JPH0755672A - Electrohydraulic material testing unit - Google Patents

Abstract

PURPOSE:To provide an electrohydraulic material testing unit which can switch a negative feedback control mode, without causing trouble to test pieces and other members, and with hydraulic pressure kept applied, and allows easy handling and reduction in the time for switching modes. CONSTITUTION:To switch a negative feedback control mode, a control means 24b sets the gain of the signal gain adjustment means 24a2 of negative feedback loop means 241, 242 to zero before and after the switching, and gradually decreases the gain of the forward gain adjustment means 24a4 of the negative feedback loop means 241 to zero before the switching, and gradually increases the gain of the forward gain adjustment means 24a4 of the negative feedback loop means 242 to a predetermined value after the switching. A position signal is set by a positioning means 24b1 so that the magnitude of the negative feedback signal of the negative feedback loop means after the switching is held at a certain value.

Description

Detailed Description of the Invention

[0001]

BACKGROUND OF THE INVENTION 1. Field of the Invention The present invention relates to an electrohydraulic material testing apparatus for testing the properties of various materials by applying a hydraulic pressure to a test piece to electrically detect a measured value and, in particular, to test one unit. The present invention relates to an electrohydraulic material testing apparatus that tests a test piece in a plurality of negative feedback control modes by a machine.

[0002]

2. Description of the Related Art Generally, a material test is conducted by an operator selecting various negative feedback control modes and applying a load to a test piece in the selected mode. There are modes such as displacement, elongation, and load in this negative feedback control mode.For example, when chucking a test piece to the actuator of the testing machine, it is performed in the displacement negative feedback control mode. When switching to the negative feedback control mode, the complicated operation is required to avoid shock to the test piece due to the level difference between the modes.

That is, as shown in FIG. 10, signals from the signal generator 1, the position setting volume 2, and the displacement, extension, and load detectors 3, 4, and 5 corresponding to the negative feedback control mode of each test. Via the adder 6 to the test piece TP
Input to the servo valve 8 of the hydraulic control system of the actuator 7 that applies the hydraulic pressure to the, and the test mode changeover switch 9 selectively switches to the desired mode state to electrically detect the mode measurement value. It is composed. In the figure, 10 and 11 are an amplifier and an ammeter interposed in the signal line between the adder 6 and the servo valve 8, and 1
Reference numerals 2, 13, and 14 denote sensor amplifiers provided on signal lines between the detectors 3 to 5 and the test mode changeover switch 9, respectively.

Generally, a material testing apparatus using this type of hydraulic pressure has a central position of the spool of the servo valve 8 and a position of the actuator 7 when the hydraulic pressure of the hydraulic pressure source does not act on the actuator 7, that is, when the actuator 7 is not used. When the pump of the hydraulic power source is driven to apply hydraulic pressure in such a state, a large displacement is momentarily given to the actuator 7 by the position of the spool and the actuator 7, and at the same time, the actuator 7 is attached to the actuator 7. Even if the various sensors 3 to 5 and the test piece TP and other parts are destroyed or not destroyed, the test cannot be continued as it is,
There are problems that the test piece TP is replaced and the test is performed again, the test piece TP is reattached, and the reference level from the sensor must be readjusted.

For this reason, in the conventional device, when the use of the device is started, the hydraulic pressure supplied from the hydraulic source to the servo valve 8 is cut off in advance to switch to the displacement mode state.
The complicated operation of operating the position setting volume 2 to monitor the servo valve ammeter 11 and adjusting it so that the value becomes zero, and then applying the hydraulic pressure to the servo valve 8 was required.

Therefore, conventionally, when the power switch of the device is turned on, the displacement mode changeover switch is turned on in association with this, and signals other than the signal generator are prevented from being input to the control system of the actuator. By configuring the hydraulic power source drive switch to turn on when signals other than the generator are not input to the control system of the actuator, complicated operations are not required at the start and end of use of the device. Devices have been proposed that facilitate handling without giving test pieces or other parts use.

[0007]

In the above-mentioned conventional apparatus, the handling is easy without any trouble on the test piece or the like without complicated operation of the apparatus, but
Only when the signals other than the signal generator are not input to the actuator control system, the drive switch of the hydraulic source is turned on and the hydraulic pressure from the hydraulic source acts on the actuator. It is supposed to become.

However, since it takes a relatively long time for the hydraulic pressure from the hydraulic pressure source acting on the actuator to stabilize, there is a problem that the test time in the test involving the switching of the negative feedback control mode becomes long. It was

Therefore, in view of the above-mentioned conventional problems, the present invention makes it easy to handle the switching of the negative feedback control mode without disturbing the test piece or the like, and moreover, the switching work can be performed with the hydraulic pressure applied. An object of the present invention is to provide an electro-hydraulic material testing device capable of shortening the time required for a test involving switching of the negative feedback control mode.

[0010]

In order to achieve the above object, an electrohydraulic material testing apparatus according to the present invention is shown in FIG.
In the electrohydraulic material testing apparatus for testing the test piece TP in a plurality of negative feedback control modes by one testing machine, each is provided corresponding to each negative feedback control mode. , A plurality of negative feedback loop means 24 _{1 to} 24 ₃ having outputs connected to each other, and a servo valve provided between an interconnection point of outputs of the plurality of negative feedback loop means and the servo valve 8 of the hydraulic actuator 7. Drive amplification means 25
And each negative feedback loop means, in addition to the control target signal,
Negative feedback addition means 24a _{1 to} which a negative feedback signal of each mode is added respectively, position setting means 24b ₁ for setting a position signal added to the negative feedback addition means so as to adjust its output signal, and said negative feedback addition A signal gain adjusting means 24a provided in the preceding stage of the means for adjusting the gain for the control target signal applied to the negative feedback adding means.
₂ , a forward gain adjusting means 24a ₄ provided after the negative feedback adding means for adjusting the gain with respect to the output signal of the negative feedback adding means, the position setting means, the signal gain adjusting means and the forward gain adjusting means. And a control means 24b, and when switching the negative feedback control mode, the control means sets the gain of the signal gain adjusting means of the negative feedback loop means before and after the switching to 0,
The gain of the forward gain adjusting means of the negative feedback loop means before switching is gradually reduced to 0, and the gain of the forward gain adjusting means of the negative feedback loop means after switching is gradually increased to a predetermined value. The position setting means sets the position signal so that the magnitude of the negative feedback signal of the negative feedback loop means maintains a constant value.

[0011]

In the above structure, a plurality of negative feedback loop means 2 are provided.
4 ₁ 24 ₃ of the interconnection point of the output to be connected to the servo valve drive amplifying means 25 provided between the servo valve 8 of the hydraulic actuator 7, when switching of the negative feedback control mode, the control means 24b is The gain of negative feedback loop means before and after switching, for example, the signal gain adjusting means of 24 ₁ and 24 ₂ such as 24a ₂₁ and 24a ₂₂ is set to 0, and the forward gain adjusting means 24a ₄₁ of the negative feedback loop means 24 ₁ before switching is changed. The gain is gradually reduced to 0 and the gain of the forward gain adjusting means 24a ₄₂ of the negative feedback loop means 24 ₂ after switching is gradually increased to a predetermined value, at which time the magnitude of the negative feedback signal of the negative feedback loop means after switching is constant. Position setting means 24 to hold the value
The position signal is set by b ₁ .

Therefore, there is almost no change in the negative feedback signal before and after the switching, that is, the sensor signal. In other words, the magnitude of the displacement, elongation or load acting on the test piece TP before and after the control mode switching changes. There is no needless shock to the test piece even if the switching work is performed by applying hydraulic pressure.

[0013]

Embodiments of the present invention will be described below with reference to the drawings. FIG. 2 shows a schematic configuration of an embodiment of the electro-hydraulic material testing apparatus according to the present invention. In FIG. 2, reference numeral 21 is a host computer equipped with a CRT, a keyboard, a storage device and the like (not shown). Various constants used for the material test and various data obtained as a result of the material test are stored in the storage device. Reference numeral 22 denotes a control computer configured by a microcomputer (CPU) that operates according to a predetermined control program, and controls a test according to one selected from various test conditions set by the host computer 21.

The control computer 22 is provided with a displacement negative feedback loop 24 ₁ and an extension negative feedback loop 24 via a common bus 23.
₂ and the load negative feedback loop 24 ₃ and controls the relationship between each of the negative feedback loops 24 _{1 to} 24 ₃ and each other.
The negative feedback loops 24 _{1 to} 24 ₃ receive the displacement signal from the displacement sensor (not shown), the elongation signal from the elongation sensor, and the load signal from the load sensor, respectively, and process the input signals to deviate from the control target signal. And the deviation signal is output. The outputs of the negative feedback loops 24 _{1 to} 24 ₃ are interconnected and then connected to the input of a servo valve drive amplifier 25 serving as servo valve drive amplification means, and the servo valve drive amplifier 25 outputs the output signal of a hydraulic actuator (not shown). Drive the servo valve.

The negative feedback loops 24 _{1 to} 24 ₃ have the same hardware configuration, and one of them, 24 ₁ , is shown in detail in FIG. That is, the negative feedback loop 24 ₁ is a digital signal processor (DSP) 24a.
And a microcomputer (CPU) 24b as a control means for controlling the DSP 24a. DSP
24a operates in accordance with a control program stored in a ROM 24c connected thereto, takes in a signal from the sensor converted into a digital signal by the A / D conversion circuit 24d, processes this signal, and obtains a deviation from a control target signal. ,
Outputs a deviation signal in digital format. This deviation signal is D
After being converted into an analog signal by the / A conversion circuit 24e, it is sent to the servo valve drive amplifier 25. DSP24
Also, a is a common RAM 24 shared with the CPU 24b.
f is also connected.

On the other hand, the CPU 24b has an R connected to it.
Operates according to the control program stored in OM24g,
The bus 23 via the interface (I / F) circuit 24h
And executes a command based on a command signal received from the negative feedback loop 24 ₁ via the bus 23, takes in the signal from the sensor converted into a digital signal by the A / D conversion circuit 24d, and stores this signal in the RAM 24i. Write and process to control the DSP 24a. A common RAM 24f shared with the DSP 24a is also connected to the CPU 24b.

The DSP 24a realizes a circuit configuration as shown in FIG. 4 by performing processing according to a control program stored in the ROM 24c. That is, the DSP 24a and the addition unit 24a ₁ as a negative feedback addition unit that takes the deviation between the function data Ei corresponding to the target signal from the common RAM 24f and the sensor data Es corresponding to the sensor signal from the A / D conversion circuit 24d. , Adder 2
A signal gain adjusting unit 24a ₂ as a signal gain adjusting unit for adjusting the function data Ei added to 4a ₁ and a sensor gain adjusting for adjusting the sensor data Es of the output of the A / D conversion circuit 24d added to the adding unit 24a _1. Part 24a
₃ and a forward gain P (proportional) adjusting section 24a ₄ as a forward gain adjusting means for adjusting the deviation data Ee corresponding to the deviation signal obtained at the output of the adding section 24a _1.
And an ID adjustment unit 24a ₅ that performs I (integration) D (differential) adjustment before the output data of the forward gain P adjustment unit 24a ₄ is converted into an analog signal by the D / A conversion circuit 24e.

It should be noted that in the addition section 24a ₁ , the common RAM stores the position data Ep generated by the position setting section 24b ₁ as the position setting means constituted by the CPU 24b.
It is supplied via 24f. A second adder 27 is provided between the sensor amplifier 26 and the A / D conversion circuit 24d to adjust the sensor zero.
7. Zero adjustment signal generator 24b configured by CPU 24b
The adjustment signal from ₂ is supplied. Further, the sensor data Es output from the A / D conversion circuit 24d is taken into the CPU 24b for monitoring and is stored in the RAM 24i.
Memorized in. Furthermore, the deviation signal of the output of the D / A conversion circuit 24e is supplied to the servo valve drive amplifier 25.

The signal gain adjusting section 24a₂, Senge
IN adjusting section 24a₃And the forward gain P adjustment unit 24
a_FourGain coefficients Ki, Ks, and Kf of the ID adjustment unit 2
4a _FiveThe coefficient ID of is stored in the common RAM 2 by the CPU 24b.
It is written in 4f, and DSP24a
To read and obtain the multiplication and deviation for gain adjustment
The deviation signal is D / A
It is sent to the input of the conversion circuit 24e. The above calculation is A / D change
This is performed within the sampling interval by the conversion circuit 24d.
This allows everything to be configured by digital means,
The S / N, which is a drawback in the log, can be greatly improved,
No adjustment, improvement of reliability, and cost reduction can be realized.

Since the DSP 24a functions as in the configuration of FIG. 4, the processing performed according to the control program stored in the ROM 24c will be described below with reference to the flowchart of FIG. The DSP 24a is activated by, for example, turning on the power source, and the A / D conversion circuit 2
The sensor data Es sampled by 4d is read and stored in the common RAM 24f. Then, in step S2, the function data Ei stored in the data area of the common RAM 24f is read, and in the next step S3, the position data Ep stored in the data area of the common RAM 24f is read, and these data are shared. It is stored in the work area of the RAM 24f.
Then, in the next step S4, the coefficients Ki, Ks and Kf and the ID coefficient are read from the common RAM 24f, and this data is also stored in the work area of the common RAM 24f.

After that, the process proceeds to step S5, where the function data Ei and the sensor data Es are multiplied by the coefficients Ki and Ks respectively to perform gain adjustment, and the deviation between the gain adjusted function data Ei and the sensor data Es is obtained. Obtain data and adjust position. By adding / subtracting the function data Ei, the sensor data Es, and the position data Ep, the deviation between the function data Ei and the sensor data Es is obtained to obtain the deviation data Ee, and the position is adjusted. Further, the deviation data Ee is multiplied by a coefficient Kf to perform a gain adjustment P, and then the deviation data Ee subjected to the gain adjustment is ID adjusted using an ID coefficient.

Next, the process proceeds to step S6, the calculation result is output and the D / A conversion circuit 24e performs D / A conversion, and then the process proceeds to step S7, where T seconds are waited before the above step S
Returning to 1, the next sampling is performed, and the above processing is repeated. In this way, the sensor signal is sampled every T seconds to obtain the sensor data Es, and all the calculations including the gain adjustment of each part are completed and the deviation data is output until the next sensor data is obtained. Will be able to.

The above-described operation is a test operation in the selected negative feedback control mode, and the simplified diagram of FIG. 6 is taken as an example in which the method of switching the control mode of the above-described device is switched from displacement to extension. A description will be given below with reference to FIG.

When the negative feedback control mode is in the displacement mode, the gain coefficient K of the forward gain adjusting section 24a ₄₁ is set.
f ₁ is set to a predetermined value, and the gain coefficient Kf _{2 of the} forward gain adjusting unit 24a ₄₂ is set to 0, and the open state is established. Now, the gains Ki ₁ and Ki _{2 of} the signal gain adjusters 24a ₂₁ and 24a ₂₂ are both set to 0,
It is assumed that the function data added to the adders 24a ₁₁ and 24a ₁₂ are both 0. In this state, the adding unit 24a
The position data Ep ₁ of a size designated by the CPU 24b ₁ is supplied to ₁₁ , and the sensor data Es ₁ which is the negative feedback signal at this time is fetched and monitored by the CPU 24b ₁ . As a result, the deviation data Ee ₁ of the output of the adder a ₁₁ is substantially 0, but the switching process is performed while always holding this value.

Next, the value of the sensor data Es ₂ is calculated by the CPU ₂
4b ₂ monitors the CPU 24 so that the deviation data Ee ₂ becomes 0 based on the monitored value of Es _2.
b ₂ is to specify the position data Ep ₂ (-Es _2). Then gradually increasing the gain coefficient Kf ₂ of forward gain adjustment section 24a ₄₂ to a predetermined value, the gain coefficient Kf ₂ of forward gain adjustment section 24a ₄₁ gradually decreases to 0, switching to extend from the displacement of the negative feedback control mode However, by adjusting the position data Ep ₂ so that Es ₂ being monitored at this time maintains a substantially constant value, a shock to the test piece is avoided.

The displacement negative feedback loop 24 ₁
CPU 24b ₁ inside and CP in the extension negative feedback loop 24 ₂
This will be described in detail with reference to the flowcharts of FIGS. 7 and 8 showing the processing performed by the U 24b ₂ according to a predetermined control program.

In the flow chart of FIG. 7, the CPU 24b
_In the first step S11, it is determined whether or not there is a step-down command from the extension negative feedback loop 24 ₂ in response to the start of the mode switching operation.
When ES, the process proceeds to step S12, and the gain coefficient Kf ₁ of the forward gain adjusting unit 24a ₄₁ is reduced by a predetermined value ΔKf ₁ . The predetermined value ΔKf ₁ is a value that makes Kf ₁ 0 at an N equal division ratio, and Kf ₁ / N = ΔKf ₁ . After that, the process returns to step S11 to wait for the next step down command, and when there is the step down command, the above operation is repeated.

On the other hand, in the flow chart of FIG.
In response to the start of the mode switching operation, 24b ₂ reads the sensor data Es ₂ and holds it as the initial value Es ₂₀ in the first step S21. After that, the process proceeds to step S22, where the CP of the displacement negative feedback loop 24 ₁
A step-down command is sent to U24b ₁ , and in the next step S23, the forward gain adjusting unit 24a
The gain coefficient Kf _{2 of 42} is increased by a predetermined value ΔKf ₂ .
The predetermined value ΔKf ₂ is a value that makes Kf _{2 a} predetermined value at an N equal division ratio, and Kf ₂ / N = ΔKf ₂ . Then the process proceeds to step S24, where monitoring the value of the sensor data Es _2, in the next step S25, whether the monitor value Es ₂ has either increased relative to the initial value Es _20, or decreased, or equal To judge. That is, Es
₂₀ −Es ₂ = ΔEs ₂ is determined to be negative, positive, or 0.

If the determination in step S25 is YES, the process proceeds to step S26, the value obtained by subtracting the predetermined value ΔEp ₂ from the current position data Ep ₂ is supplied to the adder 24a ₁₂ as new position data, and then the above step is performed. Returning to S24, the operations of steps S24 and S25 are repeated. On the other hand, when the determination in step S25 is decreased, the process proceeds to step S27 and the position data E
A value obtained by adding the predetermined value ΔEp ₂ to p ₂ is supplied to the adder 24a ₁₂ as new position data, and then the process returns to step S24 and the operations of steps S24 and S25 are repeated.

If the determinations in step S25 are the same, the process proceeds to step S28 to determine whether or not the gain coefficient Kf ₂ of the forward gain adjusting section 24a ₄₂ has reached the specified value. Returning to step S22, the operation after step S22 is repeated, and when the determination in step S28 becomes YES and the gain coefficient Kf _{2 of the} forward gain adjusting section 24a ₄₂ reaches the designated value, the operation of switching the negative feedback control mode is performed. finish. At this time, it becomes a gain coefficient Kf ₁ are 0 forward gain adjustment section 24a ₄₁ of the displacement negative feedback loop 24 _1, negative feedback control mode is switched-out fully extended from the displacement. By the way, the speed at which the process returns from steps S26 and S27 to step S24 is linear because the control is linear.
It is determined by the stability conditions of the system.

As described above, the control mode is switched by increasing or decreasing the gain coefficient of the forward gain adjusting section provided at the output of the adding section of each system by a predetermined amount and monitoring the change in the sensor output at that time. Since the increase / decrease of the position signal applied to the addition unit so that the sensor output holds the initial value is automatically repeated until the gain coefficient of the forward gain adjustment unit reaches a predetermined value, the hydraulic pressure remains applied. In addition to being able to perform switching work, switching between different control loops can be performed accurately due to the characteristic error of the negative feedback control loop, and it does not require troublesome operation and damages the test piece without shock. Can be achieved smoothly.

Further, as described above, since the outputs of the negative feedback loops 24 _{1 to} 24 ₃ for displacement, elongation and load are interconnected, they are connected to the input of the servo valve drive amplifier 25. , Each negative feedback loop 24 ₁
When ˜24 ₃ and the servo valve drive amplifier 25 are respectively configured on independent circuit boards, the boards can be interconnected by a single signal line L, which simplifies the structure and reduces cost and structure. , Which is advantageous in terms of reliability. Further, since the signal line between the negative feedback loops 24 _{1 to} 24 ₃ and the servo valve drive amplifier 25 has a low impedance, it also has excellent noise resistance.

[0033]

As described above, according to the present invention, the displacement acting on the test piece before and after the control mode switching,
There is no change in elongation or load, and even if switching work is performed with hydraulic pressure applied, there is no need to give unnecessary shock to test pieces and other obstacles, and the work can be performed automatically with hydraulic pressure applied. Therefore, it is easy to handle and the time required for a test involving mode switching can be shortened.

[Brief description of drawings]

FIG. 1 is a diagram showing a basic configuration of an electrohydraulic material testing device according to the present invention.

FIG. 2 is a diagram showing an overall configuration of an electrohydraulic material testing device according to the present invention.

FIG. 3 is a diagram showing details of a displacement negative feedback loop in FIG.

FIG. 4 is a diagram showing a negative feedback loop formed by the DSP shown in FIG.

5 is a flowchart showing processing performed by the DSP of FIG. 3 so as to form the loop of FIG.

FIG. 6 is a diagram for explaining how to switch the negative feedback control mode.

FIG. 7: FIG. 3 performed to switch the negative feedback control loop
It is one flowchart which shows the process which the inside CPU performs.

FIG. 8: FIG. 3 performed to switch the negative feedback control loop
It is another flowchart which shows the process which the inside CPU performs.

FIG. 9 is a diagram for explaining an advantage obtained by the configuration of FIG.

FIG. 10 is a diagram showing an example of a conventional device.

[Explanation of symbols]

TP test piece 7 Actuator 8 Servo valve 24 _{1 to} 24 ₃ Negative feedback loop means (negative feedback loop) 24a ₁ Negative feedback addition means (adding section) 24a ₂ Signal gain adjusting means (Signal gain adjusting section) 24a ₄ Forward gain adjusting means (Forward gain adjusting section) 24b Control means (CPU) 24b ₁ Position setting means (position setting section) 25 Servo valve drive amplification means (servo valve drive amplifier)

Claims (1)

[Claims] 1. An electro-hydraulic material testing apparatus for testing a test piece in a plurality of negative feedback control modes by one testing machine, each of which is provided corresponding to each negative feedback control mode, and outputs are interconnected. Negative feedback loop means, and servo valve drive amplification means provided between the interconnection point of the outputs of the negative feedback loop means and the servo valve of the hydraulic actuator. However, in addition to the control target signal, a negative feedback addition means to which a negative feedback signal of each mode is added respectively, and a position setting means for setting a position signal added to the negative feedback addition means to adjust its output signal,
A signal gain adjusting unit that is provided in the preceding stage of the negative feedback adding unit and adjusts a gain for the control target signal applied to the negative feedback adding unit, and an output signal of the negative feedback adding unit that is provided after the negative feedback adding unit. It has a forward gain adjusting means for adjusting the gain, and a control means for controlling the position setting means, the signal gain adjusting means and the forward gain adjusting means, and when the negative feedback control mode is switched, the control means is used before and after the switching. The gain of the signal gain adjusting means of the negative feedback loop means is set to 0, the gain of the forward gain adjusting means of the negative feedback loop means before switching is gradually reduced to 0, and the forward of the negative feedback loop means after switching. The gain of the gain adjusting means is gradually increased to a predetermined value, and at this time, the negative feedback after switching is performed. An electro-hydraulic material testing apparatus, wherein the position setting means sets the position signal so that the magnitude of the negative feedback signal of the return loop means holds a constant value.