JPS5852241B2 - Acceleration waveform correction device - Google Patents

Description

DETAILED DESCRIPTION OF THE INVENTION The present invention relates to a device for correcting disturbances in acceleration waveforms of equipment having a friction mechanism, and in particular for correcting input waveforms so that input signals given to hydraulic servo equipment can be faithfully reproduced in their output. related to a device for

It is well known that pulse-like disturbances are generally observed in hydraulic servo equipment when its response is measured using an accelerometer.

For example, in a hydraulic servo-type shaking table device, when the shaking table is driven with a simple signal such as a sine wave, the displacement waveform is sufficiently clean, but when measured with an accelerometer, the peaks and valleys of the sine wave, i.e. Pulse-like disturbances are observed near the peak.

This can be said to occur when the acceleration reaches its maximum, that is, when the speed of the shaking table decreases and its direction of motion changes.

There are three main causes of such pulse-like disturbances.
It turns out that there are two possible causes.

That is, one effect is due to the frictional resistance of the vibration table support mechanism and the drive device, and the other two are due to the flow characteristics of the servo valve.

Moreover, all of these factors have nonlinear characteristics,
It depends on many factors such as vibration table amplitude, acceleration, oil flow rate, and drive frequency.

In the conventional technology, as a countermeasure against the above-mentioned pulse-like disturbance, methods such as cutting off the disturbance using a filter etc. have been taken, but with this method, the above-mentioned essential cause of the disturbance can be compensated for. It was not possible to do so, and the only apparent effect was to make the upper response waveform resemble the input waveform.

Therefore, an object of the present invention is to provide an input waveform correction device that corrects the frictional resistance of the support mechanism and drive device, which is considered to have a particularly large influence among the causes of disturbance.

DESCRIPTION OF THE PREFERRED EMBODIMENTS Preferred embodiments of the present invention will be described in detail below as illustrated in the accompanying drawings.

First, an example of a hydraulic servo mechanism to which the device of the present invention is applied will be explained.

FIG. 1 shows an example of a horizontal and vertical vibration type vibration table device, and FIG. 2 shows an example of the vibration device.

The vibration table 2 is horizontally moved by a horizontal actuator 4.
It is driven vertically by a vertical actuator 6 and can be vibrated horizontally and vertically at the same time.

These actuators 4 and 6 are connected to the siebel head 8
One end is fixed to the shaking table 2 and the other end is fixed to the inner wall.

The Siebel head 8 on the vibration table side is directly connected to the piston rond of the actuator internal piston 12, and the Siebel head 8 on the wall side is fixed to the cylinders of the actuators 4 and 6.

The operation of the piston 12 is controlled by a servo valve 10, and the servo valve 10 controls injection and discharge of hydraulic pressure into the cylinder based on an input signal.

A differential transformer 14 is attached to the tip of the piston rond, and detects the movement of the piston 12, that is, the displacement of the vibration table.

FIG. 3 is a block diagram showing the entire vibration table device equipped with a waveform correction device.

Reference numeral 20 denotes an input signal source, such as a function generator or a tape recorder for reproducing and outputting the signal to be excited.

The output of the input signal source 20 is a waveform correction device 22 according to the present invention.
The side splitting device 24 is connected to a vibration device 26 and a hydraulic power source 28.

Control device 24 includes horizontal and vertical controls.

These controllers are connected via line 30 to a servo valve signal input in force device 26 and via line 32 to differential transformer 14 .

It is also connected via line 34 to hydraulic power source 28 to control a hydraulic pump.

The hydraulic source 28 is connected via a conduit 36 to a servo valve hydraulic input of the force applying device 26 .

The waveform correction device 22 is comprised of a simulation circuit 56 and an inverse transfer function circuit 58, as shown in FIG.

The simulation circuit 56 is composed of a circuit that assumes that there is no frictional resistance in the vibration table system including the drive control device and the controlled object, and a circuit that applies frictional resistance in exactly the opposite direction to the previously analyzed frictional resistance.

Further, the inverse transfer function circuit 58 is a simulation circuit 56
It gives the inverse of the transfer function of a circuit system assuming that there is no frictional resistance.

Input terminal 40 is connected to the output of the function generator or tape recorder of input signal source 20.

In the simulation circuit 56, the input terminal 40 is connected to the transfer element G1 adder 44, the transfer element ω2, and further to the adder 46 via an adder 42 which is a summing point.

Adder 46 is connected to adder 48 via first integral element i, and element 2hω is feedback-coupled to adder 46.

The adder 14B is connected to the third integral element I via the second integral element to simulate the transfer function of the system.

Further, the output of the second integral element M is feedback-coupled to the adder 48 via the nonlinear element 50 and element M, which provide a force in the direction exactly opposite to the frictional resistance actually acting on the vibration table.

The inverse transfer function circuit 58 is a circuit that expresses the inverse 2h transfer function of the circuit excluding the nonlinear element 50 of the simulation circuit 56, and has an element G' (3-c
The output of the adder 52 is connected to the control device 24 via the output terminal 54. .

Here each symbol is G: System gain ω: Natural frequency of the system M: Weight of test object h: damping constant of the system It represents.

The simulation circuit 56 includes a nonlinear element 50 that forms a reverse friction circuit that generates a nonlinear waveform signal in the direction exactly opposite to the pulse-like disturbance that appears in the response signal of the system to an input signal of the system, such as a sine wave input signal. .

In this way, if the system is given an input that responds with a waveform in exactly the opposite direction as described above, it is possible to cancel the disturbance in the waveform due to the influence of frictional resistance.

Therefore, in this device, the output of the simulation circuit 56 is multiplied by an inverse transfer function, which is the reciprocal of the transfer function excluding the frictional resistance of the system, to cancel the transfer function other than the inverse frictional resistance, and then input to the system. There is.

In this way, when the input signal of the system is input to the control device 24 via the waveform correction device 22, the response waveform C is the same as the response of the system to the input signal at the input terminal 40 when no frictional resistance acts and the system is linear. This can be seen in the response waveform of the vibration excitation device 26.

This means that the disturbance in response due to frictional resistance has been corrected and is a special price.

When using such a waveform correction device, it is necessary to know in advance the transfer function of the entire equipment having the hydraulic servo mechanism to be applied and the characteristics of the frictional resistance acting on the system.

This can be easily determined by measuring during a trial run.

From this transfer function, the variables of the waveform correction device, namely, G,
09M and h are set, and the positive and negative values are reversed based on the measured frictional resistance characteristics to set the characteristics of the nonlinear element 50.

Since these values change depending on the test object to be vibrated, they are made variable and set for each test object.

By inputting an input signal to the waveform correction device 22 in which variables are set, and inputting the output signal to the control device 24, the output of the hydraulic servo equipment can be faithfully reproduced to the original human input signal.

Examples of this output waveform are shown in FIGS. 5 and 6.

Figures 5 and 6 show the case where a sine wave is input as the input signal, Figure 5 shows the case without using the waveform correction device, and Figure 6 shows the case when the waveform correction device is used. .

As seen in FIG. 6, the output waveform is well reproduced, and this also shows that most of the disturbances in the acceleration waveform are due to frictional resistance.

As mentioned above, in the past, even if the cause of waveform distortion observed in hydraulic servo systems was known, it was extremely difficult to mechanically improve it. However, according to the present invention,
The cause of these distortions is considered to be one of the transfer characteristics of a series of hydraulic servo systems, and by correcting the input waveform using a simulation circuit that generates inverse disturbances and an inverse transfer function, waveform disturbances can be easily corrected. It is now possible to improve.

As a result, the operation of the machine can be ensured,
As a result, it has become possible to obtain more reliable data in vibration experiments and the like.

Furthermore, in other fields such as seismic engineering and control engineering, it becomes possible to accurately operate and control devices with friction mechanisms such as actuators.

Although the present invention has been described above in detail with reference to specific examples thereof, the present invention is not limited to these specific examples, and it goes without saying that many changes and modifications can be made without departing from the spirit of the invention.

For example, the device of the present invention can be applied to general servo mechanisms that are subject to the action of frictional resistance. Servo mechanisms include not only hydraulic servos, but also electric servos, pneumatic servos, etc. Also, for displacement control and speed control, reverse It is also possible to apply the principle of the device of the present invention of multiplying the output of the simulation circuit that generates the disturbance by an inverse transfer function, and modify the circuit shown in FIG. 4 accordingly.

[Brief explanation of drawings]

Fig. 1 is a diagram showing an example of equipment using a hydraulic servo, Fig. 2 is a diagram showing a force applying device, Fig. 3 is a diagram showing the configuration of equipment using a waveform correction device according to the present invention, and Fig. 4 is a circuit diagram of a waveform correction device according to the present invention, FIG. 5 is a diagram showing an example of a response wave (sine wave) of a device using a hydraulic servo that does not use the device of the present invention, and FIG. It is a figure which shows the example of a response wave. 2... Vibration table, 4, 6... Actuator, 8... Sebel head, 10...
・Servo valve, 12...Piston, 14...
... Differential transformer, 20 ... Input signal source,
22... Waveform correction device, 24... Control device, 26... Vibration device, 28... Hydraulic power source, 42.44.46.48. 52...Adder, 50...Nonlinear element, 56...Simulation circuit, 58...Inverse transfer function circuit.

Claims (1)

[Claims] 1. A simulation circuit that creates a response simulation waveform by mixing a disturbance in the direction exactly opposite to the disturbance in the response waveform that occurs when a system including a drive control device of a device having a friction mechanism and a controlled object is driven by a certain human signal. and an inverse transfer function circuit that multiplies the simulation waveform by a reciprocal of a transfer function excluding frictional resistance of the system, and the simulation circuit includes a nonlinear element that provides frictional resistance in the opposite direction to the actual one. Acceleration waveform correction device.