JPS62217304A - Automatic controller - Google Patents

Abstract

PURPOSE:To simplify the design of both servo characteristics and regulator characteristics by deciding the controlled variable of a controlled system based on the simulated input signal and the output compensating signal. CONSTITUTION:The target voltage VR is calculated by a simulated compensating circuit 6 with input of the position command value xR so that a model position xM serves as an optimum answer. The impressing voltage (v) of a motor 1 is decided by the voltage VR. The optimum answer is obtained if the coincidence is secured between the characteristics covering the voltage (v) of the motor 1 through a table position (x) and those of a controlled system simulating circuit 7. While a position deviation epsilon is produced if no coincidence of said characteristics is secured. Thus the position compensating signal vepsilon calculated by an output compensating circuit 8 is added with the voltage (v) of the motor 1 for reduction of the deviation epsilon.

Description

DETAILED DESCRIPTION OF THE INVENTION [Field of Industrial Application] The present invention relates to an automatic control device suitable for use in position control, speed control, etc.

[Conventional technology]

In recent years, in various control devices such as XY tables and motors, (a) control characteristics that follow changes in command values c
There is a strong demand to improve both the servo characteristics (hereinafter referred to as servo characteristics) and (b) the control characteristics that attempt to maintain a constant value in the event of disturbance etc. (hereinafter referred to as regulator characteristics).

However, in conventional PID control and the like, there is a drawback that generally when the regulator characteristics are optimized, the servo characteristics become oscillatory, and on the other hand, when the servo characteristics are optimized, the regulator characteristics become slow. Therefore, various two-degree-of-freedom control systems have been proposed as methods for improving both characteristics. for example.

Proceedings of the Society of Instrument and Control Engineers, Volume 18, No. 1 (1981)
This document is written on pages 8 to 14 of ``Design of a model-following servo controller for a linear multivariable system.'' In this document, a model that can obtain an ideal step response is used, and the It describes a method for controlling a plant using the amount, the difference between the output of the model and the output of the plant, and the state amount of the plant. According to this method, not only the response of the servo system but also the response to disturbances can be controlled. can be improved.

[Problem that the invention seeks to solve]

However, the compensation constant of the control system is influenced by both the servo characteristics and the regulator characteristics. Therefore, in order to optimize both the servo characteristics and the regulator characteristics, compensation constants must be determined taking both into consideration, which complicates the design process.

An object of the present invention is to provide an automatic control device that can easily design servo characteristics and regulator characteristics independently.

[Means for solving problems]

An optimal feedback control system is configured for a controlled object simulation circuit that simulates the controlled object, and a simulated input signal input to the controlled object simulation circuit and a simulated output signal obtained from the controlled object simulation circuit are used to control the controlled object. A two-degree-of-freedom control system is constructed for the controlled object.

In addition, by calculating a state compensation signal using the difference between the state quantity of the controlled object and the state quantity of the controlled object model 11 circuit, and adding it to the input of the controlled object, the characteristics can be brought closer to the optimal characteristics. .

[Effect]

By using signals from an optimal feedback control system using a controlled object simulation circuit, it is possible to obtain control signals that always take into account the constraints of the controlled object. Thereby, even if there are constraints on the controlled object, both the servo characteristics and the regulator characteristics can be optimized.

In addition, by using a state compensation signal calculated based on the difference in state quantities, it is possible to reduce the difference in state quantities between the controlled object and the controlled object simulation circuit, so the output value of the controlled object can be brought closer to the simulated output signal. be able to.

〔Example〕

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

FIG. 1 shows an embodiment in which the present invention is applied to position control of an XY table.

In FIG. 1, by driving the motor 1,
The table 2 is positioned. Motor 1
and the XY table 2 are the controlled objects, and the table position [x] of the XY table 2, which is the output value state detection value, is detected by the position detector 3. The position command value XR obtained from the command device 4 is input to the simulated feedback control device 5. The simulated feedback control device 5 calculates the difference between the model position XM, which is an am output signal, and the position command value XR, and calculates a certain target voltage VR. Target voltage VR is motor 1 and
The signal is input to a controlled object simulation circuit 7 that simulates the Y table 2. Since the output of the controlled object simulation circuit 7 becomes the model position XM, the simulation feedback control device 5 constitutes a feedback control system for the controlled object simulation circuit 7. The output compensation circuit 8 has a model position XM and a table position X.
Position compensation signal v which is an output compensation signal using position deviation ε
& calculate. Position compensation signal V and feed ε

The applied voltage V of the motor 1 is determined by adding the target voltage VR which becomes the C forward signal. Note that since the characteristics of the controlled object simulation circuit 7 are clear, the model position
The constants of the simulation compensation circuit 6 can be determined so that the response of H is optimized. Furthermore, the maximum value i of the motor current ^
By inserting a limiter into the simulation compensation circuit 6 even when there are physical constraints such as χ and maximum speed ωMAX, it is easy to obtain the optimal response of the model position XH under those constraints. can.

6 is a model! A target voltage VR is calculated so that xM has an optimal response. The voltage V applied to the motor 1 is determined based on this target voltage VR. If the characteristics from the applied voltage V of the motor 1 to the table position W1x match the characteristics of the controlled object simulation circuit 7, the response will be the same as at the table position or model position X.

In other words, the table position X is an optimal response considering physical constraints. On the other hand, if the characteristics from the applied voltage V of the motor 1 to the table position X are different from the characteristics of the controlled object simulation circuit 7, the table position X does not match the model position X)I, resulting in a positional deviation ε. If there is a positional deviation ε, the positional compensation signal V calculated by the output compensation circuit 8 is added to the applied voltage ε of the motor, so the positional deviation ε can be made very small. Positional deviations, if they occur, can be similarly reduced.

FIG. 2 shows a block diagram of the transfer function in FIG. 1. In FIG. 2, KIN(8) is a transfer function that represents the characteristics of the simulated compensation circuit 6aX(S), which are the controlled objects, the motor and the XY table 2, respectively. .

Note that S is a Laplace operator.

Now, in Fig. 2, the transfer function Hs(s) representing the servo characteristics from the position command value XR to the table position X, and the transfer function HR(S) representing the regulator characteristics from the disturbance d to the table position X are as follows. It is expressed by the formula.

(1+Gz(s)Kz(g))(1+Gt(s)Krq
(s)...(1) The characteristic 0x(s) of the controlled object simulation circuit 7 is the characteristic G of the motor 1 and the XY table 2! When it is very close to (S), equation (1) can be approximated and expressed as equation (3).

1+Gz(s)KrH(s) As is clear from equation (3), the transfer function Hs(s) indicating the servo characteristics is approximately equal to the characteristic KIM([1
) is determined only by Furthermore, from equation (2), the transfer function HR(8) representing the regulator characteristic is determined only by the characteristic Kz(s) of the output compensation circuit 8.

In other words, this control system is KIN(s), KxCs)
It can be seen that this is a two-degree-of-freedom control system in which each of the characteristics has very little influence on other characteristics and can be determined independently. From the above, the characteristic Kr5(8) of the simulation compensation circuit 6 can be designed so that the servo characteristic for the controlled object simulation circuit 7 is optimized. Moreover, since the controlled object simulation circuit 7 is free from disturbances and parameter fluctuations, it is possible to design the circuit focusing only on the response. At this time, by inserting a voltage limiter that can be set below the maximum voltage that can be applied to the motor 1 into the output part of the simulation compensation circuit 6, the design aims to easily satisfy the constraint conditions for the applied voltage V of the motor. Bye. Note that if designed in this way, the gain of Kz(s) can generally be larger than that of KlK(S).

Furthermore, the characteristics Gl(8) of the motor 1 and the XY table 2
Even slight differences in the characteristics G1(S) and parameter fluctuations of the controlled object simulation circuit 7 can be compensated for by the characteristics Kz(s) of the output compensation circuit 8.

FIG. 3 shows the position control characteristics when a stepwise position command value XR is given in this embodiment.

When the position command value XR is changed stepwise at time to, the target voltage VR also changes as shown in FIG. At this time, if the characteristic Gl(s) of the motor 1 and the XY table 2 is the same as the characteristic at(S) of the controlled object simulation circuit 7, the table position X matches the model position XH, and an optimal response can be obtained. . Note that if the period from time to to tz is different from G1(s) of the simulated compensation circuit 6, a positional deviation ε occurs as shown in FIG. However, since the gain of the characteristic Kl(S) of the output compensation circuit 8 is large, the positional deviation ε can be made extremely small by feedback control.

As a result, although the applied voltage V is slightly different from the target voltage VR, the table level I! It is possible to make x almost coincide with the model position [XH. Generally, when the response to the position command value XR is optimized, the robustness may deteriorate. However, according to the present invention, it is possible to compensate for the difference between the model position xM and the table position x, and thus the robustness can also be improved.

FIG. 4 shows another embodiment of the invention. The embodiment shown in FIG. 4 is an example in which a general speed control system in which current control is a minor loop is included inside the controlled object. In other words, in Figure 4, the controlled object is moved from the speed command ωψ to the table position fla.
It is assumed that the characteristics are up to x.

In FIG. 4, the table speed ω obtained by the speed detector 9 is fed back and a speed control circuit 10 calculates a current command i. The current control circuit 12 controls the applied voltage V of the motor 1 based on the difference between the current command jL# and the motor current j detected from the current detector 1. This is a typical speed control system.

In the embodiment of FIG. 4, the simulated feedback control bag W
The controlled object simulation circuit 7a in 15a is the speed command ω.
It simulates the characteristics from the fist to table position X. Therefore, the simulation compensation circuit 6a changes the model position X from the position command value XR to the controlled object simulation circuit 7a.
The constants can be determined so that the servo characteristics for M are optimized.

In the embodiment shown in FIG. 4 as well, as in the embodiment shown in FIG. 1, the position deviation ε can be further reduced by performing feedback control by the output compensation circuit 8a using the position deviation ε.

At this time, changes in constants in the motor 1 and the XY table 2 and disturbances in the control system can be compensated to some extent by the speed control system, so according to the controlled embodiment, the robustness of the control system can be further improved.

FIG. 5 shows another embodiment. The difference between FIG. 5 and FIG. 4 is that the target current iR is used instead of the target speed ωR, and the current command i
This is the point in which s is determined. In addition, in the simulated feedback control device 5b, the controlled object simulated circuit 7b
is the current speed simulation circuit 13 that simulates the characteristics from the current command 111 to the table speed ω, and the low level from the table speed ω! ! The position simulation circuit 14 simulates the characteristics up to x. The first simulation compensation circuit 6b calculates the target speed ωR based on the difference between the position command value XR and the model position XH, and the second simulation compensation circuit 6C calculates the target speed ωR and the model speed ω obtained by the current speed simulation circuit 13. The target current jR is calculated based on the difference. As a result, the controlled object simulation circuit 7
Since the characteristics of b are clear, the model rank [not only XM,
The compensation gain of the pseudo-compensation circuit can be determined so as to optimize the mode, deflection, 11 degrees, and 4M for the servo characteristics. By adding the difference between the model speed ω and the table speed ω to the speed compensation circuit 15, which is the state compensation circuit of this embodiment, the table speed ω can be made approximately equal to the model speed ωH.

Therefore, according to the embodiment shown in FIG. 5, not only position control but also speed control can be optimized in the simulated feedback control device 5b, so that responsiveness can be further improved while maintaining robustness.

FIG. 6 shows another embodiment of the invention.

The embodiment shown in FIG. 6 extends the concept of the embodiment shown in FIG. 5 to a current control system.

In FIG. 6, the controlled object is from the voltage V applied to the motor 1 to the table position X. The controlled object simulation circuit 7 in FIG. 6 is the same as that in FIG. 1.

Regarding the embodiment shown in FIG. 6, parts different from those shown in FIG. 5 will be explained.

A target voltage VR is calculated in the third control simulation circuit 6d based on the difference between the target current iy+ obtained by the second control simulation circuit 6c and a model current iH, which will be described later. The controlled object simulation circuit 7 that inputs the target voltage VR is composed of three circuits. In other words, a current simulation circuit 16 that simulates the characteristics from the motor applied voltage V to the motor current i, and a speed simulation circuit 17 that simulates the characteristics from the motor current i to the table speed ω.
and a position simulation circuit 14 that simulates the characteristics from table speed ω to table position X. When the current simulation circuit 16 inputs the target voltage VR, the model current iM
Calculate. Thereby, in the third control simulation circuit 6d, it is possible to determine the optimum constants of the current control system for the servo characteristics.

In addition, the embodiment shown in FIG. 6 has a model current iM and a motor current i.
The sum of the difference between the two and the speed compensation signal i obtained from the speed compensation circuit 15 is input to the current compensation circuit ε 18. The voltage V applied to the motor is the sum of the current compensation signal V 2 obtained as a result and the target voltage VR.

Therefore, according to the embodiment shown in FIG. 6, in addition to the features of the embodiment shown in FIG. corresponds to

〔Effect of the invention〕

As explained above, according to the present invention, it is possible to construct a two-degree-of-freedom control system in which the constants of the servo characteristics and the regulator characteristics can be independently determined, so that the servo characteristics and the regulator characteristics can be easily designed.

Although the embodiments described above are applied to position control of an XY table, they can also be applied to robots, NC machine tools, and the like. Furthermore, any control system that can use the same concept as position control can be applied to speed control devices and plant control devices. Furthermore, although the above-described embodiments have been described in terms of a case where the system is constructed using an analog control circuit, it goes without saying that it can also be constructed using a digital control circuit using a microprocessor.

[Brief explanation of drawings]

It is a block diagram which shows another Example of this invention. DESCRIPTION OF SYMBOLS 1... Motor, 2... XY table, 3... Position detector, 4... Command device, 5... Simulated feedback control device, 6... Simulated compensation circuit, 7... Target Controlled object simulation circuit, 8... Output compensation circuit, 9... Speed detector, 10... Speed control circuit, 11... Current detector,
12... Current control circuit, 13... Current speed simulation circuit, 14... Position simulation circuit, 15... Speed compensation circuit,
16...Current simulation circuit, 17...Speed simulation circuit, 1
8... Current compensation circuit.

Claims (1)

[Claims] 1. A controlled object that is driven to a command value, and a control device that inputs the command value and a detected state value of the controlled object and determines a control amount of the controlled object. It consists of
The control device includes a controlled object simulating means that simulates the controlled object, and generates a simulated input signal to be input to the controlled object simulating means based on the difference between the command value and a simulated output signal of the controlled object simulating means. and an output compensation means that inputs the simulated output signal and the state detection value and calculates an output compensation signal such that the difference between the two is small, the simulated input signal and the output compensation An automatic control device that determines a control amount of the controlled object based on a signal. 2. Consisting of a controlled object that is driven to a command value, and a control device that inputs the command value and a detected state value of the controlled object and determines a control amount of the controlled object,
The control device includes a controlled object simulating means that simulates the controlled object, and generates a simulated input signal to be input to the controlled object simulating means based on the difference between the command value and a simulated output signal of the controlled object simulating means. a simulated compensation means for calculating; an output compensation means for inputting the simulated output signal and the state detection value and calculating an output compensation signal such that the difference between the two becomes small;
and a state compensation means for calculating a state compensation signal such that the difference between the state quantities of the controlled object and the corresponding state quantity of the controlled object simulating means is reduced by using the difference between the state quantity of the controlled object and the corresponding state quantity of the controlled object simulating means. An automatic control device characterized in that a control amount of the controlled object is determined based on the simulated input signal, the output compensation signal, and the state compensation signal.