Rotorcraft autopilot system, components and methods

• US 9,586,681 B2
• Filed: 09/18/2015
• Issued: 03/07/2017
• 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
• Primary Examiner(s): Luo, David S
• Application Number:
  US14/858,080
• Publication Number:
  US 20160023758A1
• Time in Patent Office: 536 Days
• Field of Search: 318/3, 318/8, 318/34
• US Class Current: 1/1
• 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. 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.

2. 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.

3. The cyclic vibration isolator of claim 2 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.

4. The cyclic vibration isolator of claim 2 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.

5. The cyclic vibration isolator of claim 4 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.

6. The cyclic vibration isolator of claim 5 wherein the output arm supports a tuning weight on an opposite side of the pivot axis with respect to the output shaft.

7. The cyclic vibration isolator of claim 4 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.

8. 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.

9. The apparatus of claim 8 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.

10. The apparatus of claim 9 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.

11. The apparatus of claim 10 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.

12. The apparatus of claim 11 wherein the resilient member is a helical coil spring having first and second opposing ends.

13. The apparatus of claim 12 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.

14. The apparatus of claim 12 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.

15. 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.