JPH0690644B2 - Control device - Google Patents

Description

BACKGROUND OF THE INVENTION 1. Field of the Invention The present invention relates to, for example, a control device for a material testing machine, and more particularly to negative feedback control of an electrohydraulic servomechanism for applying a predetermined load to a test piece. .

B. Conventional Technology Conventionally, this type of control device basically performs PID (proportional / integral / derivative) control from the viewpoint of improving control accuracy. FIG. 5 is a control block diagram showing a schematic configuration of a conventional device.

That is, the conventional control device includes a PID control unit 1, a hydraulic actuator 2 that applies a predetermined load to a test piece (not shown) based on the operation amount v from the PID control unit 1, and the test piece. A load detector 3 such as a load cell that detects a load acting thereon is connected in cascade. The control amount c, which is the detection signal of the load detector 3, is fed back to the difference circuit 4
Given as a negative input to. The setting signal i is given to the difference circuit 4 as a positive input. The difference circuit 4 outputs a difference signal e between the setting signal i and the control amount c to the PID control unit 1. Then, the PID control unit 1 determines the operation amount v such that the difference signal e becomes zero and outputs it to the actuator 2. In this way, the load corresponding to the setting signal i is applied to the test piece.

C. Problems to be Solved by the Invention However, the above-described conventional device has the following problems.

In general, this type of control device has a decrease in signal level in a high frequency range. Therefore, when a signal including a high frequency component such as an earthquake waveform or a pier vibration waveform is used as the setting signal i, There is a problem that the control accuracy in the range cannot be secured.

It is possible to set a large differential (D) coefficient of the PID control unit 1 in order to improve control accuracy in a high frequency range.
This causes another problem that the control system is easily affected by noise.

The present invention has been made in view of such circumstances, and provides a control device capable of improving control accuracy in a high frequency range without setting a large differential coefficient of a PID control unit. Has an aim.

D. Means for Solving the Problem In general, this type of control system has a delay element of third order or higher, as shown in FIG. Such a control system is considered to be equivalent to a control system having a time delay τ. The present invention utilizes such an equivalent time delay τ of the control system to improve the control accuracy in the high frequency range.

The accuracy of the present invention will be described below with reference to FIG.

That is, according to the present invention, the output of the detector A for detecting the physical quantity of the controlled object is set as the control amount c, and the difference signal e between the control amount c and the setting signal i is given to the PID control unit B. In the device that controls the control operation means C so that the physical quantity of the controlled object changes according to i, the current control quantity c
Processing means D for obtaining the changing speed component cs of the control signal, second processing means E for holding the speed component is ′ of the setting signal for a period corresponding to the equivalent delay time of the control system, and the speed of the current setting signal. Third processing means F for obtaining the component is, first computing means G for calculating the ratio between the speed component cs of the present controlled variable and the speed component is ′ of the setting signal past by the delay time,
An output signal e ′ of the PID control unit B is obtained by multiplying the calculation result of the first calculation unit G by the speed component is of the current setting signal and the calculation result v ′ of the second calculation unit H. The output signal e'is corrected by adding to the correction signal I'and the correction means I for giving the result to the control operation means C as the operation amount v.

E. Action Refer to FIG. 7A is a waveform diagram of the setting signal i, and FIG. 7B is a waveform diagram of the control amount c equivalently delayed by τ time with respect to the setting signal i.

In a control system having an equivalent delay time τ, at present (t =
The control amount c of 0) is past (t = −τ) by the delay time.
It is considered to be dominated by the setting signal i. However, in general, the controlled variable c appears in a form in which the setting signal i is attenuated. Therefore, the speed component cs (corresponding to the inclination θ in FIG. 3B) of the current control amount obtained from the first processing means D and the delay time obtained from the second processing means E are set to the past setting signal. The speed component is ′ (corresponding to the inclination θ ′ in FIG. 3 (a)) is given to the first calculating means G, and the ratio between the two is calculated, so that the setting signal i is attenuated to obtain the control amount c. You can see what is reflected in. And
By multiplying the result obtained by the first calculating means G by the speed component is of the current setting signal obtained from the third processing means G, a correction amount v'in consideration of the attenuation amount of the control system is obtained. By giving this correction amount v ′ to the correction means I, adding it to the output signal e ′ of the PID control section B, and giving it to the control operation means C, the value of the control amount c that occurs in the τ time future,
The value can be set according to the current setting signal i.

F. Example Hereinafter, an example in which the present invention is applied to an electrohydraulic servo type material testing machine will be described with reference to the drawings.

FIG. 4 is a block diagram showing the outline of the configuration of an embodiment of the present invention.

In the figure, the parts designated by the same reference numerals as those in FIG. 5 are the same parts as the conventional device, and therefore the description thereof is omitted here.

In the figure, reference numeral 10 indicates a correction processing unit which is a characteristic part of this embodiment. The correction processing unit 10 compares the speed component of the current controlled variable c with the speed component of the past setting signal i by the equivalent delay time of the control system, and outputs the output signal e of the PID control unit 1. It is a processing unit for correcting ‘

The control amount c is negatively fed back to the difference circuit 4 and converted into a digital signal by the A / D converter 11a to be stored in the buffer memory 12a.
Stored in. The current control amount c stored in the buffer memory 12a is differentiated by the differentiation processing unit 13a to calculate the velocity component cs thereof. This differential processing unit 13
a corresponds to the first processing means D in FIG.

The setting signal i is given to the difference circuit 4, converted into a digital signal by the A / D converter 11b, and stored in the ring buffer memory 12b. The ring buffer memory 12b has a storage area for storing the data of the sampled setting signal i for at least the period corresponding to the delay time τ of the control system, and moves the stored data in sequence for each data sampling. To go. Differentiation processing unit 13b
Is given a data area in which past data is stored by the delay time τ, the data is given, and the velocity component is ′ is obtained by differentiating the data. The data area corresponding to the delay time τ is predetermined according to the delay time τ of the control system and the sampling time. Therefore, the ring buffer memory 12b and the differentiation processing unit 13b
Corresponds to the second processing means E in FIG.

The differential processing unit 13c is given the data of the current setting signal i stored in the first data area of the ring buffer memory 12b, and differentiates this data to obtain the velocity component is. This differential processing section 13c corresponds to the third processing means F in FIG.

The velocity component cs of the current controlled variable c obtained by the differentiation processing unit 13a is given as one input of the division processing unit 14. Further, the velocity component is ′ of the past setting signal i by the delay time τ obtained by the differentiation processing unit 13b is given as the other input of the division processing unit 14. The division processing unit 14 calculates these ratios (is' / ic). The division processing unit 14 corresponds to the first calculating means G in FIG.

The calculation result Kv output from the division processing unit 14 is averaged by the averaging processing unit 15 for an appropriate number of data, and is given as one input of the multiplication processing unit 16. Also,
The current setting signal i obtained by the differentiation processing unit 13c
The velocity component is of is given as the other input of the multiplication processing unit 16. The multiplication processing unit 16 determines the speed component is of the current setting signal i.
Is multiplied by the averaging result of the ratio of the speed component cs of the current controlled variable c and the past setting signal is ′ by the delay time τ. The multiplication processing unit 16 corresponds to the second calculation means H in FIG.

The correction amount v ′, which is the calculation result of the multiplication processing unit 16, is converted to an analog signal by the D / A converter 17, and then input to one of the adder circuits 18 and given. The adder circuit 18 adds the correction amount v ′ to the output signal e ′ of the PID control unit 1 and outputs the addition result to the hydraulic actuator 2 as the operation amount v.
This adder circuit 18 corresponds to the correction means I in FIG. Here, the correction amount v ′ obtained by multiplying the current speed component of the setting signal i by Kv is added before the hydraulic actuator 2 because the hydraulic actuator 2 includes an integral element. This is because the correction amount v ′ relating to is integrated and reflected in the control amount in a form corresponding to the original setting signal.

As is clear from the above description, the correction amount v'is given by the following equation.

Here, Kv is the output of the division processing unit 14, Given in.

In the above equation, (di / dt) _{t = 0} is the velocity component of the current setting signal i and corresponds to the output signal is of the differentiation processing unit 13c.
(Di / dt) _{t = -2} is the velocity component of the setting signal i in the past by the delay time (t = -τ), and is the output signal i of the differential processing unit 13b.
Corresponds to s'. (Di / dt) _{t = 0} is the speed component of the current controlled variable c and corresponds to the output signal cs of the differential processing unit 13a.

As described above, the ratio Kv between the speed component of the current controlled variable c and the speed component of the past setting signal i for the delay time τ is calculated,
The output signal e ′ of the PID control unit 1 is calculated by the correction amount v ′ obtained by multiplying the speed component is of the current setting signal by this ratio Kv.
By increasing or decreasing, the decrease in the signal level in the high frequency range of the control system is corrected and the control accuracy can be improved.

In the above embodiment, the delay time τ of the control system is known, the data area corresponding to this delay time is preset in the ring buffer memory 12b, and the data stored in the data area is set as the delay time. It is given to the differentiation processing unit 13b as a setting signal in the past by τ. However, when the delay time of the control system is unknown, or when it is desired to set the delay time of the control system with high accuracy, a delay time detection processing unit as shown by reference numeral 20 in FIG. 4 should be added. May be.

The delay time processing unit 20 includes a buffer memory 21 for temporarily storing the current controlled variable c converted into a digital signal.
A ring buffer memory 22 for sequentially storing the setting signal i converted into a digital signal for at least a period longer than the delay time τ, and an autocorrelation detection circuit 23.
The self-operation detection circuit 23 correlates the current control amount c stored in the buffer memory 22 and each data of the setting signal i stored in the ring buffer memory 22 from the past to the present for a predetermined time. The strength is calculated and the data with the strongest correlation is detected. This data is a past setting signal that governs the present controlled variable c. In this way, when the data corresponding to the delay time τ is detected, the autocorrelation detection circuit 23 detects the address signal of the data area as
It is transmitted to the ring buffer memory 12b of the correction processing unit 10. In this case, the ring buffer memory 12b also has the same address as the ring buffer memory 22 described above,
The data of the setting signal i is sequentially stored in synchronization with the ring buffer memory 22. Therefore, the autocorrelation detection circuit
Since the data of the address designated by 23 is the setting signal in the past by the accurate delay time τ, the control accuracy can be further improved by giving this data to the differential processing unit 13b.

Further, in the above-described embodiment, the buffer memory 12a and the ring buffer memory 12b each store the data before the differential processing, but the differential processing unit is installed in the preceding stage of each of the memories 12a and 12b, and is obtained by the differential processing. The velocity component may be stored in each memory.

Further, in the embodiments, the case where the device is configured by digital data processing has been described as an example, but the present invention can also be realized by analog processing. In this case, the setting signal in the past by the delay time can be obtained by passing through the delay circuit set to an appropriate delay time.

Furthermore, in the embodiment, the load acting on the test piece was taken as an example of the control amount, but this may be a displacement amount or other load, and the present invention is applicable to a material testing machine. The present invention is not limited to this, and can be applied to a control device that requires various feedback controls with respect to a control operation means including an integral element.

G. Effects of the Invention As is clear from the above description, the control device according to the present invention uses the equivalent delay time of the control system to calculate the current control amount and the delay time corresponding to the current control amount in the past. The ratio of the setting signal is obtained, the output signal of the PID control unit 1 is increased or decreased by the correction amount obtained by multiplying the ratio by the speed component of the current setting signal, and the result is given to the control operation means as the operation amount. Therefore, it is possible to improve the decrease in the signal level in the high frequency range without setting a large differential coefficient of the PID control unit, and it is possible to relatively easily improve the control accuracy.

[Brief description of drawings]

1 to 3 are explanatory views of the present invention.
FIG. 3 is a block diagram of a control device according to the present invention, FIG. 2 is a response characteristic diagram of a control system with a time delay, and FIG. 3 is a waveform diagram for explaining the operation of the present invention. FIG. 4 is a schematic control block diagram of an embodiment of the present invention. FIG. 5 is a schematic control block diagram of a conventional device. 1 …… PID control unit 2 …… Hydraulic actuator 3 …… Load detector 4 …… Differential circuit 12a …… Buffer memory 12b …… Ring buffer memory 13a to 13c …… Differentiation processing unit 14 …… Division processing unit 16… ... Multiplication processing unit

Claims (1)

[Claims] 1. An output of a detector for detecting a physical quantity of a controlled object is used as a control quantity, and a differential signal between this control quantity and a setting signal is set as PI.
In a device for controlling the control operation means so that the physical quantity of the controlled object changes according to the setting signal, the first processing means for obtaining the changing speed component of the current control quantity and the control system. Second processing means for holding the speed component of the setting signal for a period corresponding to the equivalent delay time of the above, third processing means for obtaining the speed component of the current setting signal, the speed component of the current control amount, and First computing means for calculating the ratio of the speed component of the past setting signal by the delay time, second computing means for multiplying the computation result of the first computing means by the speed component of the current setting signal, and the second computing means. 2. A control device comprising: a correction unit that corrects the output signal by adding the calculation result of the calculation unit to the output signal of the PID control unit and gives the result to the control operation unit as an operation amount. .