JP7180506B2 - Material testing machine and control method for material testing machine - Google Patents

Description

The present invention relates to a material testing machine and a control method for the material testing machine.

Various testing machines such as compression testing machines, hardness testing machines, and fatigue testing machines are known as material testing machines for performing material tests for examining mechanical properties and properties of materials.
A material testing machine generally includes a load mechanism that applies a test force as a load to a test object, a control device that controls the load mechanism, a test force measuring device that measures the test force applied to the test piece, and a test material. and a physical quantity measuring device for measuring a change in a predetermined physical quantity that has occurred. Also, during the material test, the controller feedback-controls the load mechanism based on the deviation between the measured test force and the target test force. Also, in feedback control, a phenomenon in which the measured value of the test force oscillates due to various factors, that is, so-called "hunting" may occur.

The following methods are known for detecting hunting. That is, a method of detecting based on the amplitude in the time-series data of the signal for hunting detection (for example, see Patent Document 1, Patent Document 2, and Patent Document 3), and FFT analysis of the time-series data of the signal for hunting detection. detection method (see, for example, Patent Documents 4 and 5).

JP 2013-221430 A Japanese Patent Application Laid-Open No. 2000-320383 JP-A-10-105201 JP 2013-145692 A JP-A-04-274725

However, although the compression testers described in each of Patent Documents 1 to 5 can detect hunting, the occurrence of hunting cannot be suppressed in some cases.

SUMMARY OF THE INVENTION It is an object of the present invention to provide a material testing machine capable of suppressing the occurrence of hunting in the material testing machine, and a control method for the material testing machine.

A first aspect of the present invention is a material testing machine that applies a test force to a test material and deforms the test material to perform a material test, wherein the deviation indicates the difference between the measured value of the control object and the target value adjusts the gain of at least the integrator in the feedback control based on the feedback control unit that performs feedback control so that the is zero, the design response speed of the material testing machine, and the actual response speed of the material testing machine each of the design response speed and the actual response speed is defined by a delay time of a first-order delay system, and the adjustment unit includes a first delay time corresponding to the design response speed, and the and a second delay time corresponding to the actual response speed .

A second aspect of the present invention is a control method for a material testing machine that performs a material test by applying a test force to a test material and deforming the test material, wherein the difference between the measured value of the controlled object and the target value Based on the feedback control step of executing feedback control so that the deviation indicating is zero, the design response speed of the material testing machine, and the actual response speed of the material testing machine, at least the integrator in the feedback control and an adjusting step of adjusting a gain, wherein each of the designed response speed and the actual response speed is defined by a delay time of a first-order lag system, and the adjusting step comprises a first delay corresponding to the designed response speed. The present invention relates to a material testing machine control method for adjusting the gain based on time and a second delay time corresponding to the actual response speed .

According to the first aspect of the present invention, the adjusting section adjusts the gain in the feedback control based on the designed response speed of the material testing machine and the actual response speed of the material testing machine.
For example, if the actual response speed is too fast relative to the designed response speed, the feedback control gain is adjusted to be smaller. Therefore, it is possible to suppress the occurrence of hunting in the material testing machine.

According to the second aspect of the present invention, in the adjusting step, the gain in the feedback control is adjusted based on the designed response speed of the material testing machine and the actual response speed of the material testing machine.
For example, if the actual response speed is too fast relative to the designed response speed, the feedback control gain is adjusted to be smaller. Therefore, it is possible to suppress the occurrence of hunting in the material testing machine.

It is a figure showing an example of composition of a compression testing machine concerning this embodiment. It is a figure which shows an example of a structure of the control circuit unit which concerns on this embodiment. It is a figure which shows an example of a structure of the feedback control part which concerns on this embodiment. 7 is a graph showing an example of changes in control compliance, first delay time, second delay time, and deviation in a comparative example; It is a graph which shows an adjustment coefficient in this embodiment, a 1st lag time, a 2nd lag time, and an example of a change of a deviation. 4 is a flow chart showing an example of processing of the control circuit unit of the present embodiment;

Embodiments of the present invention will be described below with reference to the drawings.

[1. Configuration of compression tester]
FIG. 1 is a diagram showing an example of the configuration of a compression tester 1 according to this embodiment.
The compression tester 1 of this embodiment applies a test force F to a test material TP to perform a material test for measuring mechanical properties such as compressive strength, yield point, strain, and reduction of area of the sample. The test force F is a compressive force.
The compression tester 1 includes a compression tester body 2 that performs a compression test by applying a test force F to a test material TP, which is a material to be tested, a control unit 4 that controls the compression test operation by the compression tester body 2, Prepare.
The compression testing machine 1 corresponds to an example of a "material testing machine".

The testing machine main body 2 includes a table 6, a pair of screw rods 8, 9 rotatably erected on the table 6 in a vertical direction, and movable along the screw rods 8, 9. A crosshead 10, a load mechanism 12 for moving the crosshead 10 to apply a load to the test material TP, and a load cell 14 are provided. The load cell 14 is a sensor that measures a test force F, which is a compressive force applied to the test material TP, and outputs a test force measurement signal SG1.

A pair of threaded rods 8,9 pass through a crosshead 10 and the crosshead 10 is connected to each threaded rod 8,9.
The load mechanism 12 includes worm reduction gears 16 and 17 connected to the lower ends of the screw heads 8 and 9, a servo motor 18 connected to the worm reduction gears 16 and 17, and a rotary encoder 20. The rotary encoder 20 is a sensor that measures the amount of rotation of the servomotor 18 and outputs a rotation measurement signal SG2 having the number of pulses corresponding to the amount of rotation to the control unit 4 .
The load mechanism 12 transmits the rotation of the servomotor 18 to the pair of screw necks 8 and 9 through the worm reduction gears 16 and 17, and the screw necks 8 and 9 rotate synchronously to thereby generate a crosshead. 10 moves up and down along the screw rods 8 and 9.

The crosshead 10 is provided with an upper compression plate 21 for applying a compressive force to the upper end of the test material TP, and the table 6 is provided with a lower compression plate 22 for supporting the lower end of the test material TP. It is During the compression test, the testing machine main body 2 lowers the crosshead 10 under the control of the control unit 4 while holding both ends of the test material TP between the upper compression plate 21 and the lower compression plate 22. , exerting a test force F on the test material TP. The test force F is a compressive force.

A displacement sensor 15 is arranged on the test material TP. The displacement sensor 15 is a sensor that measures the strain measurement value ED by measuring the distance between a pair of reference points on the test material TP and outputs a strain measurement signal SG3. The strain metric ED measures the amount of compression of the test material TP as strain.

The control unit 4 includes an overall control device 30 , a display device 32 and a test program execution device 34 .
The integrated control device 30 is a device that centrally controls the tester main body 2 and is connected to the tester main body 2 so that signals can be transmitted and received. Signals received from the testing machine main body 2 include a test force measurement signal SG1 output by the load cell 14, a rotation measurement signal SG2 output by the rotary encoder 20, a strain measurement signal SG3 output by the displacement sensor 15, and appropriate signals required for control and testing. signal, etc.
The display device 32 is a device that displays various kinds of information based on signals input from the general control device 30. For example, the general control device 30 displays the strain measurement signal SG3 of the test material TP during the compression test. A strain measurement value ED, which is a strain measurement value, is displayed on the display device 32 . Also, for example, the overall control device 30 displays the displacement measurement value XD indicating the displacement of the crosshead 10 based on the rotation measurement signal SG2 on the display device 32 during the compression test.

The test program execution device 34 receives user operations such as setting operations of various setting parameters such as compression test test conditions and execution instruction operations, and functions to output to the overall control device 30 and analyze data of test force measurement values FD. It is a device equipped with functions.
The test program execution device 34 of this embodiment includes a computer, which includes a processor such as a CPU (Central Processing Unit) or MPU (Micro-Processing Unit), a ROM (Read Only Memory), and a RAM (Random Access Memory). , storage devices such as HDDs (Hard Disk Drives) and SSDs (Solid State Drives), and interface circuits for connecting the overall control unit 30 and various peripheral devices. Then, the processor executes the compression test program, which is a computer program stored in the memory device or storage device, thereby realizing the various functions described above.

Next, the integrated control device 30 of the present embodiment will be further detailed.
The integrated control device 30 includes a signal input/output unit 40 and a control circuit unit 50, as shown in FIG.
The signal input/output unit 40 constitutes an input/output interface circuit that transmits and receives signals to and from the testing machine main body 2. In this embodiment, a first sensor amplifier 42, a second sensor amplifier 45, a counter It has a circuit 43 and a servo amplifier 44 .
The first sensor amplifier 42 is an amplifier that amplifies the test force measurement signal SG<b>1 output from the load cell 14 and outputs the amplified signal to the control circuit unit 50 .
The second sensor amplifier 45 is an amplifier that amplifies the strain measurement signal SG3 output from the displacement sensor 15 and outputs it to the control circuit unit 50 .
The counter circuit 43 counts the number of pulses of the rotation measurement signal SG2 output by the rotary encoder 20, and measures the amount of rotation of the servomotor 18, that is, the displacement measurement value XD of the crosshead 10 that moves up and down due to the rotation of the servomotor 18. The signal A3 is output to the control circuit unit 50 as a digital signal.
The servo amplifier 44 is a device that controls the servo motor 18 under the control of the control circuit unit 50 .

[2. Configuration of control circuit unit]
FIG. 2 is a block diagram showing the functional configuration of the control circuit unit 50. As shown in FIG.
The control circuit unit 50 includes a communication section 51 , a feedback control section 52 , a filtering section 53 , an identification section 54 and an adjustment section 55 .
The control circuit unit 50 communicates with a processor such as a CPU or MPU, a memory device such as a ROM or RAM, a storage device such as an HDD or SSD, an interface circuit for the signal input/output unit 40, and the test program execution device 34. A computer including a communication device for controlling the display device 32, a display control circuit for controlling the display device 32, and various electronic circuits. 2 is realized by the processor of the control circuit unit 50 executing the control program stored in the memory device or storage device.
An interface circuit of the signal input/output unit 40 is provided with an A/D converter, and the analog test force measurement signal SG1 and the strain measurement signal SG3 are converted into digital signals by the A/D converter.
Note that the control circuit unit 50 is not limited to a computer, and may be configured by one or a plurality of appropriate circuits such as integrated circuits such as IC chips and LSIs.

The communication unit 51 communicates with the test program execution device 34 and receives, from the test program execution device 34, settings of test conditions, setting values of various setting parameters, execution instructions and interruption instructions of the compression test. The communication unit 51 also transmits the strain measurement value ED based on the strain measurement signal SG3 and the test force measurement value FD based on the test force measurement signal SG1 to the test program execution device 34 at appropriate timings. Further, the communication unit 51 transmits the displacement measurement value XD based on the rotation measurement signal SG2 to the test program execution device 34 at appropriate timing.

[2-1. Configuration of Feedback Control Unit]
The feedback control unit 52 feedback-controls the servomotor 18 of the testing machine main body 2 to perform the compression test. The feedback control section 52 is a circuit that performs feedback control of the servomotor 18 .
When the feedback control unit 52 executes position control, the feedback control unit 52 executes position control on the test force measurement value FD output by the load cell 14, for example. In this case, the feedback control unit 52 calculates the command value dX of the displacement measurement value XD so as to match the test force measurement value FD with the test force target value FT, and the command signal A4 (Fig. 1) is output to the servo amplifier 44 . Note that the test force target value FT indicates the target value of the test force measurement value FD.
In this embodiment, the term "position control" refers to controlling a detected value measured by a sensor or the like to match its target value.

In the present embodiment, the case where position control is performed for the measured test force value FD will be described, but the position control may be performed for the measured displacement value XD. In this case, the feedback control unit 52 calculates a command value dX of the displacement measurement value XD so as to match the displacement measurement value XD with the displacement target value XT, and generates a command signal A4 (FIG. 1) indicating the command value dX. is output to the servo amplifier 44 . The displacement target value XT indicates the target value of the displacement measurement value XD.
Also, position control may be performed on the strain measurement value ED measured by the displacement sensor 15 . In this case, the feedback control unit 52 calculates the command value dX of the displacement measurement value XD so that the strain measurement value ED measured by the displacement sensor 15 matches the strain target value ET, and indicates the command value dX. A command signal A 4 ( FIG. 1 ) is output to the servo amplifier 44 . The strain target value ET indicates the target value of the strain measurement value ED.

Also, in this embodiment, the case where position control is executed will be described, but the feedback control section 52 may execute speed control. The feedback control unit 52, for example, executes speed control on the test force measurement value FD output by the load cell 14. FIG. In this case, the feedback control unit 52 calculates the command value dX of the displacement measurement value XD so that the test force measurement value velocity VF matches the test force velocity target value VFT, and the command signal A4 indicating the command value dX ( FIG. 1 ) is output to the servo amplifier 44 . The test force measurement value velocity VF indicates the amount of change per unit time in the test force measurement value FD, and the test force velocity target value VFT indicates the target value of the test force measurement value velocity VF.
In the present embodiment, "speed control" means controlling the amount of change per unit time of the detection value measured by a sensor or the like so as to match the target value.

Further, velocity control may be performed on the displacement measurement value XD measured by the rotary encoder 20. FIG. In this case, the feedback control unit 52 calculates the command value dX of the displacement measurement value XD so that the displacement measurement value velocity V coincides with the displacement velocity target value VT, and a command signal A4 (Fig. 1) is output to the servo amplifier 44 . The displacement measurement value velocity V indicates the amount of change in the displacement measurement value XD per unit time, and the displacement velocity target value VT indicates the target value of the displacement measurement value velocity V. FIG.
Further, speed control may be performed on the strain measurement value ED measured by the displacement sensor 15 . In this case, the feedback control unit 52 calculates the command value dX of the displacement measurement value XD so that the strain measurement value velocity VE coincides with the strain velocity target value VET, and a command signal A4 (Fig. 1) is output to the servo amplifier 44 . The strain measurement value velocity VE indicates the amount of change per unit time of the strain measurement value ED measured by the displacement sensor 15, and the strain velocity target value VET indicates the target value of the strain measurement value velocity VE.

FIG. 3 is a diagram showing an example of the configuration of the feedback control section 52. As shown in FIG.
PID (Proportional-Integral-Differential) control is used for feedback control, and the feedback control section 52 includes a proportionalor 523 , an integrator 524 and a differentiator 525 .
The feedback control section 52 also includes a subtractor 521 , a multiplier 522 and an adder 526 .

The subtractor 521 subtracts the measured test force value FD from the target test force value FT to calculate the first deviation E1. The first deviation E1 corresponds to an example of "deviation".
A multiplier 522 multiplies the first deviation E1 by the control compliance CP to calculate a second deviation E2.
The control compliance CP is calculated by the following formula (1).
CP(t)=ΔX(t)/ΔF(t) (1)
In equation (1), time t indicates the execution timing of the control cycle. Control compliance CP(t) indicates control compliance CP in each control cycle. Further, the movement amount ΔX(t) indicates the movement amount ΔX of the crosshead 10 in each control cycle. The test force change amount ΔF(t) indicates the test force change amount ΔF in each control cycle, and is, for example, the difference between the test force measurement value FD in the current control cycle and the test force measurement value FD in the previous control cycle.

The second deviation E2 is input to each of the proportionalor 523, the integrator 524, and the differentiator 525.
The proportional device 523 outputs the first manipulated variable U1, the integrator 524 outputs the second manipulated variable U2, and the differentiator 525 outputs the third manipulated variable U3.
The adder 526 calculates the manipulated variable U by adding the first manipulated variable U1, the second manipulated variable U2, and the third manipulated variable U3.
A manipulated variable U is input to the testing machine main body 2 . The amount of operation U indicates, for example, the amount of rotation of the servomotor 18 .

Note that the differentiator 525 is not used in this embodiment. In other words, the gain of differentiator 525 is zero.

Returning to FIG. 2, the functional configuration of the control circuit unit 50 will be described.
The filtering unit 53 reduces the component corresponding to the natural frequency FA of the compression tester 1 from the displacement measurement value XD when the compression tester 1 performs the compression test.
Specifically, by passing the detection signal of the displacement measurement value XD through a high-pass filter and a low-pass filter, the component corresponding to the natural frequency FA of the compression tester 1 included in the detection signal of the displacement measurement value XD is reduced. do. The high-pass filter passes frequencies higher than the natural frequency FA by the frequency ΔFA, that is, frequencies equal to or higher than the frequency (FA+ΔFA). The low-pass filter passes frequencies that are lower than the natural frequency FA by the frequency ΔFB, that is, frequencies below the frequency (FA-ΔFB). The natural frequency FA is, for example, 17.55 kHz, and each of the frequencies ΔFA and ΔFB is, for example, 1 kHz.

[2-3. Identification of testing machine]
The identification unit 54 identifies the characteristics of the compression tester main body 2 based on the actual response speed of the compression tester main body 2 . Specifically, the identification unit 54 identifies the characteristics of the compression tester body 2 as, for example, a first-order lag system based on changes in the target test force value FT and changes in the measured test force value FD.

A transfer function GA(S) that indicates the characteristics of the compression tester main body 2 at the time of design is defined by the following equation (2).
GA(S)=1/(TA×S+1) (2)
Here, the first delay time TA indicates the delay time corresponding to the designed response speed. The first delay time TA is stored, for example, in a memory device or storage device of the control circuit unit 50 .

A transfer function GB(S) that indicates the characteristics of the compression tester main body 2 when executing a material test is defined by the following equation (3).
GB(S)=1/(TD×S+1) (3)
Here, the second delay time TD indicates the delay time corresponding to the actual response speed. The identification unit 54 identifies the second delay time TD.

Specifically, the identification unit 54 identifies the transfer function G2(S) by, for example, applying the iterative least-squares method to an ARMA (Autoregressive Moving Average) model. As a result, the identification unit 54 calculates the second delay time TD.

The first delay time TA corresponds to an example of a parameter indicating "designed response speed", and the second delay time TD corresponds to an example of a parameter indicating "actual response speed". For example, the shorter the first delay time TA, the faster the designed response speed, and the shorter the second delay time TD, the faster the actual response speed.

In this embodiment, the design response speed is defined by the first delay time TA, and the actual response speed is defined by the second delay time TD, but the present invention is not limited to this. For example, each of the design response speed and the actual response speed may be defined by the response speed at a specific frequency.

Moreover, in the present embodiment, the second delay time TD is calculated by applying the iterative least squares method to the ARMA model, but the present invention is not limited to this. Other methods may be used to calculate the second delay time TD.

Moreover, in the present embodiment, the response characteristics of the compression tester main body 2 are approximated by a first-order lag system, but the present invention is not limited to this. The response characteristic of the compression tester main body 2 may be approximated by a transfer function model or a state space model. Alternatively, the response characteristics of the compression tester main body 2 may be defined by a Bode diagram showing the response of the compression tester main body 2 for each frequency.

[2-4. Calculation of adjustment coefficient]
The adjuster 55 calculates an adjustment coefficient GD for adjusting the gain. Specifically, adjustment factor GD adjusts gain GI of integrator 524 .

The adjustment unit 55 determines whether or not the second delay time TD satisfies the following formula (4).
(TA/TD)-1≧SH (4)
Here, the threshold SH is, for example, 0.1.

When the second delay time TD satisfies the formula (4), the adjusting section 55 calculates the adjustment coefficient GD by the following formula (5).
GD=1-∫(TA-TD)dt (5)
However, the second term on the right side of Equation (5) is the time integral of the difference between the first delay time TA and the second delay time TD from the time when the second delay time TD satisfies Equation (4) to the present time. indicates

The adjuster 55 adjusts the gain GI of the integrator 524 when the second delay time TD satisfies Equation (4). Specifically, the adjustment unit 55 replaces the gain GI with a value obtained by multiplying the gain GI by the adjustment coefficient GD.

In this embodiment, the adjustment unit 55 adjusts the gain GI of the integrator 524, but the invention is not limited to this. The adjuster 55 may adjust the gain of each of the proportionalor 523 and the integrator 524 .

[3. Experimental result]
[3-1. Experimental results in comparative example]
The test results of the rubber compression test will be described with reference to FIGS. 4 and 5. FIG.
FIG. 4 is a graph showing an example of changes in control compliance CP, first delay time TA, second delay time TD, and deviation ΔFD in a comparative example.
The comparative example differs from the present embodiment in that the gain GI of the integrator 524 is not adjusted. In other words, the comparative example is different from the control circuit unit 50 of the present embodiment in that the adjustment section 55 is not provided.

The horizontal axis of the upper, middle, and lower diagrams of FIG. 4 indicates time T. FIG. The vertical axis in the upper diagram indicates the control compliance CP. The vertical axis in the middle diagram indicates the first delay time TA and the second delay time TD. The vertical axis in the lower diagram indicates the deviation ΔFD. The deviation ΔFD indicates the difference between the target test force value FT and the measured test force value FD.

A graph G11 in FIG. 4 shows changes in the control compliance CP. As shown in graph G11, control compliance CP decreased as time T passed.

A graph G12 in FIG. 4 shows changes in the first delay time TA. As shown in graph G12, the first delay time TA was a constant value.
A graph G13 in FIG. 4 shows changes in the second delay time TD. As shown in graph G13, the second delay time TD decreased over time. That is, the response speed of the compression tester main body 2 increased as the time T passed.

A graph G14 in FIG. 4 shows changes in the deviation ΔFD. As shown in graph G14, the deviation .DELTA.FD decreased over time, and hunting HT occurred after time TS. The amplitude of hunting HT increased with time T.
Thus, in the experimental results of the comparative example, the response speed of the compression tester main body 2 increased with the passage of time T, and the control of the compression tester main body 2 became unstable, so hunting HT occurred after time TS. did.
In this embodiment, "hunting" indicates a phenomenon in which measured values such as the test force measured value FD vibrate.

[3-2. Experimental results in the present embodiment]
FIG. 5 is a graph showing an example of changes in the adjustment coefficient GD, first delay time TA, second delay time TD, and deviation ΔFD in this embodiment.
The horizontal axis in the upper, middle, and lower diagrams of FIG. 5 indicates time T. FIG. The vertical axis in the upper diagram indicates the adjustment factor GD. The vertical axis in the middle diagram indicates the first delay time TA and the second delay time TD. The vertical axis in the lower diagram indicates the deviation ΔFD. The deviation ΔFD indicates the difference between the target test force value FT and the measured test force value FD.

A graph G21 in FIG. 5 shows changes in the adjustment factor GD. The adjustment factor GD was constant until time T2, and decreased as time T elapsed from time T2.
Time T2 was the time when the first delay time TA reached 1.1 times the second delay time TD, as will be described later with reference to graphs G22 and G23.

A graph G22 in FIG. 5 shows changes in the first delay time TA. As shown in graph G22, the first delay time TA was a constant value.
A graph G23 in FIG. 5 shows changes in the second delay time TD when the adjustment unit 55 does not adjust the gain GI of the integrator 524. FIG. As shown in the graph G23, when the gain GI of the integrator 524 is not adjusted, the second delay time TD decreases as time T elapses after time T1.
Also, at time T2, the first delay time TA reaches 1.1 times the second delay time TD. That is, the time difference ΔTD1 shown in FIG. 5 indicates 0.1 times the first delay time TA. The time difference ΔTD1 indicates the difference between the first delay time TA and the second delay time TD at time T2.

A graph G24 in FIG. 5 shows changes in the second delay time TD when the adjustment unit 55 adjusts the gain GI of the integrator 524. FIG. The adjustment unit 55 adjusts the gain GI of the integrator 524 by multiplying by the adjustment coefficient GD. As shown in graph G21, the adjustment factor GD decreased with the lapse of time T from time T2.
As a result, as shown in the graph G24, the second delay time TD decreases with the passage of time T from time T1 to time T3, but increases with the time after time T3, reaching the first delay time TD. approached TA.

A graph G25 in FIG. 5 shows changes in the deviation ΔFD when the adjustment unit 55 does not adjust the gain GI of the integrator 524 . As shown in the graph G25, the deviation ΔFD decreased over time after time T1.
A graph G26 in FIG. 5 shows changes in the deviation ΔFD when the adjustment unit 55 adjusts the gain GI of the integrator 524. FIG. As shown in graph G26, the deviation ΔFD decreased from time T1 to time T2, and increased over time after time T2.

As described above with reference to FIG. 5, as a result of the adjustment unit 55 adjusting the gain GI of the integrator 524, the second delay time TD is suppressed from becoming excessively small, and the occurrence of hunting can be suppressed. .

[4. Processing of control device]
Next, the processing of the control circuit unit 50 will be described with reference to FIG.
First, in step S101, the control circuit unit 50 acquires the first delay time TA. Specifically, the control circuit unit 50 reads the first delay time TA from the memory device or storage device.
Next, in step S103, the identification unit 54 acquires a change in the target test force value FT.
Next, in step S105, the identification section 54 acquires a change in the test force measurement value FD.
Next, in step S107, the identification unit 54 identifies the transfer function GB(S) that indicates the characteristics of the compression tester main body 2 based on the change in the target test force value FT and the change in the measured test force value FD. and calculates the second delay time TD.

Next, in step S109, the adjustment unit 55 determines whether or not the second delay time TD is smaller than the first delay time TA by a predetermined value or more. The predetermined value is, for example, 10% of the first delay time TA.
When the adjustment unit 55 determines that the second delay time TD is not smaller than the first delay time TA by a predetermined value or more (step S109; NO), the process proceeds to step S115. When the adjustment unit 55 determines that the second delay time TD is smaller than the first delay time TA by a predetermined value or more (step S109; YES), the process proceeds to step S111.

Then, in step S111, the adjustment unit 55 calculates the adjustment coefficient GD. Specifically, the adjustment coefficient GD is calculated by the equation (5) described with reference to FIG.
Next, in step S113, the adjustment unit 55 adjusts the gain GI of the integrator 524 by replacing the gain GI of the integrator 524 with a value obtained by multiplying the gain GI by the adjustment coefficient GD.
Next, in step S115, the control circuit unit 50 determines whether or not the material test has ended.
When the control circuit unit 50 determines that the material test has not ended (step S115; NO), the process returns to step S103. If the control circuit unit 50 determines that the material test has ended (step S115; YES), the process ends.

Step S113 corresponds to an example of an "adjustment step."

[5. mode and effect]
It will be understood by those skilled in the art that the above-described embodiments and modifications are specific examples of the following aspects.

(Section 1)
A material testing machine according to one aspect is a material testing machine that performs a material test by applying a test force to a test material and deforming the test material, wherein the deviation indicating the difference between the measured value of the controlled object and the target value A feedback control unit that performs feedback control so that is zero, and an adjustment unit that adjusts the gain in the feedback control based on the design response speed of the material testing machine and the actual response speed of the material testing machine. is a material testing machine comprising:

According to the material testing machine according to item 1, the adjusting section adjusts the gain in the feedback control based on the design response speed of the material testing machine and the actual response speed of the material testing machine. For example, if the actual response speed is too fast relative to the designed response speed, the feedback control gain is adjusted to be smaller. Therefore, it is possible to suppress the occurrence of hunting of the material testing machine.

(Section 2)
In the material testing machine according to item 1, when the actual response speed is faster than the design response speed by a threshold speed or more, the adjusting section adjusts the gain.

According to the material testing machine of item 2, the gain can be adjusted appropriately. Therefore, it is possible to suppress the occurrence of hunting in the material testing machine.

(Section 3)
In the material testing machine according to item 1 or 2, the adjustment unit reduces the gain as the actual response speed increases with respect to the design response speed.

According to the material testing machine described in item 3, the gain can be adjusted more appropriately. Therefore, it is possible to suppress the occurrence of hunting in the material testing machine.

(Section 4)
3. In the material testing machine according to any one of items 1 to 3, each of the design response speed and the actual response speed is defined by a delay time of a first-order lag system, and the adjustment unit controls the design The gain is adjusted based on a first delay time corresponding to the response speed and a second delay time corresponding to the actual response speed.

According to the material testing machine according to item 4, in order to adjust the gain based on the first delay time corresponding to the design response speed and the second delay time corresponding to the actual response speed, simple With such a configuration, the gain can be properly adjusted.

(Section 5)
In the material testing machine according to item 4, the adjustment section adjusts the gain based on an integrated value of the difference between the first delay time and the second delay time.

According to the material testing machine of item 5, since the gain is adjusted based on the integrated value of the difference between the first delay time and the second delay time, the gain can be adjusted more appropriately.

(Section 6)
A control method for a material testing machine according to one aspect is a control method for a material testing machine that performs a material test by applying a test force to a test material and deforming the test material, wherein a measured value and a target value of a controlled object are Based on the feedback control step of executing feedback control so that the deviation indicating the difference between is zero, the design response speed of the material testing machine, and the actual response speed of the material testing machine, the gain in the feedback control and an adjusting step of adjusting the

According to the material testing machine control method of the sixth item, the same effects as those of the material testing machine of the first item are obtained.

[6. Other embodiments]
In this embodiment, the case where the material testing machine is the compression testing machine 1 has been described, but the present invention is not limited to this. A material test may be performed by applying a test force to the test material TP by the material testing machine to deform the test material TP. For example, the material testing machine may be a tensile tester, bend tester, or torsion tester.

Moreover, although the case where the control circuit unit 50 functions as a control device has been described in the present embodiment, the present invention is not limited to this. The control device should just have a computer. For example, a personal computer may function as the control device, or a tablet terminal may function as the control device.

The compression tester 1 according to this embodiment is merely an example of a material testing machine according to the present invention, and can be arbitrarily modified and applied without departing from the gist of the present invention.

1 Compression tester (material tester)
2 compression testing machine body 4 control unit 10 crosshead 12 load mechanism 14 load cell 15 displacement sensor 18 servo motor 20 rotary encoder 21 upper compression plate 22 lower compression plate 30 integrated control device 32 display device 34 test program execution device 40 signal input/output unit 42 first sensor amplifier 43 counter circuit 44 servo amplifier 45 second sensor amplifier 50 control circuit unit 51 communication unit 52 feedback control unit 53 filter processing unit 54 identification unit 55 adjustment unit 521 subtractor 522 multiplier 523 proportional device 524 integrator 525 Differentiator 526 Adder CP Control compliance dX Command value E1 First deviation (deviation)
E2 second deviation FD test force measurement value FT test force target value GD adjustment factor GI gain SG1 test force measurement signal SG2 rotation measurement signal SG3 strain measurement signal SH threshold TA first delay time TB second delay time U manipulated variable U1 first Operation amount U2 Second operation amount U3 Third operation amount TP Test material XD Displacement measurement value XT Displacement target value ΔF Test force change amount ΔX Movement amount

Claims (5)

A material testing machine that applies a test force to a test material and deforms the test material to perform a material test,
a feedback control unit that performs feedback control so that the deviation indicating the difference between the measured value and the target value of the controlled object becomes zero;
an adjusting unit that adjusts at least the gain of the integrator in the feedback control based on the designed response speed of the material testing machine and the actual response speed of the material testing machine;
with
Each of the design response speed and the actual response speed is defined by the delay time of a first-order lag system,
The material testing machine, wherein the adjustment section adjusts the gain based on a first delay time corresponding to the designed response speed and a second delay time corresponding to the actual response speed. 2. The material testing machine according to claim 1, wherein said adjustment unit adjusts said gain when said actual response speed is faster than said designed response speed by a threshold speed or more. The material testing machine according to claim 1 or 2, wherein said adjustment unit reduces said gain as said actual response speed is faster than said designed response speed. The material testing machine according to any one of claims 1 to 3, wherein said adjustment section adjusts said gain based on an integrated value of a difference between said first delay time and said second delay time. A control method for a material testing machine that applies a test force to a test material and deforms the test material to perform a material test,
a feedback control step of performing feedback control so that the deviation indicating the difference between the measured value of the controlled object and the target value becomes zero;
an adjusting step of adjusting at least the gain of the integrator in the feedback control based on the designed response speed of the material testing machine and the actual response speed of the material testing machine;
including
Each of the design response speed and the actual response speed is defined by the delay time of a first-order lag system,
The method of controlling a materials testing machine, wherein the adjustment step adjusts the gain based on a first delay time corresponding to the design response speed and a second delay time corresponding to the actual response speed.

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