Defect diagnosis method and defect diagnosis apparatus

• US 6,498,992 B1
• Filed: 04/13/1999
• Issued: 12/24/2002
• Est. Priority Date: 12/04/1998
• Status: Expired due to Fees

• Current Assignee: RION Company Limited
• Original Assignee: RION Company Limited
• Inventors: Komura, Hidemichi, Niho, Tomoya, Toyota, Toshio, Jinyama, Hou
• Primary Examiner(s): Hoff, Marc S.
• Assistant Examiner(s): Charioui, Mohamed
• Application Number:
  US09/291,260
• Time in Patent Office: 1,351 Days
• Field of Search: 702/35, 702/66, 702/67, 702/70, 702/75, 702/76, 702/77, 702/54, 702/56, 702/58, 702/81, 702/91, 702/93, 702/103, 702/168, 702/FOR.104, 702/FOR.110, 702/FOR.125, 342/192, 735/70
• US Class Current: 702/35
• CPC Class Codes: G01M 13/028 Acoustic or vibration analysis
• CPC Class Codes: G01M 13/045 Acoustic or vibration analysis

Abstract

A method for diagnosis of a defect of an object to be inspected, such as a rotational machine, etc., by measuring a vibration generated thereby, wherein a measured signal generated by the object is detected, an amplitude probability density function of wave-form of the obtained measured signal is expanded orthogonally through a Gram-Charlier series, and the Gram-Charlier series are calculated so as to make diagnosis of defect(s) in the object to be inspected.

Claims

1. A method for diagnosis of a defect of an object to be inspected, comprising:

detecting a measured signal being generated by said object to be inspected;

expanding orthogonally an amplitude probability density function of a wave-form of the obtained measured signal in a Gram-Charlier series; and

calculating the Gram-Charlier series so as to make diagnosis of the defect in the object to be inspected.

2. A method for diagnosis of a defect as defined in claim 1, wherein said measured signal is a vibration.

3. A method for diagnosis of a defect as defined in claim 1, wherein said measured signal is an acoustic, an acoustic emission, a fluctuation of current or a fluctuation of effective electric power.

4. A method for diagnosis of a defect as defined in claim 1, wherein said object to be inspected is any one of a machine, a vehicle, an aircraft and a building.

5. A defect diagnosis apparatus for implementing the method for diagnosis as defined in claim 1, comprising a probe which is made to touch the object to be inspected.

6. A method for diagnosis of a defect of an object to be inspected, comprising:

detecting a measured signal being generated by said object to be inspected;

expanding orthogonally an amplitude probability density function of a wave-form of the obtained measured signal in a Gram-Charlier series; and

calculating a difference from a normal distribution so as to make diagnosis of the defect in the object to be inspected.

7. A method for diagnosis of a defect of an object to be inspected, comprising:

detecting a measured signal being generated by said object to be inspected;

expanding a wave-form of the obtained measured signal in a Fourier series to obtain a frequency spectrum;

expanding orthogonally an amplitude probability density function by viewing the obtained frequency spectrum from an axis of an amplitude thereof in a Gram-Charlier series; and

calculating the Gram-Charlier series so as to make diagnosis of the defect in the object to be inspected.

8. A method for diagnosis of a defect of an object to be inspected, comprising:

detecting a measured signal being generated by said object to be inspected;

expanding a wave-form of the obtained measured signal in a Fourier series to obtain a frequency spectrum;

expanding orthogonally an amplitude probability density function by viewing the obtained frequency spectrum from an axis of an amplitude thereof in a Gram-Charlier series; and

calculating a difference from a normal distribution so as to make diagnosis of the defect in the object to be inspected.