Fault tolerant automatic control system utilizing analytic redundancy

• US 6,085,127 A
• Filed: 10/05/1998
• Issued: 07/04/2000
• Est. Priority Date: 03/18/1997
• Status: Expired due to Term

• Current Assignee: Rockwell Collins Control Technologies, Inc. (Rtx Corporation)
• Original Assignee: Aurora Flight Sciences Corporation (The Boeing Co.)
• Inventors: Vos, David W.
• Primary Examiner(s): Chin, Gary
• Application Number:
  US09/166,116
• Time in Patent Office: 638 Days
• Field of Search: 701/3, 701/4, 701/29, 701/34, 701/35, 318/563, 318/564, 244/194, 244/75 R, 371/67.1, 364/148, 364/150, 364/151, 364/152, 364/157, 364/176
• US Class Current: 701/4
• CPC Class Codes: G05B 9/02 electric
• CPC Class Codes: G05B 9/03 with multiple-channel loop, i.e. redundant control systems
• CPC Class Codes: G05D 1/0077 using redundant signals or controls

Abstract

Method and apparatus for a fault tolerant automatic control system for a dynamic device having a sensor and a predetermined control algorithm include structure and steps for receiving a status signal from the sensor. Structure and steps are provided for transforming the sensor status signal and a predetermined reference signal into a linear time invariant coordinate system, generating a sensor estimate in the linear time invariant coordinate system based on the transformed sensor status signal and the transformed reference signal, transforming the sensor estimate into a physical coordinate system, detecting an error in the sensor status signal based on a comparison of the transformed sensor estimate and the sensor status signal, and reconfiguring the predetermined control algorithm based on the detected error. Preferably, the apparatus and method are implemented in an aircraft flight control system capable of detecting an aircraft sensor fault and reconfiguring the flight control program such that flight control surface actuators are commanded by ignoring or mitigating the failed sensor.

Claims

1. An automatic control apparatus for controlling a dynamic device having control means, the apparatus comprising:

processing structure which (i) transforms control criteria, which controls the dynamic device control means, into a linear time invariant coordinate system;

(ii) determines an expected response for the device according to the transformed control criteria;

(iii) compares the expected response with a measured response of the device; and

(iv) reconfigures the control means based on the comparison.

2. Apparatus according to claim 1, wherein the dynamic device comprises an aircraft.

3. Apparatus according to claim 1, wherein the control criteria comprise flight control surface criteria.

4. Apparatus according to claim 3, wherein the step of reconfiguring the control means comprises the step of providing modified control signals to the flight control surfaces.

5. Apparatus according to claim 1, wherein the step of determining an expected response comprises the step of determining the expected response in the linear time invariant coordinate system.

6. Apparatus according to claim 1, wherein the step of comparing the expected response with the measured response comprises the step of comparing the expected response and the measured response in a physical coordinate stem.

7. A method of determining the operational status of a control system for controlling a dynamic device, said method comprising the steps of:

transforming dynamic device control signals into a linear time invariant system;

generating an estimated behavior of the device from the transformed signals;

transforming the estimated behavior into a physical coordinate system; and

evaluating the status of the system by comparing the actual device behavior with the transformed estimated behavior.

8. A method according to claim 7, wherein the dynamic device comprises an aircraft.

9. A method according to claim 7, wherein the dynamic device comprises a land vehicle.

10. A method according to claim 7, further comprising the step of reconfiguring the control system of the dynamic device based on the evaluating step.

11. A programmed computer for determining the operational status of a parameter dependent control system for controlling a dynamic device, said programmed computer comprising:

a memory having at least one region for storing computer executable code; and

a processor which executes the program code stored in said memory;

wherein the program code includes code responsive to;

(i) receiving a current state signal representing a current state of the device and a control signal for effecting control of the device;

(ii) transforming the current state signal and the control signal into a linear time invariant coordinate system;

(iii) estimating an expected behavior of the device using the transformed current state signal and the transformed control signal and for generating an estimate signal corresponding to the expected behavior; and

(iv) determining the operational status of the control system by comparing the expected behavior of the device with the current state signal in physical coordinates.

12. A computer according to claim 11, wherein the code responsive to estimating the expected behavior includes code for estimating the expected behavior in the linear time invariant coordinate system.

13. A computer according to claim 12, wherein the code responsive to determining the operational status includes code responsive to determining the operational status of the dynamic device in a physical coordinate system.

14. A computer according to claim 11, wherein the computer is installed in an aircraft.

15. A computer according to claim 11, wherein the program code includes code responsive to inverse coordinate transforming the expected behavior of the dynamic device from the linear time invariant coordinate system to a physical coordinate system.

16. Computer executable software codes stored on a computer readable medium, the codes for determining the operational status of a parameter dependent control system for controlling a dynamic device, the codes comprising:

code responsive to receiving a current state signal representing a current state of the device and a control signal for effecting control of the device;

code responsive to transforming the current state signal and the control signal into a linear time invariant coordinate system;

code responsive to estimating an expected behavior of the device using the transformed current state signal and the transformed control signal and for generating an estimate signal corresponding to the expected behavior; and

code responsive to determining the operational status of the control system by comparing the expected behavior of the device with the current state signal in physical coordinates.

17. Software code according to claim 16, wherein the code responsive to estimating the expected behavior includes code responsive to estimating the expected behavior in the linear time invariant coordinate system.

18. Software code according to claim 16, wherein the code responsive to determining the operational status includes code responsive to determining the operational status of the dynamic device in a physical coordinate system.

19. Software code according to claim 16, wherein the dynamic device includes control means, and further comprising code responsive to reconfiguring the dynamic device control means based on the comparison of the expected behavior of the device with the current state signal.

20. A method of reconfiguring a control system for mitigating the effect of a failed component in a dynamic device, said method comprising the steps of:

transforming component and control signals into a linear time invariant system;

generating an estimated signal from the transformed component and control signals;

transforming the estimated signal into a physical coordinate system;

comparing the estimated signal with the component signal to detect a component failure; and

adjusting the control system to mitigate the effect of the detected failed component.

21. A method according to claim 20, wherein the dynamic device comprises an aircraft.

22. A method according to claim 20, wherein the step of generating an estimated signal comprises the step of generating an estimated behavior of the dynamic device by failure detection filtering the transformed component and control signals to generate the estimated behavior in linear time invariant coordinates.

23. A method according to claim 20, wherein the step of transforming the estimated signal into a physical coordinate system includes the step of inverse coordinate transforming dynamic device expected behavior into the physical coordinate system.

24. Computer executable software codes stored on a computer readable medium, the codes for reconfiguring a control system to mitigate the effect of a failed component in a dynamic device, said codes comprising:

code responsive to transforming component signals and control signals into a linear time invariant coordinate system;

code responsive to generating an estimated signal by filtering the transformed component and control signals;

code responsive to transforming the estimated signal into a physical coordinated system;

code responsive to comparing the transformed estimated signal with the component signal to detect a component failure; and

code responsive to adjusting the control system to mitigate the effect of the detected failed component.

25. Software code according to claim 24, wherein the dynamic device comprises an aircraft, and wherein the code responsive to adjusting the control system includes code responsive to adjusting flight control surfaces of the aircraft.

26. Software code according to claim 24, wherein the code responsive to adjusting the control system to mitigate the effect of the detected failed component includes code responsive to ignoring signals from the detected failed component.

27. Software code according to claim 24, wherein the code responsive to adjusting the control system to mitigate the effect of the detected failed component includes code responsive to modifying control signals received from a non-failed component.

28. Computer executable software code stored on a computer readable medium, the code identifies a failed component in a dynamic device, the code comprising;

code responsive to transforming at least a component signal into a linear time invariant coordinate system;

code responsive to defining an estimated behavior for the component in the linear time invariant coordinate system;

code responsive to comparing a measured component behavior with the estimated component behavior; and

code responsive to identifying a component failure based on the comparison between the estimated and measured component behavior in physical coordinates.

29. Software code according to claim 28, wherein the code responsive to transforming includes code responsive to transforming both the component signal and a reference signal into the linear time invariant coordinate system.

30. Software code according to claim 29, wherein the code responsive to defining an estimated behavior includes code responsive to defining the estimated behavior in the linear time invariant system based on the transformed component signal and the transformed reference signal.

31. Software code according to claim 28, wherein the code responsive to comparing includes code responsive to comparing a measured component behavior with the estimated component behavior in a physical coordinate system.

32. Software code according to claim 28, wherein the dynamic device includes a control system, and further comprising code responsive to reconfiguring the dynamic device control system based on the identified component failure.

33. Software code according to claim 28, further comprising code responsive to transforming the estimated behavior for the component in the linear time invariant coordinate system to physical coordinates.

34. Software code according to claim 28, wherein the code responsive to transforming at least the component signal into a linear time invariant system includes code responsive to measuring a status of the dynamic device including operational parameters as well as a dynamic state of said dynamic device.