JPH0678936B2 - Vibration test equipment inspection method - Google Patents

Description

DETAILED DESCRIPTION OF THE INVENTION [Outline] Regarding an inspection method of a vibration test apparatus, an object is to provide an inspection method of a vibration test apparatus capable of accurately checking an accident or failure of the vibration test apparatus. A vibration test of the DUT including a vibrating section that applies vibration to the DUT based on the drive signal, and a detection section that detects the magnitude of acceleration that the DUT responds to the vibration In the device for carrying out the method, means for generating a signal for driving the vibrating section, means for fast Fourier transforming the drive signal from the generating means and the detection signal from the detecting section, and a means based on the fast Fourier transformed signal And a means for calculating a coherence function, and the vibration test apparatus is inspected based on the calculation result of the calculating means.

BACKGROUND OF THE INVENTION 1. Field of the Invention The present invention relates to an inspection method for a vibration test device that performs a vibration test.

In recent years, vibration test equipment has been applied to the manufacturing industry for the purpose of improving the product by obtaining the frequency response spectrum by applying vibration to the DUT and grasping the resonance point and vibration resistance of the DUT to the frequency. Widely used. Therefore, there is a demand for an inspection method for a vibration test apparatus that detects a failure, failure, etc. of the vibration test apparatus and confirms that the signal transmission system operates correctly without being affected by noise or the like.

[Conventional technology]

FIG. 3 is a block diagram showing a conventional example. The same reference numerals denote the same objects throughout the drawings.

In the figure, the controller 9a outputs an electric drive signal that sweeps and changes a signal frequency such as a sine wave in a predetermined frequency band, and the shaker 2a causes the table 2b to generate vibration of a frequency corresponding to the drive signal. Vibration is applied to the DUT 1a and the table 2b
The sensor 3a attached to converts the acceleration to which the device under test 1a responds into an electric signal and outputs the electric signal. The controller 9a is
A vibration test is performed by analyzing this response signal and obtaining a frequency response spectrum. Before carrying out this test, it is necessary to confirm that the vibration test device operates normally, and the controller 9a detects a voltage level of a predetermined value or more from the sensor when the drive signal is generated, so that the control loop is disconnected. Form a closed loop without
When the drive signal is stopped, the sensor does not detect a voltage level equal to or higher than a predetermined value, thereby confirming that the control loop is not affected by noise or the like and confirming that the vibration test apparatus is normal.

[Problems to be Solved by the Invention]

In the vibration test, the sensor 3a may come off, contact failure may occur, or there is a high possibility of failure, but according to the conventional method as described above, the response signal from the sensor 3a when the drive signal is generated or stopped Since the normality of the vibration system is checked by the level of the output voltage, there is a problem that the correlation between the response signal from the sensor 3a and these accidents and failures cannot be accurately checked.

It is an object of the present invention to provide an inspection method for a vibration test device that can accurately check for accidents and failures in the vibration test device.

[Means for Solving the Problems]

 FIG. 1 shows a block diagram of the principle of the present invention.

In the figure, 2 is a vibrating section that applies vibration to the DUT 1 based on an input drive signal, 3 is a detection section that detects the magnitude of acceleration at which the DUT 1 responds to the vibration, 4 is a means for generating a signal for driving the vibrating section 2, 5 is a means for performing a fast Fourier transform on the drive signal from the generating means 4 and the detection signal from the detecting section 3, and 6 is based on the fast Fourier transformed signal. It is a means of calculating the coherence function.

Therefore, the vibration testing device is inspected based on the calculation result of the calculating means 6.

[Action]

According to the present invention, the vibrating section 2 vibrates the DUT 1 based on the drive signal from the generating means 4, and the detecting section 3 causes the DUT 1 to vibrate.
Detects the magnitude of the acceleration that responds to, the conversion means 5 performs a fast Fourier transform on the drive signal from the generation means 4 and the detection signal from the detection unit 3, and the calculation means 6 is based on the fast Fourier transformed signal. Since the coherence function is calculated, the vibration test apparatus can be inspected by determining the mixing of noise and other signals based on the calculation result of the calculation means 6.

〔Example〕

An embodiment of the present invention will be described below with reference to FIG. The same reference numerals denote the same objects throughout the drawings. First in Figure 2
The ones corresponding to the figures are surrounded by the one-dot chain line.

In the figure, the signal generator 4b outputs a digital signal for driving the vibrator 2a as a function x (t) of time t.

The A / D converter 5b digitally converts the analog response signal of the acceleration from the sensor 3a and outputs a function y (t) of time t.

The fast Fourier transform (hereinafter referred to as FFT) unit 5c is x
Fast Fourier transform is performed on (t) and y (t) to output frequency functions X (f) and Y (f), respectively.

The inspection unit 6b uses the frequency functions X (f) and Y from the FFT unit 5c.
Based on (f) the coherence function: (Here, the symbol || indicates the absolute value of a complex number, and | XY (f) |
² is the cross spectrum between the input and output signals, | X (f) | ² is the auto power spectrum of the input signal, and | Y (f) | ² is the auto power spectrum of the output signal. ) Is calculated for all frequencies of the inspection and the average value is calculated. The coherence function has a value of 0 to 1 and is a known function indicating that the closer to 1 the higher the degree of association between the input signal to the transmission system and the output signal thereof, the predetermined value (eg 0.9) or more. The degree of mixing of noise and other signals is determined based on whether or not the determination result is displayed on the display unit 7b.

Therefore, in advance, the FFT unit 5c and the inspection unit 6b have the signal generation unit 4b.
By analyzing the drive signal from the sensor and the response signal from the sensor 3a, the presence of noise in the signal transmission system, disconnection, etc. are inspected and the inspection result is displayed. After confirming the normality of the device, a production vibration test for obtaining the frequency response spectrum of the device under test 1a is performed.

[Effects of the Invention] As described above, according to the present invention, it is possible to simultaneously inspect the control loop for noise and disconnection without adding special hardware and simply by adding an inspection program to the controller 9a. In addition, there is an effect that it is possible to detect a fault, which is difficult to detect by the conventional inspection method, such as a sensor mounting failure.

[Brief description of drawings]

 FIG. 1 is a block diagram showing the principle of the present invention, FIG. 2 is a block diagram showing an embodiment of the present invention, and FIG. 3 is a block diagram showing a conventional example. In the figure, 1 and 1a are DUTs, 2 is a vibrating section, 2a is a vibrating machine, 2b is a table, 3 is a detecting section, 3a is a sensor, 4 is a signal generating means, 4b is a signal generating section, and 5 is Reference numeral 5b is an A / D conversion unit, 5c is an FFT unit, 6 is a calculation unit, 6b is an inspection unit, 7b is a display unit, and 9a and 9b are controllers.

Claims (1)

[Claims] 1. A vibrating section (2) for applying vibration to a device under test (1) based on an input drive signal, and a magnitude of acceleration to which the device under test (1) responds to the vibration. A detection unit (3) for detecting a vibration, and a device (4) for generating a signal for driving the vibration unit (2) in an apparatus for performing a vibration test of the device under test (1).
And a drive signal from the generating means (4) and the detection section (3)
A means (5) for performing a fast Fourier transform on the detection signal from and a means (6) for calculating a coherence function based on the signal subjected to the fast Fourier transform are provided, and based on the calculation result of the calculating means (6) A vibration test apparatus inspection method, characterized by inspecting the vibration test apparatus.