessible to those skilled in the art, some of which have been described previously or simply mentioned.

[0103] Of course, the present invention is not limited to the examples and embodiment described and illustrated, but is defined by the claims. In particular, it is susceptible of numerous variations accessible to those skilled in the art.

Claims

DEMANDS 1. Method for communicating values ​​measured by at least one sensor (21, 22, 23) of a device (20) associated with a pneumatic (11) to a remote receiving organ (30), comprising steps of: acquisition (S1) of measurements by said at least one sensor; sampling (S2) and storage (S3) of said measurements to constitute an ordered series; determination (S4) of a sequence of values ​​from said ordered series; transmission (S5) of a frame (40) to said remote receiving organ (30), comprising a unique identifier (441) of said device, an increment indicator (442), incremented at each transmission, an indicator of the format (444) of said sequence of values ​​and said sequence of values ​​(443), said sequence of values ​​comprising at least one reference value and a set of representations of other values ​​in the form of a deviation relative to said reference value.

2. A method according to the preceding claim, wherein said sequence of values ​​is determined so as to partially overlap a previous sequence.

3. A method according to any one of the preceding claims, wherein each element of the set of representations of the sequence of values ​​corresponds to the absolute value of a relative deviation multiplied by a multiple of two to which has been added or subtracted the value one to the smallest unit of representations of said relative deviation according to one of the two possible signs for said relative deviation.

4. A method according to the preceding claim, wherein said sequence of values ​​comprises values ​​from different sensors and / or corresponding to different sampling periods.

5. Method according to any one of the preceding claims, wherein said device (20) is positioned on an inner surface of said tire (11) or on a rim associated with said tire or on a valve associated with said tire.

6. A method according to any one of the preceding claims, wherein said frame is transmitted according to the BLE protocol, in particular in an announcement channel.

7. Computer program capable of being implemented on a device (20), the program comprising code instructions which, when executed by a processor, carries out the steps of the process defined in claims 1 to 6.

8. Device (20) suitable for being associated with a pneumatic (11), comprising circuits (24) adapted for sampling measurements acquired by sensors (21, 22, 23), a memory (25) for storing said measurements to constitute an ordered series, said circuits being further adapted for determining a sequence of values ​​from said ordered series and for, in collaboration with a radio frequency interface (26), transmitting a frame (40) to a remote receiving organ (30), comprising a unique identifier of said device (441), an increment indicator (442), incremented at each transmission, a format indicator (444) of said sequence of values, and said sequence of values ​​(443), said sequence of values ​​comprising at least one reference value and a set of representations of other values ​​in the form of a deviation relative to said reference value.

9. Assembled assembly (10) comprising a device (20) according to the preceding claim.

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