JPH0721438B2 - Vibration tester - Google Patents

Description

DETAILED DESCRIPTION OF THE INVENTION A. Field of Industrial Application The present invention relates to a vibration tester used for a seismic resistance test of various structures and a vibration test of vehicles, home appliances and the like, and particularly,
The present invention relates to a vibration tester that vibrates one vibration table with a plurality of actuators.

B. Prior Art FIG. 4 is a block diagram showing an outline of the configuration of a conventional vibration tester.

Normally, seismic waves are recorded as an acceleration waveform, so an acceleration input signal is given to this type of vibration tester. On the other hand, since the conventional vibration tester adopts the displacement control method as described later, the acceleration input signal is given to the double integrator circuit 1 and double-integrated here to be converted into the displacement input signal before each control. Given to systems 2A-2D.

The control systems 2A to 2D are independently provided corresponding to four actuators (not shown) supporting one vibrating table. A double-acting hydraulic cylinder is used as the actuator. Since the control systems 2A to 2D have the same configuration, the control system 2A will be described as an example here.

The control system 2A includes a displacement sensor 3A that detects the displacement of the piston of the actuator, a displacement amplifier 4A that amplifies the output of the displacement sensor 3A, a servo amplifier 5A, and a servo valve 6A. The difference between the displacement input signal output from the double integration circuit 1 and the displacement amplifier 4A is the servo valve 6A via the servo amplifier 5A.
The servo valve 6A controls the flow rate given to the actuator based on its output. As a result, the actuator applies a displacement corresponding to the displacement input signal to the vibrating table, and as a result, the vibrating table is moved at an acceleration corresponding to the acceleration input signal.

C. Problems to be Solved by the Invention However, the conventional vibration testing machine employing the displacement control method as described above 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, when this is second-order differentiated and converted into acceleration, a considerably large acceleration causes the vibration. You are joining the stand. Therefore, the conventional device has a problem that the reproducibility of the acceleration waveform is poor.

Also, since there is a slight difference in characteristics between each actuator and each servo valve, when one vibration table is vibrated by multiple actuators, the force applied to each actuator is not uniform, and as a result, There is also a problem in that some actuators are overloaded, causing failure of the actuators or abnormal movement of the vibration table.

The present invention has been made in order to solve such a problem, and it is possible to accurately reproduce an acceleration waveform and to even out the force applied to each actuator so that the vibration table vibrates smoothly. The purpose is to provide a testing machine.

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

That is, the present invention is, in a vibration tester for vibrating one vibrating table with a plurality of actuators, a displacement control mechanism which is provided corresponding to each of the actuators and holds a reference position of each actuator, and an acceleration of the vibrating table. The acceleration control mechanism that controls the acceleration of each actuator by collectively operating the acceleration input signal by detecting, and the static correction amount that equalizes the average differential pressure of each actuator by detecting the differential pressure of each actuator. A dynamic correction amount for equalizing the dynamic differential pressure of each actuator is calculated for each actuator, and the static correction amount is given to each displacement control mechanism, while the dynamic correction amount is given to the acceleration control mechanism. It is characterized in that it is provided with a calculation control unit for giving.

E. Working acceleration control mechanism directly controls the acceleration of each actuator, while the arithmetic control unit controls the average differential pressure of each actuator to be equal and the dynamic differential pressure of each actuator is equal. Are controlled so that each actuator moves the vibrating table with a force of almost the same strength.

F. Examples Hereinafter, examples of the present invention will be described with reference to the drawings.

FIG. 1 is a block diagram showing the outline of the configuration of an embodiment of the present invention, and FIG. 2 is an explanatory view of a tester main body in the embodiment.

First, the tester main body will be described with reference to FIG. FIG. 2 (a) is a plan view of the tester body, and FIG. 2 (b) is a front view.

In FIG. 2, reference numeral 11 is a vibrating table on which a sample (not shown) is placed. The vibrating table 11 is supported by four actuators 12A to 12D whose four corners are pin-connected. The vibrating table 11 is vertically vibrated by these actuators 12A to 12D. The actuators 12A to 12D are composed of double-acting hydraulic cylinders that convert a flow rate into a displacement and output the displacement. Servo valves 13A to 13D for flow rate control, differential pressure sensors 14A to 14D for detecting the pressure difference between the upper and lower chambers of the piston, and displacement sensors 15A to 15D for detecting the displacement of the piston are respectively associated with the actuators 12A to 12D. It is provided.
Further, an acceleration sensor 16 that detects the acceleration applied to the vibration table 11 is attached to the vibration table 11. The acceleration sensor 16 is attached to the central portion of the vibrating table 11 so as to be equally affected by the actuators 12A to 12D.

Next, the control system of this embodiment will be described with reference to FIG.

In FIG. 1, constituent parts of each control system corresponding to each actuator 12A to 12D are represented by suffixes A to D. Since the components of each control system are the same, the control system related to the actuator 12A will be described here as an example.

Displacement sensor 15A, displacement amplifier 17A, displacement gain setting circuit 18
A, the servo amplifier 19A, and the servo valve 13A constitute a displacement control system for holding the reference position of the actuator 12A. Reference numeral 20 is a reference position setter for setting the reference positions of the actuators 12A to 12D, and outputs a DC voltage according to the set positions. The difference between the output of the displacement sensor 15A amplified by the displacement amplifier 17A and the output of the reference position setting device 20 is given to the displacement gain setting circuit 18A. The output of the displacement gain setting circuit 18A is applied to the servo valve 13A via the servo amplifier 19A, so that the actuator 12A holds the reference position set by the reference position setter 20.
Is displacement controlled. Similar displacement control is performed for the other actuators 12B to 12D, and as a result, the vibration table 11 supported by the actuators 12A to 12D is held at the reference position.

The acceleration sensor 16, the acceleration amplifier 21, the acceleration total gain setting circuit 22, the acceleration gain setting circuit 23A, the servo amplifier 19A, and the servo valve 13A are an acceleration control system corresponding to the actuator 12A. However, the acceleration sensor 16, the acceleration amplifier 21, and the acceleration total gain setting circuit 22
Are common to the other actuators 12B to 12D. The acceleration total gain setting circuit 22 is an acceleration sensor amplified by the acceleration amplifier 21 and an acceleration input signal such as seismic wave.
The difference from the output of 16 is given, and this is appropriately amplified and output to the acceleration gain setting circuit 23A. The output of the acceleration gain setting circuit 23A is given to the servo valve 13A via the servo amplifier 19A added to the output of the displacement gain setting circuit 18A. As a result, the actuator 12A vibrates around the reference position held by the displacement control system, and the vibration table
Add the acceleration (force) corresponding to the acceleration input signal to 11.

The output of the acceleration total gain setting circuit 22 corresponds to the acceleration gain setting circuit 23B corresponding to the other actuators 12B to 12D.
23D to 23D in the same manner, the four actuators 12A to 12D that support the vibrating table 11 are similarly acceleration-controlled. This is different from the displacement control system that controls each actuator. As described above, the four actuators 12A to 12D are directly acceleration-controlled by the signals obtained by collectively operating the acceleration input signals.

By the way, since there are the displacement control system and the acceleration control system as the control system of each actuator as described above, in order to accurately reproduce the acceleration input signal, it is necessary to configure the interference between the two control systems as small as possible. Is desirable.
Therefore, in this embodiment in which a seismic wave is used as an acceleration input signal, the following is performed.

That is, since a seismic wave usually has a power spectrum of about 0.1 to 100 Hz, the displacement control system operates a frequency component of 0.1 Hz or less, and the acceleration control operates a frequency component of 0.1 Hz or more (acceleration input signal). Avoiding interference between both control systems.

Further, since the servo valve is a flow rate (speed) control valve, the input signal (speed signal) of the servo valve and the acceleration input signal have a first-order differential relationship. Therefore, the acceleration control system may become unstable. Therefore, a single integral element is added to the acceleration total gain setting circuit 22 to stabilize the control system. Such a single integral element may be provided in any part of the acceleration control system as long as it does not overlap with the displacement control system, and may be added to each of the acceleration gain setting circuits 23A to 23D, for example.

Next, a configuration provided for correcting the imbalance of forces between the actuators 12A to 12D and the servo valves 13A to 13D caused by variations in the characteristics of the actuators will be described.

The pressure difference between the upper and lower chambers of the piston of each actuator is detected by the differential pressure sensors 14A to 14D provided in each actuator. FIG. 3 shows an example of signal waveforms detected by the differential pressure sensor while the actuator is being driven. In the figure, S _P represents the average differential pressure obtained by averaging the differential pressure, and G _P represents the dynamic differential pressure corresponding to the amplitude of the differential pressure. The average differential pressure S _P and the dynamic differential pressure G _P are usually slightly different for each differential pressure sensor 14A to 14D due to variations in the characteristics of each actuator.

The outputs of the differential pressure sensors 14A to 14D are amplified by the differential pressure amplifiers 24A to 24D and then given to the arithmetic control circuit 25. The arithmetic control circuit 25, based on the outputs of the differential pressure sensors 14A to 14D, the static correction amounts S _{A to} S _D such that the respective average differential pressures S _{P of} the actuators 12A to 12D are equal, and the actuators 12A to 12D. The dynamic correction amounts G _{A to} G _D are calculated so that the respective dynamic differential pressures G _P are equal to each other. Specifically, the average value S _AVE of the average differential pressure S _P of each differential pressure sensor 14A to 14D is calculated, and the difference between this average value S _AVE and the average differential pressure S _{P of} each actuator is calculated as the static value of each actuator. Correction amount S _A ~ S _D.
The average value of each dynamic differential pressure is similarly applied to the dynamic correction amounts G _{A to} G _{D.
Calculated} from the difference between G _AVE and each dynamic differential pressure.

The static correction amounts S _{A to} S _D calculated in this way are used in the displacement gain setting circuit of the displacement control system of each actuator 12A to 12D.
As a result of being added to the respective inputs of 18A to 18D, displacement control is performed so that the average differential pressure S _P of each actuator 12A to 12D becomes equal.

On the other hand, the dynamic correction amounts G _{A to} G _D are set by the respective acceleration gain setting circuits 23
The gains of the acceleration gain setting circuits 23A to 23D are controlled so that the dynamic differential pressures G _{P of the} actuators 12A to 12D become equal to each other.

As described above, the average differential pressure S _P of each actuator 12A to 12D is
And the dynamic differential pressure G _P is controlled so as to be equal to each other, the variations in the characteristics of the actuators and the like are corrected, and the vibration table 11 is driven by the actuators 12A to 12D with equal forces.

It should be noted that, in the above-mentioned embodiment, the vibration tester in which four actuators are vertically driven by the vibrating table has been described as an example, but the present invention is not limited to such a vibration tester, and a plurality of vibration testers are used. It can be applied to a vibration tester that vibrates a vibrating table with a table actuator. It goes without saying that the invention can also be applied to a vibration tester in which the vibration table is moved in the horizontal direction.

Further, since the arithmetic control circuit 25 described in the embodiment is provided with the differential pressure detection signal of each actuator, by adding a function of detecting an abnormal differential pressure to this arithmetic control circuit, an alarm signal is output when the differential pressure is abnormal. Then, it is possible to easily realize a safety mechanism that informs the operator of the abnormality or stops the actuator.

G. Effect of the Invention As is clear from the above description, according to the vibration tester of the present invention, the acceleration of a plurality of actuators that move one vibrating table is collectively controlled, and each actuator has substantially the same strength. Since the vibrating table is moved by the force of, the movement of the vibrating table is smoother than that of the conventional device that uses an independent displacement control method for each actuator.
It is possible to accurately reproduce the acceleration waveform.

[Brief description of drawings]

FIG. 1 is a block diagram showing the outline of the configuration of an embodiment of the present invention, FIG. 2 is an explanatory view of the tester main body in the embodiment, and FIG. 3 is an output waveform of the differential pressure sensor in the embodiment. FIG. 4 is a block diagram showing the outline of the configuration of a conventional vibration tester. 11 …… Shaking table 12A ～ 12D …… Actuator 13A ～ 13D …… Servo valve 14A ～ 14D …… Differential pressure sensor 15A ～ 15D …… Displacement sensor 16 …… Accelerometer 18A ～ 18D …… Displacement gain setting circuit 20 …… Reference position setter 22 …… Acceleration total gain setting circuit 23A ～ 23D …… Acceleration gain setting circuit 25 …… Computation control circuit

Claims (1)

[Claims] 1. A vibration testing machine for vibrating one vibrating table with a plurality of actuators, wherein a displacement control mechanism, which is provided corresponding to each of the actuators, holds a reference position of each actuator, and an acceleration of the vibrating table. The acceleration control mechanism that controls the acceleration of each actuator by collectively operating the acceleration input signal by detecting, and the static correction amount and the static correction amount that equalize the average differential pressure of each actuator by detecting the differential pressure of each actuator. A dynamic correction amount for equalizing the dynamic differential pressure of the actuator is calculated for each actuator, and the static correction amount is given to each displacement control mechanism, while the dynamic correction amount is given to the acceleration control mechanism. A vibration testing machine comprising an arithmetic control unit.