ROTORCRAFT AUTOPILOT SYSTEM, COMPONENTS AND METHODS

• US 20140027566A1
• Filed: 02/08/2013
• Published: 01/30/2014
• Est. Priority Date: 02/10/2012
• Status: Active Grant

• Current Assignee: Merlin Technologies Incorporated
• Original Assignee: Merlin Technologies Incorporated
• Inventors: Mercer, John E., Feifel, Marc, Marvin, Mark, Albion, Nicolas
• Granted Patent: US 9,150,308 B2
• Time in Patent Office: Days
• US Class Current: 244/17.13
• CPC Class Codes: B64C 13/04 actuated personally
• CPC Class Codes: B64C 13/0421 control sticks for primary flight controls
• CPC Class Codes: B64C 13/18 using automatic pilot
• CPC Class Codes: B64C 13/30 using cable, chain, or rod mechanisms
• CPC Class Codes: B64C 13/343 overriding of personal controls; with automatic return to inoperative position
• CPC Class Codes: B64C 27/57 automatic or condition responsive, e.g. responsive to rotor speed, torque or thrust
• CPC Class Codes: B64C 27/58 Transmitting means, e.g. interrelated with initiating means or means acting on blades means acting on blades B64C27/72
• CPC Class Codes: F16F 15/121 using springs as elastic members, e.g. metallic springs F16F15/133 takes precedence
• CPC Class Codes: Y02T 50/40 Weight reduction

Abstract

An autopilot actuator includes first and second motors each including a rotatable motor output shaft such that either one or both of the motors can drive an actuator output shaft. An autopilot main unit enclosure is removably mounted to the helicopter proximate to a cyclic control and commonly houses autopilot actuators as well as main autopilot electronics. A cyclic vibration isolator is removably supported by an actuator shaft for co-rotation and coupled to the cyclic control to attenuate a cyclic vibration frequency at the actuator shaft while output rotations of the actuator shaft below a resonant frequency are coupled to the cyclic control. A force limited link includes first and second ends and a variable length between. The force limited link having a relaxed length when less than an unseating force is applied and the variable length changes when an applied force exceeds the unseating force to permit pilot override.

Claims

1. As part of an autopilot for providing automatic control of a helicopter by actuating one or more flight controls, an actuator comprising:

a redundant pair of first and second motors each including a rotatable motor output shaft; and

a gear arrangement including an actuator output shaft for operative coupling to said flight controls and configured to engage the output shaft of each one of the first and second motors for operation at least in (i) a first mode in which both the first and second motors contribute to rotation of the actuator output shaft, (ii) a second mode in which first motor rotates the actuator output shaft due to a failure of the second motor and (iii) a third mode in which the second motor rotates the output shaft due to a failure of the first motor.

2. The actuator of claim 1 wherein the first and second motors are electric motors.

3. The actuator of claim 1 wherein the motor output shaft of each of the motors drives a common input gear of the gear arrangement.

4. The actuator of claim 3 wherein a failure of one of the first and second motors causes the other one of the motors to drive the common input gear and thereby the motor output shaft of the other, failed motor.

5. The actuator of claim 1 including a clutch arrangement that is inserted in the gear arrangement at an intermediate position to selectively and simultaneously disable both of the first and second motors from rotating the actuator output shaft.

6. The actuator of claim 1 wherein said motors cooperate with the gear arrangement to provide an available output force of at least 300 pounds.

7. The actuator of claim 1 wherein the gear arrangement provides a gear ratio of approximately 1720:

1.

8. An actuator control arrangement, comprising:

the actuator of claim 1 wherein each of the first and second motors is a brushless DC motor that includes an arrangement of Hall sensors that generate Hall output signals that are indicative of a current position of the motor output shaft responsive to rotation; and

an actuator controller that is configured to receive the Hall output signals and to resolve the current position of each motor output shaft, and thereby the actuator output shaft, based on the Hall output signals.

9. The actuator control arrangement of claim 8 wherein the position of the actuator output shaft of the gear arrangement is detectable to a resolution of approximately 0.017 degrees based on the Hall output signals.

10. An autopilot system for a helicopter, comprising:

an autopilot display unit that is mounted in an instrument console of the helicopter at least for displaying autopilot flight data to a pilot of the helicopter;

an autopilot main unit enclosure that is removably mounted to the helicopter proximate to a cyclic control of the helicopter and which defines a main unit interior;

a set of actuators supported within the main unit interior including a pitch actuator having a pitch actuator output shaft and a roll actuator having a roll actuator output shaft such that no more than the pitch actuator shaft and the roll actuator shaft of the set of actuators extend at least partially outward from said autopilot main unit enclosure for providing mechanical control forces to the cyclic control of the helicopter; and

a main unit electronics section supported within said main unit interior and in electrical communication with said autopilot display unit and with said set of actuators for providing electrical control signals to the actuators such that the main unit electronics section and the set of actuators are commonly housed within the main unit interior.

11. The autopilot system of claim 10 wherein the main unit enclosure is L-shaped in a plan view.

12. The autopilot system of claim 11 wherein the main unit enclosure is configured for removable attachment to a pair of existing bulkheads of the helicopter without supplemental reinforcement of the existing bulkheads.

13. The autopilot system of claim 11 wherein the pitch actuator and the roll actuator are supported at opposing ends of the L-shape within the main unit interior.

14. The autopilot system of claim 10 wherein each actuator includes an actuator housing having an upper housing wall and a lower housing wall and the main unit enclosure includes an upper cover and a lower cover such that the actuator housing is supported in the main unit interior with the upper housing wall received against the upper cover and the lower housing wall received against the lower cover.

15. The autopilot system of claim 14 wherein each actuator housing includes a front housing wall and the actuator housing is supported in the main unit interior with the front housing wall received against a sidewall of the main unit enclosure which sidewall extends between the upper cover and the lower cover.

16. The autopilot system of claim 14 wherein the upper cover and the lower cover are each L-shaped.

17. The autopilot system of claim 14 wherein the upper housing wall of each actuator is removably attached to the upper cover and the lower housing wall of each actuator is removably attached to the lower cover.

18. The autopilot system of claim 14 wherein the main unit enclosure includes a first sidewall and a second sidewall each of which sidewalls maintain the upper cover and lower cover in a spaced apart relationship and the pitch actuator shaft extends through the first sidewall while the roll actuator shaft extends through the second sidewall.

19. The autopilot system of claim 18 wherein the main unit enclosure is configured for removable attachment to a pair of existing bulkheads of the helicopter without supplemental reinforcement of the existing bulkheads and the pitch actuator shaft extends through a first one of the bulkheads while the roll actuator shaft extends through a second one of the bulkheads.

20. The autopilot system of claim 10 wherein the main unit electronics section includes an inner loop that is configured to control at least approximately instantaneous attitude of the helicopter.

21. The autopilot system of claim 20 wherein the autopilot display unit includes an outer loop that is configured to issue navigation commands to the inner loop of the main unit electronics section.

22. In an autopilot system that is configured for automated control of a helicopter by actuating a cyclic control of the helicopter which cyclic control is subject to a cyclic vibration frequency responsive to rotation of a rotor of the helicopter, an apparatus comprising:

a cyclic vibration isolator that is removably supported by said actuator shaft for co-rotation therewith and coupled to the cyclic control of the helicopter to exhibit a resonant frequency that is at least approximately matched to the cyclic vibration frequency for movement of the cyclic control relative to the actuator shaft such that the cyclic vibration frequency is attenuated at the actuator shaft and output rotations of the actuator shaft below the resonant frequency are coupled to the cyclic control.

23. In an autopilot system that is configured for automated control of a helicopter by actuating a cyclic control of the helicopter which cyclic control is subject to a cyclic vibration responsive to rotation of a rotor of the helicopter, a cyclic vibration isolator comprising:

a control arm that is removably attached to the actuator shaft to support the cyclic vibration isolator such that the control arm co-rotates with the actuator shaft;

an output arm that is coupled to the cyclic control of the helicopter and therefore subject to said cyclic vibration; and

a resilient arrangement that is captured between the control arm and the output arm such that the output arm oscillates responsive to the cyclic vibration and relative to the control arm to mechanically isolate the actuator shaft from the cyclic vibration while transferring rotational actuation motions of the actuator shaft to the output arm to thereby transfer the rotational actuation motions to the cyclic control for autopilot actuation of the cyclic control.

24. The cyclic vibration isolator of claim 23 wherein the control arm, the output arm and the resilient arrangement are configured to cooperate such that the output arm oscillates at a resonant frequency that is at least approximately equal to a cyclic vibration frequency of the cyclic vibration.

25. The cyclic vibration isolator of claim 23 wherein the output arm pivots about a pivot axis that is defined by the control arm and the pivot axis is spaced apart from the actuator shaft.

26. The cyclic vibration isolator of claim 25 wherein the output arm supports an output shaft that is coupled to the cyclic control and the output shaft is on an opposite side of the pivot axis with respect to the resilient arrangement.

27. The cyclic vibration isolator of claim 26 wherein the output arm supports a tuning weight on an opposite side of the pivot axis with respect to the output shaft.

28. The cyclic vibration isolator of claim 25 wherein the output arm includes an output shaft that is coupled to the cyclic control and the output shaft is on an opposite side of the actuator shaft with respect to a position at which the resilient arrangement contacts the control arm.

29. In an autopilot system that is configured for automated control of a helicopter by driving an actuator having an actuator shaft to actuate a cyclic control of the helicopter, an apparatus comprising:

a force limited link having a first end, a second end and a variable length therebetween oriented along an elongation axis with the first end coupled to the actuator shaft and the second end coupled to the cyclic control, said force limited link having a relaxed length as the variable length between the first and second ends when less than an unseating force is applied to the first and second ends along said elongation axis to provide compliant movement of the cyclic control responsive to the actuator and configured such that the variable length changes from the relaxed length responsive to an external force that is applied to the first and second ends along the elongation axis which is equal to or greater than the unseating force to provide for a pilot override of actuator cyclic control.

30. The apparatus of claim 29 wherein the variable length decreases from the relaxed length responsive to the external force being applied in compression along the elongation axis and the variable length increases from the relaxed length responsive to the external force being applied in tension along the elongation axis.

31. The apparatus of claim 30 wherein the first end is supported by a housing that defines a housing interior and an extension shaft is supported to extend outward from the housing interior and for movement along the elongation axis and a distal end of the extension shaft supports the second end.

32. The apparatus of claim 31 wherein the housing interior receives a resilient member that is in a minimum compressed condition for said relaxed length and responsive to movement changing the relaxed length the resilient member is subjected to an additional compression.

33. The apparatus of claim 32 wherein the resilient member is a helical coil spring having first and second opposing ends.

34. The apparatus of claim 33 wherein the helical coil spring is supported such that the first end of the spring moves toward the second end of the spring when the variable length is extended beyond the relaxed length such that the spring is displaced toward the second end of the force limited link.

35. The apparatus of claim 33 wherein the helical coil spring is supported such that the second end of the spring moves toward the first end of the spring when the variable length is reduced to less than the relaxed length such that the spring is displaced toward the first end of the force limited link.

36. In an autopilot system that is configured for automated control of a helicopter by providing electrical command signals to an actuator to actuate a cyclic control of the helicopter which cyclic control is subject to a cyclic vibration responsive to rotation of a rotor of the helicopter, an autopilot linkage comprising:

a force limited link to provide a pilot override of cyclic control by said actuator, said force limited link having a first end, a second end and a variable length therebetween oriented along an elongation axis with the first end coupled to the cyclic control, said force limited link having a relaxed length as the variable length between the first and second ends when less than an unseating force is applied to the first and second ends along said elongation axis to provide compliant movement of the second end with the first end and configured such that the variable length changes from the relaxed length responsive to an external force that is applied to the first and second ends along the elongation axis which is equal to or greater than the unseating force for said pilot override; and

a cyclic vibration isolator that is removably supported by said actuator shaft for co-rotation therewith and connected to the second end of the force limited link such that said cyclic vibration is coupled to the cyclic vibration isolator by the force limited link and the cyclic vibration isolator is configured to exhibit a resonant frequency that is at least approximately matched to a cyclic vibration frequency of the cyclic vibration to allow movement of the second end of the force limited link relative to the actuator shaft at the cyclic vibration frequency while isolating the actuator shaft from the cyclic vibration frequency and for transferring output rotations of the actuator shaft below the resonant frequency to the force limited link for transfer to the cyclic control.