Mechanical flight control system of an aircraft with measurement of force in the mechanical flight control system

Abstract

The present invention relates to a mechanical flight control system (2) for an aircraft equipped with an actuator (30) and a force measurement system (40), said actuator (30) comprising at least one electric motor and one duplex computer per motor, each duplex computer comprising one control channel, one monitoring channel, and two input interfaces, said force measurement system (40) comprising several measurement channels, each comprising a sensor, an electronic module, and an output interface connected to one of said input interfaces. Said electronic module is connected to said sensor to generate an analog measurement signal and is configured to digitize said analog measurement signal, at least one of said measurement channels applying delta-sigma modulation, and then to transform it into a digital transfer signal carrying a transfer value representative of a force in said mechanical flight control system (2).Abbreviated figure: figure 1.

Description

Title of the invention: Mechanical flight control system for an aircraft with force measurement in the mechanical flight control chain

[0001] The present invention is in the field of aircraft flight controls.

[0002] The present invention relates to a mechanical flight control system for an aircraft comprising a force measurement system and an aircraft equipped with this mechanical flight control system. The present invention also relates to a method for measuring a representative value of a force in a mechanical flight control system for an aircraft.

[0003] An aircraft may include movable aerodynamic control surfaces steered by a mechanical flight control system to direct the aircraft. Such aerodynamic control surfaces may include rotor blades, propeller blades, elevators or rudders, for example.

[0004] A mechanical flight control system may include several connecting rods forming a linkage between a control element, such as a lever, a joystick, or a rudder pedal, and an aerodynamic control surface to be moved, possibly by means of a servo control. A mechanical flight control system may also include one or more actuators.

[0005] For example, a series actuator can be interposed between two connecting rods of the mechanical flight control chain, an extension or retraction of this series actuator causing a change in the order transmitted to the servocontrol without having an effect on the position of the piloting element.

[0006] According to another example, a parallel actuator, also called a "trim actuator," can connect the control element or a connecting rod of the flight control system to a fixed point on the aircraft structure. Such a parallel actuator can, for example, cause simultaneous changes in the command transmitted to the servocontrol and in the position of the control element. This parallel actuator can also allow the control element to be anchored in a predetermined position. Such a parallel actuator can also act as soft or hard stops to indicate, in particular, to a pilot the approach and / or exceeding of a flight limit, or even provide haptic feedback.

[0007] Furthermore, in order to achieve the required level of safety, these actuators may comprise two motors, controlled respectively by separate, or even dissimilar, duplex computers. Such duplex computers thus comprise a first computing channel dedicated to controlling the movements of the actuator and a second channel dedicated computing power for monitoring the first computing path, and allowing it to be inhibited if an anomaly or failure is detected.

[0008] Regardless of their type, these actuators can be controlled according to a force. For this purpose, and to adapt the control setpoint of the actuators, a force measurement in the mechanical flight control chain, and in particular on a connecting rod, is necessary.

[0009] One or more analog force measurement devices can, for example, be integrated into a mechanical flight control system as described in document EP 3301019. Such force measurement devices can be particularly sensitive to constrained environments. Furthermore, these force measurement devices can induce significant friction on the control components due to the numerous electrical connecting wires of these devices.

[0010] Furthermore, the signal provided by a force measurement device arranged on a mechanical flight control system can be processed and / or filtered to improve its resolution or limit its noise, for example. An analog signal can also be transformed into a digital signal as described, for example, in document US2014 / 0266259.

[0011] To meet the high level of security required for an aircraft's flight control system, such a force measurement device arranged on the flight control system may be duplex, i.e., comprising two independent measurement channels, or even quadruplex, i.e., comprising four independent measurement channels. In particular, the use of a quadruplex force measurement device makes it possible to achieve a failure rate of less than or equal to 10⁶ / flight hour for the loss of one or more measurement channels of the force measurement device, as well as a failure rate of less than or equal to 10¹⁰ / flight hour for the emission of an undetected erroneous signal on one or more measurement channels and for a mechanical failure leading to the loss of the control element.

[0012] The present invention relates to an innovative method for measuring force in a flight control mechanical system of an aircraft. The present invention also relates to a flight control mechanical system comprising a force sensor capable of applying such a method, and to an aircraft comprising such a flight control mechanical system.

[0013] The present invention thus relates to a mechanical flight control chain for an aircraft comprising at least one connecting rod and one actuator, the actuator comprising at least one electric motor and one duplex computer per motor, each duplex computer comprising one control channel, one monitoring channel and two interfaces The inputs are connected to the control channel and the monitoring channel, respectively. The flight control system also includes a force measurement system mounted on the connecting rod and configured to control the actuator. The control and monitoring channels of each duplex computer constitute processing channels for that duplex computer.

[0014] The flight control mechanical chain is notable in that the force measurement system comprises at least two measurement channels connected respectively to the two input interfaces of said at least one duplex computer, and each of said measurement channels comprises a sensor, an electronic module, and an output interface. The output interface is connected to one of the input interfaces of said at least one duplex computer, the electronic module being connected to the sensor to generate an analog measurement signal, the electronic module being configured to digitize the analog measurement signal to transform it into a digital measurement signal, the electronic module being configured to transform the digital measurement signal into a digital transfer signal carrying a transfer value representative of a force in the flight control mechanical chain.At least one of the measurement channels applies delta-sigma modulation to digitize the analog measurement signal and applies Manchester coding and low-voltage differential transmission to transform the digital measurement signal to obtain the digital transfer signal, the mechanical flight control chain including a clock per measurement channel intended to time the delta-sigma modulation.

[0015] The mechanical flight control chain can be connected at one end to a piloting device, such as a joystick, a lever or a rudder pedal for example, and at another end to an aerodynamic control surface of the aircraft, such as one or more rotor blades or one or more flaps for example, possibly via a servo control.

[0016] The electronic module may include a printed circuit board carrying electronic components such as integrated circuits and / or microswitches. In this case, this electronic module does not apply any program stored in memory to carry out the steps of the process.

[0017] Alternatively, the electronic module may include a computer, for example a microcontroller, and a memory storing a program applied by the computer to carry out the steps of the process.

[0018] The analog measurement signal carries a value measured by the sensor, this measured value being a function of a force suffered or transmitted by the mechanical flight control chain, and in particular by the connecting rod of this mechanical flight control chain.

[0019] Delta-sigma modulation transforms the measured value acquired in analog form into a digitized value carried by the digital measurement signal. This digital measurement signal is encoded on one or more bits by oversampling, the rate of change of which, between 0 and 1, is a function of the amplitude of the analog measurement signal. This delta-sigma modulation is clocked by the clock for the relevant measurement channel. The use of the time signal emitted by this clock, as well as the frequency of this time signal, influences the resolution of the digital measurement and transfer signals, as well as their accuracy. This digitized value carried by the digital measurement signal is a function of the measured value and therefore also of the force experienced or transmitted by the flight control system.

[0020] Next, Manchester encoding and low-voltage differential transmission, known by the acronym "LVDS" (Low Voltage Differential Signaling), allow the digitized value carried by the digital measurement signal to be transformed into the transfer value carried by the digital transfer signal. Manchester encoding is a synchronous encoding that has the advantage of transmitting both the transfer value and the time signal provided by the clock through this single digital transfer signal. At each clock cycle, a bit is encoded either by a 0-to-1 transition or a 1-to-0 transition at mid-cycle, depending on whether the bit to be encoded is a "1" or a "0," thus allowing the receiver of the digital transfer signal to reconstruct the clock.

[0021] Furthermore, low-voltage differential transmission has the advantage of being more immune to electrical noise, supporting higher frequency signals, and traveling longer distances than TTL (Transistor-Transistor Logic) physical layers. Low-voltage differential transmission also requires the use of smaller twisted wires and lightning protection devices.

[0022] The transfer value carried by the digital transfer signal is thus a function of the digitized value and therefore also of the effort suffered or transmitted by the mechanical flight control chain.

[0023] This mechanical flight control chain therefore advantageously allows, through the processing applied successively to the analog measurement signal and the digital measurement signal, for a precise transfer value, insensitive in particular to electromagnetic disturbances, and representative of the effort in the mechanical flight control chain to be transmitted to the actuator in order to control it optimally.

[0024] This actuator can be, for example, a series actuator connecting two connecting rods of the flight control mechanical chain. This actuator can also be a A parallel actuator connects the control surface or a connecting rod of the flight control system to a fixed point on the aircraft structure. The actuator can be hydraulic, pneumatic, or electric. The flight control system thus allows the movement of an aerodynamic control surface to be controlled, for example, by adjusting the blade pitch or flap orientation, possibly via a servo control.

[0025] The mechanical flight control chain according to the invention may further comprise one or more of the following features, taken alone or in combination.

[0026] According to one possibility, the sensor may include at least one strain gauge, a piezoelectric sensor, or a linear displacement sensor known by the acronym "LVDT" for "Linear Variable Differential Transformer". This sensor then makes it possible to measure a displacement or deformation of the connecting rod that is a function of the force experienced or transmitted by this connecting rod in the flight control chain between the control element and the servo control of an aerodynamic control surface.

[0027] Each measurement channel may include a sensor of the same type. Alternatively, at least two measurement channels may respectively include sensors of different types, to contribute to a dissimilarity of these at least two measurement channels.

[0028] According to a possibility compatible with the preceding ones, the force measurement system may include clocks. In particular, the electronic module of each measurement channel may include a clock, thus ensuring the independence of each of the measurement channels.

[0029] Alternatively, the actuator may include the clocks. In particular, a duplex controller for this actuator may include such a clock on each of the control and monitoring channels. The time signal from each clock is then transmitted to the measurement channels of the force measurement system via the input and output interfaces. Consequently, the force measurement system can be simplified, lighter, and less expensive when it does not include such a clock.

[0030] According to a possibility compatible with the preceding ones, for at least one of the measurement channels, the electronic module may include an analog-to-digital converter to digitize the analog signal and the output interface includes a digital bus.

[0031] The measurement channel(s) of an electronic module comprising such an analog-to-digital converter are measurement channels that do not apply delta-sigma modulation

[0032] Advantageously, the processing of the analog measurement signal is thus carried out dissimilarly by at least two measurement channels, at least one measurement channel applying delta-sigma modulation and at least one measurement channel applying analog-to-digital conversion

[0033] In this way, at least two measurement channels are dissimilar, at least with respect to the digitization method used. Additionally, the electronic module may be different for this or these measurement channels, also introducing a technological dissimilarity.

[0034] The digital bus can be, for example, of a known type chosen from among the types TIA / EIA-485, TIA / EIA-422, ARINC 429, CAN bus, I2C, AFDX, Time-Triggered Ethernet, FlexRay, LIN or MIL-STD-1553.

[0035] According to a possibility compatible with the preceding ones, at least one of the measurement channels may include a memory in which at least one calibration law is stored, and said at least one duplex computer is configured to apply a calibration of the transfer value carried by the digital transfer signal for each measurement channel using said at least one calibration law.

[0036] It is indeed known that the value measured by the sensor can be modified or can drift before being transmitted by the force measurement system. This drift can be related to various factors such as electrical voltage, temperature, and / or the aging of each measurement channel, for example. Errors can also be introduced by drift in the electronic components used on the measurement channels, or even by the sensor itself.

[0037] In this way, the value measured by the sensor and carried by the analog measurement signal may be different from the transfer value carried by the digital transfer signal.

[0038] Calibration thus makes it possible to improve the accuracy of the transfer value representing the effort in the mechanical flight control chain for each measurement channel.

[0039] The modifications or deviations to be corrected can be determined by calculations, tests or simulations and implemented in the calibration law(s). Depending on the complexity of the corrections to be made, the calibration law may include a single calibration formula, a table containing several calibration formulas, or a calibration table.

[0040] The single calibration formula provides a corrected value representative of the force as a function of the transfer value. The calibration formula table contains several formulas; the formula to be applied to obtain the corrected value representative of the force is defined as a function of the transfer value. The calibration table includes a table of correspondence between transfer values ​​and corrected values.

[0041] Furthermore, the calibration law can be generic and identical for all measurement channels. Alternatively, the calibration law can be specific to each measurement channel, particularly when they are dissimilar, and therefore different from one measurement channel to another.

[0042] Said at least one duplex computer of the actuator can thus apply the calibration on each control and monitoring channel in order to correct the transfer value carried by the digital transfer signal received from each measurement channel, said at least one measurement channel having the memory transferring said at least one calibration law to the duplex computer.

[0043] Alternatively, this calibration can be carried out by the force measurement system, and by each measurement channel, before emission of the digital transfer signal.

[0044] Alternatively, the actuator may include at least one memory in which the calibration law(s) are stored, and said at least one duplex computer is configured to apply a calibration of the transfer value carried by the digital transfer signal for each measurement channel using said at least one calibration law.

[0045] In this case, the calibration law(s) can be stored in at least one memory of said at least one duplex computer of the actuator, the measurement channels not storing any calibration law.

[0046] For example, in the presence of a single duplex computer, each control and monitoring channel of this duplex computer may include a memory storing the calibration law(s), this duplex computer applying such a calibration law to the transfer value carried by the digital transfer signal circulating in the control channel and the monitoring channel of this duplex computer.

[0047] According to a possibility compatible with the preceding ones, the actuator may comprise two electric motors and two duplex computers, the force measurement system comprising two first measurement channels connected to the control channels of the two duplex computers and two second measurement channels connected to the monitoring channels of the two duplex computers, the first measurement channels being dissimilar to the second measurement channels.

[0048] The use of two duplex computers associated with four measurement channels of the measurement system thus makes it possible to obtain a quadruplex device capable of compensating for failures, both at the level of a measurement channel of the measurement system and at the level of a control or monitoring channel of a duplex computer. Furthermore, the use of dissimilar measurement channels, depending on whether they are connected to the control or monitoring channels of the duplex computers, makes it possible to limit the sensitivity of the measurement system to certain failures.

[0049] The mechanical flight control chain according to the invention thus makes it possible to improve the failure resistance of the measurement system and / or the actuator. In particular, the mechanical flight control chain according to the invention can thus achieve a high level of safety, corresponding, for example, to a failure occurrence rate of less than or equal to 1010 per flight hour.

[0050] The invention also relates to an aircraft equipped with at least one movable aerodynamic control surface for steering this aircraft and comprising at least one mechanical flight control chain as previously described for piloting this aerodynamic control surface.

[0051] The invention also relates to a method for measuring a representative value of a force in a mechanical flight control chain of an aircraft using a force measurement system.

[0052] This measurement method is remarkable in that the force measurement system is provided with at least two measurement channels, each comprising a sensor arranged on a connecting rod of the flight control chain, an electronic module and an output interface, the method comprising the following steps applied to each measurement channel of the force measurement system:

[0053] - generation of an analog measurement signal using the sensor,

[0054] - digitization of the analog measurement signal to form a digital signal of measurement using the electronic module,

[0055] - transformation of the digital measurement signal into a digital transfer signal using the electronic module, the digital transfer signal carries a transfer value representative of the force in the mechanical flight control chain,

[0056] - emission by the electronic module of the digital transfer signal via the interface output of the measurement channel, and - a calibration of said transfer value by application of a calibration law, said calibration law comprising a single calibration formula, a table of calibration formulas, or a calibration table,

[0057] on at least one measurement channel, said digitization a clock-driven delta-sigma modulation, said transformation being carried out by Manchester coding and low-voltage differential transmission.

[0058] The method according to the invention thus applies processing to the analog measurement signal carrying a measured value as a function of the effort in the mechanical flight control chain of an aircraft in order to digitize it, then to modify the digital measurement signal obtained to obtain the digital transfer signal carrying the transfer value which is emitted towards a piece of equipment, and for example to a series or parallel actuator of the mechanical flight control chain.

[0059] Following these processes, the transfer value is less sensitive, or even immune, to an electromagnetic environment and more accurate compared to current force measurement solutions, while protecting against the loss of accuracy associated with the transmission of purely analog signals and potential noise introduction due to disturbances. The use of delta-sigma modulation also contributes to the high accuracy of the representative force value.

[0060] This method can in particular be implemented by the mechanical flight control chain described above.

[0061] The invention and its advantages will become apparent in more detail in the following description, with illustrative examples given by reference to the accompanying figures, which represent: - [Fig. 1], a view of a mechanical flight control system according to the invention, - [Fig.2], a view of an aircraft including the mechanical flight control system of [Fig.1] - [Fig. 3], a partial view of the flight control mechanical chain of [Fig. 1], and - [Fig.4], a partial view of the flight control mechanical chain of [Fig.1],

[0062] Elements present in several separate figures are assigned one and the same reference.

[0063] Fig. 1 presents a mechanical flight control chain 2 for an aircraft 1.

[0064] Such a mechanical flight control chain 2 control, possibly via a servocontrol 28, movements of one or more aerodynamic control surfaces 10 allowing the aircraft 1 to be steered. Such aerodynamic control surfaces 10 may include first blades 12 of a main rotor 11, second blades 14 of a yaw control rotor 13, or even propeller blades, elevator or rudder flaps.

[0065] According to the example in [Fig. 2], the aircraft 1 may be a helicopter comprising a main rotor 11 equipped with variable-pitch first blades 12 and a yaw control rotor 13 equipped with variable-pitch second blades 14. In this case, the aircraft 1 may include several mechanical flight control systems 2 controlling, respectively, by means of a collective pitch lever 25, a collective variation of the pitch of the first blades 11, by means of a cyclic pitch control stick 26, a cyclic variation of the pitch of the first blades 12, and by means of a rudder pedal 27, a collective variation of the pitch of the second blades 14.

[0066] Regardless of the nature of the aerodynamic control surfaces 10, the mechanical flight control chain 2 comprises a steering element 25, 26, 27 and Several connecting rods 21, 21', 22, 22', 22", 23, 24 articulated together, possibly via a control horn 29 or even a combiner. The flight control mechanical chain 2 also includes one or more actuators 30, as well as a force measurement system 40. The reference "30" designates any of the actuators in a flight control mechanical chain 2, while the references "301, 302" designate specific actuators if necessary.

[0067] According to the example in [Fig.1], a mechanical flight control chain 2 may include at least one parallel actuator 301 and at least one series actuator 302.

[0068] The parallel actuator 301 connects, according to the illustrated example, a connecting rod 21' of the flight control mechanical chain 2, via a connecting rod 303, to a fixed point of the structure 15. This parallel actuator 301 may include, for example, a cylinder or an electric motor.

[0069] According to the illustrated example, two 302 series actuators can respectively connect two of the connecting rods 22, 22', 22" of the flight control mechanical chain 2 by one of their respective ends. These 302 series actuators can, for example, each include an electric actuator.

[0070] Regardless of its type and as shown in Figures 3 and 4, the actuator 30 comprises at least one electric motor 31, 32 and one duplex computer 33, 34 per motor 31, 32. Each duplex computer 33, 34 is provided with two independent computing channels, namely a control channel 35, 36 and a monitoring channel 37, 38, as well as an input interface 351, 361, 371, 381 per computing channel 35, 36, 37, 38.

[0071] Each computing channel 35, 36, 37, 38 comprises a processing unit 352, 362, 372, 382 which may include, for example, a processor, at least one integrated circuit, at least one logic circuit, these examples not limiting the scope given to the expression "processing unit". The term processor may refer to a central processing unit known by the acronym CPU, a graphics processing unit GPU, a digital signal processing unit known by the acronym DSP, a microcontroller, etc.

[0072] The force measurement system 40 is arranged in the flight control mechanical chain 2, and for example on one of the connecting rods 21-24. This force measurement system 40 makes it possible in particular to measure directly or indirectly a force experienced or transmitted by this connecting rod 21-24.

[0073] The force measurement system 40 comprises at least two measurement channels 41, each equipped with a sensor 42 arranged on the connecting rod 21-24, an electronic module 43 and an output interface 44. A purely numerical reference "41", "42", "43", "44" generally designates a measurement channel or one of its components, a letter "A", "B", "C" or "D" being associated with these numerical references to designate a specific measurement channel or one of its components if necessary.

[0074] The electronic module 43 may, for example, comprise various electronic components, such as integrated circuits, microswitches, and / or passive electronic elements, connected together by a printed circuit board or equivalent.

[0075] The output interface 44 of each measurement channel 41 is electrically connected, via an electrical harness 20 to a single input interface 351,361,371,381 of a calculation channel 35,36,37,38 of the actuator 30, each input interface 351,361,371,381 being connected to a single output interface 44.

[0076] The sensor 42 may, for example, include at least one strain gauge, a piezoelectric sensor, or a linear voltage distance transducer (LVDT). In these examples, this sensor 42 allows for the measurement of a displacement or deformation of the connecting rod 21-24 that is a function of, or even proportional to, the force experienced or transmitted by this connecting rod 21-24, and consequently the force experienced or transmitted by the flight control system 2.

[0077] The measurement channels 41 may optionally include sensors 42 of different types in order in particular to make these measurement channels 41 dissimilar.

[0078] Examples of embodiments of the force measurement system 40 and the actuator 30 are shown in Figures 3 and 4.

[0079] According to a first embodiment shown in [Fig.3], the force measurement system 40 comprises two measurement channels 41A,41B and the actuator 30 comprises a single duplex computer 33. The two measurement channels 41A,41B are connected respectively to the control channels 35 and monitoring channels 37, via the output interfaces 44A,44B and the input interfaces 351,371.

[0080] The processing unit 352 of the control channel 35 of the duplex computer 33 includes a clock 355 and a memory 356, the processing unit 372 of the monitoring channel 37 of this duplex computer 33 also including a clock 355.

[0081] According to a second embodiment shown in [Fig.4], the force measurement system 40 comprises four measurement channels 41A, 41B, 41C, 41D and the actuator 30 comprises two duplex computers 33, 34. The four measurement channels 41A, 41B, 41C, 41D are connected respectively to the control channels 35, 36 and monitoring channels 37, 38, via the output interfaces 44A, 44B, 44C, 44D and the input interfaces 351, 361, 371, 381.

[0082] The electronic module 43A,43B,43C,43D of the four measuring channels 41A,41B,41C,41D includes a clock 435A,435B,435C,435D, the electronic module 43A of the first measuring channel 41A also including a memory 436.

[0083] According to this second example, the two measurement channels 41A, 41C which are connected to the control channels 35, 37 of the two duplex computers 33, 34 can be dissimilar of the two measurement channels 41B,41D connected to the monitoring channels 36,38 of the two duplex computers,33,34.

[0084] Regardless of these two embodiments, each measurement channel 41 generates, via the sensor 42, an analog measurement signal carrying a measured value that is a function of the force experienced or transmitted in the flight control mechanical chain 2. The electronic module 43 of each measurement channel 41 receives this analog measurement signal and can apply various processing steps to it, firstly, to digitize it in order to obtain a digital measurement signal carrying a digitized value that is a function of the measured value and, consequently, of the force experienced or transmitted in the flight control mechanical chain 2. Secondly, the electronic module 43 transforms the digital measurement signal into a digital transfer signal carrying the transfer value that is a function of the digitized value and, consequently, of the force experienced or transmitted in the flight control mechanical chain 2.

[0085] In particular, the electronic module 43 of at least one of the measurement channels 41, or even of each measurement channel 41, applies delta-sigma modulation to digitize the analog measurement signal, then Manchester coding and low-voltage differential transmission to obtain the digital transfer signal.

[0086] The transfer value thus obtained is accurate and relatively immune to an electromagnetic environment.

[0087] The time signal from the clock 355,435 is used in particular by the electronic modules 43 for delta-sigma modulation and for applying Manchester coding. Furthermore, when the clock 355 is located in the duplex computer 33,34, the time signal is transmitted to each measurement channel 41 via the input interfaces 351,361,371,381 and output interface 44.

[0088] In addition to at least one of the measurement channels 41A applying delta-sigma modulation, and as shown in [Fig. 4], the electronic module 43D of at least one other measurement channel 41D may include an analog-to-digital converter 48D for digitizing the analog measurement signal, and the output interface 44D of this at least one other measurement channel 41D then includes a digital bus 49D to allow the transformation of the digital measurement signal into a digital transfer signal. This other measurement channel 41D does not, in this case, apply delta-sigma modulation or Manchester encoding. The mechanical flight control chain 2 according to the invention thus advantageously comprises at least two dissimilar measurement channels 41A, 41D, thereby making it possible to overcome failures likely to affect the measurement channels 4L

[0089] Furthermore, memory 356,436 can store one or more calibration laws. This or these calibration laws make it possible to correct discrepancies between the value of transfer carried by the digital transfer signal and the value measured by sensor 42.

[0090] A first correction provided by this or these calibration laws can be obtained by implementing a so-called "static" calibration, which is a function solely of the transfer value. Such a static calibration makes it possible to compensate, in particular, for gain and / or offset errors intrinsic to the measurement channel 41.

[0091] A second correction can be obtained by implementing a so-called "dynamic" calibration based on the transfer value and the temperature of the relevant measurement channel 41. Such a dynamic calibration makes it possible to compensate for gain and offset errors related to the temperature of the measurement channel 41. To implement this dynamic calibration, a temperature sensor 47 can be integrated on each measurement channel 41 of the force measurement system 40 to measure the temperature of each measurement channel 41.

[0092] Regardless of the correction method used, a calibration law may consist of a single calibration formula, a table containing several calibration formulas, or a calibration table. The single calibration formula provides a corrected value representative of the effort as a function of the transfer value and, where applicable, the temperature of the measurement channel 41 for dynamic calibration.

[0093] The calibration formula table contains several formulas, the formula to be applied to obtain the corrected value representing the effort being defined as a function of the transfer value and, where applicable, the temperature of the measuring channel 41 for dynamic calibration. A search for a close corrected value can also be carried out using at least one algorithm, for example by bisection, in the case where this table does not provide formulas for the current transfer value.

[0094] The calibration table includes a correspondence table between transfer values ​​and corrected values, and where applicable, as a function of the temperature of the measuring channel 41 for dynamic calibration. Again, a search for a close corrected value can also be carried out using at least one algorithm, for example by binary search, in the case where this table does not provide a corrected value for the current transfer value.

[0095] Thus, the duplex computer(s) 33, 34 of the actuator 30 can perform a calibration of the transfer value carried by the digital transfer signal received from each measuring channel 41 using the calibration law(s). Alternatively, this calibration can be performed by the force measurement system 40, and in particular by the electronic module 43 for each measuring channel 41, before the transmission of the digital transfer signal.

[0096] According to the example in [Fig. 3], the first processing unit 352 of the duplex computer 33 of the actuator 30 includes the memory 356 in which the calibration law(s) are stored. This first processing unit 352 can therefore directly apply the calibration to the transfer value carried by the digital transfer signal received by the first control channel 35. In addition, the second processing unit 326 communicates with the first processing unit 352 to receive the calibration law(s), in order to apply the calibration to the transfer value carried by the digital transfer signal received by the first monitoring channel 36.

[0097] In the presence of several duplex computers 33, 34, only one of the duplex computers 33, 34 can contain the memory 352 and transmit this or these calibration laws to one or more other duplex computers 33, 34 via a wired or wireless connection. In this way, a single memory 352 is sufficient for at least two duplex computers 33, 34, simplifying at least one of these duplex computers 33, 34 and also reducing its cost.

[0098] According to the example in [Fig. 4], only the first electronic module 43A contains the memory 436 storing the calibration law(s). The calibration law(s) are then transmitted to at least one of the duplex computers 33, 34 to perform the calibration of the transfer value on each of the control channels 35, 37 and monitoring channels 36, 38.

[0099] In the presence of several duplex computers 33, 34, one of these duplex computers 33, 34 can receive the calibration law(s) via the measurement channel 41, storing it. Then, this duplex computer 33, 34 can transmit the calibration law(s) to one or more other duplex computers 33, 34 via a wired or wireless connection.

[0100] Regardless of the correction implemented, the calibration law can be the same for all measurement channels 41. Alternatively, the calibration law can be different from one measurement channel 41 to another, particularly when these measurement channels 41 are dissimilar.

[0101] In the case of calibration laws specific to each measurement channel 41, a single measurement channel 41 may include the memory 436 to store all the calibration laws. Alternatively, each measurement channel 41 may include a memory 436 storing the calibration law to be applied specifically for that measurement channel 41. Alternatively, each measurement channel may include a memory 436 storing all the calibration laws relating to each of the measurement channels 41 in order to compensate for a possible failure of one of the memories of these measurement channels 41.

[0102] In addition, the flight control mechanical chain 2 can implement a method for measuring a representative value of a force in the flight control mechanical chain 2 using a force measurement system 30.

[0103] This method comprises the following steps applied to each measuring channel 41 of the force measuring system 30:

[0104] First, an analog measurement signal is generated using the sensor 43 of each of the measurement channels 41, this analog measurement signal carrying the value measured by the sensor 43.

[0105] Next, a digitization of this analog measurement signal is carried out using said electronic module 43 of each of the measurement channels 41 to form a digital measurement signal, carrying the digitized value.

[0106] A transformation of this digital measurement signal into a digital transfer signal is then carried out using the electronic module 43 of each of the measurement channels 41, the digital transfer signal carrying a transfer value representative of the effort in the mechanical flight control chain 2.

[0107] For at least one measurement channel 41, this digitization is carried out by a clock-driven delta-sigma modulation, and the transformation is carried out by Manchester coding and low-voltage differential transmission.

[0108] An emission of said digital transfer signal to said output interface of said measurement channel is carried out, for example to actuator 30, via these input interfaces 351,361,371,381.

[0109] Finally, a calibration of the transfer value can be carried out by applying a calibration law, this calibration law comprising a single calibration formula, a table of calibration formulas, or a calibration table.

[0110] This calibration can be implemented indifferently within the duplex computer(s) 33,44 of the actuator 30 or within the electronic modules 43 of the measurement channels 41 of the force measurement system 40.

[0111] Naturally, the present invention is subject to numerous variations in its implementation. Although several embodiments have been described, it is understood that it is not conceivable to exhaustively identify all possible embodiments. It is, of course, conceivable to replace a described means with an equivalent means without departing from the scope of the present invention as defined by the claims.

Claims

Demands

1. A flight control mechanical chain (2) of an aircraft (1), comprising at least one connecting rod (21-24) and an actuator (30), said actuator (30) comprising at least one electric motor (31, 32) and one duplex computer (33, 34) per motor (31, 32), each duplex computer (33, 34) comprising one control channel (35, 37), one monitoring channel (36, 38) and two input interfaces (351, 361, 371, 381) connected respectively to said control channel (35, 37) and to said monitoring channel (36, 38), said flight control mechanical chain (2) comprising a force measurement system (40) arranged on said connecting rod (21-24) and configured to control said actuator (30), characterized in that said force measurement system (40) comprises at least two measurement channels (41) respectively connected to said two input interfaces (351,361,371,381) of said at least one duplex computer (33,34) and each of said measurement channels (41) includes a sensor (42),an electronic module (43) and an output interface (44), said output interface (44) being connected to one of said input interfaces (351, 361, 371, 381) of said at least one duplex computer (33, 34), said electronic module (43) being connected to said sensor (42) to generate an analog measurement signal, said electronic module (43) being configured to perform a digitization of said analog measurement signal to transform it into a digital measurement signal, said electronic module (43) being configured to perform a transformation of said digital measurement signal into a digital transfer signal carrying a transfer value representative of a force in said flight control mechanical chain (2),at least one of said measurement channels (41) applying delta-sigma modulation to digitize said analog measurement signal and applying Manchester coding and low-voltage differential transmission to transform said digital measurement signal into said digital transfer signal, said mechanical flight control chain (2) comprising a clock (355,435) per measurement channel intended to time said delta-sigma modulation.

2. Mechanical flight control chain (2) according to claim 1, in which said sensor (42) comprises at least one strain gauge, a piezoelectric measuring system or a linear displacement measuring system.

3. Mechanical flight control chain (2) according to any one of claims 1 to 2, wherein said force measurement system (40) or said actuator (30) comprises said clocks (355,435).

4. Mechanical flight control chain (2) according to any one of claims 1 to 3, wherein, for at least one of the measurement channels (41), said electronic module (43) includes an analog-to-digital converter (48) and said output interface (44) includes a digital bus (49).

5. Mechanical flight control chain (2) according to any one of claims 1 to 4, wherein at least one of said measurement channels (41) comprises a memory (436) in which at least one calibration law is stored, and said at least one duplex computer (33,34) is configured to apply a calibration of said transfer value carried by said digital transfer signal for each measurement channel (41) using said at least one calibration law.

6. Mechanical flight control chain (2) according to any one of claims 1 to 5, wherein said actuator (30) comprises at least one memory (356) in which at least one calibration law is stored, and said at least one duplex computer (33,34) is configured to apply a calibration of said transfer value carried by said digital transfer signal for each measurement channel (41) using said at least one calibration law.

7. A mechanical flight control chain (2) according to any one of claims 1 to 6, wherein said actuator (30) comprises two electric motors (31, 32) and two duplex computers (33, 34), said force measurement system (40) comprising two first measurement channels (41A, 41C) connected to said control channels (35, 37) of said two duplex computers (33, 34) and two second measurement channels (41B, 41D) connected to said monitoring channels (36, 38) of said two duplex computers (33, 34), said first measurement channels (41A,41C) being dissimilar to the said second measurement channels (41B,41D).

8. Aircraft (1) equipped with at least one movable aerodynamic control surface (10) for moving said aircraft (1), and with at least one mechanical flight control chain (2) according to any one of claims 1 to 7 for piloting said aerodynamic control surface (10).

9. A method for measuring a representative value of a force in a flight control mechanical chain (2) of an aircraft (1) using a force measurement system (40), characterized in that, said force measurement system (40) being provided with at least two measurement channels (41) each comprising a sensor (42) arranged on a connecting rod (21-24) of said flight control mechanical chain (2), an electronic module (43) and an output interface (44), said method comprises the following steps applied for each measurement channel (41) of said force measurement system (40): - generation of an analog measurement signal using said sensor (42), - digitization of said analog measurement signal to form a digital measurement signal using said electronic module (43), - transformation of said digital measurement signal into a digital transfer signal using said electronic module (43), said digital transfer signal carrying a transfer value representative of said force in said mechanical flight control chain (2), and - transmission by said electronic module (43) of said digital transfer signal to said output interface (44) of said measurement channel (41), and - a calibration of said transfer value by application of a calibration law, said calibration law comprising a single calibration formula, a table of calibration formulas, or a calibration table, on at least one measurement channel, said digitization being carried out by a delta-sigma modulation clocked by a clock (355,435), said transformation being carried out by Manchester coding and low-voltage differential transmission.

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