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

• US 7,170,251 B2
• Filed: 01/21/2005
• Issued: 01/30/2007
• Est. Priority Date: 01/23/2004
• Status: Expired due to Fees

• Current Assignee: Novanta Corporation (Novanta Inc.)
• Original Assignee: GSI Group Corporation (Novanta Inc.)
• Inventors: Huang, Yuhong
• Primary Examiner(s): Ro; Bentsu
• Application Number:
  US11/040,332
• Publication Number:
  US 20050174124A1
• Time in Patent Office: 739 Days
• Field of Search: 318/560, 318/563, 318/565, 318/568.19, 318/568.24, 318/569, 318600-601, 318606-610, 318/685, 318/696, 388/906, 388/909
• US Class Current: 318/563
• CPC Class Codes: B23K 26/04 Automatically aligning, aiming or focusing the laser beam, e.g. using the back-scattered light
• CPC Class Codes: B23K 26/043 along the beam path, i.e. alignment of laser beam axis relative to laser beam apparatus
• CPC Class Codes: B41M 5/26 Thermography B41M5/20, B41M5/24 take precedence; Marking by high energetic means, e.g. laser otherwise than by burning, and characterised by the material used B23K takes precedence; thermographic or photothermographic systems using noble metal compounds G03C1/494
• CPC Class Codes: G01R 31/343 in operation
• CPC Class Codes: G02B 26/0816 by means of one or more reflecting elements
• CPC Class Codes: G02B 26/101 with both horizontal and vertical deflecting means, e.g. raster or XY scanners colour television using laser beams scanning a display screen H04N9/3129
• CPC Class Codes: G05B 11/42 for obtaining a characteristic which is both proportional and time-dependent, e.g. P. I., P. I. D.
• CPC Class Codes: G05B 13/042 in which a parameter or coefficient is automatically adjusted to optimise the performance
• CPC Class Codes: Y02P 70/10 Greenhouse gas [GHG] capture, material saving, heat recovery or other energy efficient measures, e.g. motor control, characterised by manufacturing processes, e.g. for rolling metal or metal working

Abstract

A diagnostic system is disclosed for analyzing a limited rotation motor system. The diagnostic system includes a first transform unit, a second transform unit, a closed loop frequency response unit, and a diagnostic system. The first transform unit is for receiving a first digital signal that is representative of a motor control signal, and is for providing a motor control frequency domain signal that is representative of a frequency domain representation of the motor control signal. The second transform unit is for receiving a second digital signal that is representative of a position detection signal, and is for providing a position detection frequency domain signal that is representative of a frequency domain representation of the position detection signal. The closed loop frequency response unit is for identifying a representation of the frequency response of the limited rotation motor responsive to the position detection frequency domain signal and the motor control frequency domain signals. The diagnostic unit is for 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.

Claims

1. A diagnostic system for analyzing a limited rotation motor system, said diagnostic system comprising:

first transform means for receiving a first digital signal that is representative of a motor control signal, and for providing a motor control frequency domain signal that is representative of a frequency domain representation of the motor control signal;

second transform means for receiving a second digital signal that is representative of a position detection signal, and for providing a position detection frequency domain signal that is representative of a frequency domain representation of the position detection signal;

closed loop frequency response means for 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

diagnostic means for 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 system as claimed in claim 1, wherein said first transform means and said second transform means each perform a Fast Fourier Transform.

3. The system as claimed in claim 1, wherein said representation of the frequency response identified by the closed loop frequency response means includes a ratio of the position detection frequency domain signal and the motor control frequency domain signal.

4. The system 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 system as claimed in claim 1, wherein said diagnostic means compares a low frequency range of the frequency response with the prior frequency response.

6. The system as claimed in claim 5, wherein said diagnostic means provides a failed bearing error signal that is indicative of whether a bearing is at risk of failing.

7. The system as claimed in claim 1, wherein said diagnostic means compares a mid frequency range of the frequency response with the prior frequency response.

8. The system as claimed in claim 7, wherein said diagnostic means provides a torque constant error signal that is indicative of a change in torque constant of the limited rotation motor.

9. The system as claimed in claim 1, wherein said diagnostic means provides 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 system as claimed in claim 1, wherein said limited rotation motor system includes a proportional, integral, derivative controller.

11. The system as claimed in claim 10, wherein said diagnostic means provides corrective signals to the proportional, integral, derivative controller.

12. A diagnostic system for analyzing a limited rotation motor system, said diagnostic system comprising:

first FFT means for receiving a first digital signal that is representative of a motor control signal, and for providing a motor control frequency domain sequence that is representative of a frequency domain representation of the motor control signal for a plurality of frequencies;

second FFT means for receiving a second digital signal that is representative of a position detection signal, and for providing a position detection frequency domain sequence that is representative of a frequency domain representation of the position detection signal for the plurality of frequencies;

closed loop frequency response means for 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

diagnostic means for 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 system as claimed in claim 12, wherein said representation of the frequency response identified by the closed loop frequency response means includes a ratio of the position detection frequency domain signal and the motor control frequency domain signal.

14. The system 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 system as claimed in claim 12, wherein said diagnostic means compares a low frequency range of the frequency response with the prior frequency response.

16. The system as claimed in claim 15, wherein said diagnostic means provides a failed bearing error signal that is indicative of whether a bearing is at risk of failing.

17. The system as claimed in claim 12, wherein said diagnostic means compares a mid frequency range of the frequency response with the prior frequency response.

18. The system as claimed in claim 17, wherein said diagnostic means provides a torque constant error signal that is indicative of a change in torque constant of the limited rotation motor.

19. The system as claimed in claim 12, wherein said diagnostic means provides 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 system as claimed in claim 12, wherein said limited rotation motor system includes a proportional, integral, derivative controller.

21. The system as claimed in claim 20, wherein said diagnostic means provides corrective signals to the proportional, integral, derivative controller.