JPS6038648B2 - Control device for electro-hydraulic servo material testing machine - Google Patents

Description

DETAILED DESCRIPTION OF THE INVENTION The present invention relates to a control device for an electro-hydraulic servo material testing machine.

FIG. 1 shows a control device for a conventional electro-hydraulic servo material testing machine.

The input signal is an electrical signal introduced from a programming device or function generator that provides the reference waveform to be tested, such as a sine wave, triangle wave, trapezoidal wave, ramp wave, complex wave, or other irregular program wave.

The control circuit 1 converts a control error by PID operation and outputs a manipulated variable. The controlled object 2 is a hydraulic device such as a servo valve or an actuator. The state of the controlled object 2 is the load cell,
It is detected as an electrical signal by a strain detector, an acceleration detector, etc., and is derived as a control amount to a data processing device, fed back, and compared with an input signal. In such a control device, the followability of the controlled object becomes poor in a high frequency region such as in a high-speed cyclic fatigue test, and the followability also becomes poor in the case of a large capacity such as an earthquake resistance test.

In such cases, the follower is usually compensated by differential operation, but differential operation has the disadvantage of amplifying noise sensitively and impairing stability, making adjustment difficult. Moreover, there are problems such as there are limits to compensation by differential operation. An object of the present invention is to provide a control device that faithfully controls a controlled object with respect to a reference wave to be tested without time delay without using differential operation. Second
The figure shows a block diagram of an embodiment of the invention. The input signal is T.
The first delay element 3 and the second delay element 4 that delay (T, 10T2) are connected vertically, and the difference (A-C) between the input signal A and the output C of the second delay element is The output of the first adder 5 to be calculated is input to the amplifier circuit 6. Furthermore, using the output B of the first delay element 3 as a control input, the deviation (B-D) of the control amount D with respect to the control input is calculated at the second addition point 7, and this is defined as a control error, which is at least proportional to the control input. A signal (E+F
) is input to the controlled object 101 as the manipulated variable to operate the controlled object. Next, the operation of this device will be explained with reference to the waveform diagram of FIG. 3 in the case where a triangular wave is input as an input signal. The input signal A, the output B of the first delay element 3 which is delayed by T, and the output C of the second delay element 4 which is further delayed by T2 are as shown in FIG. 3a.

Of these two waveforms, when signal B is used as a control input, the ideal manipulated variable is a square wave shown in FIG. 3b. However, in reality, the response speed of the controlled object does not completely follow the manipulated variable, so a time delay occurs, for example, as shown by the dotted line in FIG. 3b. Therefore, depending on the conventional device shown in Figure 1,
The control amount has poor followability to the input signal waveform, as shown by the dotted line in FIG. 3g. In the embodiment of the present invention, the delay time and T2 are set corresponding to the above-mentioned time delay, but the best values of these are determined experimentally from the entire system. Note that the reason why the delay element is divided into two is to provide symmetry between the control amount D and the control input B. On the other hand, since the adder 5 calculates (A-C), a waveform as shown in FIG. 3c is obtained. That is, signal A
and the signal A is transmitted to the first and second delay elements 3 and 4.
The difference (A-C) between the signal C and the signal C that has passed is equivalent to taking the differential value of the signal A. In other words, if time t is a variable, A(t)=B(t-T,), C(t)B(t+
L), so A(t)-C(t)=B(t-T.)
10B (t1L) Therefore, A-C is time (T, 10T
2) represents the rate of change of signal A.

By increasing such signals (A-C) as appropriate, the control symmetry 10
When the control amount D is supplied as a manipulated variable, that is, when the signal E is 0 in FIG. 2, the control amount D becomes as shown in FIG. 3d. Further, a signal E representing the deviation of the above-mentioned control amount D with respect to the control input B via the control circuit 8 is as shown in FIG. 3e. When the signal F obtained by suitably increasing the signal (A-C) described above is added to this signal E by the adder 9, the signal waveform becomes as shown in FIG. 3f. This E+F signal waveform has a shape approximated by the square wave shown in FIG. 3b, and when this is supplied as the manipulated variable to the control target 101,
The control amount D has a waveform extremely close to the waveform of the input signal B, as shown by the solid line in FIG. 3g. FIG. 4 shows a block diagram of another embodiment of the invention. This embodiment differs from the previous embodiment in that the delay element 3 in the previous stage is omitted.
This also makes it possible to approximately obtain an ideal manipulated variable. FIG. 5 shows a modified embodiment of the invention that can be applied when two servo valves are used.

A servo valve 12 driven by the output F of the amplifier circuit 6 gives a rough flow rate, and a servo valve 11 driven by the output of the control circuit 8 performs precise control. in general,
A small-capacity servo valve has a fast response speed, and the larger the capacity, the slower the response speed. Therefore, by using a large-capacity servo valve 12 and a small-capacity servo valve 11, it is possible to control large-capacity objects. can also provide high-speed response. Here, if the response delay of the large-capacity servo valve 12 is larger than the response of the servo valve 11, the control input supplied to the adder 7 is not signal B as shown in FIG. It is only necessary to make the signal C' as shown in FIG. As explained above, according to the present invention, even if the controlled object has a large capacity and a slow response speed, drive control can be performed faithfully to the input signal and without time delay, and especially when irregular programs Great effect against waves.

[Brief explanation of the drawing]

FIG. 1 is a block diagram showing a conventional example. Fig. 2 is a block diagram showing an embodiment of the present invention, and Fig. 3 is a block diagram showing an embodiment of the present invention.
FIG. 3 is a waveform diagram illustrating the operation of the illustrated embodiment. FIG. 4 is a block diagram showing another embodiment of the present invention. Figure 5 is the second
FIG. 5 is a block diagram showing a modified embodiment that can be applied to either the embodiment of FIG. 3, 4... Delay element, 6... Difference signal amplification circuit, 8... Control circuit, 10... Controlled object, 5, 7, 9...・・・
・Adder. Figure 1 Figure 2 Figure 3 Figure 4 Figure 5

Claims (1)

[Claims] 1 A device that controls a hydraulically controlled object according to an electrical input signal that provides a reference waveform to be tested, including a delay element that delays the input signal for a predetermined period of time, and the difference between the input signal and output signal of the delay element. An electro-hydraulic device, characterized in that a difference signal amplification circuit is provided for extracting and amplifying the difference signal, the output signal of the delay element is used as a control input signal, and the output signal of the difference signal amplification circuit is added to the output of the control circuit. Control device for servo type material testing machine.