System for controlling a rotorcraft rotor, a rotorcraft fitted with such a system, and an associated control method

Abstract

A control system for controlling a rotorcraft rotor, to a rotorcraft fitted therewith, and to a corresponding control method. The system comprises selector means for defining at least two disjoint position ranges for the control member between two physical abutments corresponding to the movement limits of the control member, a first position range being defined between at least two first limit values about a zero force position of the control member, and at least one second position range being defined between at least one of the at least two first limit values and at least one second limit value; and control means for allocating a first control law to the first position range of the control member and a second control law to the second position range of the control member, the first and second control laws being selected to be mutually distinct.

Claims

1. A control system for controlling a rotorcraft rotor, the control system comprising at least one control member for use in piloting the rotor, the control system further comprising: selector means for defining at least two disjoint position ranges and for the control member between two physical abutments corresponding to the movement limits of the control member, a first position range being defined between at least two first limit values about a zero force position of the control member, and at least one second position range being defined between at least one of the at least two first limit values and at least one second limit value; and control means for allocating a first control law to the first position range of the control member and a second control law to the second position range of the control member, the first and second control laws being selected to be mutually distinct.

2. A control system according to claim 1, wherein the control system includes monitor means allowing to identify a landed state of the rotorcraft on a support.

3. A control system according to claim 1, wherein the first control law is of the type that is linear in position, each position of the control member in the first position range corresponding to a position of a plane of the rotor.

4. A control system according to claim 1, wherein the second control law is of the type that is linear in speed, each position of the control member in the second position range corresponding to a speed of tilt of a plane of the rotor.

5. A control system according to claim 1, wherein the at least one second limit value coincides with one of the two physical abutments of the control member.

6. A control system according to claim 1, wherein the second position range of the control member comprises two range portions, each of the two range portions being defined between one of the at least two first limit values of the first range and one of the at least one second limit values, the two second portions of the second position range being arranged on respective sides of the first position range of the control member.

7. A control system according to claim 1, wherein the control system includes adjustment means suitable for modifying a reference position of a plane of the rotor relative to a drive plane, the reference position corresponding to an angle of inclination of the rotor when the control member is in the zero force position.

8. A control system according to claim 1, wherein the control member includes a projection of length less than 30 cm between a free end of the projection and a hinge giving the projection at least one degree of freedom to move in rotation relative to a stand.

9. A control system according to claim 8, wherein the hinge imparts two degrees of freedom to the projection to move in rotation relative to the stand, and wherein the at least two disjoint position ranges and described by the projection are in the form of cones with different angles, the at least two first limit values forming an angle of a first cone forming the first range and the at least one second limit value forming an exterior angle of a hollow second cone forming the second range.

10. A rotorcraft, including at least one control system according to claim 1.

11. A method of controlling a rotorcraft rotor by means of a control member, wherein the method comprises the steps of: defining at least two distinct position ranges and of the control member, a first position range being defined between at least two first limit values about a zero force position of the control member, and at least one second position range being defined between at least one of the at least two first limit values and at least one second limit value; and allocating a first control law to the first position range of the control member and a second control law to the second position range of the control member, the first and second control laws being selected to be mutually distinct.

12. A method according to claim 11, wherein the method includes a step of identifying a landed state of the rotorcraft on a support.

13. A method according to claim 11, wherein the first control law being of the type that is linear in position, with each position of the control member in the first position range corresponds to a position of a plane of the rotor.

14. A method according to claim 11, wherein the second control law being of the type that is linear in speed, with each position of the control member in the second position range corresponds to a speed of tilting a plane of the rotor.

15. A method according to claim 11, wherein at least one second limit value is selected in such a manner that it coincides with a physical abutment of the control member.

16. A method according to claim 11, wherein two second limit values are defined for the second position range of the control member, and wherein the second position range of the control member is formed by two range portions, the two range portions being arranged on respective sides of the first position range of the control member.

Description

BRIEF DESCRIPTION OF THE SEVERAL VIEWS OF THE DRAWINGS

(1) The invention and its advantages appear in greater detail from the context of the following description of examples given by way of illustration and with reference to the accompanying figures, in which:

(2) FIG. 1 is a diagrammatic view of a control system including a control member in a first embodiment in accordance with the invention;

(3) FIG. 2 is a side view of a control member in a first embodiment in accordance with the invention;

(4) FIGS. 3 and 4 are diagrams showing different graphical representations of ranges of positions corresponding to two schemes for a control member in accordance with the first embodiment of FIG. 2;

(5) FIG. 5 is a perspective view of a control member in a second embodiment in accordance with the invention; and

(6) FIGS. 6 and 7 are diagrams showing different graphic representations of ranges of positions corresponding to the control member in accordance with the second embodiment of FIG. 5.

DETAILED DESCRIPTION OF THE INVENTION

(7) As mentioned above, the invention relates to a system for controlling a rotorcraft rotor.

(8) As shown in FIG. 1, such a control system 1 comprises at least one control member 3 that may be in various forms, and in particular in the forms of a stick, a mini-stick, a joystick, or pedals. Such a control member 3 thus serves to control the collective pitch and/or the cyclic pitch of blades of a main rotor and/or of a tail rotor of a rotorcraft. Below, in order to simplify the description, reference is thus made merely to a rotor 2 without being limited to one or the other of these possibilities.

(9) Furthermore, such a control system 1 also includes selector means 4 serving to define disjoint position ranges for the control member 3. A first position range generally includes a zero force position for the control member in which the forces on the control member 3 are low or zero. A second range of positions is remote from the zero force position of the control member and is in the proximity of or includes a physical abutment of the control member 3.

(10) In addition, the control system 1 includes control means 5 suitable for imparting mutually distinct control laws to each of the two position ranges of the control member 3.

(11) Finally, the control system 1 includes monitor means 6 serving to identify a landed state of the rotorcraft. Such monitor means generally incorporate sensors suitable for identifying the resultant force of the ground on landing gear of the rotorcraft. By way of example, for the range of rotorcraft sold by the Applicant, such a landed state of the rotorcraft thus corresponds to a measured force of several thousands of Newtons.

(12) As shown, and by way of example, such a control system 1 serves to modify a tilt angle of a plane P.sub.R of the rotor 2 relative to a drive plane P.sub.E that is perpendicular to a rotor shaft 7. The plane P.sub.R of the rotor 2 has a reference position P.sub.R0, and when the pilot actuates the control member 3 that can then cause the rotor 2 to tilt, enabling the rotorcraft to change direction and/or to modify its travel speed.

(13) As shown in FIG. 5, in a second embodiment, the control member 3 may be in the form of a stick or a mini-stick for controlling the cyclic pitch of the blades of the rotor.

(14) Nevertheless, in a first embodiment as shown in FIG. 2, the control member 13 may be suitable for controlling the collective pitch of a rotor. Under such circumstances, the control member 13 has a hinge 10 providing a projection 8 with one degree of freedom to move in rotation relative to a stand 16. Such a hinge 10 thus enables a free end 9 of the projection 8 to describe a movement in rotation through an angle relative to a zero force position of the control member 13, and in a plane that is substantially perpendicular to the plane on which the stand 16 is secured.

(15) In the first embodiment, the projection 8 may form a collective pitch lever for a rotor. Under such circumstances, the free end 9 of the projection 8 may move in two opposite directions along the same arc.

(16) As shown diagrammatically in FIG. 3, in a first scheme, the positions of the control member 13 can then correspond to the values for the angle a plotted along a horizontal abscissa axis representing variations in the angle of the control member 13 relative to the stand 16. Thus, as shown, over the entire stroke of the control member 13 it is then possible to define two position ranges P.sub.1 and P.sub.2 that are mutually distinct, i.e. that do not have any overlap.

(17) The first range P.sub.1 then lies between two first limit values .sub.1 and it includes a zero force position .sub.0 for the control member 13. The second range P.sub.2 in this embodiment is made up of two range portions arranged on either side of the first range P.sub.1. Each portion of the second range P.sub.2 then lies between a first limit value .sub.1 and a second limit value .sub.2. As shown, the control member 13 also has two physical abutments of positions .sub.B which, as shown, need not coincide with any of the first and second limit values.

(18) In contrast, in a second scheme as shown in FIG. 4, it is also possible to cause the physical abutments of the control member 13 to correspond with the first and second limit values for each position range.

(19) Specifically, one of the two first limit values .sub.11 of the first position range P.sub.11 may correspond with one of two physical position abutments .sub.B. Likewise, the second limit value .sub.12 of the second position range P.sub.12 may correspond with the other physical position abutments .sub.B.

(20) Furthermore, under such circumstances, the second range P.sub.12 is in a single piece, i.e. it is not subdivided into a plurality of portions arranged on either side of the first range P.sub.11 that incorporates a zero force position .sub.0 of the control member 13.

(21) As already mentioned above, and as shown in FIG. 5, the control system 11 may comprise a control member 23 for controlling the cyclic pitch of the blades of a rotorcraft rotor. Such a control member 23 then comprises a projection 18 that is movable in rotation relative to a stand 26 with two degrees of freedom. Such a projection 18 thus forms a stick or a mini-stick for controlling the cyclic pitch of the blades of a rotor.

(22) The axes of rotation of the hinge 20 thus lie in a plane xOy and they are mutually perpendicular. Such a projection 18 is thus free to pivot with two angles and representative of different positions of the control member 23 and of different paths followed by the free end 19 of the projection 18. Under such circumstances, the positions of the control member 23 can be defined by coordinates (, ). Consequently, a graphical representation of the positions of the control member 23 may, as shown in FIGS. 6 and 7, consist in areas with an abscissa axis representing angular variations of the control member and with an ordinate axis representing angular variations of the control member.

(23) Under such circumstances, the limit values of the positions of the control member and enabling at least two position ranges to be defined form conical bodies of revolution.

(24) Nevertheless, as shown in FIG. 6, it is more explicit to provide a graphical representation of the various positions of the control member 23 in the form of surfaces that are disjoint but juxtaposed, and representative of position ranges P.sub.21 and P.sub.22 of the member.

(25) Thus, as shown, the surface representative of the first range P.sub.21 is in the form of a disk of center of and of radius .sub.21 or .sub.21 corresponding to the first limit values for the positions of the control member 23 respectively along the axes and . Likewise, the surface representative of the second range P.sub.22 is in the form of a circular ring of center O and of radius lying between .sub.21 and .sub.22 corresponding respectively to the first limit value for the first range and the second limit value for the second range.

(26) Naturally, and as shown in FIG. 7, the first limit values .sub.31 and .sub.31 corresponding to two distinct axes need not necessarily be equal to each other. Consequently, the surface representative of the first range P.sub.31 may be in the form of an ellipse of center O. Under such circumstances, the first limit value .sub.31 is less than the first limit value .sub.21.

(27) Furthermore, the surface representative of the second area P.sub.32 is of any non-symmetrical shape when the center of its outline does not coincide with the center of the surface representative of the first range P.sub.31. In such a configuration, one of the first limit values a.sub.31 coincides with a second limit value .sub.32. Nevertheless, the other second limit value .sub.32 is greater than the opposite first limit value .sub.31. Furthermore, and as shown, this second limit value .sub.32 may coincide with the physical abutment of the control member 23.

(28) As shown in FIG. 7, the graphical representation of the various positions of the control member 23 may include a third surface that is disjoint from the first and second surfaces, this third surface thus being representative of a third position range P.sub.31 for the control member 23.

(29) As shown, and as above for the second surface, this third surface lies between a second limit value .sub.32 and a third limit value .sub.33 which, in this example, coincides with a physical abutment .sub.B.

(30) Such a surface is then crescent-shaped since it extends in only one direction along the axis and since the third limit values .sub.33 along the axis coincide with the second limit values .sub.32 of the second position range P.sub.32 of the control member 23.

(31) Furthermore, and as shown in FIG. 5, the control member 23 may include adjustment means 17 arranged at the free end 19 of the projection 18.

(32) Such adjustment means 17 then enable the anchor position of the control member to be adjusted with great accuracy. Such adjustment is generally formed using the pilot's thumb and it provides great control sensitivity.

(33) Naturally, the present invention may be subjected to numerous variations as to its implementation. Although several embodiments are described, it will readily be understood that it is not conceivable to identify exhaustively all 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 invention.