JPS61198038A - Feedback control switching device in electric hydraulic servo-material testing machine - Google Patents

Abstract

PURPOSE:To switch automatically a feedback control by correcting a ratio of two detecting signals and a target value by an adding means, so as to hold a detecting signal of pressure piece, when a detecting signal of a load becomes a prescribed value. CONSTITUTION:A displacement of a pressure piece in an electric hydraulic servo-material testing machine is detected by a detecting means 1, a load is detected by a detecting means 2, and by adding both of them, a feedback signal for controlling a servo-valve is obtained. In this case, it is detected by a detecting means 5 that a signal of the detecting means 2 becomes a prescribed value, and in accordance with it, a value of a signal the detecting means 1 of that time is stored in a storage means 6. In this state, at every prescribed time, the stored value is compared with the signal from the detecting means 1, a ratio of two detecting signals and a target value 4 are corrected, and a feedback signal is outputted. Accordingly, a shock applied to the material is minimized and switching of an electric hydraulic servo-mechanism to a load state from pressure can be executed.

Description

DETAILED DESCRIPTION OF THE INVENTION [Field of Industrial Application] The present invention relates to a feedback control switching device in an electro-hydraulic servo material testing machine.

In materials testing machines, it may be necessary to switch feedback between different modes during operation, such as displacement and load. For example, in the case of a buckling test on steel materials, the steel material is placed in a predetermined position on the testing machine, and then the indenter of the hydraulic actuator is gradually extended using displacement feedback control while gradually increasing the set target value, and the indenter touches the steel material. Upon contact, control must be switched to load feedback.

[Prior art and problems to be solved by the invention] Conventionally, switching of this feedback control has generally been performed by manual operation.

However, in the servo valve, the change in oil amount and pressure per unit change in the spool, that is, the gain, is large in the oil amount control region and the pressure control region, as shown in FIGS. Therefore, the switching operation described above requires an extremely delicate and troublesome adjustment operation, and it is difficult to perform this adjustment operation without applying a shock to the sample. There were problems such as the impact on

[Means for solving problems]

The present invention solves the above-mentioned conventional problems and provides a feedback control switching device for an electro-hydraulic servo material testing machine that does not require troublesome adjustment operations and does not affect the sample. The first one showing the basic configuration
As shown in the figure, first and second detection means 1 and 2 detect first and second control amounts of the sample and output first and second detection signals, respectively; an adding means 3 for multiplying the detection signals by a predetermined ratio and outputting the results as a feedback signal; a target value setting means 4 for setting a control target value; Set the ratio of the second detection signal to be added to 0.
During the feedback control in the first mode, the second
detection means 5 for detecting that the detection signal of has reached a predetermined value;
and the first one at that time according to the detection by the detection means.
A storage means 6 for storing the value of the detection signal of the first detection means compares the value stored in the storage means with the first detection signal from the first detection means at predetermined time intervals, and when the two are substantially equal, the addition is performed. a control means 7 that performs control to correct the addition ratio in the means little by little, and to correct the set value by the target value setting means so that the two become equal when the two are not equal, the correction of the addition ratio; This is accomplished by a feed control switching device in an electro-hydraulic servo material testing machine, characterized in that the first and second detection signals are O and 1, respectively, and the feedback control is switched to the second mode. .

[For production]

In response to the second detection signal from the second detection means reaching a predetermined value, the addition means adds the first and second detection signals so as to maintain the value of the first detection signal at that time. The ratio of the detection signal and the target value are corrected at predetermined time intervals, and the first and second detection signals are finally set to 0 and 1, respectively, thereby automatically switching the feedback control.

〔Example〕

DESCRIPTION OF THE PREFERRED EMBODIMENTS An embodiment of a feedback control device for an electro-hydraulic servo material testing machine according to the present invention will be described below with reference to the drawings.

In FIG. 2, 10 is a hydraulic actuator fixed to a fixed part 12, and the direction and flow rate of pressure oil supplied to the cylinder of the hydraulic actuator are controlled by an electric signal applied to a servo valve 14, and a pressurizer 10a is moved. It will be done.

16 is a displacement detector that detects the displacement of the pressurizer 10a; 18
is a load detector that detects the load applied by the presser 10a through the sample 20, and this load detector is fixed to the fixed part 12. 22.24 is a displacement detector 16,
Obtained by the load detector 18, sensor amplifiers 23, 2
It is an A/D converter that converts the displacement and load detection signals, which are analog signals after being amplified by 5, into digital signals, respectively, and its output is sent to inputs X and Y of a central processing unit (CPU) 26, respectively. input.

The CPU 26 includes an arithmetic unit, read-only memory (ROM), and random access memory (RAM).
etc., and according to the program stored in the ROM in advance, the data stored in the RAM in advance, the input
The data input to Y is processed by the calculation unit, and the output is 0,
2, the target value and the feedback value are output as digital signals.

The target value and feedback value respectively outputted from the outputs 0 and Z of the CPU 26 are inputted into the 10 manpower and -manpower of the deviation counter 28, respectively, and the deviation corresponding to the difference between the two manpowers is determined by the deviation counter 28. The deviation signal is D
The signal is converted into an analog signal by the /A converter 30, amplified by the servo amplifier 32, and applied to the servo valve 14, thereby moving the pressurizer 10a in the direction where the deviation becomes zero.

In the above configuration, the operation will be explained with reference to the flowcharts of FIGS. 3 and 4 showing the work performed by the CPU 26 according to the control program stored in the ROM.

First, when the sample is set at a predetermined position in the testing machine and the operation is started, the target value from output 0 is gradually increased at a predetermined speed in step S1, and the indenter 10a detected by the displacement detector 16 is Displacement feedback control is performed so that the displacement follows the target value. When the target value is increased by a predetermined amount in step S1, the process moves to the next step S2, where the load detection signal from the load detector 18 is
If the determination is No, the process returns to step SL and the target value is further increased by a predetermined amount. Steps St and B2 are repeatedly executed as described above, and when the determination in step S2 becomes YES, step S3
Then, the target value is fixed and the pressurizer 10a is stopped.

Then, in the following step S4, it is determined whether or not to switch the feedback. If the determination is No, the process proceeds to step S5, where a test using displacement feedback control is started. Such a test using displacement feedback is performed, for example, when examining how much displacement is applied to a ceramic material before it breaks.

When the determination in step S4 is YES, the fourth step is used to switch the feedback from displacement to load.
Jump to the subroutine shown in the figure.

In the subroutine, in the first step Sll, the value of the displacement detection signal at the time of switching is stored in the C address in the CPU 26, and then the process proceeds to step S12, where constants α and β are set to 1 and 0, respectively. In the following step S13, it is determined whether the constant α is 1, but the determination immediately after execution of step S12 naturally becomes YES, and the process proceeds to step S14.

In step S14, the value of the displacement detection signal at that point is set to C.
Stored in address A in PU 26, then step 51
Proceed to step 5 and store the value of the load detection signal in the B address. The values stored in the A and B addresses in steps S14 and S15 are determined in step S16 as A×α=
It is used to calculate A1, 'BXβ-B, and obtain A1 and B1.

A1 and B obtained in step S16 are added in the subsequent step S17 to obtain M, and this M is used as a feedback value in the next step 318.
It is output from the output Z of U26 and added to the single power of the deviation counter 28. The feedback values added at this time are M=A, 10B, =A, which are unchanged from the previous feedbank values, and the deviation appearing in the output of the deviation counter 28 does not change.

In the above state, the process waits for a predetermined period of time in step S19, and then stores the value of the displacement detection signal in address A in step 520. If the value of the displacement detection signal at this storage time is different from the previous value in the A address, it is replaced with the previous value.

Thereafter, in step S21, the difference between the value in the C address, that is, the value of the displacement detection signal at the start of feed bank switching, and the value in the A address, L20-A, is calculated, and in the subsequent step S22, L is equal to O. A determination is made as to whether or not there is. The value in C address and A
If the values in the addresses are equal and the determination is No, that is, during the time waiting in step 519, the pressurizer 10a
is not displaced, the process proceeds to step 323, where 0.01 is subtracted from the constant α and 0.01 is added to the constant β. When the calculation in step 323 is finished, the process returns to step s13, where it is determined whether α=1 or not. However, since α is not 1 but No, the determination after this point is not performed through step SI4. Proceed directly to step S15.

In step S15, the value of the load detection signal at that time is stored in the B address again, and in the subsequent step 316, the value in the B address and the value in the Δ address stored in step S20 are used to -AXo, 99 B, = BX0.01 is calculated. Then, in step 818, the sum M obtained by adding these two values is output as a new feedback value to the output Z of the CPU 26 in step S18. The deviation counter 28 to which this new feedback value has been added to the single force outputs a deviation signal at its output, and therefore the pressurizer 10
a is moved in the direction where the deviation becomes 0.

After waiting for a certain period of time, the value of the displacement detection signal is stored in the A address in step S20, and the difference L=C-A between this stored value and the value in the C address is determined in step S21, and this difference is 0. A determination as to whether there is one is made in the subsequent step S22.

If the pressurizer 10a still does not move even after changing the constants α and β, the determination in step S22 is N.

The process then proceeds to step S23, but since the pressurizer 10a actually moves, the determination in step S22 is YES, and the process proceeds to step S24.

In step S24, whether L is greater than 0 or not,
That is, it is determined whether it is positive or not, and if the determination is YES, the process advances to step S25, where L is added to the target value output from the output O, and if the determination is NO, the process advances to step S26. Here, the output target value must be subtracted from the output 0 to correct the target values.

After the correction in step S25 or S26 is completed, the process proceeds to step S27, where it is determined whether or not β-1.The above-mentioned steps S13 to S26 are repeated until the determination becomes YES. When the feedback control is executed and β=1 and the determination is YES, the switching from displacement to load in feedback control is completed, and the process proceeds to step S6 of the flowchart in FIG. Material testing is performed using feedback control.

In the embodiments described above, feedback control switching is shown only for switching from displacement to load, but the present invention can also be applied to switching between any other arbitrary different modes.

〔effect〕

As explained above, according to the present invention, the switching operation is automatically started upon detecting that the detection signal has reached a predetermined value, and the ratio of the two detection signals to the feedback value is gradually changed. Since the switching operation is automatically performed while correcting the target value, there is no need for manual adjustment at all, and it has excellent effects such as being able to switch while minimizing the shock applied to the sample. is obtained.

[Brief explanation of the drawing]

FIG. 1 is a block diagram showing the basic configuration of a device according to the present invention, FIG. 2 is a block diagram partially showing an embodiment of the present invention in line diagrams, and FIGS. 3 and 4 are CPUs shown in FIG. 2. FIG. 5 is a flowchart showing the work performed by the servo valve, and FIG. 5 is a graph showing changes in oil amount and pressure relative to the spool of the servo valve. 1... First detection means, 2... Second detection means, 3
. . . addition means, 4. target value setting means, 5. detection means, 6. storage means, 7. control means. Patent applicant: Saginomiya Seisakusho Co., Ltd. Figure 3

Claims (1)

[Claims] first and second detection means for respectively detecting first and second control amounts of the sample and outputting first and second detection signals, respectively; and a predetermined ratio for the first and second detection signals. an addition means for adding together the multiplied products and outputting the result as a feedback signal; a target value setting means for setting a control target value; and a ratio of a second detection signal to be added to the first detection signal in the addition means. a detection means for detecting that the second detection signal reaches a predetermined value during feedback control in a first mode in which a storage means for storing a value of , and a value stored in the storage means is compared at predetermined time intervals with a first detection signal from the first detection means, and when the two are substantially equal, the addition ratio in the addition means is determined. and control means for correcting the set value by the target value setting means so that the two become equal when the two are not equal, the correction of the addition ratio is carried out by the first and second
1. A feedback control switching device in an electrohydraulic servo material testing machine, characterized in that the feedback control is switched to a second mode by making the detection signals of 0 and 1 respectively.