System and method for diagnosing a controller in a limited rotation motor system

1. A method of analyzing a limited rotation motor system, said method comprising the steps of:

providing a motor control frequency domain signal that is representative of a frequency domain representation of a motor control signal responsive to a first digital signal that is representative of the motor control signal;

providing a position detection frequency domain signal that is representative of a frequency domain representation of a position detection signal responsive to a second digital signal that is representative of the position detection signal;

identifying a representation of the frequency response of the limited rotation motor responsive to the motor control frequency domain signal and the position detection frequency domain signal; and

comparing the representation of the frequency response with a previously recorded representation of a prior frequency response to identify an error condition with respect to the limited rotation motor system.

2. The method as claimed in claim 1 , wherein said step of providing a motor control frequency domain signal and said step of providing a position detection frequency domain signal each involve performing a Fast Fourier Transform.

3. The method as claimed in claim 1 , wherein said representation of the frequency response includes a ratio of the position detection frequency domain signal and the motor control frequency domain signal.

4. The method as claimed in claim 3 , wherein said ratio is provided by the position detection frequency domain signal divided by the motor control frequency domain signal.

5. The method as claimed in claim 1 , wherein said step of comparing the representation of the frequency response with a previously recorded representation of a prior frequency response involves comparing a low frequency range of the frequency response with the prior frequency response.

6. The method as claimed in claim 5 , wherein said step of comparing the representation of the frequency response with a previously recorded representation of a prior frequency response involves providing a failed bearing error signal that is indicative of whether a bearing is at risk of failing.

7. The method as claimed in claim 1 , wherein said step of comparing the representation of the frequency response with a previously recorded representation of a prior frequency response involves comparing a mid frequency range of the frequency response with the prior frequency response.

8. The method as claimed in claim 7 , wherein said step of comparing the representation of the frequency response with a previously recorded representation of a prior frequency response involves providing a torque constant error signal that is indicative of a change in torque constant of the limited rotation motor.

9. The method as claimed in claim 1 , wherein said step of comparing the representation of the frequency response with a previously recorded representation of a prior frequency response involves providing an asymmetry error signal that is indicative of whether the range of movement of a rotor shaft of the limited rotation motor is not symmetrical with respect to the torque constant.

10. The method as claimed in claim 1 , wherein said limited rotation motor system includes a proportional, integral, derivative controller.

11. The method as claimed in claim 10 , wherein said step of comparing the representation of the frequency response with a previously recorded representation of a prior frequency response involves providing corrective signals to the proportional, integral, derivative controller.

12. A method of analyzing a limited rotation motor system, said method comprising the steps of:

providing a motor control frequency domain sequence that is representative of a frequency domain representation of a motor control signal for a plurality of frequencies responsive to a first digital signal that is representative of the motor control signal using a first Fast Fourier Transform;

providing a position detection frequency domain sequence that is representative of a frequency domain representation of a position detection signal for the plurality of frequencies responsive to a second digital signal that is representative of the position detection signal using a second Fast Fourier Transform;

identifying a representation of the frequency response for the plurality of frequencies of the limited rotation motor responsive to the motor control frequency domain signal and the position detection frequency domain signal; and

comparing the representation of the frequency response with a previously recorded representation of a prior frequency response to identify an error condition with respect to the limited rotation motor system.

13. The method as claimed in claim 12 , wherein said representation of the frequency response includes a ratio of the position detection frequency domain signal and the motor control frequency domain signal.

14. The method as claimed in claim 13 , wherein said ratio is provided by the position detection frequency domain signal divided by the motor control frequency domain signal.

15. The method as claimed in claim 12 , wherein said step of comparing the representation of the frequency response with a previously recorded representation of a prior frequency response involves compares a low frequency range of the frequency response with the prior frequency response.

16. The method as claimed in claim 15 , wherein said step of comparing the representation of the frequency response with a previously recorded representation of a prior frequency response involves providing a failed bearing error signal that is indicative of whether a bearing is at risk of failing.

17. The method as claimed in claim 12 , wherein said step of comparing the representation of the frequency response with a previously recorded representation of a prior frequency response involves comparing a mid frequency range of the frequency response with the prior frequency response.

18. The method as claimed in claim 17 , wherein said step of comparing the representation of the frequency response with a previously recorded representation of a prior frequency response involves providing a torque constant error signal that is indicative of a change in torque constant of the limited rotation motor.

19. The method as claimed in claim 12 , wherein said step of comparing the representation of the frequency response with a previously recorded representation of a prior frequency response involves providing an asymmetry error signal that is indicative of whether the range of movement of a rotor shaft of the limited rotation motor is not symmetrical with respect to the torque constant.

20. The method as claimed in claim 12 , wherein said limited rotation motor system includes a proportional, integral, derivative controller.

21. The method as claimed in claim 20 , wherein said step of comparing the representation of the frequency response with a previously recorded representation of a prior frequency response involves providing corrective signals to the proportional, integral, derivative controller.