Detection of whether a flight control is being gripped

Abstract

The invention relates to a control system (100) for an aircraft, comprising: - a moveable flight control (101); - an active return system (106) for returning the flight control (101), comprising: an electric motor (108) for driving the flight control (101), a measurement device (112) designed to deliver a measurement () representative of a position () of the flight control (101), and a device (114) for controlling the electric motor (108) designed to deliver a torque setpoint to the electric motor (108) based on the measurement () and on a position setpoint (*); and - a device (118) for detecting whether the flight control (101) is being gripped. The detecting device (118) comprises a state observer (120) designed to deliver, based on the measurement (), an estimate () of an external force () applied to the flight control (101), the state observer (120) using a model of the flight control (101) and of the active return system (106), and the detecting device (118) is designed to detect whether the flight control (101) is being gripped based on the estimate () of the external force ().

Description

Description TITLE: DETECTION OF A FLIGHT CONTROL OVERHAND Technical field of the invention

[0001] The present invention relates to a control system with a device for detecting a grip of a flight control, and a method for detecting a grip of a flight control and a corresponding computer program. Technological background

[0002] Known from the state of the art is an aircraft control system, comprising: a mobile flight control; an active flight control feedback system, comprising: • an electric motor for driving the flight control, • a measuring device designed to provide a representative measurement of a flight control position, and • an electric motor control device designed to provide a torque instruction to the electric motor from the measurement and a position instruction; and a device for detecting a takeover of the flight control.

[0003] The sensing device typically uses a capacitive sensor. Detection is then based on a change in capacitance when the flight control is taken in hand.

[0004] Alternatively, it is also known to use a force sensor.

[0005] In both cases, the detection device involves the addition of elements to the flight control (capacity element in the first case, force sensor in the second), which therefore present an additional cost due to their purchase, but also their integration requiring, for example, safety studies, which are critical in the avionics field.

[0006] It may therefore be desirable to provide a control system which makes it possible to overcome at least some of the aforementioned problems and constraints. Summary of the invention

[0007] An aircraft control system is therefore proposed, comprising: a mobile flight control; an active flight control feedback system, comprising: • an electric motor for driving the flight control, • a measuring device designed to provide a representative measurement of a flight control position, and • an electric motor control device designed to provide a torque setpoint to the electric motor from the measurement and a position setpoint; and a device for detecting a grip of the flight control; characterized in that the detection device comprises a state observer designed to provide, from the measurement, an estimate of an external force applied to the flight control, the state observer using a modeling of the flight control and the active feedback system, and in that the detection device is designed to detect the grip of the flight control from the estimate of the external force.

[0008] Thus, thanks to the invention, the grip detection uses the measurement made by the measuring device, the latter being present in any case to enable the active return function. It is therefore not necessary to add an additional element to the flight control.

[0009] The invention may further comprise one or more of the following optional features, in any technically possible combination.

[0010] Optionally, the state observer is linear proportional integral.

[0011] Also optionally, the state observer uses a state comprising at least one of: an angular position of the electric motor, an angular velocity of the electric motor, the position of the flight control and a velocity of the flight control.

[0012] Also optionally, the active return system includes a mechanical chain connecting the electric motor to the flight control.

[0013] Also optionally, the control system includes an automatic pilot system designed to provide the position setpoint and an electric motor control device designed to provide, to the motor electrical, a torque setpoint from the position setpoint and the measurement.

[0014] Also optionally, the autopilot system is designed to deactivate, in particular to stop providing the position instruction, when a takeover of the flight control is detected and / or to activate, in particular to provide the position instruction, when an absence of takeover of the flight control is detected.

[0015] Also optionally, the flight control actuates at least one of: a control surface of the aircraft, an incidence of blades of a rotor or a propeller, a direction of landing gear, a piloted actuator.

[0016] Also optionally, the flight control includes a stick.

[0017] Also optionally, the representative measurement of the flight control position is that flight control position, and the position setpoint is a setpoint of that flight control position.

[0018] A method for detecting a gripping of a mobile flight control is also proposed, characterized in that it comprises: an estimation by a state observer of an external force applied to the flight control, the state observer using a modeling of the flight control and an active feedback system of the flight control, the estimation being carried out from a measurement representative of a position of the flight control, the active feedback system comprising: • an electric motor for driving the flight control, • a measuring device designed to provide the measurement, and • an electric motor control device designed to provide a torque setpoint to the electric motor from the measurement and a position setpoint; and detection of the flight control grip from the estimation of the external force.

[0019] There is also provided a computer program downloadable from a communication network and / or recorded on a computer-readable medium, characterized in that it comprises instructions for executing the steps of a method according to the invention, when said program is executed on a computer. Brief description of the figures

[0020] The invention will be better understood with the aid of the following description, given solely by way of example and with reference to the appended drawings in which: Figure 1 is a functional view of a control system in which the invention is implemented, Figure 2 is a schematic view illustrating an example of a modeling of a flight control and an active feedback system of the control system of Figure 1, Figure 3 is a functional view of an example of a state observer of a grip detection device of the control system of Figure 1, Figure 4 is a graph illustrating the evolution over time of different signals of the control system of Figure 1, in an example of use, and Figure 5 is a functional view of a computer device in which the detection device can be implemented. Detailed description of the invention

[0021] With reference to FIG. 1, an example of a control system 100 of an aircraft, in which the invention is implemented, will now be described.

[0022] The control system 100 firstly comprises a flight control 101 having a position that can be changed. The flight control 101 is in particular designed to be taken in hand and manipulated by a pilot of the aircraft to change its position, this position defining one or more flight parameters. A possible flight parameter is for example an orientation of a control surface 104 of the aircraft. The flight control 101 comprises for example a stick 102 that can rotate and thus has an angular position 6 a can be changed by the pilot. The control surface 104 is then, for example, actuated by the stick 102, so that its orientation depends on the angular position 6 a of the handle 102.

[0023] The control system 100 further comprises a torque application system 106 to the flight control 101, designed to: move the latter to a set position, without external intervention, particularly from the pilot, and / or to provide resistance when the pilot manipulates the flight control (active feedback).

[0024] The torque application system 106 firstly comprises an electric motor 108 for driving the flight control 101. The torque application system 106 may further comprise a mechanical chain 110 by which the flight control 101 is connected to the electric motor 108.

[0025] The torque application system 106 further comprises a measuring device 112 designed to provide a measurement representative of the position of the flight control 101. This measurement is for example a measurement of the position of the flight control 101 and / or a measurement of an angular position 0 aof the electric motor 108. In the case of the handle 102, as in the example illustrated, this is for example a measurement 0 a from angular position 0 a of the handle 102.

[0026] The control system 100 further comprises a control device 114 of the motor 108 designed to provide a torque setpoint C* i to engine 108 from measurement (measurement 0 a from angular position 0 a of the handle in the illustrated example). More precisely, in the presence of a position instruction (an instruction 0a of the angular position 0 a of the stick 102 in the illustrated example), for example provided by an automatic pilot system 116 of the control system 100, the control device 114 provides the torque setpoint C* ifrom the position measurement and the position setpoint, to follow this position setpoint. Thus, the flight control 101 moves without pilot intervention to reflect the piloting of the autopilot system 116. In the absence of the position setpoint, for example when the autopilot system 116 is deactivated, the control device 114 is designed to implement active feedback, by providing the torque setpoint C„, from the position measurement, so as to produce resistance to the manipulation of the flight control by the pilot.

[0027] Subsequently, we will describe more specifically the case of the handle 102 and the use of its angular position 0 a . So the measure used will be measure 0 a from this angular position 0 a and the instruction 0a will apply to this angular position 0 a. However, this case is not limiting and the person skilled in the art will easily be able to adapt the following description to the case of other types of flight controls, such as a steering wheel, and to other measured positions representative of the position of the flight control, such as the angular position 0 m of the electric motor 108.

[0028] The control system 100 further comprises a device 118 for detecting a grip of the stick 102 by the pilot and / or an absence of grip of the stick 102 by the pilot.

[0029] The detection device 118 firstly comprises a state observer 120 designed to provide an estimate C p of the external force C p , from at least the position measurement 0 a , for example from the position measurement 0 a and the torque setpoint C^, as in the example illustrated.

[0030] The detection device 118 further comprises, for example, a comparator 122 designed to compare an absolute value of the estimate C p to a predefined threshold. The comparator 122 is thus designed to detect a grip on the handle when the absolute value of the estimate C p is greater than the predefined threshold and to detect a lack of grip when the absolute value of the estimate C p is lower than the predefined threshold. The comparator 122 is thus designed to provide a detection result D indicating either grip or no grip.

[0031] This detection result D is for example provided to the automatic pilot system 116, the latter then being designed to deactivate, in particular to stop providing the position instruction 0*, when the detection result D indicates a gripping of the stick 102 and / or to activate, in particular to provide the position instruction 0*, when the detection result indicates an absence of gripping of the stick 102.

[0032] With reference to FIG. 2, an example of a model 200 that can be used by the state observer 120 will now be described.

[0033] The modeling 200 models at least the handle 102 and the torque application system 106, and takes into account the external force C p . Modeling 200 is for example linear.

[0034] Thus, the handle 102 and the torque application system 106 can be modeled by the following state representation: ï " at ~ Ax + B™ Cm + B P C P, 0I J (y = Cx is a state matrix, B m is a control matrix associated with the motor torque setpoint C^, B p is a control matrix associated with the external torque C p , C is an observation matrix, x is a state vector, and y is a measurement vector.

[0035] The state vector x includes for example at least one of: the angular position 0 a from handle 102, an angular speed of 0 a of the handle 102, the angular position 0 m of the electric motor 108, and an angular speed of 0 m of the electric motor 108. Preferably, the state vector x comprises these four variables. Furthermore, the measurement vector y comprises, for example, at least the measurement of

[0036] For example, the electric motor 108 is modeled by its angular position 0 m , an inertia J m and viscous friction fmot . Still for example, the mechanical chain 110 is modeled by a reduction ratio R, an equivalent stiffness k and an equivalent viscous damping coefficient f. Still for example, the handle 102 is modeled by an inertia J a .

[0037] With these models of the different elements, the matrices of the previous state representation can for example be expressed by: A =

[0038] With reference to Figure 3, an example of a state observer 120 using the modeling of Figure 2 will now be described.

[0039] In this example, the linear observer from the article "Robust control system design with a proportional integral observer" by SR Beale and B. Shafai, published in the journal "International Journal of Control, 1989 - Taylor & Francis" is used. In this case, the observer 120 is linear proportional integral and implements the following equations: is a proportional gain of the estimator, G! is an integral gain of the estimator, and Cx = y is an estimate of the measure y.

[0040] As is apparent, the state observer 120 operates iteratively and, at each iteration, produces in parallel an estimate x of the state x and an estimate C p of the external force C p from the previous estimates, so as to seek to cancel the error between the measurement y and its estimate y. The speed of cancellation of this error is done, in particular, by choosing the gains G p and G adapted which guarantee the convergence of the observer.

[0041] G gains p , G, are further preferably chosen so that, in response to the application of a constant external force, the estimate C p reaches 95% of the external effort within a convergence time preferably between 100 ms and 200 ms.

[0042] G gains p , G! are for example chosen according to the following method.

[0043] Noting e = C p - C p and e = x - x respectively the estimation error of

[0044] In the present invention, it is not necessary to estimate the external force with high precision. Thus, it is possible to choose the gains G P , G! assuming that the external force is continuous and not a Dirac or an impulse resulting for example from an accidental elbow, which simplifies the previous equation

[0045] To further simplify the determination of G gains p , G it is possible to consider the simple case or all the eigenvalues ​​of the matrix are equal to the same scalar a, chosen sufficiently negative to guarantee acceptable convergence, in particular to guarantee the convergence time of 100 ms to 200 ms.

[0046] With these different simplifications, the gains G p , G, can be given by:

[0047] With reference to Figure 4, the results of a numerical simulation will now be presented.

[0048] These results were obtained using the following numerical values: J m = 8.2 x 10~ 5 kg. m 2 , f mot = 7.7 x 10~ 6 N. m. s / rad, J a = 3.8 x 10~ 5 kg. m 2 , k = S72N. m / rad, f = 10 -2 IV. m. s / rad, and R = 48.

[0049] As is apparent, initially, the torque setpoint is sinusoidal which may be the consequence of the position regulation carried out in the control device 114.

[0050] At a time t1, an external force C p constant is exerted on the handle 102.

[0051] Then, the estimate C pof this external effort C p is improved at each iteration and gradually approaches the external force C p actually applied, while remaining below the predefined threshold S. The detection result D therefore remains an absence of handling (D = 0).

[0052] At time t2, the estimate C p reaches the predefined threshold. The detection result D therefore represents a grip detection (D = 1).

[0053] In response to this detection, the autopilot system 116 therefore stops transmitting the position instruction 0*, so that the control device 114 transmits a zero torque instruction, thereby stopping the electric motor 108 and therefore the active feedback. The stick 102 can thus be maneuvered by the pilot without the latter being hindered by the active feedback.

[0054] With reference to FIG. 5, the detection device 118 is for example a computer system comprising a data processing unit 502 (such as a microprocessor) and a main memory 504 (such as a RAM memory, from the English “Random Access Memory”) accessible by the processing unit 502. The computer system further comprises for example a network interface and / or a computer-readable medium 506, such as for example a local medium (such as a local hard disk) or a remote medium (such as a remote and accessible hard disk via the network interface through a communication network) or a removable medium (such as a USB key, from the English "Universal Serial Bus", or a CD, from the English "Compact Disc" or a DVD, from the English "Digital Versatile Disc") readable by means of an appropriate reader of the computer system (such as a USB port or a CD and / or DVD disk reader). A computer program 508 containing instructions for the processing unit 502 is recorded on the medium 506 and / or downloadable via the network interface. This computer program 508 is for example intended to be loaded into the main memory 504, so that the processing unit 502 executes its instructions to implement the observer 120 and / or the comparator 122.

[0055] Alternatively, all or part of the computer program 508 could be implemented in hardware form, i.e. in the form of an electronic circuit, for example micro-wired, not involving a computer program.

[0056] In conclusion, it appears clearly that a control system such as that described above makes it possible to do without elements to be added to the flight control to detect its grip.

[0057] It will also be noted that the invention is not limited to the embodiments described above. It will indeed appear to those skilled in the art that various modifications can be made to the embodiments described above, in light of the teaching which has just been disclosed to them.

[0058] In the detailed presentation of the invention given above, the terms used should not be interpreted as limiting the invention to the embodiments set forth in this description, but should be interpreted to include all equivalents the prediction of which is within the reach of those skilled in the art by applying their general knowledge to the implementation of the teaching just disclosed to them.

Claims

Claims [1] System (100) for controlling an aircraft, comprising: a movable flight control (101); a system for applying torque (106) to the flight control (101), comprising: • an electric motor (108) for driving the flight control (101), • a measuring device (112) designed to provide a measurement (0 a ) representative of a position (0 a ) of the flight control (101), and • a device (114) for controlling the electric motor (108) designed to provide a torque setpoint (C„) to the electric motor (108) from the measurement (0 a ); and a device (118) for detecting a gripping of the flight control (101); characterized in that the detection device (118) comprises a state observer (120) designed to provide, from the measurement (0 a ), an estimate of an external effort applied to the flight control (101), the state observer (120) using a modeling of the flight control (101) and the torque application system (106), and in that the detection device (118) is designed to detect the grip of the flight control (101) or the absence of grip from the estimation (C p ) of the external force (C p ). [2] The control system (100) of claim 1, wherein the state observer (120) is linear proportional integral. [3] The control system (100) of claim 1 or 2, wherein the state observer (120) uses a state comprising at least one of: an angular position of the electric motor, an angular velocity of the electric motor, the position (0 a ) of the flight control (101) and a speed of the flight control (101). [4] Control system (100) according to any one of claims 1 to 3, wherein the active feedback system (106) comprises a mechanical chain (110) connecting the electric motor (108) to the flight control (101). [5] Control system (100) according to any one of claims 1 to 4, comprising an automatic piloting system (116) designed to provide a position setpoint (0*), and in which the control device (114) is designed, when the automatic piloting system (116) is activated, to provide the torque setpoint (C„) from the position setpoint (0*) and the measurement (0 a ). [6] Control system (100) according to claim 5, wherein the automatic pilot system (116) is designed to deactivate, in particular to stop providing the position instruction (0*), when a takeover of the flight control (101) is detected. [7] A control system (100) according to any one of claims 1 to 6, wherein the control device (114) is adapted to implement active feedback of the flight control (101). [8] Control system (100) according to claims 6 and 7, wherein the control device (114) is adapted to implement the active feedback of the flight control (101) when the autopilot system is deactivated, and wherein the autopilot system (116) is adapted to activate itself, in particular to provide the position setpoint (0*), when a lack of grip of the flight control (101) is detected when the control device (114) implements the active feedback. [9] Control system (100) according to any one of claims 1 to 8, in which the flight control (101) actuates at least one of: a control surface of the aircraft, an incidence of blades of a rotor or of a propeller, a direction of landing gear, a piloted actuator. [10] A control system (100) according to any one of claims 1 to 9, wherein the flight control (101) comprises a stick (102). [11] A control system (100) according to any one of claims 1 to 10, wherein the measurement (0 a ) representative of the position (0 a ) of the flight control (101) is this position (0 a ) of the flight control (101), and in which the position instruction (0*) is an instruction of this position (0 a ) of the flight control (101). [12] Method for detecting a gripping of a mobile flight control (101), characterized in that it comprises: an estimation by a state observer (120) of an external force (C p ) applied to the flight control (101), the state observer (120) using a modeling of the flight control (101) and of a torque application system (106) to the flight control (101), the estimation being carried out from a measurement (0 a ) representative of a position (0 a ) of the flight control (101), the torque application system (106) comprising: • an electric motor (108) for driving the flight control (101), • a measuring device (112) designed to provide the measurement (0 a ), And • a device (114) for controlling the electric motor (108) designed to provide a torque setpoint (C„) to the electric motor (108) from the measurement (0 a); and a detection of the taking in hand or the absence of taking in hand of the flight control (101) from the estimation of the external effort (C p ). [13] Computer program (508) downloadable from a communication network and / or recorded on a computer-readable medium (506), characterized in that it comprises instructions for executing the steps of a method according to claim 12, when said program is executed on a computer.

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