Method and system for automatically determining the mechanical clearances of an aircraft's control surfaces

Abstract

A method and system for automatically determining the actual relative mechanical backlash between at least two actuators of an aircraft control surface is proposed herein. The method comprises: executing (302) a position control loop to position said at least two actuators, collecting, for at least a predetermined period of measurements: first data and second data, determining, from the first data, a theoretical relative displacement without mechanical backlash between said at least two actuators and determining (303), from said second data and the theoretical relative displacement, an actual relative mechanical backlash between said at least two actuators, and, if the actual relative mechanical backlash is greater than or equal to a predetermined threshold, then issuing (305) an alert message.Thus, this disclosure significantly reduces the time required to diagnose actual mechanical play in aircraft control surfaces. Figure to be published with the abbreviation: Fig. 3.

Description

Title of the invention: Method and system for the automatic determination of mechanical clearances in the control surfaces of an aircraft technical field

[0001] The present disclosure relates to the determination of the actual mechanical play existing in control surface actuators of an aircraft. STATE OF PRIOR ART

[0002] The flight controls of an aircraft are sensitive to mechanical play existing within the various mechanical parts composing an aircraft flight control system, such as actuators that deflect control surfaces (e.g., ailerons, elevators) of the aircraft. More specifically, in an aircraft, a control surface is held in position by means of joints (e.g., ball joints) at the actuators and at the aircraft structure. These joints introduce mechanical play, thus creating a so-called "dead zone" where there is no movement of the control surface despite movement of the actuators. Thus, "mechanical play" can be defined as the maximum distance of movement of the actuator(s) that does not result in any perceptible movement of the control surface (and conversely, a movement of the control surface without movement of the actuators).

[0003] In certain flight situations, the vibrations related to this mechanical play are felt by the pilots at the flight controls. If the vibrations are too significant, they may then abort the flight and divert the aircraft to a nearby airport. The aircraft is thus grounded, notably to identify the mechanical play that could be causing the felt vibrations.

[0004] Currently, the identification of mechanical play is carried out manually, which leads to significant aircraft downtime, quickly reaching half-days of operational interruption. This therefore has a significant impact on the airline, air traffic, and the local management of the airport and its material and human maintenance resources.

[0005] It is therefore desirable to overcome this drawback of the prior art. In particular, it is desirable to provide a solution that reduces the time required to identify and characterize the mechanical clearances of an aircraft's flight control surfaces. Description of the invention

[0006] A method for automatically determining the actual relative mechanical clearance between at least two actuators of an aircraft control surface is proposed herein. This method is implemented in a system implemented as electronic circuitry and comprises:

[0007] - execute a position control loop to control the neutral position at least one of the said at least two actuators and to control the position of the other actuator of the said at least two actuators according to a setpoint signal of triangular or sinusoidal shape,

[0008] - during the execution of said position control loop, collect, during at least one predetermined period of measurements k, where k is an even integer greater than or equal to 2: of the first data representing measurements of the forces exerted by each of said at least two actuators for stressing said control surface and of the second data representing measurements of the displacements of each of said at least two actuators,

[0009] - to determine, from the said initial data collected, a relative displacement theoretical without mechanical play between said at least two actuators,

[0010] - determine, from the said second data collected and the said displacement relative theoretical determined, a real relative mechanical clearance between said at least two actuators, and, if said real relative mechanical clearance determined is greater than or equal to a predetermined threshold, then issue an alert message.

[0011] Thus, the present disclosure makes it possible to significantly reduce the diagnostic time, i.e., the identification and characterization, of actual mechanical clearances at the actuator joints and attachments to the aircraft's control surface structure by replacing the current manual process with an automated process initiated from the cockpit. This allows airlines that so wish to optimize their scheduled maintenance strategy. In particular, an airline can favor shorter scheduled maintenance intervals in order to reduce the risk of operational downtime due to vibration problems related to actual mechanical clearances in the control surfaces.

[0012] According to one embodiment, the actual relative mechanical clearance is determined from the following equation:

[0013] T \

[0014] with: n being an even integer greater than or equal to 2, Xm^ and Xm, / , corresponding, for each of the said at least two actuators (i, j), to an average of the second data, Kÿ corresponding to an inter-actuator stiffness between the said at least two actuators (i, j), Fm, k and Fm,, k corresponding, for each of the said at least two actuators, to an average of the first data.

[0015] According to one embodiment, the method further comprises: correcting a setting error between said at least two actuators.

[0016] According to one embodiment, the control loop comprises: a first direct gain control loop combined with a second control loop comprising an integrator.

[0017] A method for maintaining at least one actuator of an aircraft control surface is also proposed here, comprising:

[0018] - automatically determine an actual relative mechanical clearance between at least two actuators of the control surface according to an automatic determination process as described previously,

[0019] - to perform and / or schedule maintenance on at least one of said at least two actuators when an alert message is issued by the execution of an automatic determination process as described above.

[0020] Also proposed here is a system for automatically determining the actual relative mechanical clearance between at least two actuators of an aircraft control surface. This system comprises electronic circuitry configured for:

[0021] - execute a position control loop to control the neutral position at least one of the said at least two actuators and to control the position of the other actuator of the said at least two actuators according to a setpoint signal of triangular or sinusoidal shape,

[0022] - during the execution of said position control loop, collect, during at least one predetermined period of measurements k, where k is an even integer greater than or equal to 2: of the first data representing measurements of the forces exerted by each of said at least two actuators for stressing said control surface and of the second data representing measurements of the displacements of each of said at least two actuators,

[0023] - to determine, from the said initial data collected, a relative displacement theoretical without mechanical play between said at least two actuators,

[0024] - determine, from the said second data collected and the said displacement relative theoretical determined, a real relative mechanical clearance between said at least two actuators, and, if said real relative mechanical clearance determined is greater than or equal to a predetermined threshold, then issue an alert message.

[0025] An aircraft comprising the system as described above is also proposed here.

[0026] A computer program product is also proposed, comprising instructions leading to the execution, by a processor, of the process mentioned above according to any one of its embodiments, when said instructions are executed. by the processor. A storage medium is also offered, storing such instructions. Brief description of the drawings

[0027] The features of the invention mentioned above, as well as others, will become clearer upon reading the following description of at least one exemplary embodiment, said description being made in relation to the accompanying drawings, among which:

[0028] [Fig-1] schematically illustrates, in side view, an aircraft equipped with a system automatic determination of a real relative mechanical clearance between at least two actuators of an aircraft control surface, according to an embodiment;

[0029] [Fig.2] schematically illustrates an example of hardware architecture of an automatic determination system for a real relative mechanical clearance between at least two actuators of an aircraft control surface, according to one embodiment;

[0030] [Fig.3] illustrates in diagram form the steps of a method for determining an actual relative mechanical clearance between at least two actuators of an aircraft control surface, according to one embodiment;

[0031] [Fig.4] illustrates in graphical form an example of the movement of two actuators of the same control surface of an aircraft during the process of determining an actual relative mechanical clearance between these two actuators of a control surface of an aircraft, according to one embodiment;

[0032] [Fig.5] schematically illustrates a position control loop controlling the position of the actuators of an aircraft control surface, according to one embodiment.

[0033] DETAILED DESCRIPTION OF IMPROVEMENTS

[0034] The general principle of this disclosure concerns the automatic determination of the actual mechanical play within the actuators of an aircraft control surface. This determination is described as "automatic" because it is performed without human intervention, as opposed to the known prior art manual method. This disclosure applies to aircraft comprising control surfaces that can be steered by two or more actuators. Each actuator is already equipped with at least one pressure or force sensor suitable for measuring the force exerted by the actuator during extension and retraction, and at least one position sensor suitable for measuring the displacement of the actuator. The term "force" is defined here as the sum of the forces exerted by the actuator to move the control surface, either during a movement in the direction of "extension" or during a movement in the direction of "retraction."The term "extension" refers to a movement of the actuator by which the actuator unfolds or lengthens relative to to a starting position (e.g., neutral position). The term "retraction" corresponds to a movement of the actuator by which the actuator folds back or shrinks relative to a starting position.

[0035] For illustrative purposes hereafter, a control surface is considered to comprise two actuators. It should be noted that the method described below can also be applied to control surfaces comprising more than two actuators.

[0036] Fig. 1 thus schematically illustrates, in side view, an aircraft 100 equipped with a system 101 for automatically determining the actual relative mechanical play between at least two actuators of a control surface of the aircraft 100 (also referred to hereafter as system 101), according to one embodiment.

[0037] System 101 is an electronic device embedded in aircraft 100. For example, system 101 is part of the avionics electronic circuitry of aircraft 100. For example, system 101 is integrated with the flight control computers of aircraft 100. The flight control computers are configured to transmit a control command (e.g., in the form of a deflection angle of the control surfaces) to the actuators, which then deflect the control surfaces of aircraft 100. In addition, the flight control computers are configured to receive measurements taken by the pressure sensors and the position sensors of the actuators of the control surfaces of aircraft 100.

[0038] Thus, the system 101 is configured to exploit the capabilities of the flight control computers of aircraft 100 and in particular, to exploit the data and measurements already made available to the flight control computers of aircraft 100. The present disclosure therefore does not require the use of new hardware (e.g. sensor, gauge, or new computer).

[0039] Furthermore, the system 101 is configured to receive, via a human-machine interface of the cockpit of the aircraft 100, a request for automatic determination of the mechanical clearances of the control surface actuators of the aircraft 100.

[0040] Figure 2 schematically illustrates an example of a hardware platform enabling to implement, in the form of electronic circuitry, system 101, according to an embodiment.

[0041] The hardware platform comprises, connected by a communication bus 210, a processor or CPU (Central Processing Unit) 201; a random-access memory (RAM) 202; a read-only memory 203, for example of the ROM (Read Only Memory) or EEPROM (Electrically-Erasable Programmable ROM) type, such as Flash memory; a storage unit, such as a hard disk drive (HDD) 204, or a storage media reader, such as an SD card reader (“Secure Digital” in English); and a COM interface manager 205.

[0042] The COM 205 interface manager allows the system 101 to interact with the avionics systems of the aircraft 100 such as: the flight control computers and the human-machine interface of the cockpit of the aircraft 100 through which a user (e.g., technicians, pilots...) requests an automatic diagnosis of the actual mechanical play existing within the control surface actuators of the aircraft 100.

[0043] The processor 201 is capable of executing instructions loaded into RAM 202 from ROM 203, external memory, a storage medium (such as an SD card), or a communication network. When the hardware platform is powered on, the processor 201 is capable of reading instructions from RAM 202 and executing them. These instructions form a computer program causing the processor 201 to implement all or part of the steps, processes, or, more broadly, the operating sequences of the aircraft described herein.

[0044] All or part of the steps, processes, and operations described herein can thus be implemented in software form by the execution of a set of instructions by a programmable machine, for example, a DSP (Digital Signal Processor) or a microcontroller, or be implemented in hardware form by a dedicated machine or electronic component (chip) or a dedicated set of electronic components (chipset), for example, an FPGA (Field Programmable Gate Array) or ASIC (Application-Specific Integrated Circuit). Generally speaking, the system 101 comprises electronic circuitry adapted and configured to implement all or part of the operations, processes, and steps described herein.

[0045] Figure 3 illustrates, in diagram form, the steps of a method for automatically determining the actual relative mechanical clearance between at least two actuators of the same control surface of the aircraft 100, according to one embodiment. All or part of this method is implemented by the system 101 described above.

[0046] Indeed, in order to be able to diagnose mechanical play in control surface actuators of aircraft 100, the system 101 determines a real relative mechanical play between the different actuators of the same control surface.

[0047] First, during step 301, a user (e.g., technician, pilot, etc.) requests that an automatic diagnosis of the actual mechanical play existing within the actuators of one or more control surfaces of the aircraft 100 be performed. To do this, the user interacts with a human-machine interface in the cockpit of the aircraft 100. This human-machine interface then transmits to the system 101 a request for automatic determination of the actual mechanical clearances of the actuators of one or more control surfaces of the aircraft 100. Then, upon receipt of this request for automatic determination, the automatic diagnosis of the actual mechanical clearances in the actuators of one or more control surfaces of the aircraft 100 is carried out by the system 101. This automatic diagnosis includes the steps 302 to 304 described below.

[0048] Thus, during a step 302, a first actuator, denoted i, is controlled in a neutral position (i.e., zero-position control), and the second actuator, denoted j, is controlled according to a triangular or sinusoidal signal via the execution of a position control loop. This then introduces an opposing force between the two actuators i and j, respectively in tension and then in compression for each of the actuators i and j.

[0049] According to this position control loop, the system 101 outputs a position command for the actuators i and j. This command is then transmitted to the flight control computer, which determines, based on this command, a movement command for the actuators to steer the control surface in question. The position sensors integrated into and / or associated with the actuators i and j measure the displacement of said actuators i and j and transmit the displacement (or position) measurements to the flight control computer. If necessary, the flight control computer corrects the position of the actuators i and j to reduce the difference between the position command and the actual position of the actuators i and j. Figure 4 illustrates graphically an example of the displacements of two actuators i and j of the same control surface of the aircraft 100 during this step 302, according to this position control loop.

[0050] The control of the second actuator j according to the signal of triangular or sinusoidal shape causes a displacement of the latter in a direction called extension, then in a direction called retraction, relative to a starting position.

[0051] According to one embodiment, the maximum amplitude of the triangular or sinusoidal signal is less than the limit load of the actuators, for example, 80% of the limit load of the actuators.

[0052] The flight control computer of aircraft 100 then receives, from pressure sensors and position sensors integrated and / or associated with actuators i and j, respectively, force measurements and displacement (or position) measurements of said actuators i and j. These force and displacement measurements are performed at a predetermined frequency and over one or more predetermined periods called measurement periods, denoted k, with k an integer such that 1 < k < n, n being an even integer greater than or equal to 2, during a measurement cycle. In an example related to [Fig. 4], the measurement cycle comprises four measurement periods such that k=1, k=2, k=3 and k=4. According to one embodiment, these measurement periods are dimensioned (in terms of time) such that they allow the acquisition of a large number of force measurements and displacement measurements, for example on the order of 300 measurements per period.

[0053] Next, the flight control computer records the following data in memory for each measurement period k=1, k=2, k=3, k=4, and for each actuator i and j:

[0054] - initial data corresponding to measurements of efforts exerted by each actuators i and j, denoted F / t and F7b and

[0055] - second data corresponding to displacement (or position) measurements of each of the actuators i and j denoted X4 k and X,, k.

[0056] System 101 then collects these first and second data points via the flight control computer. System 101 then aggregates these data points for each measurement period k, for example by determining, from these data points:

[0057] - the first information corresponding to the average of the force measurements exerted by actuator i, denoted Fm 4 k, respectively by actuator j, denoted Fm7> k,

[0058] - the second information corresponding to the average of the measurements of displacements (or positions) of actuator i, denoted Xm, k, respectively of actuator j, denoted Xm7 k.

[0059] According to an embodiment shown in connection with [Fig. 5], the position control loop enabling system 101 and the flight control computer to control the position of each of the two actuators i and j comprises a first direct-gain control loop K combined with a second control loop including an integrator (also called an integral control loop). The use of this complementary integral control loop makes it possible to increase the accuracy of the force and position measurements of the two actuators i and j, by reducing the difference between the position setpoint and the actual position of the actuators i and j, measured by the position sensors integrated with and / or associated with the actuators i and j.In particular, it allows limiting the displacement range of the servo-controlled actuator to zero, a displacement induced by moving the servo-controlled actuator according to a triangular or sinusoidal signal. The reduced displacement range increases the accuracy of displacement measurements of the "static" (i.e., zero-controlled) actuator.

[0060] During a step 303, the system 101 determines the actual relative mechanical clearance between the two actuators i and j of the control surface under consideration from the first and second pieces of information described above. More specifically, the system 101 first determines, for each measurement period k, the difference, denoted X / 7 k between the average of the displacement measurements of actuator i Xm, k and of actuator j Xm7> k and the theoretical relative displacement without mechanical backlash, denoted Y,-,7, k, between actuators i and j which is calculated from the average of the force measurements exerted by actuator i Fm, k and by actuator j Fm7 k, according to the following equation EQ1:

[0061] v _

[0062] With Kÿ corresponding to the inter-actuator stiffness, which is known by aircraft design 100 and is also systematically measured during the development of each aircraft. The various inter-actuator stiffnesses are recorded, for example, in a table or in a database accessible to the system 101.

[0063] Thus, for each measurement period k, the difference X; 7 k is obtained from the following equation EQ2:

[0064] Y iz v™ \i lFma-FmJ^

[0065] The actual relative mechanical clearance, denoted JI>7, between actuators i and j is equal to the sum of the differences Xu k, in compression and tension. In the example related to Fig. 4, the measurement cycle comprises two measurement periods in compression: k=1 and k=2, and two measurement periods in tension: k=3 and k=4. Thus, the actual relative mechanical clearance Jÿ is measured twice: first, from the periods: k=1 (compression / extension) and k=3 (tension / retraction), and second, from the periods: k=2 (compression / retraction) and k=4 (tension / extension). The actual relative mechanical clearance Jÿ is equal to the average of these two measurements. Thus, the actual relative mechanical clearance Jÿ between these two actuators i and j, with i = 1 and j = 2, and ke { I, 2, 3, 4}, is determined from the following equation EQ3:

[0066] , vv \i Fm* FiFiX\ J[2~ n^k \ I ( ~ 2. Kv, /

[0067] It should be noted that when the control surface is set in motion by two actuators, then the actual relative mechanical clearance Jÿ between the two actuators corresponds to the sum of the mechanical clearances of the two actuators.

[0068] According to a particular embodiment, when the control surface is actuated by three actuators, the automatic diagnostic is similar to that described previously in connection with steps 302 to 303, but it is performed in three different actuator configurations, whereas a single actuator configuration is sufficient in the case of a control surface actuated by two actuators. More specifically, in the case of three actuators, the first, second, and third actuators are alternately either zero-controlled, controlled according to the triangular or sinusoidal signal, or driven in mode Passive (or damped) mode. Passive mode is when the actuator is not position-controlled and simply follows the position of the active actuators (i.e., those controlled to zero or according to a sinusoidal or triangular waveform). Therefore, the actuator driven in passive mode does not contribute to determining the actual relative mechanical clearances between the two other active actuators considered for automatic diagnostics.

[0069] Given a first actuator 1, a second actuator 2 and a third actuator 3, the three actuator configurations are as follows:

[0070] - first configuration: the first actuator 1 is locked to zero, the second Actuator 2 is controlled according to the triangular or sinusoidal signal, the third actuator 3 is driven in passive or damped mode. System 101 determines the actual relative mechanical clearance between the first actuator and the second actuator, denoted J12, in this first configuration according to equation EQ3 above;

[0071] - second configuration: the first actuator 1 is controlled in passive mode, the The second actuator 2 is zero-controlled, the third actuator 3 is controlled according to the triangular or sinusoidal signal. System 101 determines the actual relative mechanical clearance between the second actuator and the third actuator, denoted J23, in this second configuration according to equation EQ3 above;

[0072] - third configuration: the first actuator 1 is locked to zero, the second Actuator 2 is driven in passive mode, while the third actuator 3 is controlled according to a triangular or sinusoidal waveform signal. System 101 determines the actual relative mechanical clearance between the first and third actuators, denoted Jn, in this third configuration according to equation EQ3 above.

[0073] Thus, in the case of a control surface set in motion by three actuators, the total actual relative mechanical clearances of each actuator are determined. These total actual relative mechanical clearances correspond to the actual individual mechanical clearances for each actuator (1, 2, 3), namely:

[0074] =

[0075] j2 = iji2+4j234jî3

[0076] J3=4j12Uj23 + |jn

[0077] With Ji the actual individual mechanical play of the first actuator 1, J2 the actual individual mechanical play of the second actuator 2 and J3 the actual individual mechanical play of the third actuator 3.

[0078] As described previously, there is an opposing force between the two actuators i and j. Since the two actuators i and j are in opposition, their pressure sensors therefore measure the same force, differing only in sign. Furthermore, according to certain aircraft architectures, the actuators are designed to include two sensors independent pressure sensors: a first pressure sensor to control the actuator force and a second pressure sensor to ensure the validity of the signals and the system. Thus, according to one embodiment, in order to measure the forces even more accurately, the average of the forces measured by the two sensors of the two actuators during an extension and retraction movement is determined. Thus, the average of the force measurements exerted on the actuator i over the period k, Fm, k corresponds to the average of the force measurements taken by the first sensor 1 (Fml 4 k ) and by the second sensor 2 (Fm2 kk ) i.e.: Fm 4 k = (Fml kk + Fm2 4 k) / 2.

[0079] During step 304, the actual relative mechanical clearance J,7 between the two actuators i and j is compared to a predetermined threshold S. If the actual relative mechanical clearance J,7 is greater than or equal to this predetermined threshold S, then an alert message is generated by system 101 during step 305 to notify the crew (for example, via the human-machine interface) and / or ground personnel via air-to-ground communication of a maintenance need to be checked and / or performed on the actuators. It should be noted that if a control surface is set in motion by more than two actuators, it is the individual mechanical clearance at each of the actuators that is compared to the predetermined threshold S.

[0080] In one embodiment, this alert message includes a request for equipment maintenance to be performed and / or scheduled. In one example, in the case of a control surface actuated by two actuators, the alert message identifies the control surface with excessive play. In another example, in the case of a control surface actuated by more than two actuators, the message includes additional information specifying the equipment exhibiting excessive play.

[0081] Thus, the automatic determination method as described above in its various embodiments makes it possible to perform an automatic diagnosis of the actual mechanical clearances of the control surface actuators in a few minutes instead of several half-days with the existing manual method. In other words, the determination method as described above makes it possible to perform a maintenance procedure for the control surface actuators of aircraft 100. In particular, thanks to the generation of an alert message including a request for maintenance to be performed and / or scheduled, a technician / operator, for example, can perform and / or schedule this maintenance of these actuators.

[0082] Optionally, prior to this automatic diagnosis, the system 101 corrects the setting error between the two actuators i and j. The term "setting errors" here refers to the position difference between two actuators controlled by the The same control order is used. To achieve this, the control loop also includes an integrator in parallel with the loop itself, in order to limit any error between the position setpoint and the displacement measurement. The first actuator i is initially set to zero (i.e., in the neutral position). Then, the position sensors integrated with and / or associated with the second actuator j measure its position, denoted XJ0. The position XJ0 of the second actuator j is then transmitted to the flight control computer. Thus, during automatic diagnostics (i.e., steps 302 to 304), the commanded position of the second actuator j is shifted by -XJ0 to compensate for the setting error between the two actuators i and j. This preliminary step increases the accuracy of the position measurements.

Claims

Demands

1. A method for automatically determining the actual relative mechanical clearance between at least two actuators (i, j) of an aircraft control surface (100), said method being implemented in a system (101) implemented as electronic circuitry, said method comprising: - executing a position control loop to neutralize at least one of said at least two actuators (i, j) and to position control the other actuator of said at least two actuators according to a triangular or sinusoidal setpoint signal, - during the execution of said position control loop, collecting, for at least a predetermined measurement period k, where k is an even integer greater than or equal to 2: the first representative data of measurements of the forces exerted by each of said at least two actuators (i, j)(j) for the activation of said control surface and the second representative data of displacement measurements of each of said at least two actuators (i, j), - determine, from said first collected data, a theoretical relative displacement without mechanical backlash between said at least two actuators (i, j), - determine, from said second collected data and said determined theoretical relative displacement, an actual relative mechanical backlash between said at least two actuators (i, j), and, if said determined actual relative mechanical backlash is greater than or equal to a predetermined threshold, then issue an alert message.

2. Method according to claim 1, wherein said actual relative mechanical play is determined from the following equation: JLj-nLk [\(XmU(-Xmjj()\- ^Kij J with: - n being an even integer greater than or equal to 2, - Xm, ,k and Xm, ,k corresponding, for each of said at least two actuators (i, j), to an average of the second data - Kÿ corresponding to an inter-actuator stiffness between said at least two actuators (i, j), - Fm, k and Fm7 ^corresponding, for each of the said at least two actuators, to an average of the first data.

3. A method according to any one of claims 1 or 2, further comprising: correcting a setting error between said at least two actuators.

4. A method according to any one of claims 1 to 3, wherein said control loop comprises: a first direct gain control loop combined with a second control loop comprising an integrator.

5. A method for maintaining at least one actuator of an aircraft control surface (100) comprising: - automatically determining an actual relative mechanical clearance between at least two actuators of the control surface according to an automatic determination method according to any one of claims 1 to 4, - performing and / or scheduling maintenance of at least one of said at least two actuators when an alert message is issued by the execution of an automatic determination method according to any one of claims 1 to 4.

6. System (101) for automatically determining the actual relative mechanical clearance between at least two actuators (i, j) of an aircraft control surface (100), said system (101) comprising electronic circuitry configured to: - execute a position control loop to neutralize at least one of said at least two actuators (i, j) and to position the other actuator of said at least two actuators according to a triangular or sinusoidal setpoint signal, - during the execution of said position control loop, collect, for at least a predetermined period of measurements k, where k is an even integer greater than or equal to 2: the first representative data of measurements of the forces exerted by each of said at least two actuators (i,j) for the constraint setting of said control surface and of the second representative data of displacement measurements of each of said at least two actuators (i, j), - determine, from the said first data collected, a theoretical relative displacement without mechanical backlash between the said at least two actuators (i, j), - determine, from the said second data collected and the said theoretical relative displacement determined, an actual relative mechanical backlash between the said at least two actuators (i, j), and, if the said actual relative mechanical backlash determined is greater than or equal to a predetermined threshold, then issue an alert message.

7.

8. Aircraft comprising the system (101) according to claim 6. Product computer program, comprising instructions causing a processor to execute a process according to any one of claims 1 to 4, when said instructions are executed by said processor.

9. Storage medium, storing a computer program comprising instructions causing a processor to execute a process according to any one of claims 1 to 4, when said instructions are read and executed by said processor.

Images