Rotorcraft autopilot and methods

• US 9,272,780 B2
• Filed: 02/08/2013
• Issued: 03/01/2016
• Est. Priority Date: 02/10/2012
• Status: Active Grant

• Current Assignee: Merlin Technologies Incorporated
• Original Assignee: Merlin Technologies Incorporated
• Inventors: Mercer, John E., Albion, Nicolas, Bartel, Mark, Feifel, Marc, Marvin, Mark
• Primary Examiner(s): Marc-Coleman, Marthe
• Application Number:
  US13/763,574
• Publication Number:
  US 20140027564A1
• Time in Patent Office: 1,117 Days
• Field of Search: 701/11, 701/12, 701/3, 244/17.13, 244/118.5, 244/75.1, 244/175, 244/183, 244/177, 244/182
• US Class Current: 1/1
• CPC Class Codes: B64C 13/0421 control sticks for primary flight controls
• CPC Class Codes: B64C 13/044 operated by feet, e.g. pedals
• CPC Class Codes: B64C 13/18 using automatic pilot
• CPC Class Codes: B64C 13/341 having duplication or stand-by provisions
• CPC Class Codes: B64C 27/56 characterised by the control initiating means, e.g. manually actuated
• 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: B64C 27/59 mechanical
• CPC Class Codes: B64C 27/64 using fluid pressure, e.g. having fluid power amplification
• CPC Class Codes: B64C 27/68 using electrical energy, e.g. having electrical power amplification
• CPC Class Codes: G05D 1/0077 using redundant signals or controls
• CPC Class Codes: G05D 1/0816 to ensure stability
• CPC Class Codes: G05D 1/0858 specially adapted for vertical take-off of aircraft
• CPC Class Codes: G05D 1/102 specially adapted for vertical take-off of aircraft
• CPC Class Codes: Y02T 50/40 Weight reduction

Abstract

A helicopter autopilot system includes an inner loop for attitude hold for the flight of the helicopter including a given level of redundancy applied to the inner loop. An outer loop is configured for providing a navigation function with respect to the flight of the helicopter including a different level of redundancy than the inner loop. An actuator provides a braking force on a linkage that serves to stabilize the flight of the helicopter during a power failure. The actuator is electromechanical and receives electrical drive signals to provide automatic flight control of the helicopter without requiring a hydraulic assistance system in the helicopter. The autopilot can operate the helicopter in a failed mode of the hydraulic assistance system. A number of flight modes are described with associated sensor inputs including rate based and true attitude modes.

Claims

1. An autopilot system for a helicopter, said autopilot system comprising:

an inner loop that is configured at least for providing a true attitude estimate for the flight of the helicopter including a given level of redundancy applied to the inner loop; and

an outer, autopilot loop that is configured for providing at least one navigation function with respect to the flight of the helicopter including a different level of redundancy than the inner loop.

2. The autopilot system of claim 1 wherein said different level of redundancy for the inner loop is greater than the given level of redundancy for the outer inner loop.

3. The autopilot system of claim 2 wherein the inner loop is configured with triplex processors for triple redundancy in the inner loop.

4. The autopilot system of claim 3 wherein the inner loop is further configured such that the triplex processors each simultaneously generate a motor control signal.

5. The autopilot system of claim 4 wherein the inner loop is configured to receive a control command from the outer loop on each iteration of the inner loop as part of generating the motor control signal of each triplex processor.

6. The autopilot system of claim 5 wherein the outer loop is configured to perform one-for-one iteration with the inner loop.

7. The autopilot system of claim 4 wherein each triplex processor is configured to compare the motor control signal that is generated by that triplex processor to the motor control signal that is generated by each of the other two triplex processors and, based on the comparison, to cast a first vote for or against a first one of the other two triplex processors and a second vote for or against a second one of the other two triplex processors.

8. The autopilot system of claim 7 wherein first and second given ones of the triplex processors are each in control communication with at least one actuator motor and a third triplex processor generates said motor control signal and casts said votes but the third triplex processor is not in control communication with an actuator motor.

9. The autopilot system of claim 7 including a voting manager that disables motor control signal influence for any particular one of the triplex processors when the votes of both of the other two triplex processors are against the particular triplex processor to indicate a failure thereof.

10. The autopilot system of claim 9 wherein the inner loop and the outer loop remain fully operational responsive to a failure of a single one of the triplex processors.

11. The autopilot system of claim 4 including a pitch actuator and a roll actuator for applying pitch actuations and roll actuations, respectively, to a control linkage of the helicopter and each of which actuators includes a redundant electric motor set at least including a first motor and a second motor, and a first triplex processor generates first processor motor control signals to control the first motor of the pitch actuator and the first motor of the roll actuator and a second triplex processor generates second processor motor control signals that control the second motor of the pitch actuator and the second motor of the roll actuator.

12. The autopilot system of claim 11 wherein the pitch actuator and the roll actuator each include an output shaft and are each configured such that either one of the first and second motor and/or both of the first motor and second motor of a given one of the actuators can rotate a given output shaft of the given actuator to provide control linkage actuations.

13. The autopilot system of claim 1 wherein the inner loop is configured with triplex processors for triple redundancy in the inner loop and further comprising a set of triplex sensor suites such that each triplex processor reads one of the sensor suites that is dedicated to that triplex processor to produce sensor data.

14. The autopilot system of claim 13 wherein each triplex processor is configured to share the sensor data from a dedicated one of the sensor suites with the other two triplex processors.

15. The autopilot system of claim 14 wherein each triplex processor is configured to determine a median set of sensor data based on the sensor data from all of the triplex processors and to determine said motor control signal based on the median set of sensor data.

16. The autopilot system of claim 15 wherein each triplex processor is configured to reject any erroneous sensor data.

17. The autopilot system of claim 16 wherein each triplex processor is configured to identify the erroneous sensor data based, at least in part, on a comparison of three sensor outputs with each sensor output produced by a given sensor of each one of the sensor suites.

18. The autopilot system of claim 1 wherein the outer loop is configured to operate based on a set of control laws for a particular helicopter.

19. The autopilot system of claim 1 wherein said helicopter includes a cyclic control and wherein the system further comprises an actuator arrangement for actuating the cyclic control to provide said attitude hold and said navigation function.

20. In an autopilot system for a helicopter, a method comprising:

configuring an inner loop to at least for providing attitude hold for the flight of the helicopter including a given level of redundancy applied to the inner loop and an outer, autopilot loop to provide at least one navigation function with respect to the flight of the helicopter including a different level of redundancy than the inner loop.

21. An autopilot system for a helicopter, said helicopter including a GPS unit that provides a GPS output, said autopilot system comprising:

a sensor arrangement that is dedicated to the autopilot and that produces a set of sensor outputs to characterize the flight of the helicopter;

a control arrangement that receives the GPS output and the sensor outputs and generates electrical drive signals in response thereto, said control arrangement including an outer control loop that is configured to provide at least one navigation function with respect to the flight of the helicopter and an inner control loop that is configured at least for providing attitude hold for the flight of the helicopter, said inner loop including a set of three triplex processors to provide triple redundancy in the generation of said electrical drive signals with each triplex processor generating roll control signals and pitch control signals; and

an actuator that is electromechanical and receives said electrical drive signals to generate mechanical control outputs responsive thereto that are mechanically coupled to the helicopter to provide automatic flight control of the helicopter without requiring a hydraulic system in the helicopter.

22. The autopilot system of claim 21 wherein said actuator couples the control outputs to a cyclic control of the helicopter in parallel with any pilot actuations that are applied to the cyclic control.

23. The autopilot system of claim 21 wherein a first one and a second one of the triplex processors issue roll control signals to a roll actuator and issue pitch control signals to a pitch actuator and a third triplex processor does not provide roll control and pitch control signals to an actuator.

24. The autopilot system of claim 21 wherein the inner loop is further configured such that the triplex processors each simultaneously generate at least one motor control signal.

25. The autopilot system of claim 24 wherein the inner loop is configured to receive a control command from the outer loop on each iteration of the inner loop as part of generating the motor control signal of each triplex processor.

26. The autopilot system of claim 25 wherein the outer loop is configured to perform one-for-one iteration with the inner loop.

27. The autopilot system of claim 24 including a pitch actuator and a roll actuator for applying pitch actuations and roll actuations, respectively, to a control linkage of the helicopter and each of which actuators includes a redundant electric motor set including a first motor and a second motor and the first triplex processor generates first processor motor control signals to control the first motor of the pitch actuator and the first motor of the roll actuator and the second triplex processor generates second processor motor control signals that control the second motor of the pitch actuator and the second motor of the roll actuator.

28. The autopilot system of claim 27 wherein the pitch actuator and the roll actuator each include an output shaft and are each configured such that either one of the first and second motor and/or both of the first motor and second motor of a given one of the actuators can rotate a given output shaft of the given actuator to provide control linkage actuations.

29. The autopilot system of claim 28 wherein the output shaft of each of the pitch actuator and the roll actuator can provide at least 300 pounds of force to the control linkage of the helicopter.

30. The autopilot system of claim 21 wherein said helicopter includes a cyclic control and wherein said actuator provides mechanical inputs to actuate the cyclic control.