JPS63704A - Controller - Google Patents

Abstract

PURPOSE:To set an automatic control state in a short time at the time of start-up by using a start-up processing means. CONSTITUTION:A controller works based on pseudo set value signal outputted in steps from a set value changing part and releases a start-up mode when the process value shows a desirable transient answer to set an automatic control operation mode. In other words, a set value changing part 21 of a start-up processing means 2 outputs the pseudo set value signal SVD which changes in steps by a prescribed amount S1 in a range smaller than that of the set value signal SV. A PI control means 3 outputs the operating signal MV to a process 1 and therefore the process 1 is controlled by the signal MV. Then the process value PV is outputted in accordance with the characteristics of the process 1. An adaptive control processing part 4 observes a transient answer and calculates the PI arithmetic constant of the means 3 to obtain the desirable damping value and the desirable overshoot value. Thus the PI arithmetic constant is set and changed.

Description

Detailed Description of the Invention (Industrial Application Field) The present invention relates to a controller having a self-tuning function that automatically adjusts at least proportional (P) and integral (I) calculation constants to optimal values. More specifically, the present invention relates to a controller having startup processing means that reduces operator operations at startup.

(Prior art) Currently, in process pH moderators used for feedback control, the setting of PI calculation constants is done manually based on the many years of knowledge and experience of process operators or instrumentation engineers. be. However, manual settings may cause periodic or steady process operation disturbances during process startup, load fluctuations, unexpected disturbances, or systems with nonlinear gain characteristics. , depending on the situation, it could cause economic loss.

Therefore, a controller has been proposed in which the PI calculation constant is self-tuned. Self-tuning controllers that have been proposed so far connect an auxiliary controller in parallel to the main controller, increase the gain of the auxiliary controller to generate vibration, and change the amplitude from one frequency to the Xiegler.

Determining the PI constant based on the so-called Z-N limit sensitivity method by N1chols (1972 Society of Instrument and Control Engineers Proceedings Vol. 6. L 6 P55 ~ P6fl Research on adaptive control systems using the limit sensitivity method, Toshiyuki Kitamori ),on.

A limit cycle is generated using an off generator, and the optimal PI calculation constant is determined from the amplitude etc. (1970 Society of Instrument and Control Engineers Society of Instrument and Control Engineers 12th Academic Conference Proceedings P617 - PH4PIO automatic setting shape adaptive controller (Sumi, Fukuda), etc. In addition, the applicant must first apply for special application! In No. 0-N8451, we proposed a self-tuning controller that adjusts PI calculation constants to provide the optimal response by looking at changes in the control amount due to randomly occurring disturbances, etc., without causing any disturbance to the process. There is.

(Problem to be solved by the invention) By the way, in all of these self-tuning controllers, at startup, the operator determines the PI calculation constant in the absence of any signal from the process, and then the operator determines the PI calculation constant while observing changes in the controlled variable, etc. The PI calculation constants are changed based on the operator's experience or through trial and error and are set to optimal values. Therefore, it takes a long time until the optimum PIi* calculation constant is set. This becomes a problem especially when starting up a plurality of control loops at once.

The present invention was made in view of these problems, and
The purpose is to create a controller that automatically determines the optimal PI calculation constants in a short time at startup by providing a startup processing means, and automatically shifts to an automatic control state using the optimal PI calculation constants. That is.

(Means for Solving the Problems) The present invention, which solves the above-mentioned problems, is based on a method that is at least proportional to the process amount and the set value signal from the process.

PI control means that performs an integral calculation and outputs the obtained manipulated variable to the process; a proportionality constant that inputs the process variable and a set value signal and is set in the PI control means according to the transient response of the process variable; an adaptive control processing means for setting an integral constant to an optimum value; and a startup processing means for inputting a set value signal at startup and outputting a 'Q-like film set value signal that changes stepwise within a range smaller than the set value. At startup, the adaptive control processing means and the PIMm means operate by inputting a pseudo set value signal from the startup processing means, and the Q overcontrol processing means observes the transient response of the process amount at that time.
The PI calculation constant in the I control means is gradually set and changed, and when the pseudo setting signal becomes a set value signal and the process variable shows a desired transient response, the startup mode is canceled, and the adaptive control processing means and A set value signal is input to the PI control means.

(Embodiment) FIG. 1 is a functional block diagram showing an example of a device according to the present invention. In the figure, 1 is a block indicating a process object, and its dynamic characteristics change depending on the operating object. 2 is a startup processing means that functions at startup, and 3 is a set value S output from this startup processing means 2 and a process amount P from process 1.
A PI control means which inputs the deviation ε from the deviation signal () performs at least P and I calculations on the deviation signal (and outputs the obtained manipulated variable MV to the process 1. 4 is the process lpv from the process l, the startup processing means Input the set value S■ from 2 and the manipulated variable MV to the process 1 as necessary, and adjust the P! calculation constant set in the control means 3, ■calculation constant according to changes in the process amount Pv, etc. This is an adaptive control processing means that sets the value to an optimal value.

In the startup processing means 2, 21 is a set value changing unit that inputs a set value signal Sv and outputs a pseudo set value signal SVD that changes in a stepwise manner within a range smaller than this set value signal sV; The set value signal S■ and the pseudo set value signal SVD are selected and applied to the adaptive control processing means 4 by the first switch having the first switch. SW2 is the first
A second switch is driven in synchronization with the switch SWI, has contacts a and b, selects the set value signal S■ and the pseudo set value signal SVD, and supplies it to the PII control means 3. This first. Second switch SWI.

SW2 constitutes a start-up mode switch, and in the start-up mode state, the contacts 1 (other than the normal PI control light start-up) are connected to the contact a side.

The operation of the apparatus configured as described above will now be described with reference to the time chart shown in FIG.

First, after turning on the power, the operator performs an operation to start the startup mode. In this startup mode, the first. The second switches SWI and SW2 are
The PII control means 3 and the adaptive control processing section 4 both receive the pseudo setting signal VD output from the setting value changing section 2I. Next, the operator
Settings for operating the controller, e.g. set value signal Sv
Set as shown in the solid line in (a). In addition, the adaptive control processing unit 4 is provided with preferable damping (m D
M P , a preferred overshoot value OVt is set.

After completing these settings, switch to the auto state (automatic: section J8 state). Subsequently, the set value changing unit 21 in the startup processing means 2 outputs a pseudo set value signal SVD that changes stepwise by a predetermined amount S1 within a smaller range than the set value signal S, as shown by the broken line in (A). . PII
The control means 3 receives the pseudo set value signal SVD and outputs the operation signal MV to the process 1. Process 1 is controlled by this operation signal MV, and from here, as shown in (b), a process amount pv according to the characteristics of process 1 is output.

The adaptive control processing unit 4 controls the process amount P■ of the process 1
PI to realize a preferable damping value and a preferable overshoot value by observing the transient response.
The PII calculation constant of the I control means 3 is calculated, and this is set and changed.

Here, as an algorithm for observing the transient response of the process quantity PV and setting a PII calculation constant, for example, the one proposed in the above-mentioned Japanese Patent Application No. 6O-24N51 can be used.

Subsequently, the set value changing section 21 again changes the pseudo set value signal SVD in steps by a predetermined amount, as shown by the broken line in (A), to bring it closer to the original set value signal S■. The adaptive control processing unit 4 observes the transient response based on this and calculates P
The PII calculation constant of the II control means 3 is set or changed again based on the calculation result.

Thereafter, in the same manner, the set value changing unit 21 further changes the pseudo set value signal SVD in steps as shown by the broken line in (A) until it matches the original set value signal Sv, and then changes the pseudo set value signal SVD in a stepwise manner as shown by the broken line in (A). The PII calculation constant of means 3 is set or changed based on the calculation result.

In addition, although FIG. 2 shows an example in which the pseudo setting value signal SVD is changed repeatedly three times, the reason for this is that the adaptive control processing unit 4 cannot change the pseudo setting value only once for boat fishing. This is because it is difficult to calculate the PII calculation constant to obtain a preferable damping value and a preferable overshoot value, and the number of repetitions is not limited to three.

Here, the adaptive control processing unit 4 always observes the excessive g response of the process amount P■ from the process 1, and the damping value DMP of this transient response and the overshoot value OVR are set to the target damping value The startup processing means 2 detects that the process amount PV and the pseudo set value SVD almost match the overshoot value and that the deviation DV between the process amount PV and the pseudo set value SVD becomes almost zero, and the startup processing means 2 detects that the pseudo set value signal SVD and the set value signal Sv When they become equal, the first. second switch SWI,
Connect SW2 to contact a@, end the startup mode, and shift to PII dynamic control mode using auto-tuning. In this state, the set value signal S■ is applied to the PII control means 3. The signal is applied to the adaptive control processing section 4, and the PII control means 3 auto-tunes its PI calculation constant according to the signal given from the adaptive control processing section 4, thereby automatically controlling the process 1.

In addition, in Figure 2, step! Io, (1) ~ (3
) is by Saku.

In addition, although the above description uses the P I It' control means, it is also possible to use the PID control means.

(Effects of the Invention) As explained above, in the startup mode, the device of the present invention operates based on the pseudo set value signal output in steps from the set value changing unit, and the optimal control processing unit The Pl calculation constant is gradually set and changed by observing the transient response of the quantity, and finally the pseudo setting signal SVD
When the value becomes the original set value signal S■ and the process quantity shows a desired transient response, the startup mode is canceled and the automatic control operation is started. Therefore, according to the present invention, it is possible to eliminate the trouble of setting PI calculation constants, which has been done by an operator at startup, and to realize a controller that can be started up quickly and easily.

[Brief explanation of drawings]

FIG. 1 is a functional block diagram showing an example of a device according to the present invention, and FIG. 2 is a time chart for explaining its operation. l...process, 2...startup processing means,
3... PI control means, 4... adaptive control processing means, 2
1...Set value change section, 5WIjSW2...Switch.

Claims (1)

[Scope of Claims] PI control means for performing at least proportional and integral calculations on process quantities and set value signals from a process, and outputting the obtained manipulated variables to the process; adaptive control processing means for setting the proportional constant and integral constant set in the PI control means to optimal values according to the transient response of the quantity; startup processing means for outputting a pseudo setting value signal that changes in a stepwise manner; the adaptive control processing means and the PI control means operate by inputting the pseudo setting value signal from the startup processing means at startup; The optimum control processing means observes the transient response of the process quantity at that time and gradually sets and changes the PI calculation constant in the PI control means so that the pseudo setting signal becomes the set value signal and the process quantity shows the desired transient response. When this happens, exit startup mode and
A controller in which a set value signal is input to an adaptive control processing means and a PI control means.