Systems and Methods for Controlling Dynamic Systems

• US 20080147254A1
• Filed: 06/02/2005
• Published: 06/19/2008
• Est. Priority Date: 06/02/2004
• Status: Active Grant

• Current Assignee: Rockwell Collins Control Technologies, Inc. (Raytheon Technologies Corporation d/b/a RTX)
• Original Assignee: Rockwell Collins Control Technologies, Inc. (Raytheon Technologies Corporation d/b/a RTX)
• Inventors: Piedmonte, Michael Daniel, Vos, David William, Gavrilets, Vladislav
• Granted Patent: US 8,209,068 B2
• Time in Patent Office: Days
• US Class Current: 701/8
• CPC Class Codes: G05D 1/0816 to ensure stability

Abstract

A control system (12) for controlling velocity and attitude of a dynamic system (20) includes a velocity controller configured to receive a desired velocity command and output a velocity error in the form of Euler angle commands to an attitude controller system. The attitude controller system includes a converter (14) configured to receive the Euler angle commands and output a desired quaternion based on the Euler angle commands. The attitude controller system further includes an attitude error generator (16) configured to receive the desired quaternion and an estimated quaternion indicative of an estimated velocity and attitude of the dynamic system (20) and to output attitude errors associated with the dynamic system (20). The attitude controller system also includes an attitude controller (18) configured to receive the attitude errors and to output error commands to the dynamic system (20) based on the attitude errors.

Claims

1. A control system for controlling velocity and attitude of a dynamic system, the control system comprising:

a velocity controller configured to receive a desired velocity command and output a velocity error in the form of Euler angle commands; and

an attitude controller system operatively connected to the velocity controller to receive Euler angle commands, the attitude controller system comprising

a converter configured to receive the Euler angle commands and output a desired quaternion based on the Euler angle commands,

an attitude error generator configured to receive the desired quaternion and an estimated quaternion indicative of an estimated attitude of the dynamic system, and is configured to output attitude errors associated with the dynamic system, and

an attitude controller configured to receive the attitude errors and to output error commands to the dynamic system based on the attitude errors,

wherein the error commands are configured to reduce the attitude errors and the velocity errors.

2. The control system of claim 1, wherein the attitude controller system is configured to control the dynamic system at all attitudes.

3. The control system of claim 1, wherein the dynamic system comprises a vehicle and the error commands comprise signals configured to adjust control actuators of the vehicle.

4. The control system of claim 3, wherein the vehicle comprises an air vehicle and the control actuators of the vehicle comprise control surfaces.

5. The control system of claim 4, wherein the control actuators comprise at least one of an effective aileron, an effective elevator, and an effective rudder.

6. The control system of claim 4, wherein the air vehicle is configured to take off in a substantially vertical direction and fly in a direction having a horizontal component.

7. The control system of claim 4, wherein the attitude controller system is configured to switch the desired quaternion between a first coordinate system associated with taking off in a substantially vertical direction and a second coordinate system associated with flying in a direction having a horizontal component.

8. The control system of claim 7, wherein the attitude controller system is configured to use hysteresis to prevent chatter as the attitude controller system switches between the first coordinate system and the second coordinate system.

9. The control system of claim 1, wherein the Euler command angles comprise at least one of Euler heading, Euler pitch, and Euler roll.

10. The control system of claim 9, wherein the dynamic system comprises an air vehicle having a nose, wherein when the air vehicle nose is directed in about a horizontal direction, the control system uses only the Euler pitch as a damping term.

11. The control system of claim 9, wherein the dynamic system comprises an air vehicle having a nose, wherein when the air vehicle nose is directed in about a vertical direction, the control system uses only the Euler pitch and the Euler roll as damping terms.

12. The control system of claim 1, wherein the attitude errors by virtue are generated based on the desired quaternion and the estimated quaternion, such that the attitude errors have no discontinuities

13. The control system of claim 1, wherein the attitude controller system is configured to rotate the estimated quaternion ninety degrees, thereby resulting in a rotated quaternion, such that when the rotated quaternion is converted to Euler angles, non-singular Euler roll, Euler pitch, and Euler heading are produced.

14. The control system of claim 13, wherein the Euler angle commands comprise Euler roll command, Euler pitch command, and Euler heading command, and the attitude controller system is configured to convert the Euler roll command, the Euler pitch command, and the Euler heading command into the desired quaternion and compare the desired quaternion with the rotated quaternion to produce the attitude errors.

15. The control system of claim 14, wherein the attitude errors comprise body axes attitude errors.

16. The control system of claim 1, further comprising a navigation filter configured to generate the estimated quaternion.

17. The control system of claim 16, wherein the navigation filter is configured to use an LTI'"'"'zation method in order to control the attitude errors throughout a performance envelope of the dynamic system.

18. The control system of claim 1, wherein the dynamic system comprises a vehicle configured to move along a curvilinear path, and wherein the attitude controller system is configured to control movement of the vehicle along a curvilinear path based solely on one of Euler roll commands and Euler heading commands.

19. The control system of claim 1, wherein the attitude controller system is configured such that when the dynamic system comprises a vehicle not requiring any turn coordination in order to move along a curvilinear path, Euler heading changes are controlled via Euler pitch control regardless of Euler roll orientation.

20. The control system of claim 1, wherein the attitude controller system is configured to control the dynamic system by direct input of Euler angles such that stability of body attitudes of the dynamic system is maintained.

21. An attitude controller system for controlling attitude of a dynamic system, the attitude controller system comprising:

a converter configured to receive a velocity error in the form of Euler angle commands and output a desired quaternion based on the Euler angle commands;

an attitude error generator configured to receive the desired quaternion and an estimated quaternion indicative of an estimated attitude of the dynamic system, and to output attitude errors associated with the dynamic system; and

an attitude controller configured to receive the attitude errors and to output error commands to the dynamic system based on the attitude errors,

wherein the error commands are configured to reduce the attitude errors and the velocity errors.

22. The attitude controller system of claim 21, wherein the attitude controller system is configured to control the dynamic system at all attitudes.

23. The attitude controller system of claim 21, wherein the dynamic system comprises a vehicle and the error commands comprise signals configured to adjust control actuators of the vehicle.

24. The attitude controller system of claim 23, wherein the vehicle comprises an air vehicle and the control actuators of the vehicle comprise control surfaces.

25. The attitude controller system of claim 24, wherein the control actuators comprise at least one of an effective aileron, an effective elevator, and an effective rudder.

26. The attitude controller system of claim 24, wherein the air vehicle is configured to take off in a substantially vertical direction and fly in a direction having a horizontal component.

27. The attitude controller system of claim 24, wherein the attitude controller system is configured to switch the desired quaternion between a first coordinate system associated with taking off in a substantially vertical direction and a second coordinate system associated with flying in a direction having a horizontal component.

28. The attitude controller system of claim 27, wherein the attitude controller system is configured to use hysteresis to prevent chatter as the attitude controller system switches between the first coordinate system and the second coordinate system.

29. The attitude controller system of claim 21, wherein the Euler command angles comprise at least one of Euler heading, Euler pitch, and Euler roll.

30. The attitude controller system of claim 29, wherein the dynamic system comprises an air vehicle having a nose, wherein when the air vehicle nose is directed in about a horizontal direction, the attitude controller uses only the Euler pitch as a damping term.

31. The attitude controller system of claim 29, wherein the dynamic system comprises an air vehicle having a nose, wherein when the air vehicle nose is directed in about a vertical direction, the attitude controller system uses only the Euler pitch and the Euler roll as damping terms.

32. The attitude controller system of claim 21, wherein the attitude errors have no discontinuities by virtue of being generated based on the desired quaternion and the estimated quaternion.

33. The attitude controller system of claim 21, wherein the attitude controller system is configured to rotate the estimated quaternion ninety degrees, thereby resulting in a rotated quaternion, such that when the rotated quaternion is converted to Euler angles, non-singular Euler roll, Euler pitch, and Euler heading are produced.

34. The attitude controller system of claim 33, wherein the Euler angle commands comprise Euler roll command, Euler pitch command, and Euler heading command, and the attitude controller system is configured to convert the Euler roll command, the Euler pitch command, and the Euler heading command into the desired quaternion and compare the desired quaternion with the rotated quaternion to produce the attitude errors.

35. The attitude controller system of claim 34, wherein the attitude errors comprise body axes attitude errors.

36. The attitude controller system of claim 21, further comprising a navigation filter configured to generate the estimated quaternion.

37. The attitude controller system of claim 36, wherein the navigation filter is configured to use an LTI'"'"'zation method in order to control the attitude errors throughout a performance envelope of the dynamic system.

38. The attitude controller system of claim 21, wherein the dynamic system comprises a vehicle, and wherein the attitude controller system is configured to control movement of the vehicle along a curvilinear path based solely on one of Euler roll commands and Euler heading commands.

39. The attitude controller system of claim 21, wherein the attitude controller system is configured such that when the dynamic system comprises a vehicle not requiring any turn coordination in order to move along a curvilinear path, Euler heading changes are controlled via Euler pitch control regardless of Euler roll orientation.

40. The attitude controller system of claim 21, wherein the attitude controller system is configured to control the dynamic system by direct input of Euler angles such that stability of body attitudes of the dynamic system is maintained.

41. A method of controlling velocity and attitude of a dynamic system, the method comprising:

converting a velocity error associated with the dynamic system into Euler angle commands;

converting the Euler angle commands into a desired quaternion;

generating attitude errors associated with the dynamic system based on the desired quaternion and an estimated quaternion indicative of an estimated attitude of the dynamic system; and

controlling the velocity and attitude of the dynamic system to reduce the attitude errors and the velocity errors.

42. The method of claim 41, wherein controlling the velocity and attitude occurs for all attitudes.

43. The method of claim 41, wherein dynamic system comprises a vehicle having actuators, and controlling the velocity and attitude comprises adjusting the actuators.

44. The method of claim 43, wherein the vehicle comprises an air vehicle having control surfaces, and controlling the velocity and attitude comprises adjusting the control surfaces.

45. The method of claim 41, wherein the dynamic system comprises an air vehicle, and controlling the dynamic system comprises taking the air vehicle off in a substantially vertical direction and flying the air vehicle in a direction having a horizontal component.

46. The method of claim 45, further comprising switching the desired quaternion between a first coordinate system associated with taking the air vehicle off in a substantially vertical direction and a second coordinate system associated with flying the air vehicle in a direction having a horizontal component.

47. The method of claim 46, further comprising preventing chatter when switching between the first coordinate system and the second coordinate system by using hysteresis.

48. The method of claim 41, further comprising rotating the estimated quaternion ninety degrees to generate a rotated quaternion, and converting the rotated quaternion into Euler angles comprising non-singular Euler roll, Euler pitch, and Euler heading.

49. The method of claim 48, wherein the Euler angle commands comprise Euler roll command, Euler pitch command, and Euler heading command, and wherein the method comprises converting the Euler roll command, the Euler pitch command, and the Euler heading command into the desired quaternion and comparing the desired quaternion with the rotated quaternion to produce the attitude errors.

50. The method of claim 41, wherein the dynamic system comprises a vehicle, and the method further comprises controlling movement of the vehicle along a curvilinear path based solely on one of Euler roll commands and Euler heading commands.

51. The method of claim 41, wherein the dynamic system comprises a vehicle not requiring any turn coordination in order to move along a curvilinear path, and wherein the method further comprises controlling Euler pitch for any Euler roll orientation in order to change vehicle heading.

52. The method of claim 41, further comprising maintaining the stability of body attitudes of the dynamic system while inputting the Euler angle commands and controlling the dynamic system.

53. The method of claim 41, wherein controlling the attitude of the dynamic system comprises using LTI'"'"'zation to control the attitude errors throughout an operational envelope of the dynamic system.