JPH0863202A - Controller for compensating idle time - Google Patents

Abstract

PURPOSE: To facilitate the control design of a response time. CONSTITUTION: A controller 12 consists of a response design part 121 for a transfer function obtained by dividing the reciprocal of a transfer function A/(1+TPS) excluding the idle time e<-> LS of a controlled system 13 by a primary delay quantity (1+TS) and an idle time compensation part 122 for a transfer function which compensates the output of the response design part with the idle time and is obtained by dividing the idle time e<-> LS; and it is made possible to represent the transfer function G( S) of the closed loop from the input to the output of a control system is as G( S) =(1/(1+Ts)).e<-> LS. This transfer function G( S) consists of the primary delay quantity (1+TS) and idle time e<-> LS, and does not have the e<-> LS in the denominator, so the control design of the response time is facilitated.

Description

Detailed Description of the Invention

[0001]

BACKGROUND OF THE INVENTION 1. Field of the Invention The present invention relates to a dead time compensated control device using an algorithm capable of compensating for a dead time and setting an arbitrary target response in feedback control of a controlled object having a dead time.

[0002]

2. Description of the Related Art There are two control methods for a control target having a dead time.

(1) A method in which the proportional gain P is designed to be small so that the PID controller 22 does not vibrate the dead time controlled object 25 as shown in FIG. 2 and feedback control is performed.

(2) As shown in FIG. 3, the PID controller 22 performs control not including the dead time system of the controlled object 25, and a Smith dead time compensation model 23 is added to this controller 22 to compensate for it. Deviation detector 21
Smith method for controlling the time-delayed controlled object 25 by correcting the operation signal e from E to e '.

[0005]

In the feedback control system based on the PID control described in (1) above, the transfer function of the PID controller 22 is G _(S) and the transfer function of the controlled object 13 is
e ^-LS・ (A / (1 + T _P S)) (however, e ^-ls → L _(S)
In the case of dead time, A, T _P → parameter to be controlled), the transfer function from the input to the output is given by equation (1).

[0006]

[Equation 1]

However, the dead time e in the denominator of equation (1)
^-The response time cannot be determined because the ^LS is included. Further, since the phase delay due to the dead time system is large, the open loop gain cannot be made large from the stability of the closed loop system. Therefore, it is difficult to obtain the initial control characteristics,
The output response design to the command value cannot be performed by P (proportional gain), I (integral gain), and D (differential gain) of the controller. Also, the output value will oscillate unless the response time is about three times as long as the response time in the state where no dead time is included.

In the Smith method (2), the response design of the output with respect to the command value can be performed by P, I, D of the controller, but there are many terms to be set as P, I, D. It takes time and effort. Further, since the target response time is not shown in the table, it is necessary to calculate the target response time from P, I and D.

The present invention has been made in view of the above problems of the prior art, and an object of the present invention is to provide a control device which compensates for dead time so that control design for response time is simplified. It is in.

[0010]

In order to achieve the above object, a control device for compensating for the dead time according to the present invention is a dead time control target in a controller which uses an deviation between an input and an output of a control system as an operation signal. In the controller for controlling the control function, the controller adds a dead time compensation to the response design part of the transfer function obtained by dividing the reciprocal of the transfer function excluding the dead time of the controlled object by the first-order delay and the output from this response design part. , A dead time compensating unit for a transfer function obtained by dividing the dead time by the same first-order delay as described above.

[0011]

The closed loop transfer function from the input to the output of the control system can be expressed by the first-order delay and the dead time. Therefore, the dead time of the controlled object can be compensated and the control design for the response time becomes simple.

[0012]

Embodiments of the present invention will be described with reference to FIG. FIG. 1 shows a block diagram of an algorithm for compensating the dead time of the controlled object part in the field back control and setting an arbitrary target response time. Reference numeral 11 denotes a control command and a field back value from the output of the controlled object 13. deviation detector for detecting a deviation 12 in the controller for controlling the controlled object 13 as an operation signal to the deviation, the response design portion 12 ₁ that amplifies the deviation, dead time adding the dead time compensation of the controlled portions in the output The compensation unit 12 ₂ and the adder 12 ₃ that adds the compensation amount are included.

The transfer function of the controlled object 13 is e ^−LS · (A
/ (1 + T _P S) (However, the dead time of e ^-LS → L _(S) ,
In the case of A, T _P → parameter to be controlled), the transfer function of the response designing unit 12 ₁ of the controller 12 uses the reciprocal (1 + T _P S) / A of the first-order lag of the controlled target 13 as the first-order lag (1
+ TS), and the transfer function of the dead time compensator determines the dead time e ^-LS of the control target by the first-order delay (1+
It should be divided by TS). Then, the closed loop transfer function G _(S) from the input to the output of the circuit of FIG. 1 is expressed by the equation (2).

[0014]

[Equation 2]

That is, the closed-loop transfer function is represented by the first-order delay (1 + TS) and the dead time e- ^LS , and e- ^LS is not ^included in the denominator. Therefore, the response to the target (63%
The response time T _(S) can be easily designed.

[0016]

Since the present invention is configured as described above, it has the following effects.

(1) For a controlled object having a dead time,
The dead time can be compensated, and the target response can be designed more easily.

(2) Compared with the conventional PID control system, the response time can be shortened and the control design for the response time becomes possible.

(3) Compared to the conventional PID control system to which the Smith method is added, the PID gain is not exposed, so that the control design for the response time is simplified.

[Brief description of drawings]

FIG. 1 is a block diagram showing an embodiment of the present invention.

FIG. 2 is a block diagram showing a conventional example.

FIG. 3 is a block diagram showing another conventional example.

[Explanation of symbols]

11, 21 ... Deviation detection unit 12 ... Controller 12 ₁ ... Response design unit 12 ₂ ... Dead time compensation unit 12 ₃ , 24 ... Adder 13, 25 ... Dead time control device 22 ... PID controller 23 ... Smith dead time compensation model.

Claims (1)

[Claims] 1. In a controller for controlling a dead time-controlled object by a controller using an deviation between an input and an output of a control system as an operation signal, the controller has a reciprocal of a transfer function excluding the dead time of the controlled object to a first order. By the response design unit of the transfer function divided by the delay amount and the dead time compensation unit of the transfer function obtained by adding the dead time compensation to the output from this response design unit and dividing the dead time by the same first-order delay amount as described above. A control device for compensating for dead time, characterized in that the transfer function of the closed loop from the input to the output of the control system can be represented by the first-order delay and the dead time.