Method and apparatus for enhanced mechanical signature analysis

• US 6,636,817 B2
• Filed: 06/07/2001
• Issued: 10/21/2003
• Est. Priority Date: 09/20/2000
• Status: Expired due to Fees

• Current Assignee: Seagate Technology LLC (Seagate Technology Holdings Plc)
• Original Assignee: Seagate Technology LLC (Seagate Technology Holdings Plc)
• Inventors: Fioravanti, Louis John
• Primary Examiner(s): Hoff, Marc S.
• Assistant Examiner(s): Raymond, Edward
• Application Number:
  US09/876,453
• Publication Number:
  US 20020038188A1
• Time in Patent Office: 866 Days
• Field of Search: 702/75, 702/76, 702/77, 702/79, 702/33, 702/34, 702/35, 702/38, 702/66, 702/67, 702/69, 702/70, 702/73, 702/182, 702/183, 702/190, 702/199, 360/29, 360/30, 360/6, 360/25, 324/207.13, 324/210, 324/211, 324/212, 324/213, 324/500, 324/528, 324/772, 324/612, 324/76.19, 324/76.21
• US Class Current: 702/75
• CPC Class Codes: G11B 20/1816 Testing

Abstract

A mechanical signature analysis system for analyzing frequencies and magnitudes of vibrations in an operating test disc drive includes a test data acquisition module connected to the test disc drive to acquire time domain test data and convert it into frequency domain test data, a typical disc drive data module having frequency domain data for a typical disc drive, and a failure analysis module having failure limits associated with the typical disc drive frequency domain data to determine whether the test data are within the failure limits. An output module displays failure analysis results. A method of determining a typical disc drive frequency used in analyzing vibrations in a test disc drive includes calculating a theoretical disc drive frequency that is a function of electromechanical characteristics of a class of disc drives, searching a configuration file of typical disc drive frequency data, and identifying in the configuration file a peak magnitude within a predetermined range of frequencies around the theoretical frequency.

Claims

1. A mechanical signature analysis system for analyzing frequencies and magnitudes of vibrations in an operating test disc drive, the system comprising:

a test data acquisition module connected to the test disc drive operable to acquire time domain test data from the test disc drive and convert the time domain test data into frequency domain test data;

a disc drive data module having frequency domain data for a reference disc drive;

a failure analysis module connected to the disc drive data module and the test data acquisition module, wherein the failure analysis module has failure limits associated with the reference disc drive frequency domain data and is operable to determine whether the test data are within the failure limits, and generate failure analysis results; and

wherein the disc drive data module is operable to calculate theoretical frequencies having peak magnitudes for use in analyzing the frequency domain test data.

2. The system of claim 1 further comprising an output module connected to the failure analysis module, the output module operable to provide test magnitudes, test frequencies, reference magnitudes, reference frequencies, and failure analysis results from analysis of the frequency domain test data for vibrations in the test disc drive.

3. The system of claim 1 wherein the test data acquisition module comprises a transducer fastened to an outside surface of the test disc drive, the transducer being operable to detect the vibrations within the operating test disc drive and generate a test data signal.

4. The system of claim 3 wherein the test data acquisition module further comprises:

a signal conditioner connected to the transducer operable to generate a conditioned signal having a plurality of frequencies;

a filter connected to the signal conditioner to filter unwanted frequencies out of the conditioned signal and generate a filtered signal;

a data acquisition module connected to the filter to receive the filtered signal and convert the filtered signal into a digital signal; and

a fast fourier transform module connected to the data acquisition module operable to perform a fast fourier transform on the digital signal to generate frequency domain test data corresponding to the vibrations in the test disc drive.

5. The system of claim 1 wherein the disc drive data module comprises a configuration file having reference frequency data for a predetermined number of disc drives in a class of disc drives.

6. The system of claim 2 wherein the output module is operable to output an identifier identifying each frequency as either a bearing frequency, an electromagnetic frequency, or another frequency.

7. The system of claim 1 wherein the disc drive data module is operable to identify each test frequency and each reference disc drive frequency as one of either a bearing frequency, an electromagnetic frequency, or an other frequency.

8. The system of claim 7 wherein the failure analysis module is operable to determine whether a test magnitude of a bearing frequency is within predetermined limits corresponding to a reference magnitude of a reference disc drive bearing frequency.

9. The system of claim 7 wherein the failure analysis module is operable to determine whether a test magnitude of an electromagnetic frequency is within predetermined limits corresponding to a reference magnitude of a reference disc drive bearing frequency.

10. The system of claim 1 wherein the theoretical frequencies are used to locate reference disc drive frequencies in a configuration file having reference disc drive frequency data associated with corresponding classes of disc drives.

11. The system of claim 10 wherein the reference disc drive data comprises average magnitudes at reference frequencies associated with a predetermined number of disc drives in a class of disc drives.

12. A method of analyzing a test magnitude of a test frequency associated with one or more vibrations in an operating test disc drive comprising steps of:

(a) receiving time domain test data from the operating test disc drive;

(b) converting the time domain test data into frequency domain test data having test frequencies with associated test magnitudes;

(c) comparing the frequency domain test data with theoretical disc drive frequency domain data calculated based on characteristics of the test disc drive; and

(d) determining whether a test magnitude of an associated test frequency in the test data is within a predetermined limit.

13. The method of claim 12 further comprising steps of:

(e) outputting a fail indicator if the test magnitude is not within the predetermined limit.

14. The method of claim 12 wherein the receiving step (a) comprises:

(a)(1) detecting vibrations from the test disc drive with a transducer fastened to an outside surface of the test disc drive;

(a)(2) generating a time domain test signal from the vibrations;

(a)(3) generating a conditioned test signal from the time domain test signal; and

(a)(4) filtering from the conditioned test signal unwanted frequencies to produce a filtered test signal.

15. The method of claim 12 wherein the converting step (b) comprises performing a fast fourier transform on the time domain test data.

16. The method of claim 12 wherein the comparing step (c) comprises:

(c)(1) obtaining an upper failure limit and a lower failure limit associated with reference magnitudes at a corresponding typical disc drive frequency; and

(c)(2) comparing the test magnitude at a test frequency to a reference disc drive magnitude at a typical disc drive frequency.

17. The method of claim 12 wherein the determining step (d) comprises:

(d)(1) determining whether the test magnitude is greater than the upper failure limit; and

(d)(2) determining whether the test magnitude is less than the lower failure limit.

18. A method of determining a reference disc drive frequency used in analyzing vibrations in a test disc drive, the method comprising steps of:

(a) calculating a theoretical disc drive frequency, the theoretical disc drive frequency being a function of electromechanical characteristics of a predetermined class of disc drives of which the test disc drive is a member;

(b) searching a configuration file of reference disc drive frequency data associated with the predetermined class of disc drives, using the theoretical disc drive frequency; and

(c) identifying a peak magnitude within a predetermined range of frequencies around the theoretical frequency, the peak magnitude corresponding to the reference disc drive frequency.

19. The method of claim 18 wherein the theoretical disc drive frequency is an axial rotational race frequency of the class of disc drive.

20. The method of claim 18 wherein the theoretical disc drive frequency is a radial rotational race frequency of the class of disc drive.

21. The method of claim 18 wherein the theoretical disc drive frequency is an axial ball frequency of the class of disc drives.

22. The method of claim 18 wherein the theoretical disc drive frequency is a radial ball frequency of the class of disc drives.

23. The method of claim 18 wherein the theoretical disc drive frequency is an axial radial ball stationary race frequency of the class of disc drives.

24. The method of claim 18 wherein the calculating step (a) comprises steps of:

(a)(1) calculating a plurality of theoretical disc drive frequencies at a plurality of harmonics of a fundamental frequency.

25. A computer program product readable by a computing system and encoding a computer program of instructions for executing a computer process for analyzing a test magnitude of a test frequency associated with one or more vibrations in an operating test disc drive, the computer process comprising steps of:

(a) receiving time domain test data from the operating test disc drive;

(b) converting the time domain test data into frequency domain test data having test frequencies with associated test magnitudes;

(c) comparing the frequency domain test data with theoretical disc drive frequency domain data calculated based on characteristics of the test disc drive; and

(d) determining whether a test magnitude of an associated test frequency in the test data is within a predetermined limit.

26. The computer program product of claim 25 wherein the computer process further comprises steps of:

(e) outputting a fail indicator if the test magnitude is not within the predetermined limit.

27. A disc drive mechanical signature analysis system comprising:

a test disc drive;

a reference disc drive data module having frequency domain data for a reference disc drive and operable to calculate theoretical frequencies having peak magnitudes, the theoretical frequencies being used to locate reference disc drive frequencies in a configuration file having reference disc drive frequency data associated with corresponding classes of disc drives; and

means for analyzing vibrations in the disc drive comprising a transducer fastened to an outside surface of the test disc drive, the transducer being operable to detect the vibrations within the operating test disc drive and generate a test data signal.

28. The mechanical signature analysis system of claim 27, further comprising:

a test data acquisition module connected to the test disc drive operable to acquire time domain test data from the test disc drive and convert the time domain test data into frequency domain test data; and

a failure analysis module connected to the reference disc drive data module and the test data acquisition module, wherein the failure analysis module has failure limits associated with the reference disc drive frequency domain data and is operable to determine whether the test data are within the failure limits, and generate failure analysis results.

29. The mechanical signature analysis system of claim 28 wherein the reference disc drive data module comprises the configuration file having reference frequency data for a predetermined number of disc drives in a class of disc drives.

30. A mechanical signature analysis system for analyzing frequencies and magnitudes of vibrations in an operating test disc drive, the system comprising:

a test data acquisition module connected to the test disc drive operable to acquire time domain test data from the test disc drive and convert the time domain test data into frequency domain test data;

a disc drive data module having frequency domain data for a reference disc drive;

a failure analysis module connected to the disc drive data module and the test data acquisition module, wherein the failure analysis module has failure limits associated with the reference disc drive frequency domain data and is operable to determine whether the test data are within the failure limits, and generate failure analysis results; and

wherein the disc drive data module is operable to calculate theoretical frequencies having peak magnitudes, the theoretical frequencies being used to locate reference disc drive frequencies in a configuration file having reference disc drive frequency data associated with corresponding classes of disc drives.

31. The system of claim 30 wherein the reference disc drive data comprises average magnitudes at reference frequencies associated with a predetermined number of disc drives in a class of disc drives.