ALTITUDE AND ACCELERATION COMMAND ALTITUDE HOLD ALGORITHM FOR ROTORCRAFT WITH LARGE CENTER OF GRAVITY RANGE

• US 20080249672A1
• Filed: 04/03/2007
• Published: 10/09/2008
• Est. Priority Date: 04/03/2007
• Status: Active Grant

• Current Assignee: Sikorsky Aircraft Corporation (Martin Marietta Corporation)
• Original Assignee: Sikorsky Aircraft Corporation (Martin Marietta Corporation)
• Inventors: Cherepinsky, Igor
• Granted Patent: US 8,694,182 B2
• Time in Patent Office: Days
• US Class Current: 701/7
• CPC Class Codes: B64C 19/00 Aircraft control not otherwise provided for
• CPC Class Codes: G05D 1/0858 specially adapted for vertical take-off of aircraft

Abstract

A flight control system includes an Acceleration and Attitude Command/Velocity Hold mode (AACVH) algorithm which blends attitude commands with acceleration commands. This blending determines a trim attitude for a given rotorcraft flight condition.

Claims

1. A flight control system for a rotary wing rotorcraft comprising:

a cyclic controller; and

an Attitude and Acceleration Command/Velocity Hold algorithm in communication with said cyclic controller to blend an attitude command with an acceleration command to determine a trim attitude for a given rotorcraft flight condition such that said collective controller returns to neutral.

2. The system as recited in claim 1, wherein said trim attitude is defined as an attitude where first derivatives of the primary velocity state and primary attitude sate are zero.

3. The system as recited in claim 1, wherein said given flight condition includes a hover flight condition.

4. The system as recited in claim 1, wherein said trim attitude is defined as an attitude where first derivatives of the primary velocity state and primary attitude sate are zero.

5. The system as recited in claim 1, further comprising a measured rotorcraft attitude and a measured rotorcraft velocity and acceleration in communication with said Attitude and Acceleration Command/Velocity Hold algorithm.

6. The system as recited in claim 1, wherein said Attitude and Acceleration Command/Velocity Hold algorithm generates an output to a model following controller.

7. An Attitude and Acceleration Command/Velocity Hold algorithm for a rotary wing rotorcraft flight control system comprising:

an attitude command model logic which generates an attitude command model logic output;

an attitude model logic in communication with said attitude command model logic output, said attitude model logic generates an attitude model logic output;

an acceleration model logic in communication with said attitude command model logic output, said acceleration model logic generates an acceleration model logic output; and

a model following controller in communication with said attitude model logic output and said acceleration model logic output, said model following controller generates an rotorcraft command to determine a trim attitude for a given rotorcraft flight condition.

8. The algorithm as recited in claim 7, further comprising a velocity model logic in communication with said acceleration model logic output, said velocity model logic generates a velocity model logic output in communication with said model following controller.

9. The algorithm as recited in claim 8, further comprising a measured rotorcraft velocity and acceleration in communication with said velocity model logic output and said acceleration model logic output at junction to provide a summed result as a velocity and acceleration error signal output in communication with said model following controller

10. The algorithm as recited in claim 9, further comprising a measured rotorcraft attitude in communication with said attitude model logic output at junction to provide a summed result as an attitude error signal output in communication with said model following controller

11. The algorithm as recited in claim 7, further comprising a cyclic controller in communication with said attitude command model logic.

12. A method of finding a trim attitude for a given rotary-wing rotorcraft flight condition comprising the steps of:

(A) adding an acceleration command to an ACVH mode to control a rotary-wing rotorcraft velocity.

13. A method as recited in claim 12, wherein said step (A) further comprises:

(a) blending an acceleration command and an attitude command.

14. A method as recited in claim 12, wherein said step (A) further comprises:

(a) assuring zero acceleration when a cyclic control is returned to a detent position.

15. A method as recited in claim 12, wherein said step (A) further comprises:

(a) generating a pure Attitude Command response in which rotorcraft attitude change is proportional to a cyclic controller command displacement over a short term; and

(b) estimating an acceleration that the rotorcraft will attain and engaging a control loop to maintain the acceleration after said step (a).