JP2003106966A - Hydraulic servo material testing machine - Google Patents

Abstract

(57) [Summary] [PROBLEMS] To perform stable control and to optimize both a target value response and a disturbance response.
In addition, the present invention provides a hydraulic-servo type material testing machine capable of automatically setting each constant of a feedback loop necessary for the optimization. SOLUTION: An adjustment unit 52 in a feedback loop.
Is composed of two parts 52a and 52b that execute a proportional operation and a differential operation with respect to a target value input and a detected value, respectively. In addition, a response when a step input is supplied in an open loop state is stored, and the stored contents and M as a model of a load mechanism including a test piece TP are stored.
(S) = Re ^−LS / sf (s) [where f (s) is a rational function of non-integrability including time constant T, L; delay time] There is provided a setting means for searching for an optimum combination of constants for the characteristic of (1) and automatically setting these values.

Description

DETAILED DESCRIPTION OF THE INVENTION [0001] The present invention relates to a hydraulic-servo type material.
Related to charge testing machines. [0002] 2. Description of the Related Art In a hydraulic-servo type material testing machine.
In general, an oil load mechanism for applying a load to a test piece
Driven by a pressure actuator,
Selected physical quantities, such as the displacement of the load mechanism and its
The target value for the load acting on the test piece due to the displacement
At the same time as supplying from a waveform generator,
By feeding back the output value,
And apply the load according to the target value. [0003] Such a feedback loop is provided.
Conventionally, in hydraulic-servo type material testing machines,
The deviation obtained by feeding back the detected value is referred to as PID (ratio
Example: Integral / Derivative) operation to obtain the manipulated variable, so-called PI
D control is performed. An example of the configuration of the control system is as follows.
As shown in FIG. 4, output from the waveform generator 41 and the like
Acts, for example, on the displacement of the load mechanism or the test piece against the target value r
Physical quantity selected as the control quantity z of the load
The detected value (observed amount) y obtained by detecting the
And the deviation e is determined by the PID controller 4
3 to perform proportional, integral, and derivative operations.
Operation for changing the valve opening of the servo valve 44
After obtaining the quantity u, the hydraulic actuator 45 for the load mechanism is driven.
It is configured to perform dynamic control. Note that w represents a disturbance.
Specifically, hydraulic fluctuations and hydraulic actuation
The friction of the seal portion of the cover may be considered. This control method will be described in more detail with reference to a block diagram.
This is as shown in FIG. In FIG. 5, 1 is
Kp is a proportional gain, and Tp_IIs the integral
Time, 1 / s is the integral element, T_DIs the differentiation time, D (s) is
The differential element, P (s), represents the transfer characteristic of the controlled object
You. [0005] However, as described above,
Conventional hydraulic-servo type material test that employs simple PID control
Optimize both target value response and disturbance response
There is a problem that it is difficult to do. That is, as shown in FIG.
Adjustments that optimize the response to the values
As shown in FIG. one
On the other hand, as shown in FIG.
And adjust the response to the target value
As shown in FIG. Further, a conventional hydraulic system employing PID control
In a servo-type material testing machine, the hydraulic pressure
Integral element 1 / s is included in transfer characteristic P (s) of drive system
Therefore, in addition to the integral element 1 / s in the controller,
1 / s in the transfer function^TwoTerm is included, and the control
Becomes unstable and hunting occurs in extreme cases
There is a problem that there is a possibility. Further, in the feedback control,
Generally, the gain adjustment of the feedback loop,
In the above PID control, the proportional gain
If the derivative time is not set to an appropriate value during
Control cannot be performed as shown in the figure.
When the test specimen is included in the elephant, the gain adjustment depends on the type of test specimen.
Not only do you need to do it every time you change,
It is not easy to adjust the gain of the system including
They often have to rely on,
Unable to adjust properly, uneven adjustment, hunting
And cause problems. The present invention has been made in view of such circumstances.
And stable control can be performed, and the target value
Response and disturbance response can be optimized,
Of the feedback loop necessary for the optimization
Rely on the operator's experience for each constant, including the proportional gain.
Hydraulic servo that can be set automatically without the need
It aims to provide a type material testing machine. [0010] SUMMARY OF THE INVENTION In order to achieve the above object,
Therefore, the hydraulic-servo type material testing machine of the present invention is a hydraulically driven type.
A feedback loop to control the load mechanism
In the following hydraulic-servo type material testing machine,
The adjustment section in the feedback loop controls the proportional and derivative actions.
Execute on target value and execute on detected value
And the weights of these two parts
In addition to the means for applying the test pieces independently,
Attach and provide step input in open loop state.
Response storage means for storing a response when the power is supplied, and the storage thereof
Based on the contents, the following model was used as a model of the load mechanism including the test piece.
An arithmetic means for identifying a system by using the equation (1);
Based on the results
Optimal proportional gain for multiple characteristics
Of the combinations of minute time and weight value above,
Search for things, and based on the search results,
Example Set gain, derivative time and above weight automatically
It is characterized by having setting means. [0011] M (s) = Re^-LS/ Sf (s) ··· (1) Where f (s) is a rational function of non-integrability including time constant T L: delay time Here, in the present invention, the feedback
The regulator in the group performs proportional and derivative actions
Means that the proportional and differential elements function
Therefore, the present invention provides an integral element
For the configuration that does not exist in the adjustment unit,
Set the integration time long enough that it will not work effectively
It includes both of the configurations described above. Also, in equation (1)
F (s) is, for example, (Ts + 1), (Ts
+1)^Two, (T₁s + 1) (T_Twos + 1)
Can be. The present invention provides for adjustment in a feedback loop.
Performs proportional and derivative actions, and for integral actions
Not to execute, that is, to make PD control practically
From the transfer function of the input / output of the system, 1 / s^TwoWithout the term
And adopting a two-degree-of-freedom control system.
Achieves optimization adjustment of both target value response and disturbance response
And a model of the two-degree-of-freedom PD control system is described above.
(1) It is assumed that it is expressed by the equation, and this model is used to open
Response when a step input is supplied to the system in the unlooped state
The system is identified from
Multiple characteristics obtained and stored
Of the proportional gain and differentiation in the feedback loop
Optimal combination of two weights between and with two degrees of freedom
Out of the search results and find them automatically.
Let's solve the above problems at once by setting to
It is assumed that. That is, a hydraulic-servo type material testing machine is used.
As described above, the hydraulically driven load to be controlled is
Since the transmission characteristic of the mechanism includes 1 / s,
When the integral element 1 / s functions, the input / output transfer function
1 / s in^TwoIn the present invention,
Does not allow the integral element to function in the control
1 / s to force transfer function^TwoTerm is no longer included,
Instability factors can be eliminated. [0015] Further, the adjusting section operates with respect to the target value.
The part and the part that operates on the detected value are provided separately.
Each can be given an arbitrary weight
The smaller the weight of the former, the sharper the
Even if there is a change, it is possible to suppress a sudden change in output,
The occurrence of overshoot can be suppressed. Anti
On the other hand, the output rises slowly. On the other hand, both equal
Increasing the proportional gain will increase the feedback.
Disturbances are suppressed more strongly, but they are made excessively large.
The system becomes oscillating and becomes unstable. that's all
Therefore, we simulate in advance and adjust
Of the two parts that operate on the target value
Adjust the weight and proportional gain values to be
No sudden changes in force and no vibrating system
To determine the value of disturbance suppression
More strongly suppress disturbances and produce sudden changes in output.
A control system can be realized. As a result
The target value response as shown in FIG. 5 (A) and FIG. 6 (B)
A control system that can simultaneously obtain the disturbance response as shown in
Is obtained. For such optimization, the ratio
For example, gain, derivative time, weight for target value input, etc.
It is necessary to adjust each constant to the optimum value.
In the present invention, these constants are optimized by the following method.
The automation of setting to an appropriate value is realized. That is, the results of the inventors' earnest research.
As a result, a hydraulic-servo type material test applying PD control with two degrees of freedom
It was confirmed that the model of the testing machine could be represented by equation (1). So
Then, when this model is decided, test pieces are attached, and
When a step input is supplied in the open loop state
The system can be identified from the response of Also, once the model is decided,
For each of the multiple characteristics of the system including the test piece,
A constant that can optimize both the target value response and the disturbance response
Combination: proportional gain, derivative time and target value
Simulate optimal combination of weights for input
Can be determined by Therefore, in the present invention, the system
The optimal combination of each constant for multiple characteristics of
Attach the test piece and open the
In the loop state, supply a step-like input and
Is identified and stored in advance based on the identification result.
Search for the best combination of
Search and automatically enter the proportional gain, derivative time and target value.
Each value of the weight for the force is set in the adjustment unit. This
Response and target value response without relying on operator experience.
A state in which both the disturbance response is optimized is obtained. [0019] BRIEF DESCRIPTION OF THE DRAWINGS FIG.
An embodiment will be described. FIG. 1 shows an embodiment of the present invention.
FIG. 2 is a detailed view of the control system of the apparatus.
It is a block diagram which shows a structure. The tester main body 1 has two tables 11 on a table 11.
Columns 12a and 12b are provided, and the columns 12a and 12b
b to support both ends of the cross yoke 13
Have. The table 11 has a servo valve 2
Activates the hydraulic cylinder that is operated by the pressure oil supplied by
There is provided a load mechanism 14 serving as a heater. This negative
The lower grip 15a is attached to the loading mechanism 14 and
To the cross yoke 13 via the load cell 3
The upper grip 15b is mounted. Test piece TP
Both ends of the upper and lower grippers 15a and 15b are gripped.
It is subjected to the test in a state where it is closed. That is, the upper and lower grippers 15a, 15b
The test piece TP whose both ends are gripped is driven by the load mechanism 14.
And acts on the test piece TP.
Load is detected by the load cell 3 and
The displacement of the structure 14 is detected by the displacement meter 4. The average load by the load cell 3 and the displacement meter 4
And the displacement detection signal is fetched into the control device 5 every moment.
You. The control device 5 controls the load cell 3 and the displacement meter 4 every moment.
Is stored as test data, and FIG.
A waveform generator 51 for outputting a target value r to be adjusted,
And a physical quantity selected as the control quantity z, for example,
The detection signal of the load by the load cell 3 is derived as the observation amount y.
To form a feedback loop and
An operation amount u to be supplied is generated. The control device 5 operates the operation unit 6.
As described later, the observation amount y is fed back,
State, that is, open loop state.
In this state, the waveform generator 51
Can be supplied to the adjustment unit 52,
The response (observed amount) y can be temporarily stored in the memory 54.
Swelling. The control device 5 includes
Using the memory contents, include the test piece TP by the method described later.
A program has been written to identify the system. Also,
The test piece is stored in the memory 54 as described later.
Assuming multiple characteristics of the system, including
Simulation feedback in advance
Remembers the best combination of loop constants
The control device 5 follows the identification result of the system described above.
Search for the appropriate combination of constants,
A program for setting each set constant in the adjustment unit 52 is also written.
It is rare. Now, this embodiment is adopted in the embodiment of the present invention.
The characteristic of the feedback loop shown in FIG.
Two-degree-of-freedom PD control is adopted.
The first adjusting unit 52a and the second adjusting unit 5
2b, and each of these adjusting sections 52a, 52b has
In some cases, there are proportional and differential elements, but the integral element
Absent or increase integration time if present
Is configured to not perform the integration operation by
And the weights (1−α) and (1) in the adjustment unit 52a.
-Β) can be given an arbitrary value. And two
In the adjustment units 52a and 52b, the basic parameters
Some proportional gain Kp and derivative time T_DWith two degrees of freedom
Parameters can be set independently of parameters α and β.
By setting these four values appropriately,
As described later, both the target value response and the disturbance response
The system can be optimized for it. In the embodiment of the present invention,
According to the system configuration shown in FIG.
Since the adjusting unit 52 does not perform the integrating operation,
Terms related to integral elements included in the overall input / output transfer function
Are included in the hydraulically driven load mechanism 14 to be controlled.
Only the term of the integral element 1 / s is used.
1 / s like material testing machine^TwoIs not included. Follow
Thus, control instability can be eliminated. In the above embodiment, the target value
r in the first controller 52a operating on
Data α and β, that is,
As the weights of the proportional and differential elements decrease,
There is little sudden change in the output y when the target value r suddenly changes.
And overshoot can be suppressed.
Although it can be started, the start-up becomes slow. Also the whole
Increase the proportional gain Kp that equally applies to the element
And it will be possible to suppress disturbance more strongly
However, if it is too large, the system will vibrate,
Becomes unstable. So, let's do a simulation in advance
And the response y to the target value input r is delayed
In the range where overshoot does not occur.
In addition, the disturbance suppression power is within the range where the system does not vibrate.
Find the combination of each parameter that gives the strongest
The setting of the adjusting unit 52 is performed using these values. This
Therefore, the target value response is calculated as shown in FIG.
It can be in an appropriate state. In addition, the target value response is shown in FIG.
In the condition adjusted to the optimal condition as shown in
The effect of the disturbance input w can be suppressed, and the disturbance response
However, the optimum state as shown in FIG.
Can be Next, a proportional gain K for optimizing the system
p, derivative time T_DAnd two-degree-of-freedom parameters α and β
The method of dynamically setting is described. Fee shown in FIG.
Hydraulic-servo type material testing machine with feedback loop
With the test piece TP attached, the model M (s) is
It can be represented by the above equation (1). [0030] M (s) = Re^-LS/ Sf (s) ··· (1) Where f (s) is a rational function of non-integrability including time constant T L: delay time R, L, and T in this model are determined.
Simulation, the desired value response and disturbance
A proportional gain Kp that can optimize both of the responses,
Differentiation time T_DAnd two-degree-of-freedom parameters α and β
be able to. Therefore, in advance, R,
Assuming the characteristics of the system in which L and T are variously changed,
Optimal proportional gain K by simulation for each gender
p, derivative time T_DAnd values of two degrees of freedom parameters α and β
Is obtained and stored in the memory 55. Specifically
Is expressed as Kp, T using L / T as a parameter._D, Α and
The number table of β is stored. The characteristics of the actual system equipped with the test piece TP are not
Therefore, the test piece TP is obtained by the following method.
Identify the system as mounted. That is, if the model
Since R, L, and T in this equation are expressed by the following equation (1),
Determined by the method shown in In identifying this system
Indicates that the system is in an open-loop state,
Without feedback of the quantity y, the waveform generator 5
1 to square waves with a wide frequency spectrum.
A step-like input is supplied to the adjustment unit 52,
Is stored in the memory 55, and the response y
R, L, T in the model (1) of the system are determined
I do. The M (s) expressed by the equation (1) is converted to Laplace inverse
What is converted to the time domain by the conversion is m
(T). For example f (s) = (Ts + 1)^Two.... (2) Then [0035] (Equation 1) And therefore: [0037] (Equation 2) The expression (4) can be expressed by a memory
55. When a rectangular wave is supplied in the open loop state
The response will typically be as illustrated in FIG.
By comparing the response data of
, That is, find R, L, T of the actual system
be able to. Based on the identification result, the memory 55
From the numerical table that uses L / T as a parameter,
Applicable Kp, T_D, Α and β, and find these values
It is automatically set in the adjustment unit 52. The numerical table when the model is expressed by equation (3) is [Table
1]. In this example, α is all 0.
Therefore, the description is omitted in [Table 1].
You. Now, the result of identification is L = 0.002, T = 0.00
4, if R = 0.5, L / T = 0.5.
Therefore, Kp × R = 0.829, T_D× T = 1.705
Therefore, each constant to be set in the adjustment unit 52 is
Kp = 1.6596, T _D= 0.0068204, β =
0.741 and α = 0. Each value is 2 degrees of freedom PD system
The system shown in Fig. 2
Optimized for both target and disturbance response
State. [0042] [Table 1] The block diagram in FIG. 2 shows the function of each part.
Is represented by a set of blocks that represent
The control device 5 is a digital operation type mainly composed of a computer.
And therefore some of the blocks in FIG.
Consists of software that performs that function.
You. The block diagram of FIG. 2 has a two-degree-of-freedom system.
Although it is expressed by the general formula type of control system, feed forward
Type, loop compensation type, feedback compensation type, target value
Filter type and element separation type can be equivalently expressed.
The point is that the control law in the present invention
Two-degree-of-freedom PD control that can assign a variable weight to the value input
Just do it. [0045] As described above, according to the present invention, the hydraulic pressure
The adjustment part of the servo-type material testing machine performs proportional operation and differential operation.
Execute and do not perform the integration operation, and set that operation to the target value.
Two separate runs for each of the input and detected values
Parts, each of which is given an independent weight.
Hydraulically driven type
The term 1 / s of the integral element is included in the transfer function of the load mechanism itself.
Even if it is, the 1 / s
^TwoTerm is not included, eliminating control instability.
And by setting the weights appropriately,
For a sudden change in the value input, only a sharp rise
Output can be obtained without overshoot.
Sometimes, it is necessary to perform control with excellent suppression
To optimize both the target value response and the disturbance response.
Can be. In the present invention, the model of the system is described above.
Equation (1), and a plurality of characteristics
Gain, derivative time and derivative
Specify the optimal combination of weights to be given to the input to the motion.
Remember, step in open loop
The system from the response to the input of
The appropriate proportional gain, derivative time and derivative based on the result
Search for combinations of weights to be given to the input to the motion
And there is a means to set these automatically,
Quick adjustment of system optimization without relying on operator experience
It can be performed quickly and stably. Also, the same
When setting, input the step-like input in the open loop state.
In order to supply, even the size should be selected appropriately
Hunting or damage to the specimen during adjustment.
Can be prevented.

BRIEF DESCRIPTION OF THE DRAWINGS FIG. 1 is an apparatus configuration diagram of an embodiment of the present invention. FIG. 2 is a block diagram showing a detailed configuration of a control system according to the embodiment of the present invention. FIG. 3 is a graph showing an example of a response when a step-like input is supplied in an open loop state to identify a system according to the embodiment of the present invention. FIG. 4 is a block diagram showing a configuration example of a control system of a conventional hydraulic-servo type material testing machine. FIG. 5 is a block diagram showing details of a control method shown in FIG. 3; FIG. 6 is a graph showing a target value response (A) and a disturbance response (B) at the time of adjustment in which the target value response is optimized in a conventional hydraulic-servo type material testing machine employing PID control. FIG. 7 is a graph showing a target value response (A) and a disturbance response (B) at the time of adjustment in which a disturbance response is optimized in the hydraulic-servo type material testing machine employing the conventional PID control. [Description of Signs] 1 Tester main body 11 Tables 12a, 12b Column 13 Cross yoke 14 Load mechanism 15a, 15b Gripping tool 2 Servo valve 3 Load cell 4 Displacement meter 5 Control device 51 Waveform generator 52 Adjustment unit 52a First adjustment unit 52b Second adjustment unit 53 Control target 54 Memory 6 Operation unit TP Test piece

   ────────────────────────────────────────────────── ─── Continuation of front page    (72) Inventor Noriaki Komine             1 Nishinokyo Kuwabaracho, Nakagyo-ku, Kyoto Stock Exchange             Inside Shimadzu Corporation (72) Inventor Mitsuhiko Araki             80-2 Katsumachi, Kamigamohan, Kita-ku, Kyoto-shi (72) Inventor Hidefumi Taguchi             4-8-13-303, Shibahara-cho, Toyonaka-shi, Osaka F term (reference) 2G061 AA01 DA03 EA02 EA03 EB05

Claims (1)

Claims: 1. A hydraulic-servo material testing machine comprising a feedback loop for controlling a hydraulically driven load mechanism, wherein an adjusting unit in the feedback loop comprises a proportional operation and a differential operation. It is composed of a part that performs the operation on the target value and a part that performs the operation on the detected value, and has means for independently assigning weights to these two parts. And response storage means for storing a response when a step input is supplied in an open loop state;
From the stored contents, as a model of the load mechanism including the test piece, a calculation means for identifying the system using the following equation (1), and based on the identification result, a calculation is made in advance using the above model and stored. Among the optimal combination of the proportional gain, derivative time and the value of the weight for a plurality of characteristics, a corresponding one is searched, and the proportional gain, derivative time and the weight of the adjustment unit are automatically determined based on the search result. 1. A hydraulic-servo type material testing machine, comprising: M (s) = Re− ^LS / sf (s) (1) where f (s); a rational function L of non-integralness including a time constant T; delay time