Active and hybrid flight compensation system for aircraft

Abstract

This flight control system (1) for an aircraft's flight trim system comprises a control element (3), for example, a control stick pivoting about at least one axis of rotation (5), at least one mechanical means (9) for returning the control stick (3) comprising a spring (11) and a first motor (15), the flight control system (1) further comprising at least one electrically assisted device (31) for the mechanically assisted return means (9) and a digital haptic controller (33) controlling the electrically assisted device (31) so as to independently modify the apparent stiffness and the apparent release force of the spring (11). Figure for the abbreviation: Fig. 3

Description

Title of the invention: Active and hybrid flight compensator for aircraft Technical field

[0001] The present invention relates, in general, to flight control systems for aircraft and relates more particularly to a flight compensator for aircraft, in particular for helicopters. Previous techniques

[0002] Flight compensators, or trim, have the function of compensating for drifts linked to disturbances likely to have an influence on the flight parameters of the aircraft, without the pilot having to act on the flight controls.

[0003] In addition, flight trims conventionally return to the aircraft pilot a resistive force on the flight controls in the form of force feedback. This force is generally passive, either linear (spring trimmers) or constant (friction trimmers), and can also be active. The resistive force is also called return, return force, or force feedback.

[0004] With regard to flight compensators providing a passive force of the friction or spring type, these are configured to provide a linear or even constant force once a de-anchoring force is applied to the flight controls, for example to a piloting member such as a pilot stick. These flight compensators have a parameter setting specific to each flight control axis, in particular for the control of the collective pitch and the cyclic pitch.

[0005] When one wishes to modify the restoring force, in other words the force law, it is necessary to reconfigure the equipment settings, for example by changing components. In fact, passive force returns cannot be configured.

[0006] [Fig.l] schematically shows the force law of a return force of a flight compensator providing a passive torsion spring force. In particular, the force return is illustrated by a torque C in Newton meters and given as a function of the angle A of rotation of a shaft connected to the flight controls, for example to a control stick. In particular, the force law includes an angular anchoring position P of the flight controls, the flight controls being able to move away from the anchoring position P when the pilot provides a force greater than a torque called the de-anchoring force F. For an angle A allowing the exit from the anchoring position P, the force law is linear according to a gradient G depending on the spring used.

[0007] As for flight compensators providing active effort, they include take a motor or a brake allowing variable force feedback adapted to flight conditions.

[0008] A hybrid architecture in which a flight compensator implements a mechanical force law assisted by electrical assistance is also configurable. It allows, for example, to modify the de-anchoring force and the gradient of the force feedback without changing the spring. The gradient is called the stiffness of the spring, once a force greater than the de-anchoring force is applied. The de-anchoring force corresponds to the force to be applied before the spring begins to move, that is to say, in other words, the preload of the spring.

[0009] On the other hand, the electric assistance of existing architectures is generally controlled by electronics external to the trim, of the analog type, typically the flight control computer. Thus, the electric assistance, although variable, has little flexibility in the use of this hybrid architecture. Indeed, the electric assistance simultaneously impacts the de-anchoring force and the gradient, which therefore cannot be decorrelated.

[0010] [Fig.2] shows schematically the force laws L1, L2, L3 of a hybrid architecture for the same torsion spring and different electrical assistance. For each force law, the electrical assistance is different and modifies both the unanchoring force and the stiffness gradient, the values ​​of which are therefore correlated. Statement of the invention

[0011] The present invention therefore aims to produce a flight control system whose force feedback architecture is reliable and efficient and also configurable.

[0012] The present invention relates to a flight control system for a flight trim of an aircraft, said system comprising a piloting member, for example a piloting stick, pivoting about at least one axis of rotation, at least one mechanical return means of the piloting member comprising a spring and a first motor arranged so that a first end of the spring is forced to move in rotation with the piloting member and so that a second end of the spring is forced to move in rotation under the action of the first motor, the flight control system further comprising at least one electrical assistance device for the mechanical return means, the flight control system comprising a digital haptic controller controlling the electrical assistance device so as to independently modify the apparent stiffness and the apparent unanchoring force of the spring.

[0013] Thus, the flight control system comprises a spring, a source of force feedback. passive and reliable, as well as an electric assistance device and a haptic controller allowing the implementation of an active and configurable force feedback source.

[0014] Advantageously, the haptic controller controls the electrical assistance device as a function of the angular position of the control member, the torsion angle of the spring, and the supply currents of the electrical assistance device.

[0015] In one embodiment, the electrical assistance device comprises a second motor integral in rotation with the first end of the spring via a mechanical connection between the mechanical return means and the electrical assistance device.

[0016] Advantageously, the electric assistance device comprises a torque limiter and a safety pin positioned near the mechanical connection.

[0017] In a particular embodiment, the second motor is a three-phase synchronous motor with permanent magnets, and / or a brushed motor, and / or piezoelectric.

[0018] Advantageously, the second motor is provided with a position sensor.

[0019] Advantageously, the flight control system comprises a means of control and power supply of the first motor.

[0020] In one embodiment, the mechanical return means comprises a clutch positioned between the first motor and the spring, the control member comprising a control configured to open or close the clutch, the haptic controller receiving information from the clutch on the closing state of said clutch so that said haptic controller controls the electric assistance device according to the information received.

[0021] Advantageously, the mechanical return means comprises a main shaft connecting the first end of the spring and the control member, and at least one angular position sensor of the main shaft, said angular position sensor communicating with the haptic controller so that said haptic controller controls the electrical assistance device according to information communicated by the angular position sensor.

[0022] Advantageously, said angular position sensor is connected to the main shaft via a safety pin.

[0023] The angular position sensor is for example of the RVDT type, or is a resolver, or a Hall effect sensor, a potentiometer or any other type of sensor.

[0024] Advantageously, the mechanical return means comprises at least one sensor measuring the deformation of the spring communicating with the haptic controller so that said haptic controller controls the electrical assistance device as a function of information communicated by said sensor measuring the deformation of the spring.

[0025] The spring deformation measurement sensor is for example of the RVDT type, or is a resolver, or a Hall effect sensor, a potentiometer or any other type of sensor.

[0026] In a particular embodiment, the piloting member pivots around several axes of rotation, the flight control system comprising as many mechanical return means and electrical assistance devices as there are axes of rotation around which the piloting member pivots, the flight control system comprising a single haptic controller for all the electrical assistance devices.

[0027] The present invention also relates to a helicopter comprising a flight control system as defined above, the flight control system controlling the collective pitch and / or the cyclic pitch of a swashplate, and / or the yaw rudder of said helicopter. Brief description of the drawings

[0028] Other aims, characteristics and advantages of the invention will appear on reading the following description, given solely by way of non-limiting example, and made with reference to the appended drawings in which:

[0029] [Fig.l] which has already been mentioned is a graph schematically representing the force law of a restoring force of a torsion spring flight compensator;

[0030] [Fig.2] which has already been mentioned is a graph schematically representing the force laws of a hybrid architecture comprising a torsion spring and electric assistance;

[0031] [Fig.3] is a schematic representation of a flight control system according to the invention; and

[0032] [Fig.4] is a graph schematically representing the range of possibilities of a force law of a restoring force of a flight control system according to the invention.

[0033] Detailed description of at least one embodiment

[0034] [Fig. 3] schematically shows a flight control system 1 for an aircraft according to the invention.

[0035] The aircraft is for example a helicopter comprising said control system 1 flight control controlling a collective pitch and / or a cyclic pitch of a swashplate of said helicopter.

[0036] The flight control system 1 comprises a frame (not shown) and a piloting member 3 mounted to pivot relative to the frame around at least one axis of rotation 5, for example two axes of rotation. The control member 3 is for example a control stick 3 and allows for example to control the cyclic pitch and / or the collective pitch of the aircraft.

[0037] The frame comprises mechanical stops 7 against which the control member 3 abuts to limit its angular travel.

[0038] The flight control system 1 comprises at least one mechanical means 9 for returning the piloting member 3, the return force being directed in the opposite direction to an external force applied by the pilot of the aircraft to the piloting member 3.

[0039] In a particular embodiment in which the piloting member 3 pivots around several axes of rotation, the flight control system 1 comprises as many mechanical return means 9 as there are axes of rotation 5 around which the piloting member 3 pivots, a return force therefore being able to be applied in all directions of rotation followed by the piloting member 3.

[0040] The mechanical means 9 comprises a spring 11, a main shaft 13 and a first motor 15 arranged so that a first end 17 of the spring 11 is forced to move in rotation with the control member 3 by means of the main shaft 13 and so that a second end 19 of the spring 11 is forced to move in rotation under the action of the first motor 15.

[0041] In particular, the spring 11 is a torsion spring. This spring has an intrinsic stiffness and preload, in other words an intrinsic unanchoring force.

[0042] The mechanical return means 9 also comprises a control and power supply means 21 for the first motor 15. The control means 21 is for example an electronic control unit receiving orders from an on-board computer of the aircraft, the orders also being able to come from the pilot of the aircraft.

[0043] The mechanical return means 9 further comprises a clutch 23 positioned between the first motor 15 and the spring 11. This clutch 23 plays the role of a temporary decoupling means, used in the case of the FTR or “Force trim release” function, and thus makes it possible to cancel the return force of the spring.

[0044] The mechanical return means 9 also comprises an irreversible reducer 25, such as a worm screw and a toothed wheel, positioned integral in rotation with the first motor 15 and whose position defines an anchoring point of the spring 11, a reversible reducer, such as a toothed segment 27, and a torsion damper 29 making it possible to smooth out torque fluctuations. More precisely, the irreversible reducer 25 is arranged between the first motor 15 and the clutch 23 while the toothed segment 27 and the torsion damper 29 are arranged between the spring 11 and the clutch 23.

[0045] The first motor 15 makes it possible to modify the position of the second end 19 of the spring 11 relative to the first end 17 of the spring 11, thus making it possible to modify the anchoring position P of the spring 11 and therefore modify the return force of the spring 11, for example for different phases of flight of the aircraft or when the pilot wishes to re-center the anchoring position P. The first motor 15 only operates to modify the anchoring position P.

[0046] In one embodiment, the control member 3 comprises a control (not shown), for example manual, configured to open the clutch 23 when the pilot activates said control. The activated control communicates for example with the control and power supply means 21 to modify the closing state of the clutch. The open clutch 23 makes the second end 19 of the spring 11 free and allows the pilot to move the control member 3 into the position of his choice, then to close the clutch 23 to anchor the second end 19 of the spring 11 again. In this embodiment, the anchoring position P is thus chosen only manually by the pilot.

[0047] The flight control system 1 also comprises at least one electrical assistance device 31 for the mechanical return means 9 as well as a digital haptic controller 33 controlling said electrical assistance device 31 so as to independently modify the apparent stiffness and the preload, in other words the apparent unanchoring force of the spring 11.

[0048] Indeed, for the spring 11, having its own stiffness and its own preload, the electrical assistance device 31 makes it possible to artificially modify the return force of the spring 11 by modifying the apparent stiffness of the spring 11 and / or the apparent unanchoring force of the spring 11 independently of each other.

[0049] More specifically, the electrical assistance device 31 comprises a second motor 35 integral in rotation with the first end 17 of the spring 11 via a mechanical connection 37 of the flight control system 1, arranged between the mechanical return means 9 and the electrical assistance device 31. The electrical assistance device 31 further comprises a reversible reduction device 39 optionally equipped with a torque limiter and a safety pin 41a positioned close to the mechanical connection 37. The safety pin 41a makes it possible to disconnect the electrical assistance device 31, for example in the event of a breakdown of said electrical assistance device. The mechanical return means 9 may also comprise a safety pin 41b between the spring 11 and the control member 3 so as to disconnect said mechanical return means 9, for example in the event of a breakdown.In particular, the safety pin 41b of the mechanical return means 9 has a breaking threshold higher than that of the safety pin 41a of the electrical assistance device 31.

[0050] The second motor 35 can therefore rotate the first end 17 of the spring 11 and increase or reduce the apparent return force exerted by said spring. 11.

[0051] The second motor 35 is for example a three-phase synchronous motor with permanent magnets, optionally equipped with a position sensor, and allowing for example, the creation of an additional force to the force exerted by the spring 11, and to make independent the modification of the apparent stiffness and that of the apparent unanchoring force. The force law obtained is thus freely configurable.

[0052] In a particular embodiment in which the piloting member 3 pivots around several axes of rotation 5, the flight control system 1 comprises as many electrical assistance devices 31 as there are mechanical return means 9 and as there are axes of rotation 5 around which the piloting member 3 pivots, a return force therefore being able to be applied in all the directions of rotation followed by the piloting member 3. On the other hand, the flight control system 1 comprises a single haptic controller 33 for all the electrical assistance devices 31.

[0053] The haptic controller 33 actively controls the electrical assistance device 31 as a function of all the parameters that may be deemed relevant by the aircraft's on-board computer. For example, the haptic controller 33 takes into account the angular position of the control member 3, the torsion angle of the spring 11 to determine the spring force, as well as the supply currents of the electrical assistance device 31 for its control, these currents being indicators of the force applied by the pilot to the control member 3 and the speed of movement of said control member 3.

[0054] The haptic controller 33 controls the electrical assistance device 31 in a closed loop and without a force sensor, the force measurement being carried out indirectly by measuring the supply currents in the phases, giving an image of the electromotive force applied.

[0055] The haptic controller 33 implements a first servo loop in the position of the control member 3. The haptic controller integrates into this first loop a current servo loop, used for the torque control of the electric assistance device 31.

[0056] The force law of a restoring force of a flight control system 1 according to the invention may be configurable in real time on request, for example from an operator or the on-board computer.

[0057] This function will be carried out by providing access to a parameter table included in the haptic controller 33, which will contain all the singular points of the force law profile that can be produced.

[0058] Consequently, it will be possible to independently modify the apparent stiffness and / or the apparent preload force of the spring 11, within the limits of the range of validity.

[0059] The haptic controller 33 also implements protection in order to provide a gradual torque transition between the current setpoint and a new setpoint when a setpoint is changed by a driver or the on-board computer. In addition, the setpoint values ​​are set to acceptable values ​​for system stability 1.

[0060] An alert will be raised by the haptic controller 33 if a risk of inappropriate configuration is detected, for example near the mechanical stops, in order to guarantee the mechanical integrity of the system 1.

[0061] In addition, the haptic controller 33 receives from the clutch 23 information on the closing state of said clutch 23 so that said haptic controller 33 controls the electric assistance device 31 according to the information received. For example, when the clutch 23 is open and the spring 11 is no longer linked to the irreversible reducer 25, the electric assistance device 31 can be started by the haptic controller 33 in order to provide a return force to the pilot.

[0062] Furthermore, the mechanical return means 9 comprises at least one sensor 43, for example of the rotary variable differential transformer type, also called an RVDT sensor, or of the resolver type, Hall effect sensor, potentiometer or any other type of sensor, for measuring the angular position of the main shaft 13, said sensor 43 communicating with the haptic controller 33 so that said haptic controller 33 controls the electrical assistance device 31 according to information communicated by the sensor 43, the sensor 43 being connected to the main shaft 13 via a safety pin 41c so as to be able to disconnect it, for example in the event of a breakdown. Optionally, and so as to have a redundant measurement, the mechanical return means 9 comprises several sensors 43 connected to the main shaft 13.

[0063] The mechanical return means 9 optionally comprises at least one RVDT sensor 45 and / or at least one Hall effect sensor 47 and / or a resolver, potentiometer or any other type of sensor, configured to measure the deformation of the spring 11. Advantageously, at least one of the sensors 45 and 47 communicates with the haptic controller 33 so that said haptic controller 33 controls the electrical assistance device 31 according to information communicated by the RVDT sensor 45 and / or the Hall effect sensor 47. Optionally, and so as to have a redundant measurement, the mechanical return means 9 comprises several RVDT sensors 45 for measuring the deformation of the spring 11.

[0064] [Fig. 4] shows schematically the possibilities offered to the force law of a restoring force of a flight control system 1 according to the invention. [Fig. 4] illustrates in particular the curve 49 of the force law intrinsic to the spring 11 used, as well as a range 51 of available torque values ​​delimiting the limits of the force law of the flight control system 1 according to the invention. This range 51 of values ​​illustrates the fact that the force law is configurable and can notably include changes in gradients G and changes in unanchoring force F, said changes being able to be made in real time and allowing the creation of complex force laws, more advanced than a single modification of the stiffness or the preload.

Claims

Claims

1. Flight control system (1) for an aircraft flight trim tab, said system (1) comprising a piloting member (3) pivoting about at least one axis of rotation (5), at least one mechanical means (9) for returning the piloting member (3) comprising a spring (11) and a first motor (15) arranged so that a first end (17) of the spring (11) is forced to move in rotation with the piloting member (3) and so that a second end (19) of the spring (11) is forced to move in rotation under the action of the first motor (15), the flight control system (1) further comprising at least one electrical assistance device (31) for the mechanical return means (9),the flight control system (1) being characterized in that it comprises a digital haptic controller (33) controlling the electric assistance device (31) so as to independently modify the apparent stiffness and the apparent unanchoring force of the spring (11).,

2. Flight control system (1) according to claim 1, wherein the haptic controller (33) controls the electric assistance device (31) as a function of the angular position of the control member (3), the torsion angle of the spring (11), and the supply currents of the electric assistance device (31).

3. Flight control system (1) according to one of claims 1 and 2, in which the electrical assistance device (31) comprises a second three-phase synchronous motor (35) with permanent magnets and / or a brushed motor, and / or piezoelectric, integral in rotation with the first end (17) of the spring (11) by means of a mechanical connection (37) between the mechanical return means (9) and the electrical assistance device (31).

4. Flight control system (1) according to one of claims 1 and 2, in which the electric assistance device (31) comprises a reversible reduction device (39) optionally equipped with a torque limiter, and a safety pin (41a) positioned near the mechanical connection (37).

5. Flight control system (1) according to any one of claims 1 to 4, comprising means for controlling and supplying power (21) to the first motor (15).

6. Flight control system (1) according to any one of claims 1 to 5, in which the mechanical return means (9) comprises a clutch (23) positioned between the first motor (15) and the spring (11), the control member (3) comprising a control configured to open or close the clutch (23), the haptic controller (33) receiving from the clutch (23) information on the closing state of said clutch (23) so that said haptic controller (33) controls the electric assistance device (31) according to the information received.

7. Flight control system (1) according to any one of claims 1 to 6, in which the mechanical return means (9) comprises a main shaft (13) connecting the first end (17) of the spring (11) and the control member (3), and at least one angular position sensor (43) of the main shaft (13), said angular position sensor (43) communicating with the haptic controller (33) so that said haptic controller (33) controls the electric assistance device (31) according to information communicated by the angular position sensor (43).

8. Flight control system (1) according to any one of claims 1 to 7, in which the mechanical return means (9) comprises at least one sensor (45, 47) measuring the deformation of the spring (11) communicating with the haptic controller (33) so that said haptic controller (33) controls the electrical assistance device (31) according to information communicated by said sensor (45, 47) measuring the deformation of the spring (11).

9. Flight control system (1) according to any one of claims 1 to 8, in which the piloting member (3) pivots around several axes of rotation (5), the flight control system (1) comprising as many mechanical return means (9) and electrical assistance devices (31) as there are axes of rotation (5) around which the piloting member (3) pivots, the flight control system (1) comprising a single haptic controller (33) for all the electrical assistance devices (31).

10. Helicopter characterized in that it comprises a flight control system (1) according to any one of claims 1 to 9, the flight control system (1) controlling the collective pitch and / or the cyclic pitch of a swashplate, and / or the yaw rudder of said helicopter.

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