# US 12,111,291 B2 · Structure diagnosis apparatus, structure diagnosis method, and computer-readable recording medium

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- Number: US 12,111,291 B2
- Document ID: US12111291B2
- Status: Granted
- Kind: B2
- Application number: 17/435,482
- Filed: 2020-01-16
- Published: 2022-05-05
- Granted: 2024-10-08
- Earliest claimed: 2019-03-05
- Assignees: NEC Corporation
- Applicants: NEC Corporation
- Inventors: Shohei Kinoshita; Shigeru Kasai; Yu Kiyokawa
- Web page: https://patentgrep.com/patent/US12111291B2

## CPC

- G01N 29/12: by measuring frequency or resonance of acoustic waves {(measuring frequency or resonant frequency of mechanical vibrations or acoustic waves in general G01H1/06, G01H3/04, G01H13/00; acoustic resonators G10K11/04; vibration or shock testing of structures G01M7/00)}
- G01N 29/14: using acoustic emission techniques {(echo of particles G01N29/046; measuring mechanical vibrations or acoustic waves in solids in general G01H1/00)}
- G01H 17/00: Measuring mechanical vibrations or ultrasonic, sonic or infrasonic waves, not provided for in the other groups of this subclass
- G01M 99/00: Subject matter not provided for in other groups of this subclass
- G01N 29/4427: {with stored values, e.g. threshold values}
- G01N 29/46: by spectral analysis, e.g. Fourier analysis {or wavelet analysis (spectral signal processing per se G06F17/14)}
- G01N 2291/0232: Glass, ceramics, concrete or stone
- G01N 2291/0289: Internal structure, e.g. defects, grain size, texture
- G01N 2291/106: one or more transducer arrays
- G01N: INVESTIGATING OR ANALYSING MATERIALS BY DETERMINING THEIR CHEMICAL OR PHYSICAL PROPERTIES (measuring or testing apparatus or processes other than immunoassay, involving enzymes or microorganisms C12M, C12Q)
- G01H: MEASUREMENT OF MECHANICAL VIBRATIONS OR ULTRASONIC, SONIC OR INFRASONIC WAVES
- G01M: TESTING STATIC OR DYNAMIC BALANCE OF MACHINES OR STRUCTURES; TESTING OF STRUCTURES OR APPARATUS, NOT OTHERWISE PROVIDED FOR

## Abstract

A structure diagnosis apparatus 1 for diagnosing a state of a structure in which there is a small change in the natural frequency includes: a natural vibration extraction unit 2 configured to acquire, from a plurality of sensors 21 that a structure is provided with 20, vibration information indicating vibration generated in the structure 20, and extracting natural vibration using the vibration information; a spectral shape extraction unit 3 configured to extract spectral shape information indicating a shape of a spectrum using the natural vibration; an index calculation unit 4 for calculating an index indicating a relationship between the spectral shape information and reference spectral shape information that is a preset reference; and a state estimation unit 5 for estimating the state of the structure based on the index.

## Claims

### Claim 1

A structure diagnosis apparatus comprising:
a processor; and
a memory storing program code executable by the processor to:
acquire vibration information indicating an acceleration measured by each of a plurality of sensors provided in a structure;
set a damping free vibration section for the acquired vibration information;
convert the acceleration from a time domain to a frequency domain in the damping free vibration section set for each of the sensors;
calculate a representative spectrum by combining spectra of all of the sensors or the spectra of two or more preselected of the sensors;
extract a frequency at which an amplitude of the representative spectrum is greater than or equal to a predetermined value;
set the extracted frequency as a natural frequency;
set a frequency band including the natural frequency;
extract spectral shape information used to indicate a spectral shape from a measurement spectrum by using an amplitude and phase of each of a plurality of frequencies within the set frequency band;
calculate an index based on information regarding a fitness function fitted to a function using the spectral shape information and information regarding a reference fitness function fitted to a function using reference spectral shape information; and
estimate a state of the structure based on the index.

### Claim 2 (depends on 1)

The structure diagnosis apparatus according to claim 1,
wherein the natural frequency corresponds to a natural vibration that is a primary natural vibration.

### Claim 3 (depends on 1)

The structure diagnosis apparatus according to claim 1,
wherein the natural frequency corresponds to a natural vibration that is a longitudinal vibration.

### Claim 4

A structure diagnosis method performed by a computer and comprising:
acquiring vibration information indicating an acceleration measured by each of a plurality of sensors provided in a structure;
setting a damping free vibration section for the acquired vibration information;
converting the acceleration from a time domain to a frequency domain in the damping free vibration section set for each of the sensors;
calculating a representative spectrum by combining spectra of all of the sensors or the spectra of two or more preselected of the sensors;
extracting a frequency at which an amplitude of the representative spectrum is greater than or equal to a predetermined value;
setting the extracted frequency as a natural frequency;
setting a frequency band including the natural frequency;
extracting spectral shape information used to indicate a spectral shape from a measurement spectrum by using an amplitude and phase of each of a plurality of frequencies within the set frequency band;
calculating an index based on information regarding a fitness function fitted to a function using the spectral shape information and information regarding a reference fitness function fitted to a function using reference spectral shape information; and
estimating a state of the structure based on the index.

### Claim 5 (depends on 4)

The structure diagnosis method according to claim 4,
wherein the natural frequency corresponds to a natural vibration that is a primary natural vibration.

### Claim 6 (depends on 4)

The structure diagnosis method according to claim 4,
wherein the natural frequency corresponds to a natural vibration that is a longitudinal vibration.

### Claim 7

A non-transitory computer-readable recording medium storing a program executable by a computer to perform processing comprising:
acquiring vibration information indicating an acceleration measured by each of a plurality of sensors provided in a structure;
setting a damping free vibration section for the acquired vibration information;
converting the acceleration from a time domain to a frequency domain in the damping free vibration section set for each of the sensors;
calculating a representative spectrum by combining spectra of all of the sensors or the spectra of two or more preselected of the sensors;
extracting a frequency at which an amplitude of the representative spectrum is greater than or equal to a predetermined value;
setting the extracted frequency as a natural frequency;
setting a frequency band including the natural frequency;
extracting spectral shape information used to indicate a spectral shape from a measurement spectrum by using an amplitude and phase of each of a plurality of frequencies within the set frequency band;
calculating an index based on information regarding a fitness function fitted to a function using the spectral shape information and information regarding a reference fitness function fitted to a function using reference spectral shape information; and
estimating a state of the structure based on the index.

### Claim 8 (depends on 7)

The non-transitory computer-readable recording medium according to claim 7,
wherein the natural frequency corresponds to a natural vibration that is a primary natural vibration.

### Claim 9 (depends on 7)

The non-transitory computer-readable recording medium according to claim 7,
wherein the natural frequency corresponds to a natural vibration that is a longitudinal vibration.