JPH0679243B2 - Controller - Google Patents

Description

Description: TECHNICAL FIELD The present invention relates to a controller having a self-tuning function for automatically adjusting at least proportional (P) and integral (I) operation constants to optimum values. More specifically, the present invention relates to a controller having a start-up processing means that reduces operator's operation at the time of start-up.

(Prior art) In the process PI controller used for feedback control, the PI calculation constant is currently set manually based on the long-term knowledge and experience of the process driver or instrumentation engineer. is there. However, the manual setting causes temporary or steady process disturbances during process startup, load fluctuations, unexpected disturbances, or systems with nonlinear gain characteristics. In some circumstances, it may have caused economic losses.

Therefore, a controller in which the PI calculation constant is self-tuned has been proposed. The self-tuning controllers proposed so far connect the auxiliary controller in parallel to the main controller, increase the gain of the auxiliary controller, cause vibration, and from its amplitude and frequency,
A method for determining PI constants based on the so-called ZN limit sensitivity method by Ziegler and Nichols (Proceedings of the Society of Instrument and Control Engineers vol. Toshiyuki), an on / off generator is used to generate a limit cycle, and the optimum PI calculation constant is determined from its amplitude etc. (Showa 48th 12th Academic Lecture Meeting of the Society of Instrument and Control Engineers) P617 to P624 PID automatic setting type adaptive controller Sumi, Fukuda) etc. In addition, the applicant was previously in Japanese Patent Application No. 60-248451,
We have proposed a self-tuning controller that adjusts PI operation constants so as to obtain the optimum response by observing changes in the control amount due to random disturbances without giving disturbances to the process.

(Problems to be solved by the invention) By the way, in any of these self-tuning controllers, at startup, the operator sets the PI calculation constant in the state where there is no signal from the process, and while watching the change in the control amount, etc. The PI calculation constant is changed according to the operator's experience or trial and error to set the optimum value. Therefore, it takes a long time until the optimum PI calculation constant is set. This is a particular problem when starting up a plurality of control loops at once.

The present invention has been made in view of such problems,
The purpose is to provide a controller that automatically obtains a suitable PI calculation constant in a short time at startup and automatically shifts to an automatic control state with the optimum PI calculation constant by providing a startup processing means. It is what

(Means for Solving Problems) According to the present invention for solving the above problems, at least proportional and integral calculations are performed on a process amount from a process and a set value signal, and the obtained manipulated variable is output to the process. PI control means, adaptive control processing means for inputting a process amount and a set value signal, and setting proportional constants and integration constants set in the PI control means to optimum values according to the transient response of the process amount, and at the time of startup And a start-up processing means for inputting a set value signal in and outputting a pseudo set value signal that changes stepwise within a range smaller than the set value,
At the time of startup, the adaptive control processing means and the PI control means operate by inputting a pseudo set value signal from the startup processing means, and the optimum control processing means observes the transient response of the process amount at that time, PI
The operation constant is gradually set and changed, the pseudo setting signal becomes the set value signal, the start-up mode is released when the process amount shows the desired transient response, and the adaptive control processing means and PI control means are set. A value signal is input.

(Embodiment) FIG. 1 is a functional block diagram showing an example of an apparatus according to the present invention. In the figure, reference numeral 1 is a block showing a process target, and its dynamic characteristics are assumed to change depending on the driving target. 2 is a start-up processing means that functions at the time of start-up, 3 is a set value SV output from this start-up processing means 2, and the process amount PV from the process 1.
The PI control means for inputting the deviation ε between and performs at least P and I calculation on the deviation signal ε, and outputs the obtained manipulated variable MV to the process 1. 4 is the process amount PV from the process 1, the set value SV from the start-up processing means 2 and the manipulated variable MV to the process 1 as necessary, and is set in the PI control means 3 according to changes in the process amount PV. It is an adaptive control processing means for setting the P operation constant and the I operation constant that have been set to optimum values.

In the startup processing means 2, 21 is a set value signal SV
Is input, and a set value changing unit that outputs a pseudo set value signal SVD that changes stepwise in a range smaller than this set value signal SV, SW1 is a first switch having contacts a and b, and is a set value signal SV , And the pseudo set value signal SVD are selected and given to the adaptive control processing means 4. SW2 is a second switch that is driven in synchronization with the first switch SW1, has contacts a and b, selects the set value signal SV and the pseudo set value signal SVD, and causes the PI control means 3 to perform the selection. give. The first and second switches SW1 and SW2 form a start-up mode switch, which is connected to the contact b side in the start-up mode state and to the contact a side during normal PI control (other than start-up).

Next, the operation of the apparatus thus configured will be described with reference to the time chart of FIG.

First, the operator turns on the power supply and then starts the start-up mode. In this start-up mode, the first and second switches SW1 and SW2 are connected to the contact b side, and the PI control unit 3 and the adaptive control processing unit 4 are both pseudo setting values output from the setting value changing unit 21. Signal SV
Enter D. Next, the operator sets the setting for operating the controller, for example, the set value signal SV as shown by the solid line in (a). Further, in the adaptive control processing unit 4, a preferable damping value DMP of the transient response and a preferable overshoot value OVR are set.

After such setting is completed, the mode is switched to the automatic state (automatic adjustment state). Subsequently, the set value changing unit 21 in the start-up processing means 2 outputs the pseudo set value signal SVD which changes stepwise by a predetermined amount S1 in a range smaller than the set value signal SV as shown by the broken line in (a). The PI control means 3 receives the pseudo set value signal SVD and sends the operation signal MV to the process 1.
Is output. The process 1 is controlled by the operation signal MV, and from here, the process amount PV according to the property of the process 1 is output as shown in (b).

The adaptive control processing unit 4 receives the process amount PV from the process 1, observes its transient response, and calculates a PI calculation constant of the PI control means 3 for realizing a preferable damping value and a preferable overshoot value. , Set or change this.

Here, observe the transient response of the process amount PV and see what kind of
As the algorithm for setting the PI calculation constant, for example, the one proposed in the above-mentioned Japanese Patent Application No. 60-248451 can be used.

Subsequently, the set value changing unit 21 again changes the pseudo set value signal SVD stepwise by a predetermined amount as shown by the broken line in (a) to bring it closer to the original set value signal SV. The adaptive control processing unit 4 observes the transient response based on this, and sets and changes the PI calculation constant of the PI control means 3 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 as shown by the broken line in (a) in a step-like manner until it matches the original set value signal SV, and the PI control is performed. The PI calculation constant of the means 3 is set and changed based on the calculation result.

Note that FIG. 2 shows an example in which the pseudo set value signal SVD is repeatedly changed three times, but the reason is that the adaptive control processing unit 4 generally makes preferable damping only by one change of the pseudo set value. The number of repetitions is not limited to three, because it is difficult to calculate the PI calculation constant so that the value and the preferable overshoot value are obtained.

Here, the adaptive control processing unit 4 always observes the transient response of the process amount PV from the process 1, and the damping value DMP of this transient response and the overshoot value OVR are equal to the target damping value and the overshoot value OVR. The start-up processing means 2 detects that the deviation DV between the process amount PV and the pseudo set value SVD becomes almost zero while the shot set value substantially matches the shoot value, and the pseudo set value signal SVD becomes equal to the set value signal SV. At that time, the first and second switches SW1 and SW2 are connected to the contact a side,
PI by tuning after exiting the startup mode
Switch to automatic control mode. In this state, the set value signal
SV is applied to the PI control unit 3 and the adaptive control processing unit 4, and the PI control unit 3 is self-tuned according to the signal given from the adaptive control processing unit 4, and automatically controls the process 1.

In FIG. 2, step numbers (1) to (3) are operations by the operator, and (4) to (10) are operations by the startup processing means 2 and the adaptive control processing unit 4 (STC).

Although the PI control means is used in the above description, the PID control means may be used.

(Effects of the Invention) As described above, the apparatus of the present invention operates in the start-up mode based on the pseudo set value signal output stepwise from the set value changing unit, and the optimum control processing unit performs the process at that time. The PI calculation constant is gradually set and changed by observing the transient response of the quantity, and finally the pseudo setting signal SVD becomes the original set value signal SV, and when the process quantity shows the desired transient response. , The start-up mode is released and the automatic control operation is started. Therefore, according to the present invention, it is possible to realize a controller in which the operator can save the time and effort of setting PI operation constants at the time of start-up, and can start up quickly and easily.

[Brief description of drawings]

FIG. 1 is a functional block diagram showing an example of an apparatus according to the present invention, and FIG. 2 is a time chart for explaining its operation. 1 ... Process, 2 ... Startup processing means, 3 ...
... PI control means, 4 ... Adaptive control processing means, 21 ... Set value changing section, SW1, SW2 ... Switches.

Claims (1)

[Claims] 1. PI control means for performing at least a proportional and integral operation on a process amount and a set value signal from a process and outputting the obtained manipulated variable to the process, and a process amount for inputting the process amount and the set value signal. Depending on the transient response of the PI
Adaptive control processing means for setting the proportional constants and integral constants set in the control means to optimum values, and a pseudo set value signal that inputs a set value signal at startup and changes stepwise within a range smaller than the set value. The adaptive control processing means and the PI control means operate by inputting a pseudo set value signal from the startup processing means at the time of startup, and the optimum control processing means has a process amount at that time. Of the PI control means by observing the transient response of
The operation constant is gradually set and changed, the pseudo setting signal becomes the set value signal, the start-up mode is released when the process amount shows the desired transient response, and the adaptive control processing means and PI control means are set. A controller adapted to input a value signal.