Method of managing discontinuities in vehicle control following a control transition, and a vehicle

Abstract

A method during which a current position of a pilot control is determined, an equivalent position is determined that the pilot control needs to reach following a control transition in order to avoid modifying the actuator, and at least one mismatch is determined between the equivalent position and the current position. As from a transition, a target is determined for controlling the actuator by giving a corrected value to at least one position variable in a post-transition piloting relationship, the corrected value being determined as a function of the mismatch and of the current position of the pilot control. So long as the mismatch is not zero, the value of the mismatch in the relationship is reduced in proportion to the movement of the pilot control as the pilot control comes closer to the equivalent position.

Claims

1. A method of controlling an actuator acting on a control member of a vehicle, the actuator being controlled by a human-operable pilot control in application of a plurality of piloting relationships, each piloting relationship determining a target to be reached for controlling the actuator as a function of at least one position variable relating to a position of the pilot control relative to a neutral position, wherein the method comprises the following steps: determining a current position of the pilot control, the actuator being controlled by giving the current position to the at least one position variable of a first piloting relationship; determining an equivalent position that the pilot control needs to reach after a control transition in order to avoid modifying the actuator; determining at least one mismatch between the equivalent position and the current position; determining the presence of the control transition; from the control transition, determining a target for controlling the actuator by applying a post-transition piloting relationship, the target being determined by giving a corrected value to at least one position variable in the post-transition piloting relationship, the corrected value being determined as a function of the mismatch and of the current position of the pilot control; determining a movement of the pilot control; and so long as the mismatch is not zero, reducing the mismatch in proportion to the movement when the pilot control is moved towards the equivalent position.

2. A method according to claim 1, wherein the control transition corresponds to the transition between the first piloting relationship and a second piloting relationship, the first piloting relationship being applied before the control transition, the second piloting relationship being the post-transition piloting relationship that is applied as from the control transition.

3. A method according to claim 2, wherein the vehicle is an aircraft and the presence of a control transition is determined by determining a current flight stage of the aircraft, the first piloting relationship being applied during a first flight stage, and the second piloting relationship being applied during a second flight stage that is distinct from the first flight stage.

4. A method according to claim 2, wherein the control transition is determined by monitoring a selector unit that serves to determine the piloting relationship that is to be applied.

5. A method according to claim 2, wherein in order to determine the equivalent position, a theoretical position is determined that is to be reached by the pilot control in order to transmit a target in application of the second piloting relationship that is identical to a target generated in application of the first piloting relationship when the pilot control is in the current position.

6. A method according to claim 5, wherein the first piloting relationship and the second piloting relationship generate a target relating to the same parameter, and in order to determine the equivalent position the following steps are performed: determining the current target by applying the current position to at least one position variable of the first piloting relationship; and determining the theoretical position to be reached by the pilot control in order to generate the current target when applying the theoretical position to at least one position variable of the second piloting relationship, the equivalent position being equal to the theoretical position.

7. A method according to claim 5, wherein each piloting relationship is a function of at least one position variable and of at least one reference variable corresponding to the neutral position, the first piloting relationship generating a first target relating to a first parameter and the second piloting relationship generating a second target relating to a second parameter different from the first parameter, and in order to determine the equivalent position the following steps are performed: determining a second value of the second parameter to be reached at the moment of the control transition, referred to as the “corresponding” value; and giving the corresponding value to the reference variable, the neutral position representing the equivalent position.

8. A method according to claim 5, wherein each piloting relationship is a function of at least one position variable and of at least one reference variable corresponding to the neutral position, the first piloting relationship generating a first target relating to a first parameter and the second piloting relationship generating a second target relating to a second parameter different from the first parameter, and in order to determine the equivalent position the following steps are performed: determining a second value of the second parameter to be reached at the moment of the control transition, referred to as the “corresponding” value; weighting the corresponding value in order to determine a weighted value with a given weighting factor, the weighted value being equal to the product of the corresponding value multiplied by the weighting factor; and determining the equivalent position by giving the reference variable the weighted value in the second piloting relationship.

9. A method according to claim 1, wherein the pilot control is in a neutral position in the absence of a human exerting any force on the pilot control, the first piloting relationship being a function of at least one position variable and of a reference variable corresponding to the neutral position, the post-transition piloting relationship being the first piloting relationship, the control transition corresponding to a transition between a reference value referred to as a “first” reference value and a reference value referred to as a “second” reference value for the reference variable.

10. A method according to claim 9, wherein the control transition is determined by monitoring an adjustment unit that adjusts the reference variable.

11. A method according to claim 9, wherein the pilot control is in the neutral position in the absence of a human exerting force on the pilot control, the first piloting relationship is a function of at least one position variable and of at least one reference variable corresponding to the neutral position, and the equivalent position is the neutral position.

12. A method according to claim 1, wherein the target is an order transmitted to the actuator.

13. A method according to claim 1, wherein the target is transmitted to a piloting unit, the piloting unit applying at least one piloting relationship in order to transform the target into at least one control signal transmitted to the actuator.

14. A method according to claim 1, wherein at least one mismatch is equal to a difference between the equivalent position and the current position, the corrected value being equal to the sum of the current position of the pilot control plus the mismatch.

15. A method according to claim 1, wherein at least one mismatch is equal to a difference between the equivalent position and the current position, the corrected value being equal to the difference of the current position of the pilot control minus the mismatch.

16. A vehicle provided with at least one control member, the vehicle including at least one actuator acting on the control member, the vehicle having at least one pilot control for controlling an actuator in order to act on the control member, wherein the vehicle comprises: at least one sensor for measuring the position of the pilot control relative to a neutral position; a processor unit connected to each sensor, the processor unit having a memory storing a plurality of piloting relationships, each piloting relationship determining a target to be reached for controlling the actuator as a function of at least one position variable relating to a position of the pilot control relative to the neutral position, the processor unit having a computer for determining the target in application of the method according to claim 1.

17. A vehicle according to claim 16, wherein the vehicle includes a piloting unit connected to the processor unit and to the actuator, the piloting unit including the computer wherein the target is transmitted to the piloting unit, the piloting unit applying at least one piloting relationship in order to transform the target into at least one control signal transmitted to the actuator.

Description

BRIEF DESCRIPTION OF THE SEVERAL VIEWS OF THE DRAWINGS

(1) The invention and its advantages appear in greater detail in 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 vehicle of the invention, and in particular of a rotorcraft type aircraft;

(3) FIGS. 2 and 3 are diagrams explaining how to determine the current position of a pilot control;

(4) FIG. 4 is a logic diagram explaining the method of the invention;

(5) FIGS. 5 and 6 are diagrams showing two variants of a first implementation; and

(6) FIG. 7 is a diagram showing a second implementation.

DETAILED DESCRIPTION OF THE INVENTION

(7) Elements present in more than one of the figures are given the same references in each of them.

(8) FIG. 1 shows a vehicle 1 of the invention.

(9) The vehicle 1 has at least one control member 2 used for controlling the vehicle.

(10) In the example of FIG. 1, the vehicle 1 is a rotorcraft having at least one control member 2 of the blade 3 type. This blade 3 can pivot about at least one pivot axis 5 relative to a hub 4 or the equivalent.

(11) Nevertheless, the control member may comprise in non-exhaustive manner: a wheel, an aileron, a rudder, a flap.

(12) In order to move the control member, the vehicle has at least one actuator 10. In the example of FIG. 1, the actuator is a servo-control connected to a pitch control rod of a blade. By way of example, a set of conventional swashplates may be interposed between the servo-control and the blade. Reference may be made to the literature in order to obtain information about the control members of a rotorcraft and the associated actuators.

(13) Nevertheless, any type of actuator could be used, such as a piezoelectric actuator or a rotary actuator, for example.

(14) At least one actuator can be controlled by a pilot.

(15) Consequently, the vehicle has at least one pilot control 15 suitable for generating a control order that is transmitted to an actuator.

(16) The pilot control may control at least one actuator by mechanically transmitting an order to a processor unit 30. Nevertheless, the pilot control may transmit a signal that is electrical or optical, e.g. for the purpose of controlling at least one control member. Under such circumstances, the pilot control has at least one sensor 20 for determining the spatial position of the pilot control relative to a neutral reference position POS0.

(17) In the example of FIG. 1, the pilot control 15 is in its neutral reference position POS0.

(18) This pilot control 15 may comprise a stick 16 carried by a support 17. The stick extends in elevation along an elevation axis Z. In addition, the stick 16 may be moved in a volume that is conical. Consequently, the stick 16 is movable in pivoting about a longitudinal axis X and a transverse axis Y.

(19) Consequently, and with reference to FIG. 2, a first conventional movement sensor 21 may determine the position of the stick 16 relative to the transverse axis Y, by measuring a pivot angle β.

(20) Likewise, a second conventional movement sensor 22 may determine the position of the stick 16 relative to the longitudinal axis X, by measuring a pivot angle α.

(21) In the example of FIG. 3, the pilot control 15 may be a set of pedals 18. By way of example, the set of pedals 18 includes a bar 19 that is pivotable about a pivot axis 14. The pilot control then comprises, by way of example, a sensor for measuring the pivot angle θ of the bar relative to its neutral position that is drawn in continuous lines.

(22) This pilot control thus transmits at least one signal to a processor unit 30.

(23) The processor unit 30 is also connected to each sensor 20 for determining the current position of the pilot control. More precisely, the processor unit 30 is connected to each sensor directly, or indirectly via an intermediate unit. The processor unit may be of conventional type known as a primary flight control system.

(24) Furthermore, the processor unit includes a memory 31 serving in particular to store piloting relationships that are to be applied in order to generate a target. The memory 31 may comprise one or more storage units.

(25) Each stored piloting relationship determines a target as a function of at least one variable that is referred to as a “position” variable, the value of the position variable being determined by the spatial position of the pilot control.

(26) Furthermore, at least one piloting relationship may include a reference variable having a reference value that corresponds to the value that the position variable needs to reach when the pilot control is in its neutral position. By way of example and by way of illustration, a first piloting relationship may have the following form:
Obj=C1*(V1+V0)+C2
where “Obj” represents the target or “objective” as determined by the piloting relationship, “C1” and “C2” are constants, “V1” represents the position variable adjusted as a function of the position of the pilot control, “V0” represents the reference variable, “*” represents the multiplication sign, and “+” represents the addition sign.

(27) When the pilot control is in the neutral position, V1 is then equal to zero.

(28) The reference value of the reference variable V0 may also be modified by using an adjustment unit 50 that is connected to the processor unit 30. For example, this adjustment unit includes a button arranged on the corresponding pilot control. Nevertheless, it is possible to use any means that may be operated by touch, by voice, or by eye.

(29) This piloting relationship is given by way of illustration.

(30) In order to determine the target to be reached, the processor unit 30 includes a computer 32 that executes instructions stored in the memory 31. In particular, the computer determines the piloting relationship that is required, and inputs into this required piloting relationship the values of each of the position variables representing the current position of the pilot control.

(31) Such a computer may be a conventional computer. For example, the computer may comprise a processor, a microprocessor, a microcontroller, or indeed a logic circuit.

(32) In order to determine the required piloting relationship, the processor unit 30 may be connected to measurement instruments 70 of the vehicle. Such measurement instruments 70 may comprise conventional measurement means for measuring at least one speed of the vehicle, measurement means for measuring at least one force exerted on at least one part of landing gear, . . . . In particular, the measurement instruments 70 may include air speed measuring means (of the Pitot tube type, laser anemometer, . . . ), satellite positioning means (absolute position, ground speed), inertial measurement means for measuring the dynamic behavior of the vehicle (angular speeds, load factor).

(33) The processor unit 30 may also be connected to a selector unit 60 suitable for determining the piloting relationship to be applied. For example, the selector unit may comprise a rotary knob. Nevertheless, it is possible to use any means operated by touch, by voice, or indeed by eye.

(34) The target determined by a piloting relationship serves to control an actuator 10 in order to control the vehicle. This target may be a control signal that can be used directly by an actuator 10. Under such circumstances, the processor unit is connected directly to the actuator via a connection 80 shown in dashed lines.

(35) Nevertheless, the target may be of a kind that cannot be used by an actuator. For example, the target may be a ground speed value to be reached. In order to reach this ground speed, several control members may need to be moved by a plurality of actuators.

(36) Under such circumstances, the processor unit is connected to a piloting unit 40 that is interposed between the actuators 10 and the processor unit 30. The processor unit 30 and the piloting unit 40 may possibly comprise the same unit within a single piece of equipment.

(37) The piloting unit 40 may include a memory 41 and a computer subassembly 42. The computer subassembly 42 then executes instructions that may for example be stored in the memory 41 for the purpose of determining setpoints to be transmitted to at least one actuator 10 in order to reach the target transmitted by the processor unit. For example, the memory contains relationships providing setpoints for transmitting to said actuators as a function of the received target.

(38) FIG. 4 explains the method implemented by the invention.

(39) During a first step STP1, the current position of a pilot control is transmitted to the processor unit, with at least one actuator being controlled by giving the value of at least one parameter representing said current position to at least one position variable of a first piloting relationship.

(40) Returning to the above example, the first piloting relationship is of the form:
Obj=C1*(V1+V0)+C2
A sensor acts, by way of example, to measure the pivoting of a portion of a pilot control about an axis relative to its neutral position. The processor unit receives a signal representing the measured angle. The processor unit then gives the measured angle value to the position variable V1 in order to determine the target Obj to be reached.

(41) The target Obj is then transmitted directly or indirectly to at least one actuator 10.

(42) In parallel, during a second step STP2, an equivalent position of the pilot control is determined, e.g. by determining the value of each position variable representing said equivalent position in the piloting relationship in question. This equivalent position represents the theoretical position that the pilot control 15 needs to reach as a result of a control transition in order to avoid requesting action from the actuators 10 at the moment of control transition.

(43) The processor unit then determines the piloting relationship to be applied at the moment of a future control transition. This piloting relationship is referred to as the “post-transition” positioning relationship.

(44) By way of example, a control transition may lead to a second piloting relationship being applied having the form:
Obj=C1′*(V1′+V0′)+C2′
where “Obj” represents the target determined by the second piloting relationship, “C1′” and “C2′” represent constants, “V1′” represents the position variable adjusted as a function of the position of the pilot control, “V0′” represents said reference variable, “*” represents the multiplication sign, and “+” represents the addition sign.

(45) In this example, the first piloting relationship and the second piloting relationship generate the same target Obj.

(46) By way of illustration, the first piloting relationship and the second piloting relationship generate a pitching attitude target for the aircraft, the value of this target nevertheless being calculated in application of two different relationships. For example, the first piloting relationship generates a pitching attitude for taking account of a setpoint ground speed, while the second piloting relationship generates a pitching setpoint target for maintaining a setpoint air speed.

(47) The processor unit then determines the position variable value V1′ that is to be reached in order to avoid modifying the target. This position variable value V1′ represents the equivalent position that needs to be reached by the pilot control in order to avoid leading to a modification of the actuators at the moment of transition.

(48) During a step STP3, at least one mismatch between said equivalent position and said current position is determined. For example, a mismatch is determined for each position variable representing the position of a pilot control in a piloting relationship under consideration.

(49) In a first alternative, a mismatch is equal to a difference between the equivalent position and the current position. For example, the mismatch is equal to a difference between the value of a position variable representing the equivalent position and the value of the same position variable representing the current position, i.e. V1′−V1 in the above example.

(50) In a second alternative, a mismatch is equal to a difference between the current position and the equivalent position. For example, the mismatch is equal to a difference between the value of a position variable representing the current position and the value of the same position variable representing the equivalent position, i.e. V1−V1′ in the above example.

(51) During a fourth step STP4, equipment of the vehicle determines whether a control transition is to be applied.

(52) A control transition may take place when the first piloting relationship needs to be replaced by a second piloting relationship.

(53) This change in the piloting relationship that is to be applied may be requested by a pilot operating the selector unit 60. Thus, a transition may be implemented as a result of the selector unit 60 being operated.

(54) In another possibility that is applicable to an aircraft, the piloting relationships are associated with stages of flight. For example, one piloting relationship is applied during one stage of flight, and another piloting relationship is applied during another stage of flight.

(55) Under such circumstances, the processor unit uses the measurement instruments 70 to determine the current stage of flight and the piloting relationship that is to be applied.

(56) A control transition may also occur by modifying the reference value of a reference variable representing a pilot control in its neutral position.

(57) The processor unit thus monitors the adjustment unit 50 in order to determine whether a pilot is requesting such a modification.

(58) Consequently, the processor unit is in communication with numerous members for determining the presence of a control transition, i.e. the presence of events that ought to induce the control transition.

(59) If a control transition is requested, the target in use for controlling at least one actuator is determined by applying a piloting relationship referred to as the “post-transition” piloting relationship.

(60) Depending on the situation, the post-transition piloting relationship may be a second piloting relationship that is distinct from the previously-used first piloting relationship, or it may be the previously-used first piloting relationship but with at least one reference variable that has been changed.

(61) Nevertheless, each position value input into the post-transition piloting relationship is corrected as a function of the corresponding mismatch. The corrected value input into the post-transition piloting relationship is thus determined as a function of a mismatch and of the current position of the pilot control.

(62) In a first preceding alternative, the corrected value of a position variable is equal to the sum of the value of the position variable representing the current position of the pilot control plus the corresponding mismatch.

(63) In a second preceding alternative, the corrected value of a position variable is equal to the difference of the value of the position variable representing the current position of the pilot control minus the corresponding mismatch.

(64) In addition, the processor unit uses conventional methods to determine whether a pilot moves the pilot, for example it may use a summing method.

(65) If the pilot brings the pilot control towards the equivalent position, and so long as said mismatch is not zero, then the processor unit reduces the value of this mismatch in proportion with the movement of the pilot control.

(66) The position variable is no longer corrected when the mismatch becomes zero.

(67) FIGS. 5 and 6 show two variants of a first implementation. In order to illustrate the invention, consideration is given to a first piloting relationship applied before the transition that has the simple form as described above, i.e.:
Obj=C1*(V1+V0)+C2

(68) In FIG. 5, the processor unit manages a control transition from a first piloting relationship to a second piloting relationship, both relationships providing a target relating to the same parameter, said first piloting relationship being applied before said control transition and said second piloting relationship being said post-transition piloting relationship that is applied as from the transition. The second piloting relationship may then for example have the following form:
Obj=C1′*(V1′+V0′)+C2′

(69) Before the transition, the pilot control is in a first position POSINI. The target is then determined by giving the value of the pivot angle β1 to the position variable V1.

(70) Furthermore, the processor unit determines the equivalent position POSEQUI by determining that the position variable V1′ of the second piloting relationship needs to reach a pivot angle of value β2 in order to enable the first piloting relationship and the second piloting relationship to generate the same target.

(71) The processor unit deduces therefrom a mismatch DIFF between the current position and the theoretical position.

(72) When the transition from the first piloting relationship to the second piloting relationship is requested, the processor unit implements the second piloting relationship.

(73) The processor unit then gives a corrected value to the position variable V1′ of the second piloting relationship.

(74) Thus, depending on the alternative being applied, the processor unit considers that the value of the position variable V1′ is equal:

(75) to the sum of the current value β1 of the position variable plus the mismatch DIFF, i.e.:
V1′=β1+DIFF=β2
or

(76) to the difference between the current value β1 of the position variable minus the mismatch DIFF, i.e.:
V1′=β1−DIFF=β2

(77) In addition, the value of the mismatch DIFF decreases when the pilot control comes closer to the equivalent position POSEQUI. For example, if the pilot control is tilted through an angle of 2° towards the equivalent position, the mismatch DIFF is indeed reduced by this angle of 2°.

(78) In FIG. 6, the processor unit manages a control transition from a first piloting relationship to a second piloting relationship, each supplying respective targets, one relating to a first parameter and the other to a second parameter, which parameters are different.

(79) By way of example, the second piloting relationship may then have the following form:
Obj′=C1′*(V1′+V0′)+C2′

(80) Before the transition, the pilot control is in the first position POSINI. The target Obj is then determined by giving the value of the angle β3 to the position variable V1 in the first piloting relationship. For example, this target relates to a first parameter concerning ground speed.

(81) The second piloting relationship may then for example have the following form:
Obj′=C1′*(V1′+V0′)+C2′
The target Obj′ determined by the second piloting relationship may then for example be a target relating to indicated air speed.

(82) In the method of the invention, the current value is determined for the second parameter that is referred to as the “corresponding” value, i.e. for the current indicated air speed in this example. By way of example, the processor unit may make use of the measurement instruments 70 in order to determine this current value of the second parameter involved in the second piloting relationship. Alternatively, the corresponding value may be estimated.

(83) The processor unit then gives the corresponding value to the reference variable V0′ of the second piloting relationship, said neutral position representing said equivalent position.

(84) Furthermore, the processor unit considers that the equivalent position POSEQUI for the pilot control is the neutral position POS0.

(85) The processor unit deduces therefrom a mismatch DIFF between the current position and the theoretical position.

(86) When the transition from the first piloting relationship to the second piloting relationship is requested, the processor unit implements the second piloting relationship.

(87) The processor unit then applies a corrected value to the position variable V1′ of the second piloting relationship.

(88) Thus, depending on the alternative being applied, the processor unit considers that the position variable V1′ is equal:

(89) to the sum of the current value β3 of the position variable plus the mismatch DIFF, i.e.:
V1′=β3+DIFF
or

(90) to the difference of the current value β3 of the position variable minus the mismatch DIFF, i.e.:
V1′=β3−DIFF

(91) In addition, the value DIFF of the mismatch decreases as the pilot control comes closer to the equivalent position POSEQUI.

(92) In FIG. 7, the processor unit manages a control transition resulting from modifying the reference value of a reference variable of the first piloting relationship. The first piloting relationship then uses a reference variable that is equal to a first reference value before the transition, and that is equal to a second reference value after the transition.

(93) Before the transition, the pilot control is in the first position POSINI. The target Obj is then determined by giving the value of the angle β4 to the position variable V1 in the first piloting relationship, and by giving a first reference value V11 to the reference variable V1. Under such circumstances, the target Obj is determined by the following relationship:
Obj=C1*(β4+V11)+C2

(94) The target Obj′ determined by the second piloting relationship may for example be an indicated air speed target.

(95) By way of example, the pilot operates the adjustment unit 50 in order to indicate that the target reached referred to as the “reference” target needs to be the target when the pilot control is in the neutral position.

(96) Under such circumstances, the processor unit determines the second reference value V12 that is to be reached by the reference variable when the pilot control is in its zero position. In the example described, this second reference value is then equal to:
V12=(Obj−C2)/C1

(97) Furthermore, the processor unit considers that the equivalent position POSEQUI of the pilot control is the neutral position POS0. The processor unit deduces therefrom a mismatch DIFF between the current position and the theoretical position.

(98) After the transition, the processor unit modifies the first piloting relationship by giving the second reference value V12 to the reference variable, i.e.:
Obj=C1*(V1+V12)+C2

(99) The processor unit then gives the corrected value to the position variable V1 of the second piloting relationship.

(100) Furthermore, depending on the alternative that is being applied, the processor unit considers that the position variable V1 is equal:

(101) to the sum of the current value β4 of the position variable plus the mismatch DIFF, i.e.:
V1=β4+DIFF
or

(102) to the difference of the current value β3 of the position variable minus the mismatch DIFF, i.e.:
V1=β4−DIFF

(103) In addition, the mismatch value DIFF decreases as the pilot control comes closer to the equivalent position POSEQUI.

(104) Naturally, the present invention may be subjected to numerous variants as to its implementation. Although several embodiments are described above, 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.