JPH0567170B2 - - Google Patents

Description

[Detailed Description of the Invention] [Field of Industrial Application] The present invention relates to an electro-hydraulic servo system control device,
In particular, the present invention relates to an electro-hydraulic servo system control device suitable for an electro-hydraulic servo mechanism of a hydraulic vibration testing machine.

[Conventional technology]

Conventional electro-hydraulic servo system control devices, for example, as described in Japanese Patent Publication No. 51-29419, calculate optimal values for each gain of the servo amplifier, velocity feedback, and acceleration feedback, which are set in advance according to the weight of the test object. These feedback gain values were then adjusted if the weight of the test specimen changed.

In addition, those described in Japanese Patent Publication No. 51-37547 are
Limiting the excitation to sinusoidal waves, the DC voltage command value corresponding to the magnitude of vibration acceleration is compared with the DC voltage output value obtained by converting the output of the acceleration detector of the vibration table into DC, and the difference between the two is determined by the vibration exciter. It was designed to adjust the level of the sine wave input signal sent to the control servo system.

Furthermore, the stability control device of the vibration testing machine described in JP-A-55-114930 simulates the model response corresponding to the state quantity of the vibration table by inputting input signals such as displacement, velocity, and acceleration from the signal generator. Gain adjustment that automatically adjusts the gain of the input signal and the gain of the feedback signal using the model calculation circuit that performs the calculation, the model response signal from the model calculation circuit, the state quantity signal from the feedback circuit, and the input signal from the signal generator. It had a circuit.

[Problem to be solved by the invention]

In the prior art described in Japanese Patent Publication No. 51-29419, the test weight on the vibration table is detected by a pressure transducer as the hydraulic pressure of the hydraulic flotation device, and the servo amplifier, velocity feedback, and acceleration feedback are controlled accordingly. The gain value is set automatically. Although this method is technically easy to implement and is a practical method, it has the following problems.

1. In order to experimentally determine the relationship between the live load and the optimal value of each feedback gain in advance, it is necessary to collect test data with various loads being loaded, which requires a large amount of time.

2. If the shaking table is a two-dimensional or three-dimensional shaking table with multiple vertical shakers, it is difficult to accurately determine the test weight.

3. If an abnormality occurs in the feedback gain automatic adjustment system, the control system may become unstable and oscillate.

Furthermore, in the prior art described in Japanese Patent Publication No. 51-37574, the excitation waveform is limited to a sine wave.
It cannot be applied to random waves or seismic waves.

Even in the case of a sine wave, there are problems such as a significant drop in setting accuracy when the waveform is distorted by higher-order frequency components superimposed on the fundamental frequency component.

Furthermore, the conventional technology described in JP-A No. 55-114930 is based on a theoretical approach in that it automatically sets the value of the gain adjustment section in response to fluctuations in test weight and stabilizes the control system. However, in reality, if an abnormality occurs in the feedback gain calculation system or automatic adjustment system, or if the characteristics of the test machine are significantly different from the characteristics of the response model, it is difficult to find an appropriate value. However, no consideration was given to the possibility that the control system would become unstable and oscillate.

The present invention was made in order to solve the problems of the prior art described above, and it is possible to transfer the transfer function to the shaking table control system, which changes depending on the weight of the test object, to a closed-loop control system without detecting the weight of the test object. To provide an electrohydraulic servo system control device that improves control performance and operability by adjusting and correcting the characteristics of an input signal calculator outside a closed loop control system so as to maintain a stable state at all times. This is its purpose.

[Means to solve the problem]

In order to achieve the above object, an electrohydraulic servo system control device according to the present invention has an input circuit system including a signal generator and an input signal calculator, and an input current that applies at least a displacement to a vibration table. In an electro-hydraulic servo system control device comprising an electro-hydraulic servo system equipped with a vibration exciter and a feedback circuit system that feeds back the displacement, velocity, and acceleration of the vibration table to the input side, the input signal calculator is configured to A signal corresponding to the once-integrated value and twice-integrated value of the acceleration command signal from the signal generator for giving displacement to the table is calculated, and three types of signal information corresponding to acceleration, velocity, and displacement are calculated. The characteristics of the control system including the signal calculator and the vibration table shall be output at a ratio such that the characteristics of the control system are the same as the first-order lag element, and a transfer function measuring device for determining the frequency response characteristics of the control system and a previously determined A storage device that stores a transfer function when a maximum allowable load is loaded as a target transfer function, and a comparison calculation between a transfer function when a test volume is loaded obtained by the transfer function measuring device and a target transfer function stored in the storage device. , 3 of the input signal calculator
and a gain controller that adjusts the characteristics of the input signal calculator to an appropriate value by determining an optimal ratio for approximating the transfer function when the test volume is loaded to the target transfer function for the seed signal. be.

[Effect]

According to the above technical means, first, the gains of the servo amplifier, velocity feedback, and acceleration feedback are set to optimal values when the live load is the maximum permissible load of the vibration table.

After that, even if the weight of the test specimen loaded on the shaking table changes, the responsiveness will decrease because the gains of the servo amplifier, velocity feedback, and acceleration feedback are fixed at the above values. However, stability is not compromised.

If the transfer function when the maximum allowable load is loaded is the target transfer function, the transfer function when the test weight changes is determined by a transfer function measuring device. This obtained transfer function is expressed as the product of the input signal calculator's transfer function and the servo system's transfer function, and the difference from the target transfer function is due to the change in the servo system's transfer function due to a change in the live load. This is due to the fact that Therefore, the change in the transfer function of the servo system is
If the correction is made by changing the transfer function of the input signal calculator, it becomes possible to always maintain the target transfer function in a stable state.

〔Example〕

Embodiments of the present invention will be described below with reference to FIGS. 1 to 4.

First, FIG. 1 is a system diagram showing the configuration of an electro-hydraulic servo system control device in a vibration testing machine according to an embodiment of the present invention, FIG. 2 is a block diagram of its main parts, and FIG. FIG. 2 is a control circuit diagram of an input signal calculator used in the device shown in FIG. 1; In each figure, parts with the same reference numerals are the same.

In FIGS. 1 and 2, reference numeral 1 denotes a vibration table of a hydraulic vibration testing machine, and this vibration table 1 is driven by, for example, a hydraulic flotation device using a hydrostatic bearing (not shown). 2 is a vibration exciter such as a hydraulic cylinder that gives displacement to the vibration table 1; 3 is an input current i;
A servo valve for controlling the direction and flow rate of pressure oil from the hydraulic source 4 supplied to the vibrator 2 by the
These constitute a shaking table control system, that is, an electro-hydraulic servo system.

5 is a signal generator, 6 is an input signal calculator whose details will be described later, 7 is an adder, and 8 is a servo amplifier, which constitute an input circuit system.

9 is a displacement detector, 10 is a speed detector, 11 is an acceleration detector, 13 is a speed feedback gain adjustment section, and 14 is an acceleration feedback gain adjustment section, which are used to detect the displacement, speed and This constitutes a feedback circuit that feeds back acceleration to the input circuit side.

A closed loop control system is comprised of an adder 7, a servo amplifier 8, an electro-hydraulic servo system (vibration table control system), and a feedback circuit system.

12 is a storage device that stores the target transfer function;
5 is a transfer function measuring device for determining the frequency response characteristics of the control system including the input signal calculator 6 and the vibration table 1;
6 is a gain controller whose details will be described later.

Now, in the feedback element in the electro-hydraulic servomechanism, for example, in order to perform displacement follow-up control in response to an input signal, the displacement of the vibration table 1 is detected as a voltage signal by the displacement detector 9, and the voltage signal is sent to the adder 7. In addition to the main displacement feedback circuit that receives feedback, there is also a speed feedback circuit that detects the speed of the vibration table 1 by a speed detector 10 and feeds it back to the adder 7 for compensation, and
and an acceleration feedback circuit that detects the vibration acceleration by an acceleration detector 11 and feeds it back to the adder 7.

The input signal calculator 6 takes in information corresponding to the acceleration of the output of the vibration table 1, and sequentially integrates this information so that the characteristics of the control system including the input signal calculator 6 and the vibration table 1 are first-order delay elements. Information corresponding to velocity and information corresponding to displacement are calculated at a ratio equivalent to the characteristics of , and these three types of signal information of acceleration, velocity, and displacement are converted into voltage signals and supplied.

When the main element of the feedback circuit system is displacement, the adder 7 compares this element with information corresponding to displacement, and uses the other two input information, namely velocity and acceleration information, to predict the displacement input information. It is added as a signal.

Next, the operation of the electro-hydraulic servo system control device of this embodiment will be explained.

An acceleration command for giving displacement to the vibration table 1 is given by the signal generator 5 as an electric signal Er. That is, the signal generator 5 generates information such as a past earthquake waveform recorded as an acceleration waveform, a random wave as a pseudo earthquake waveform, or a sine wave with constant acceleration amplitude, as an electric signal Er.

The input signal calculator 6 receives an electric signal corresponding to the acceleration of the vibration table 1 inputted from the signal generator 5.
From Er, calculate the single integral value (signal corresponding to velocity) and double integral value (signal equivalent to displacement) of this signal, and obtain three types of signal information corresponding to acceleration, velocity, and displacement. , Ea, Ev, Ed at a ratio such that the characteristics of the control system including the input signal calculator 6 and the vibration table 1 are equivalent to the first-order delay element.
Output as .

On the other hand, the actual displacement of the shaking table 1 is measured by the displacement detector 9.
It is detected as an electrical signal by the adder 7, and is fed back to the adder 7, where it is compared with information Ed corresponding to the displacement. The difference is transmitted to the servo amplifier 8 as a control deviation, amplified, and then sent to the servo valve 3. The servo valve 3 uses this input current i to control the direction and flow rate of the pressure oil from the hydraulic source 4 that is supplied to the vibration exciter 2, so the vibration table 1 is moved in a direction that reduces the control deviation. Furthermore, in addition to the displacement feedback, the speed of the shaking table 1 is measured by a speed detector 10, and the acceleration of the shaking table 1 is measured by an acceleration detector 10, as a compensation element for improving characteristics, that is, increasing the stability of the closed-loop control system. 11, and feeds back to the adder 7.

The transfer function measuring device 15 takes in the electric signal Er of the acceleration command for the vibration table 1 and the output signal y¨ of the acceleration detector 11, and calculates the transfer function g between the two signals.
Find (s).

This transfer function g(s) is determined by the gain controller 16
and is compared with the target transfer function (g ₀ (s)) calculated in advance and stored in the storage device 12. Here, the target transfer function g ₀ (s) is the maximum allowable load of the test bench 1 The target is a transfer function of .

Through this comparison, for example, the transfer function g(s) when loading the test volume can be approximated to the target transfer function g ₀ (s) determined in advance, that is, g(s)≒g ₀ (s). , three types of signals Ed, Ev,
The ratio of Ea is determined using equations (1) to (3) described later. As a result, the gain controller 16 converts the input signals Ev and Ea corresponding to velocity and acceleration to approximate the transfer function g(s) at the time of calculating the test volume to the target transfer function g ₀ (s). This automatically sets the optimum value and increases the stability of the control system.

FIG. 3 is a drawing of a circuit configuration explaining the operating principle of the input signal calculator 6. As shown in FIG. two integrators 20,
21 as shown in Fig. 3 and configured to calculate signals corresponding to the single integral value and double integral value of the electric signal Er of the acceleration command, the input signal Ea' corresponding to the acceleration, the velocity An input signal Ev′ corresponding to , and an input signal Ed corresponding to displacement can be obtained. The input signals Ea' and Ev' corresponding to the acceleration and velocity are sent to the multiplier 2, respectively.
3 and 22 to obtain the optimum ratio based on the ratio command values Ai and Vi corresponding to the acceleration and velocity from the gain controller 16, and output as Ea and Ev.

Next, the operation of such an electro-hydraulic servo system control device will be explained.

First, the load of the vibration table 1 is the maximum allowable load of the vibration table, and the gain of the servo amplifier 8, the speed feedback, the gains of the acceleration feedback gain adjustment units 13 and 14, and the speed of the input signal calculator 6 , the ratio designation values Vi and Ai of the input signals corresponding to the acceleration are set to optimal values.

After this, the initial transfer function obtained by the transfer function measuring device is stored in the storage device 12 as the target transfer function g ₀ (s).
is stored in At this time, if the transfer function of the input signal calculator 6 is Gi ₀ (S, A, V) and the electrohydraulic servo system transfer function is Gs ₀ (S), the target transfer function g ₀ (s)
is expressed by the following formula.

g ₀ (s)=Gi ₀ (S, A, V)・Gs ₀ (S)...(1) Here, A=A ₀ and V=V ₀ .

Next, the transfer function g(s) when the test weight on the shaking table 1 changes is expressed by the following formula.

g(s)=Gi ₀ (S, A, V)・Gs(S)...(2) Therefore, this transfer function g(s) is the target transfer function
In order to approximate g ₀ (s), the ratio command values Vi, Ai of the input signal corresponding to the speed and acceleration of the input signal calculator 6 may be calculated using the following formula.

That is, gain |Gi(S,A,V)・Gs(S)|
is approximated by the least squares method, the control function f
(A, V) is f(A, V)=Σ{20log|Gi(S, A,
V)｜・｜Gs(S)｜−20log｜g ₀ (s)｜｝ ² = Σ｛20log｜Gi (S, A, V)｜/｜G
i(S, A, V) | +20logg(s)/g ₀ (s)} ² ...(3) When loading a new test volume, the transfer function G(S) becomes the target transfer function g ₀ (s). The optimal input signal ratio command values Ai and Vi for approximation are found.

As described above, according to the electro-hydraulic servo system control device of this embodiment, even when the test weight loaded on the vibration table 1 changes, the closed-loop system (adder 7, servo amplifier 8, electro-hydraulic servo system, feedback Input signal calculator 6 of the input circuit outside the circuit system)
Since the transfer function is adjusted by , the transfer function can always be kept constant in a stable state.

In other words, the transfer function of the shaking table control system, which changes depending on the weight of the test weight, is determined by trial excitation without changing the parameters, and is corrected using the transfer function of the input signal calculator. So,
The closed-loop control system can be maintained in a stable state at all times without detecting the weight of the test specimen, resulting in significant effects such as improved control performance and operability.

Next, another embodiment of the present invention will be described with reference to FIG.

FIG. 4 is a diagram showing an example of a display screen of a visual device used in an electro-hydraulic servo system control device according to another embodiment of the present invention.

In Fig. 4, in a, the target transfer function g ₀ (s) is shown as a broken line, and the target transfer function g (s) when the test weight changes is shown as a solid line, and the ratio command value Ai corresponding to acceleration and speed,
Figure 4b shows Vi with its initial settings.
The following shows a transfer function g(s) whose characteristics are close to the initial characteristics (target transfer function) by changing the ratio command values Ai and Vi.

The gain controller 16 is provided with a visual device related to visual display means, as shown in FIG.
By displaying the transfer function g(s) and the target transfer function g ₀ (s) after setting the ratio command values Ai and Vi to their optimum values, you can visually see the characteristics after changing the ratio command values Ai and Vi in advance. Therefore, it is possible to check the errors and the degree of approximation during approximate calculation.

〔Effect of the invention〕

As described above, according to the present invention, the transfer function to the shaking table control system, which changes depending on the test weight, is
In order to keep the closed-loop control system in a stable state at all times without detecting the weight of the test object, the control performance and It is possible to provide an electro-hydraulic servo system control device that improves operability.

[Brief explanation of the drawing]

FIG. 1 is a system diagram showing the configuration of an electro-hydraulic servo system control device in a vibration testing machine according to an embodiment of the present invention, FIG. 2 is a block diagram of its main parts, and FIG.
The figure is a control circuit diagram of an input signal calculator used in the device shown in FIG. 1, and FIG. 4 is an example of a display screen of a visual device used in an electrohydraulic servo system control device according to another embodiment of the present invention. FIG. 1... Vibration table, 2... Vibrator, 6... Input signal calculator, 9... Displacement detector, 10... Speed detector, 11... Acceleration detector, 12... Storage device,
15... Transfer function measuring device, 16... Gain controller, 20, 21... Integrator, 22, 23...
Multiplier.

Claims (1)

[Scope of Claims] 1. An input circuit system equipped with a signal generator and an input signal calculator, an electrohydraulic servo system equipped with a vibrator that gives at least a displacement to the vibration table by an input current, and the vibration table. In an electro-hydraulic servo system control device comprising a feedback circuit system that feeds back the displacement, velocity, and acceleration of A signal corresponding to a single integral value and a double integral value of the signal is calculated, and three types of signal information corresponding to acceleration, velocity, and displacement are calculated based on the characteristics of the control system including the signal calculator and the vibration table. A transfer function measuring device is used to measure the frequency response characteristics of the control system, and a predetermined transfer function when the maximum allowable load is loaded is stored as a target transfer function. a storage device, and compares and calculates the transfer function obtained by the transfer function measuring device when the test volume is loaded with the target transfer function stored in the storage device, and performs the test on the three types of signals of the input signal calculator. An electro-hydraulic servo system comprising: a gain controller that adjusts the characteristics of the input signal calculator to an appropriate value by determining an optimal ratio for approximating the transfer function during volume loading to the target transfer function. Control device. 2. In what is stated in claim 1,
The gain controller is an electro-hydraulic servo characterized by having a visual display means capable of predicting and displaying the characteristics of the shaking table control system after adjusting the ratio of three types of signals of the input signal calculator to an optimal value. System control device.