JPH0718772B2 - Vibration tester - Google Patents

Description

[Detailed Description of the Invention] A. Field of Industrial Application [0001] The present invention relates to a vibration tester used for earthquake resistance tests of various structures and vibration tests of vehicles, home appliances and the like.

B. Prior Art FIG. 3 is a block diagram showing an outline of the configuration of a conventional vibration tester.

First, the tester body 1 will be described. Testing machine body 1
Includes a vibrating table 3 supported by the hydrostatic bearing 2. The sample 4 is mounted on the vibrating table 3. The vibrating table 3 is vibrated by the actuator 5. The actuator 5 is composed of a reciprocating hydraulic cylinder that converts a flow rate into a displacement and outputs the displacement. Associated with the actuator 5 is a servo valve 6 for flow control. The displacement of the vibration table 3 is detected by a displacement sensor 7 provided on one end side of the piston of the actuator 5. The acceleration of the vibration table 3 is detected by the acceleration sensor 8 attached to the vibration table 3.

Next, the control system will be described.

Data such as seismic waves are usually recorded as acceleration waveforms. Therefore, such an acceleration input signal is integrated twice by the double integration circuit 9 and converted into a displacement signal. on the other hand,
The displacement signal output from the displacement sensor 7 of the tester body 1 is amplified by the displacement amplifier 10. The table position setter 11
It is for setting the reference position of the vibrating table 3 and outputs a DC voltage. Double integration circuit 9 and table position setter 11
And the negative output of the displacement amplifier 10 are added together and given to the servo amplifier 12. Then, the output of the servo amplifier 12 is given to the servo valve 6 as a flow rate control signal. The output signal of the displacement amplifier 10 and the output signal of the acceleration sensor 8 amplified by the acceleration amplifier 13 are given to the monitor.

As described above, the conventional vibration tester converts the acceleration input signal into the displacement signal by double-integrating, gives the displacement according to the displacement signal to the vibrating table 3, and consequently the acceleration according to the acceleration input signal. (Force) is applied to the vibrating table 3.

C. Problems to be Solved by the Invention However, the conventional vibration testing machine adopting the above-mentioned double integration type displacement control has the following problems.

That is, since there is a second-order differential relationship between the displacement and the acceleration, if a slight error occurs in the displacement of the vibrating table 3, when this is second-order differentiated and converted into acceleration, a considerably large acceleration causes vibration. You are joining the stand 3. Therefore, the conventional device has a problem that the reproducibility of the acceleration waveform is poor.

Also, as the repetition frequency of displacement increases, the acceleration increases by ω ² times the displacement (ω is the angular frequency of displacement)
Will increase in size. Therefore, in the vibration test,
When it is desired to keep the acceleration applied to the specimen constant regardless of the frequency, according to the conventional device, it is necessary to reduce the displacement (1 / ω ² ) as the frequency increases. However, it is practically difficult to control the displacement in a minute range, and in this sense, the conventional device has poor reproducibility of acceleration.

The present invention has been made in view of such circumstances, and an object of the present invention is to provide a vibration tester that has good reproducibility of acceleration and can accurately analyze a vibration test.

D. Means for Solving Problems The present invention adopts the following configuration in order to solve the above problems.

That is, the vibration testing machine according to the present invention includes a displacement control mechanism that controls the drive unit of the vibration table and an acceleration control mechanism that uses the acceleration input signal as a target value. The displacement control mechanism detects the displacement of the vibrating table, and operates the frequency component that does not substantially include the frequency spectrum of the acceleration input signal to control the position of the vibrating table so as to maintain the center position of the vibrating table. On the other hand, the acceleration control mechanism detects the acceleration of the vibration table to directly operate the acceleration input signal to control the acceleration of the vibration table.

E. Action The acceleration control mechanism controls the acceleration of the shaking table by directly manipulating the acceleration input signal, while the displacement control mechanism effectively controls the frequency spectrum of the acceleration input signal to maintain the center position of the shaking table. Since the frequency components not included in are operated, the control systems do not interfere with each other, and the acceleration input waveform is accurately reproduced.

F. Embodiment FIG. 1 is a block diagram showing a schematic configuration of a vibration tester according to an embodiment of the present invention.

In the figure, the tester main body 1 has the same configuration as that shown in FIG. 3, and therefore description thereof is omitted here. The feature of this embodiment resides in that a displacement control mechanism and an acceleration control mechanism are provided as a mechanism for controlling the actuator 5 that drives the vibrating table 3.

The displacement control mechanism is a control mechanism for holding the center position of the vibrating table 3 so as not to overrun the vibrating table 3 during the vibration test, and includes a displacement sensor 7, a displacement amplifier 10, a table position setter 11, Displacement amplifier 10 and table position setter 11
Displacement control gain setting circuit that can give the difference of each output of 1
4, low-pass filter 1 with cutoff frequency set to 0.1Hz
5, a servo amplifier 12, a servo valve 6, and an actuator 5 are included in a closed loop.

This displacement control mechanism uses the actuator 5 so that the difference between the outputs of the displacement amplifier 10 and the table position setter 11 becomes zero.
The vibration table 3 by controlling the table position setter.
Hold at the position corresponding to the 11 output voltage.

On the other hand, the acceleration control mechanism controls the acceleration of the vibrating table 3 by directly operating the acceleration input signal, and gives the difference between the output of the acceleration sensor 8, the acceleration amplifier 13, and the acceleration amplifier 13 and the acceleration input signal. Single integration circuit 16, acceleration control gain setting circuit 17, high-pass filter 18 with cutoff frequency set to 0.1 Hz, servo amplifier 12, servo valve 6,
It is composed of a closed loop including the actuator 5.

This acceleration control mechanism consists of an acceleration input signal and an acceleration amplifier.
The acceleration (force) corresponding to the acceleration input signal is applied to the vibrating table 3 by controlling the actuator 5 so that the difference between the output and the output 13 becomes zero. As a result, the vibration table 3 vibrates with the center position held by the displacement control mechanism as a reference.

By the way, the reason why the single integration circuit 16 is provided in the acceleration control mechanism is as follows. That is, since the servo valve 6 is a flow rate (speed) control valve, the input signal (speed signal) of the servo valve 6 and the acceleration input signal have a first-order differential relationship. If the control system has one differential element, the control system may become unstable. Therefore, in this embodiment, by providing the single integration circuit 16 in the acceleration control mechanism,
It also aims to stabilize the control system by adding one integral element to the control system. This integral element can be provided at any position in the acceleration control system as long as it does not overlap with the displacement control system.

Further, the low pass filter 15 is provided in the displacement control mechanism and the high pass filter 18 is provided in the acceleration control mechanism for the following reason. That is, in this embodiment, the actuator 5
Since there are a displacement control system and an acceleration control system as the control system of (1), it is necessary to prevent the two control systems from interfering with each other in order to apply the acceleration that accurately reproduces the acceleration input signal to the vibration table 3. . For example, seismic waves as an acceleration input signal, usually has a power spectrum of about 0.1Hz ~ 100Hz, the frequency component of the displacement control system, so that it does not substantially include the spectrum component, that is,
It is necessary to prevent the frequency component of the displacement control system from significantly disturbing the power spectrum of the acceleration control system. Therefore,
In this embodiment, a frequency component of 0.1 Hz or less is used as the operation amount of the displacement control system, and a frequency component of 0.1 Hz or more is used as the operation amount of the acceleration control system.
The low-pass filter 15 of 1 Hz and the high-pass filter 18 with a cutoff frequency of 0.1 Hz are provided in the acceleration control mechanism. The filters 15 and 18 of each control system can be provided at arbitrary positions of each control system as long as the control systems do not overlap each other.

Since the acceleration control mechanism described above controls the acceleration applied to the vibration table 3 by directly operating the acceleration input signal, the acceleration input signal can be faithfully reproduced. Moreover,
The displacement control mechanism for maintaining the center position of the vibrating table 3 is
Since the operation amount is a frequency component that does not substantially include the spectrum of the acceleration input signal, the signal of the displacement control system does not affect the spectrum of the acceleration input signal. FIG. 2 shows respective waveforms of the acceleration input signal, the acceleration response signal and the displacement response signal of the embodiment shown in FIG.
The figure (a) is the seismic wave as the acceleration input signal a, the figure (b) is the acceleration response signal b of the vibrating table 3, and the figure (c) is the displacement response signal c of the vibrating table 3. As is clear from comparison between FIGS. 10A and 10B, it is understood that the acceleration that faithfully reproduces the acceleration input signal is applied to the vibration table 3.

In addition, in the above-mentioned embodiment, the description has been made by taking the horizontal 1-axis vibration tester as an example, but the present invention is not limited to this, and for example, a horizontal / vertical 2-axis vibration tester or a horizontal 2-axis vibration tester. It can be applied to various vibration testers such as the vibration tester of

Further, the mounting positions of the displacement sensor 7 and the acceleration sensor 8 in the embodiment are appropriately determined. For example,
Although the displacement sensor 7 is attached to one end side of the cylinder of the actuator 5 in the embodiment, it may be attached to the central portion of the vibrating table 3 to directly detect the displacement of the vibrating table 3 with respect to the floor surface. .

G. Effect of the Invention As is apparent from the above description, the vibration tester according to the present invention directly operates the acceleration input signal to control the acceleration of the vibrating table. Acceleration waveforms can be reproduced more accurately than in conventional devices that use displacement signals obtained by integration as manipulated variables. Further, since the frequency component that does not substantially include the frequency spectrum of the acceleration input signal is operated to maintain the center position of the vibration table, the displacement control system and the acceleration control system do not affect each other. Therefore, according to the present invention, the vibration analysis of the sample can be performed with high accuracy.

[Brief description of drawings]

FIG. 1 is a block diagram showing a schematic configuration of a vibration testing machine according to an embodiment of the present invention, and FIG. 2 is a waveform diagram of an acceleration input signal, an acceleration response signal and a displacement response signal of the embodiment, FIG. 3 is a block diagram showing a schematic configuration of a conventional vibration tester. 1 …… Tester main body, 3 …… Vibration table 4 …… Specimen, 5 …… Actuator 6 …… Servo valve, 7 …… Displacement sensor 8 …… Acceleration sensor, 10 …… Displacement amplifier 11 …… Table position setting Unit 12 …… Servo amplifier, 13 …… Acceleration amplifier 14 …… Displacement control gain setting circuit 15 …… Low pass filter 16 …… Single integration circuit 17 …… Acceleration control gain setting circuit 18 …… High pass filter

Claims (1)

[Claims] 1. A displacement control mechanism for controlling a drive section of a vibrating table and an acceleration control mechanism for setting an acceleration input signal as a target value, wherein the displacement control mechanism detects the displacement of the vibrating table to input the acceleration. The center position of the vibrating table is controlled by operating a frequency component that does not substantially include the frequency spectrum of the signal, and the acceleration control mechanism operates the acceleration input signal by detecting the acceleration of the vibrating table. A vibration tester that controls the acceleration of the vibration table.