JPH06117917A - Method and apparatus for measuring vibration response characteristic of machine vibration device - Google Patents

Abstract

PURPOSE:To accurately measure the response characteristics corresponding to frequency effective for the analysis of the characteristics such as a resonance point or the like of an object to be tested being a machine vibration system to be measured. CONSTITUTION:A measuring device for the vibration response characteristics of a machine vibration system is equipped with the vibrator bonded to an object to be tested to forcibly vibrate the object, the sensor 7 mounted on the object to be tested to detect the vibration state of the object and an FFT function 10 of analyzing the measured value detected by the sensor 7. The operational processing using the FFT function 10 is executed at the phase pitch corresponding to predetermined frequency. A means for recording a measured phase pitch and a function of calculating the operation timing from the measured phase pitch and the predetermined frequency are provided and the operation processing using the FFT function 10 is executed in the operation timing.

Description

Detailed Description of the Invention

[0001]

BACKGROUND OF THE INVENTION 1. Field of the Invention The present invention relates to a mechanical vibration system vibration response characteristic measuring device of a mechanical device, and more particularly to a mechanical vibration system vibration capable of accurately measuring at an appropriate measuring speed corresponding to the characteristic of a mechanical vibration system to be measured. The present invention relates to a response characteristic measuring device.

[0002]

2. Description of the Related Art For measuring the vibration dynamic characteristics of various mechanical devices, such as a drive shaft of an automobile, which includes various vibration states and transmission characteristics, forced vibration is applied to a target machine and By measuring the vibration of this mechanical (vibration) system (hereinafter referred to as the mechanical vibration system) with a sensor installed at an appropriate position of the machine, and analyzing the measurement results by, for example, FFT, the response characteristics to the forced vibration of this mechanical vibration system Is getting That is, to measure the vibration characteristics of a conventional mechanical vibration system, for example, a vibration impact sensor provided at a predetermined position of the test piece by hitting with a hammer equipped with a load cell at a predetermined position of the test object which is a mechanical system to be measured. The response vibration is detected and the detection result is analyzed by FFT. Sampling pitch for calculation execution in such FFT,
That is, the calculation pitch is generally executed at a predetermined fixed time pitch set corresponding to the frequency band of the mechanical vibration system to be measured. Further, a characteristic frequency is set, driving vibration is performed by a hydraulic motor or the like, and analysis data is obtained by FFT from the measured value by the sensor as in the above.

[0003]

By the way, the operation pitch in the analysis by the above-mentioned conventional FFT is set corresponding to the highest frequency or the lowest frequency of the target machine vibration system, and therefore the operation time of the FFT which influences the measurement time. Since it is determined, it is difficult to obtain accurate analysis results in a short time. Further, if the calculation pitch is determined by the lowest frequency, the accuracy of the high frequency component deteriorates, and if the calculation pitch is determined by the highest frequency and the measurement time is shortened, it is necessary to terminate the calculation before the analysis data of the low frequency component is determined. The present invention solves the above conventional problems and accurately measures the response characteristic corresponding to a frequency, which is effective for mechanical system characteristic analysis such as a resonance point, at a proper speed with respect to a specimen that is a mechanical vibration system to be measured. The purpose (problem) is to obtain a mechanical vibration system vibration response characteristic measuring device.

[0004]

In order to solve the above-mentioned problems, in a mechanical vibration system vibration response characteristic measuring method according to the present invention, a vibration exciter that is coupled to a test piece to apply a forced vibration and is mounted on the test piece. In a mechanical vibration system vibration response characteristic measuring means including a sensor for detecting a vibration state of the FFT device and an FFT device for analyzing a measurement value detected by the sensor, arithmetic processing in the FFT device at a phase pitch corresponding to a predetermined frequency. To run. Further, the mechanical vibration system vibration response characteristic measuring device according to the present invention is provided with a means for recording the measurement phase pitch and a function for calculating the calculation timing from the measurement phase pitch and the predetermined frequency, and the FFT is performed by the calculation timing. The calculation processing by the function was executed. In addition, the frequency setting means of the forced vibration applied to the test piece, the shaker coupled to the test piece to give the forced vibration of the set frequency, the sensor for detecting the vibration state of the test piece, and the measured value detected by this sensor In a mechanical vibration system vibration response characteristic measuring device equipped with an FFT device for analyzing
A means for recording the measurement phase pitch and a function for calculating the calculation timing from the measurement phase pitch and the forced vibration frequency are provided, and the calculation processing by the FFT function is executed at this calculation timing.

[0005]

According to the present invention, the arithmetic processing of the FFT apparatus is executed at the phase pitch corresponding to the predetermined frequency or the phase pitch corresponding to the excitation frequency as described above.
The vibration analysis data corresponding to the desired frequency as the vibration response characteristic of the mechanical vibration system can be accurately obtained in a short time even if the vibration frequency changes rapidly.

[0006]

DETAILED DESCRIPTION OF THE PREFERRED EMBODIMENTS An embodiment of a mechanical vibration system vibration response characteristic measuring device (hereinafter abbreviated as a measuring device) to which a mechanical vibration system vibration response characteristic measuring method according to the present invention is applied will be described in detail with reference to the drawings. FIG. 1 shows an example of a measuring device to which the present invention is applied. In FIG. 1, reference numeral 1 denotes a measurement management function of this measurement apparatus, and the measurement conditions or measurement commands set and recorded in the measurement management function 1 are input to a measurement excitation signal generation function 2 and an FFT operation setting function 9. Exciter drive function 3 by the excitation signal of the predetermined frequency created by the measurement excitation signal creation function 2
Drives the shaker 4. The above-mentioned measurement management function 1 and measurement excitation signal generation function 2 constitute a forced vibration frequency setting means. The shaker 4 is connected to the test load mechanism 6 via, for example, a rotary shaft 5, and the rotary shaft 5 has a sensor 7
For example, a torque pickup is coupled, and the detection signal of the sensor 7 is input to the vibration detection function 8 and converted into a predetermined electric signal and input to the FFT function 10. Also, FFT
The operation setting function 9 performs predetermined processing, which will be described in detail later, on the signal input from the measurement management function 1, inputs the signal to the FFT function 10, and the vibration signal input from the vibration detection function 8 is set under the condition set in the measurement management function 1. According to the FFT function 10, the analysis is performed. The analysis result by the FFT function 10 is recorded and output according to a predetermined condition by the analysis result processing function 11.

The operation of the above-described measuring device will be described in detail with reference to FIGS. FIG. 2 is a block diagram showing each element operation of the function according to the present invention by each functional block, and FIG. 3 is a flow chart. Figure 1
The signal indicating the measurement frequency F created by the measurement frequency creation function 1a of the measurement management function 1 shown in 1 is input to the calculation timing creation function 9a. In addition, the unit phase angle Δθ, which is a phase pitch that is preset and recorded in the measurement management function 1 (recording function is not shown), which is a phase pitch for dividing the vibration waveform to be measured into a predetermined number, and the calculation timing generation function 9a and the calculation phase. It is input to the angle calculation function 9b. The calculation timing creation function 9a and the calculation phase angle calculation function 9b are the FFs described above.
This is a function provided in the T operation setting function 9. The calculation timing creating function 9a creates a calculation timing Δt according to the following equation (1), and outputs a calculation signal to the FFT function at each calculation timing Δt. Δt = 1 / F (2π / Δθ) (1) Further, the calculation timing creation function 9a is used for one calculation cycle of the FFT function, that is, the FFT corresponding to this measurement frequency F.
An integration control signal for controlling the integration operation of the function is output to the FFT function. The calculation phase angle calculation function 9b calculates the calculation phase angle θ by integrating the unit phase angle Δθ for each calculation timing Δt. Calculation phase angle calculation function 9b
In the sine function value creation function 12, an index is made from the trigonometric function table previously recorded in the recording function (not shown) provided in the FFT function 10 according to the calculated phase angle θ calculated in
in θ, cos θ in the cosine function value creation function 13
Are being created. For example, the torsional vibration of the rotating shaft 5 forcibly excited by the vibration exciter 4 driven by the vibration signal of the measurement frequency F generated by the measurement vibration signal generation function 2 causes the sensor 7 to generate an electric vibration signal S. Is converted to. The vibration signal S is further input to the vibration detection function 8 and converted into a signal form suitable for being analyzed by the FFT function.
That is, the sample hold function 8 provided in the vibration detection function 8
a, the vibration signal S is generated at the timing corresponding to the calculation timing input from the calculation timing generation function 9a.
Is sampled and the sample value is held until the next sampling. The vibration signal S held by the sample hold function 8a is multiplied by sin θ created by the sine function value creation function 12 by the multiplication function 14, and then integrated control signal input from the operation timing creation function 9a by the integration function 15. Is integrated according to. The Ss which is the result of integration by the integration function 15 is subjected to the arithmetic processing shown in the following equation (2) by the normalization function 16. Further, the normalization function 16 is input with a unit phase angle Δθ indicating a calculation pitch which is preset and recorded in the measurement management function 1 (the recording function is not shown). The result a calculated by the normalization function 16 is input to the vector addition function 20 and the calculation processing shown in the following equation (4) is performed. Further, the vibration signal held by the sump hold function 8a is multiplied by cos θ created by the cosine function value creation function 13 by the multiplication function 17, and then the integration control signal input from the operation timing creation function 9a by the integration function 18. Is integrated according to. The Sc, which is the result of integration by the integration function 18, is subjected to the arithmetic processing shown in the following equation (3) by the normalization function 19. Further, the normalization function 19 receives the unit phase angle Δθ indicating the calculation pitch set in the measurement management function 1. Normalization function 19
The result b, which has been subjected to the arithmetic processing in (4), is input to the vector addition function 20 and the arithmetic processing shown in the following equation (4) is performed. The addition result c in the vector addition function 20 is input to the above-mentioned analysis result processing function 11, subjected to predetermined processing, and output. a = Ss × [2 / (2π / Δθ)] ... (2) b = Sc × [2 / (2π / Δθ)] ... (3) c = (a ² + b ² ) ^{1 / 2} (4) The sine function value creation function 12 or the vector addition function 20 described above is an element function generally configured as an FFT function. Further, the sine function value creating function 12 and the cosine function value creating function 13 may be calculated by directly calculating from the trigonometric function table without indexing.

Correspondence between the block diagram shown in FIG. 2 and the block diagram shown in FIG. 1 and each functional block are described for convenience of explanation of the present invention as described above. The circuits that share the functions may be distributed or integrated according to the circuit conditions that constitute the vibration analysis system. For example, all the functions shown in FIG.
It may be included in the T device. Even if all the elemental functions are configured by hardware, the FFT function configured as a dedicated device and each processing other than the analog signal can be executed by the computer provided in the upper vibration analysis system. Alternatively, the computer including the FFT function may be used to execute the process including the FFT function. Further, the analysis function shown in FIG. 2 may be executed by a computer dedicated to analysis processing. In the case of computer processing, it is natural that the program is configured so that each element function shown in FIG. 2 has an appropriate function corresponding to software processing. For example, the integration function 15 does not perform the integration operation continuously as in an analog circuit, but sequentially adds up the sampling processing results. A flow when the above-mentioned functions are executed by a computer is shown in FIG.

In the arithmetic processing for calculating Δt from Δθ shown in FIG. 2, if the frequency set for this analysis is fixed,
Of course, if the calculation is performed first, it is not necessary to calculate until the frequency is changed next. In addition, such calculation processing can be executed by using the idle time of the analysis processing computer, and since the calculation time of one cycle is set corresponding to the predetermined frequency, the analysis processing with the required accuracy can be executed in a short time. it can.

The above description is for the basic structure and the basic method in the embodiment according to the present invention, and the measuring object may be a mechanical structure exhibiting any vibration form. Therefore, it can be applied to any type of vibration exciter or sensor. Further, the configuration of functional elements for measurement processing may be configured other than that shown in FIG. 2 if the technical idea of the present invention is used.
The order of the outline flow shown in FIG. 3 may be changed as appropriate.
The arithmetic processing to which the present invention is applied has been described as being performed by the FFT function, but it is needless to say that the present invention can be applied to other analysis methods based on the FFT function.

[0011]

Since the present invention is configured as described above,
It has excellent effects as described below. Since the analysis process is performed with the phase pitch that divides the measurement frequency by a predetermined number, the analysis process with desired accuracy can be executed at the optimum speed regardless of the measured frequency. With regard to the vibration characteristics of a mechanical structure having a complicated vibration form, it is possible to quickly and accurately measure the response vibration situation corresponding to a desired frequency. When the test load mechanism is vibrated at a specific frequency, the response data corresponding to the vibration frequency can be measured quickly and accurately. According to the measuring device based on the present invention, the above-mentioned excellent effects can be obtained with a simple configuration.

[Brief description of drawings]

FIG. 1 is a schematic block diagram showing an example of a mechanical vibration system vibration response characteristic measuring device to which the present invention is applied.

FIG. 2 is a schematic block diagram showing an example of an elemental functional configuration for explaining the operation of the present invention in the mechanical vibration system vibration response characteristic measuring apparatus shown in FIG.

FIG. 3 is a schematic flowchart illustrating a case where a computer executes the functions of the schematic block diagram shown in FIG.

[Explanation of symbols]

 1: Measurement management function 2: Measurement excitation signal creation function 3: Exciter drive function 4: Exciter 5: Rotation axis 6: Test load mechanism 7: Sensor-8: Vibration detection function 9: FFT operation setting function 10: FFT function

Claims (3)

[Claims] 1. A vibration exciter that is coupled to a test piece to apply a forced vibration, a sensor that is attached to the test piece to detect a vibration state of the test piece, and an FFT function that analyzes a measurement value detected by the sensor. In the mechanical vibration system vibration response characteristic measuring means, the mechanical vibration system vibration response characteristic is characterized in that the arithmetic processing in the FFT function is executed at a phase predetermined pitch for dividing one cycle of the waveform corresponding to the measurement frequency. Measuring method. 2. A vibration exciter coupled to a test piece for giving a forced vibration, a sensor mounted on the test piece to detect a vibration state of the test piece, and an FFT function for analyzing a measurement value detected by the sensor. A mechanical vibration system vibration response characteristic measuring device provided with means for recording a phase pitch for dividing one cycle of a measured vibration waveform into a predetermined number, and a function for calculating a calculation timing from the phase pitch and a predetermined measurement frequency. The mechanical vibration system vibration response characteristic measuring device is characterized in that the arithmetic processing in the FFT function is executed at the arithmetic timing. 3. A frequency setting means for forced vibration applied to a test piece, a vibration exciter coupled to the test piece for giving forced vibration of the set frequency, and a sensor mounted on the test piece to detect a vibration state of the test piece. And a mechanical vibration system vibration response characteristic measuring device having an FFT function for analyzing a measurement value detected by this sensor, a means for recording a measurement phase pitch for dividing one cycle of a measurement vibration waveform into a predetermined number, and this measurement The FF is provided with a function of calculating a calculation timing from the phase pitch and the forced vibration frequency.
A mechanical vibration system vibration response characteristic measuring device characterized by executing arithmetic processing in the T function.