CONTROL SYSTEM FOR CONTROLLING AT LEAST ONE PROPELLER OF A COMPOUND ROTORCRAFT, ASSOCIATED COMPOUND ROTORCRAFT AND CONTROL METHOD

Abstract

A control system for controlling at least one propeller of a compound rotorcraft, the control system generating a control order for collectively controlling a pitch of the blades of at least one propeller. According to the disclosure, the control system comprises: a first piloting control for generating a first control setpoint; a second piloting control for at least generating a second control setpoint different from first control setpoint; and a control unit configured to generate control order depending on the first control setpoint and second control setpoint, the control unit implementing a control law generating the control order as a function of first control setpoint and the second control setpoint.

Claims

1. A control system for controlling at least one propeller of a compound rotorcraft, the control system generating a control order for collectively controlling a pitch of the blades of the at least one propeller, the control system including: a first piloting control for generating a first control setpoint; a second piloting control for at least generating a second control setpoint different from the first control setpoint; and a control unit configured to generate the control order depending on the first control setpoint and the second control setpoint, the control unit implementing a control law generating the control order as a function of the first control setpoint and the second control setpoint, wherein the first control setpoint is representative of a first control parameter and the second control setpoint is representative of a second control parameter corresponding to a primitive of the first control parameter.

2. The control system according to claim 1 wherein the first piloting control includes a first movable member having at least one degree of rotational mobility relative to a first support about a first rotation axis, the first movable member being capable of being rotated in two opposing directions of rotation about a first central position.

3. The control system according to claim 2 wherein the first piloting control is monostable, the first piloting control including first elastic return means configured to return the first movable member to the central position.

4. The control system according to claim 1 wherein the second piloting control includes a second movable member having at least one degree of rotational mobility relative to a second support about a second rotation axis, the second movable member being capable of being rotated in two opposing directions of rotation about a second central position.

5. The control system according to claim 4 wherein the second piloting control is monostable, the second piloting control including second elastic return means configured to return the second movable member to the second central position.

6. The control system according to claim 4 wherein the second movable member has a degree of translational mobility relative to the second support along a translation axis, the translation axis being oriented perpendicular to the second rotation axis.

7. The control system according to claim 1 wherein the first control setpoint is representative of a first control parameter chosen from the group comprising a ground speed of the compound rotorcraft, an air speed of the compound rotorcraft, a longitudinal acceleration of the compound rotorcraft relative to the ground, a first time derivative of the longitudinal acceleration of the compound rotorcraft relative to the ground, a second time derivative of the longitudinal acceleration of the compound rotorcraft relative to the ground, a speed of variation of a power transmitted to the at least one propeller and a speed of variation of the pitch of the blades of the at least one propeller.

8. The control system according to claim 1 wherein, the second piloting control including a second movable member having at least one degree of rotational mobility relative to a second support about a second rotation axis, pulsed actuation of the second movable member according to the at least one degree of rotational mobility relative to the second support generates the second control setpoint in the form of a calibrated signal representative of the second control parameter.

9. The control system according to claim 8 wherein the second control setpoint is generated by integrating the variations of the first control parameter over a time interval defined by a duration of actuation of the second piloting control.

10. The control system according to claim 1 wherein the first control setpoint is representative of a first control parameter determined according to a choice from at least two different control parameters, an actuation of the second piloting control is configured to modify the choice of the first control parameter.

11. The control system according to claim 10 wherein, the second movable member having a degree of translational mobility relative to the second support along a translation axis, moving the second movable member along the translation axis modifies the choice of the first control parameter.

12. The control system according to claim 1 wherein the first piloting control and the second piloting control are arranged on a handle of a collective pitch control stick, the collective pitch control stick enabling to collectively control a pitch of the blades of a lift rotor of the compound rotorcraft.

13. The control system according to claim 1 wherein the first piloting control and the second piloting control are separate from each other.

14. A compound rotorcraft including at least one propeller, wherein the compound rotorcraft includes the control system according to claim 1.

15. A control method for controlling at least one propeller of the compound rotorcraft, the control method including a step of generating a control order for collectively controlling a pitch of the blades of the at least one propeller, the control method including the following steps: generating a first control setpoint; and generating a second control setpoint different from the first control setpoint, the step of generating the control order being carried out depending on the first control setpoint and the second control setpoint, by implementing a control law generating the control order as a function of the first control setpoint and the second control setpoint, wherein the first control setpoint is representative of a first control parameter and the second control setpoint is representative of a second control parameter corresponding to a primitive of the first control parameter.

Description

BRIEF DESCRIPTION OF THE DRAWINGS

[0078] The disclosure and its advantages appear in greater detail in the context of the following description of embodiments given by way of illustration and with reference to the accompanying figures, in which:

[0079] FIG. 1 is a perspective view of a compound rotorcraft according to the disclosure;

[0080] FIG. 2 is a front view of a handle of a collective pitch control stick;

[0081] FIG. 3 is a transverse cross-sectional view of a first piloting control;

[0082] FIG. 4 is a transverse cross-sectional view of a second piloting control; and

[0083] FIG. 5 is a logic diagram showing a control method according to the disclosure.

DETAILED DESCRIPTION

[0084] Elements that are present in more than one of the figures are given the same references in each of them.

[0085] FIG. 1 shows a compound rotorcraft 1 according to the disclosure.

[0086] This compound rotorcraft 1 has a fuselage 4 above which at least one lift rotor 2 is arranged. This lift rotor 2 is provided with a plurality of blades referred to for convenience as “main blades 3”.

[0087] In addition, the compound rotorcraft 1 is provided with at least one propeller referred to as the “first propeller”, of the tractor or pusher type. For example, the compound rotorcraft 1 is provided with at least one first propeller 10 and with at least one second propeller 15. The first and second propellers 10, 15 respectively have a plurality of first blades 11 and a plurality of second blades 16. The first propeller 10 and the second propeller 15 may be arranged laterally relative to the fuselage 4, in particular to either side of an anteroposterior plane of the compound rotorcraft 1. In FIG. 1, the first and second propellers 10, 15 are interchangeable. The first and second propellers 10, 15 are optionally carried by a support 5. Such a support 5 may optionally be aerodynamic. For example, the support 5 comprises a wing as shown in FIG. 1. In FIG. 1, the propellers 10, 15 are arranged at the leading edge of a wing. According to another example, the propellers 10, 15 may be arranged at the trailing edge of the wing.

[0088] Furthermore, the compound rotorcraft 1 may include stabilizer or indeed manoeuvring surfaces. For example, for fore-and-aft control, the compound rotorcraft 1 may include at least one substantially horizontal empennage 20, optionally provided with movable elevators 21. For example, for directional stability and control, the compound rotorcraft 1 may include at least one substantially vertical empennage 25, optionally provided with movable rudders 26. FIG. 1 thus shows a tail assembly in an upside-down U shape, but this tail assembly may have various shapes without going beyond the ambit of the disclosure. According to another example, the tail assembly may be H-shaped, U-shaped, etc. The teaching of patent FR 3 074 142 is also applicable, for example.

[0089] Furthermore, the compound rotorcraft 1 includes a power plant 30 for delivering power to the lift rotor 2 and optionally to each propeller 10, 15. For this purpose, the power plant 30 includes at least one engine 31 that is controlled by a standard engine computer 32.

[0090] The term “computer” is used hereinafter to refer to a unit that may, for example, comprise at least one processor and at least one memory, at least one integrated circuit, at least one programmable system, at least one logic circuit, these examples not limiting the scope given to the expression “computer”. The term “processor” may refer equally to a central processing unit (CPU), a graphics processing unit (GPU), a digital signal processor (DSP), a microcontroller, etc.

[0091] In addition, the power plant 30 may include, for example within an interconnection system, at least one gearbox, at least one shaft, and/or at least one member for interconnecting two members in rotation, etc. For example, one or more engines 31 are connected mechanically by one or more mechanical connection systems to a main gearbox 33 that rotates the lift rotor 2. Furthermore, the main gearbox 33 may be connected mechanically by at least one shaft to one lateral gearbox per propeller 10, 15, which lateral gearbox is then connected in turn to a propeller 10, 15.

[0092] The speeds of rotation of the outputs of the engine or engines 31, of the propellers 10, 15, of the lift rotor 2, and of the mechanical interconnection system are optionally proportional to each other, the proportionality ratio optionally being constant regardless of the flight configuration of the compound rotorcraft 1 under normal operating conditions, i.e., except in the event of failure or during testing or training.

[0093] Furthermore, the compound rotorcraft 1 may include various controls in order to be piloted.

[0094] In particular, the compound rotorcraft 1 may include a piloting system 40 connected to flight controls for collectively and cyclically controlling the pitch of the main blades 3. Such a piloting system 40 may, for example, include a set of swashplates. Thus, at each instant, the pitch of the main blades 3 may be equal to the sum of a collective pitch that is identical for all of the main blades 3 and a cyclic pitch that varies as a function of the azimuth of each main blade 3. The pitch of the main blades 3 is referred to as the “main pitch” so as to be clearly distinguished from the pitches of the other blades.

[0095] The compound rotorcraft 1 may therefore include a collective pitch control 45 that can be operated by a pilot who acts on at least one mechanical and/or electrical control channel of the piloting system 40 in order to cause the main pitch of the main blades 3 to vary collectively, where applicable via the set of swashplates. For example, the collective pitch control 45 comprises a lever. Moreover, the collective pitch control 45 may comprise a collective pitch sensor 450 that emits an analog, digital, electrical or optical signal that varies as a function of the position of a movable member. For example, the collective pitch control 45 comprises a lever and a collective pitch sensor 450 including at least one angular position sensor for assessing a position of the lever, such as a potentiometer, for example. The collective pitch sensor 450 may also be arranged on a movable member together with the collective pitch control, for example downstream of series actuators and/or trim actuators, as applicable.

[0096] Similarly, the compound rotorcraft 1 may include a cyclic pitch control stick 47 that can be operated by a pilot who acts on one or more mechanical and/or electrical control channels of the piloting system in order to cause the pitch of the main blades 3 to vary cyclically, where applicable via the set of swashplates. Moreover, the cyclic pitch control stick 47 may comprise a position sensor 470 that emits an analog, digital, electrical or optical signal that varies as a function of the position of a movable member. For example, the cyclic pitch control stick 47 comprises a stick and a position sensor 470 including at least two angular position sensors for assessing a position of the stick, such as potentiometers, for example.

[0097] Typically, the compound rotorcraft 1 may include a control system 50 for controlling the pitch of the blades 11, 16 of the propeller or propellers 10, 15, and, in particular, the pitch of the first blades 11 and the second blades 16, as in the example shown. At each instant, and in particular in the presence of two propellers 10, 15, the first pitch of the first blades 11 of the first propeller 10 may be equal to the sum of a mean pitch component and a differential pitch component, while the second pitch of the second blades 16 of the second propeller 15 is equal to the difference between this mean pitch component and the differential pitch component.

[0098] Optionally, the compound rotorcraft 1 includes a first measurement sensor 88 for measuring the first value of the first pitch and a second measurement sensor 89 for measuring the second value of the second pitch. For example, the first measurement sensor 88 includes a position sensor that emits an analog, digital, electrical or optical signal that varies as a function of the position of a control shaft for controlling the pitch of the first blades 11. Similarly, the second sensor 89 may include a position sensor that emits an analog, digital, electrical or optical signal that varies as a function of the position of a control shaft for controlling the pitch of the second blades 16. Each position sensor may be of a usual type and may, for example, comprise a speed sensor for obtaining a position by integration, a potentiometer, etc. Such sensors 88 and 89 may in particular make it possible, with a control loop, to control a control order allowing a pitch of the blades 11, 16 to be collectively controlled.

[0099] Typically, a piloting control may be operated by a pilot who acts on one or more mechanical and/or electrical control channels of the piloting system 40 in order to cause the pitch of the propeller or propellers to vary, for example in order to control a forward speed of the compound rotorcraft 1. For example, the piloting control may either control the total pitch of the propeller or propellers or control the value of a mean pitch component, where applicable.

[0100] Similarly, the compound rotorcraft 1 may include a yaw control 55 that can be operated by a pilot who that acts on one or more mechanical and/or electrical control channels of the piloting system 40 in order to cause the differential pitch component of the pitch of the first blades 11 and the pitch of the second blades 16 to vary, as applicable. The yaw control 55 may, for example, be in the form of a rudder bar.

[0101] Furthermore, the piloting system 40 may include one or more control computers that are in communication at least with a piloting control and optionally also with the first measurement sensor 88, the second measurement sensor 89 and/or the collective pitch sensor 450, or indeed with one or more of the abovementioned controls.

[0102] In addition, such a compound rotorcraft also includes a control system 50 for controlling the propeller or propellers 10, 15 by generating a control order for collectively controlling a pitch of the blades 11, 16.

[0103] This control system 50 may be separate from or combined with the abovementioned piloting system 40 and may include, for example, an automatic flight control system referred to by the acronym AFCS.

[0104] Such a control system 50 also comprises a first piloting control 51 for generating a first control setpoint, and a second piloting control 52 for at least generating a second control setpoint different from the first control setpoint.

[0105] The control system 50 comprises a control unit 53 configured to generate the control order depending on the first control setpoint and the second control setpoint.

[0106] The control unit 53 thus implements a control law generating the control order as a function of the first control setpoint and the second control setpoint.

[0107] The term “control unit” is used hereinafter to refer to a unit that may, for example, comprise at least one processor and at least one memory, at least one integrated circuit, at least one programmable system, at least one logic circuit, these examples not limiting the scope given to the expression “control unit”. The term “processor” may refer equally to a central processing unit (CPU), a graphics processing unit (GPU), a digital signal processor (DSP), a microcontroller, etc.

[0108] Furthermore, the first control setpoint is advantageously representative of a first control parameter chosen from the group comprising a ground speed of the compound rotorcraft 1, an air speed of said compound rotorcraft 1, a longitudinal acceleration of the compound rotorcraft 1 relative to the ground, a first time derivative of the longitudinal acceleration of the compound rotorcraft 1 relative to the ground, a second time derivative of the longitudinal acceleration of the compound rotorcraft 1 relative to the ground, a speed of variation of a power transmitted to the at least one propeller 10, 15 and a speed of variation of the pitch of the blades 11, 16 of the at least one propeller 10, 15.

[0109] Moreover, the first control setpoint is representative of a first control parameter and the second control setpoint is representative of a second control parameter corresponding to a primitive of the first control parameter.

[0110] Moreover, the second control setpoint can be generated by integrating the variations of the first control parameter over a time interval defined by a duration of actuation of the second piloting control 52.

[0111] Advantageously, the first control setpoint and the second control setpoint may be generated by means of analog, digital, electrical or optical signals that vary as a function of the position of a movable member.

[0112] As shown in FIG. 2, the first piloting control 51 and the second piloting control 52 can, for example, be juxtaposed side by side on a handle 451 of the collective pitch control stick 45 for collectively controlling the pitch of the blades of the lift rotor of the compound rotorcraft. Thus, the first piloting control 51 and the second piloting control 52 are separate from each other and can be actuated by a pilot independently of each other.

[0113] The first piloting control 51 may, for example, comprise a first movable member 54 capable of moving relative to a first support 55. Thus, the first movable member 54 may have at least one degree of rotational mobility relative to the first support 55 about a first rotation axis X1.

[0114] Similarly, the second piloting control 52 may comprise a second movable member 57 having at least one degree of rotational mobility relative to a second support 58 about a second rotation axis X2.

[0115] In addition, the first support 55 and the second support 58 may be formed by the same assembly comprising a handle 451 of the collective pitch control stick 45 as described in FIG. 1.

[0116] Furthermore, when the first piloting control 51 comprises a first movable member 54 having at least one degree of rotational mobility relative to the first support 55 about the first rotation axis X1, actuation of the first movable member 54 according to its degree of rotational mobility relative to the first support 55 can generate the first control setpoint, for example in the form of an analog signal representative of the first control parameter.

[0117] Similarly, when the second piloting control 52 comprises a second movable member 57 having at least one degree of rotational mobility relative to the second support 58 about the second rotation axis X2, actuation of the second movable member 57 can generate the second control setpoint in the form of a calibrated pulsed signal representative of the second control parameter. The second control setpoint can thus be used to modify the control order precisely by a predetermined increment.

[0118] The first setpoint can be determined as a function of a current position of the first movable member 54 relative to the first support 55. The first setpoint can thus vary in a linear or non-linear manner with such a current position of the first movable member 54.

[0119] In addition, the first setpoint may vary according to different variation laws as a function of a flight parameter such as, for example, the ground or air speed of the compound rotorcraft 1.

[0120] Alternatively, such a first piloting control 51 may be monostable. In this case and as shown in FIG. 3, the first piloting control 51 may comprise first elastic return means 56 configured to automatically return the first movable member 54 to a central position P1, after having been rotated. These first elastic return means 56 may comprise a spring under torsion, for example.

[0121] In addition, the first movable member 54 may, for example, be rotated by a finger of a pilot in two opposing directions of rotation S1 and S2 about a first central position P1.

[0122] The first movable member 54 may comprise a straight protrusion 154 that may, for example, project radially from a substantially cylindrical portion 155. Such a straight protrusion 154 allows the pilot's finger to bear on it in order to transmit torque to the first movable member 54, but also to serve as a sensory marker in order to identify the current position of the first movable member 54 relative to the first central position P1.

[0123] In this case, the first control setpoint can be determined as a function of a difference between a current position of the first movable member 54 and the first central position P1. Having approached a predetermined piloting target, the first movable member 54 can be released by the pilot and can thus return to its first central position P1 without modifying the first control setpoint.

[0124] The first setpoint can thus vary in a linear or non-linear manner with such a positional deviation of the first movable member 54.

[0125] In this case, the first setpoint may also vary according to different variation laws as a function of a flight parameter such as, for example, the ground or air speed of the compound rotorcraft 1.

[0126] Similarly, the second piloting control 52 may be monostable. In this case and as shown in FIG. 4, the second piloting control 52 may comprise second elastic return means 59 configured to return the second movable member 57 to the second central position P2. These second elastic return means 59 may comprise a spring under torsion, for example.

[0127] The second movable member 57 is thus capable of being rotated in two opposing directions of rotation S3 and S4 about a second central position P2.

[0128] The second movable member 57 may comprise a knob or a substantially concave face 157. Such a face 157 projects radially from a substantially cylindrical portion 158. Such a face 157 allows the pilot's finger to bear on it in order to move the second movable member 57 with respect to the second support 58.

[0129] Such a knob may have at least three discrete states, namely a first state referred to as beep+ requesting an increase in the second control setpoint, a second state referred to as beep− requesting a decrease in the second control setpoint, and a third state requesting no modification of the second control setpoint.

[0130] Furthermore, the second movable member 57 may also have a degree of translational mobility relative to the second support 58 along a translation axis Y2 perpendicular to the second rotation axis X2. In this case, the substantially cylindrical portion 158 may then be free to move inside a substantially straight groove 160.

[0131] In this case, the second piloting control 52 may comprise other elastic return means 159 such as a spring under compression. The elastic return means 159 are thus configured to automatically return the second movable member 57 to a rest position corresponding to the second central position P2.

[0132] In addition, in a particular control mode, the first control setpoint may be representative of a first control parameter determined according to a choice from at least two different control parameters; an actuation of the second piloting control 52 may then allow the choice of the first control parameter to be modified.

[0133] Moving the second movable member 57 in translation along the translation axis Y2 can then generate a selection of another parameter and therefore a modification of the initial choice corresponding to the first control parameter.

[0134] As shown in FIG. 5, the disclosure also relates to a control method 60 for controlling at least one propeller 10, 15 of the compound rotorcraft 1.

[0135] Such a control method 60 includes a step 61 of generating a first control setpoint and a step 62 of generating a second control setpoint different from the first control setpoint.

[0136] The control method 60 then comprises a step 63 of generating a control order for collectively controlling a pitch of the blades 11, 16 of the propeller or propellers 10, 15.

[0137] Such a step 63 of generating the control order is then carried out depending on the first control setpoint and the second control setpoint by implementing a control law generating the control order as a function of the first control setpoint and the second control setpoint.

[0138] For example, the control law implemented during the step 63 of generating the control order makes it possible to combine the first control setpoint and the second control setpoint with each other.

[0139] The first control setpoint can thus be modified with a first increment in order to allow a piloting target to be approached rapidly. The second control setpoint may be modified with a second increment that is smaller than the first increment in order to allow the predetermined piloting target to be reached in a precise manner.

[0140] Furthermore, the control law implemented during the step 63 of generating the control order may be a function, for example, of the forward air or ground speed of the compound rotorcraft 1. More precisely, the first increment and/or the second increment are linearly or non-linearly variable as a function of this forward speed of the compound rotorcraft 1.

[0141] Naturally, the present disclosure is subject to numerous variations as regards its implementation. Although several embodiments are described above, it should readily be understood that it is not conceivable to identify exhaustively all the possible embodiments. It is naturally possible to envisage replacing any of the means described by equivalent means without going beyond the ambit of the present disclosure.