JPS6194104A - Pid controller - Google Patents

Abstract

PURPOSE:To attain the automatic control of a PID constant without inflicting any disturbance to a control system by increasing the proportional amplification factor when a deviation signal is set outside the reference deviation value and then reducing said amplification factor if the amplitude of oscillation is larger than a reference level within the range of the reference deviation value. CONSTITUTION:A deviation signal is obtained from a signal to be controlled and the target value and a proportional amplifying part 1 adds the value of the deviation signal to an operating amount with amplification for output. Then the absolute value of the deviation signal is compared with the reference deviation value through a comparison/decision part 21 and the amplification factor of the part 1 is increased when said absolute value exceeds the range of the reference deviation value. While the amplification of the deviation signal is detected. Then the amplification factor of the part 1 is decreased when the detected amplification of the deviation signal is larger than the reference value after comparison carried out through a comparison/decision part 22. Furthermore the deviation signal is added with amplification to the operating amount according to the actuation of a oscillation cycle estimation memory part 24 via an integration processing part 2 and a differential processing part 4. Then the proportional amplification factor, the integral amplification factor and the differential amplification factor are controlled for each timing. Thus it is possible for a signal to be controlled to approximate rapidly to the target control value.

Description

[Detailed Description of the Invention] [Industrial Application Field] The present invention provides a P Automatically change parameters
This relates to a control device from P, which is characterized by the following.

[Conventional technology]

Compared to conventional P, the control device allows humans to control P by adjusting the volume, etc.
More constant rI! It was necessary to write 4 sections. ◇In Fig. 4, we will explain the control device from the conventional P.

The deviation signal of the difference between the controlled signal and the target value is determined.

The proportional amplification section (2) amplifies and adds the deviation signal value to the manipulated variable in accordance with a P constant (proportional gain) volume (not shown). The integral processing section ■ integrates the value of the deviation signal, and the integral amplification section ■
The operation jlK is amplified and added according to the volume for the engineering constant (integration time) (not shown). The differential processing section (2) differentiates the value of the deviation signal, and the differential amplification section (2) amplifies and adds it to the manipulated variable according to a D constant (differential time) volume (not shown). Conventionally, control was achieved using P in this way. However, with such a control device, it is necessary for a person to readjust the constant from P using the volume every time the control characteristics change.
It was very inconvenient.

So far, in order to automatically adjust the PID constant, the control system has been given a disturbance and the response has been measured.
Automatic adjustment of constants was realized. However, such a method may be inconvenient in practice since it causes disturbance to the control system. Furthermore, when trying to suppress disturbances, the estimation of the controlled object may not be performed correctly, or high-precision input is required, resulting in increased costs.

[Problem that the invention seeks to solve]

In order to solve these problems, the present invention realizes automatic adjustment of the constant from P without causing any disturbance to the control system.

[Means for solving the problem] and [Operation] The present invention will be explained with reference to FIGS. 1 to 8 and FIG. 5.

FIG. 5 is an overall diagram when the controlled signal is controlled to the target value by using the control device (2) from P. Controlled object 0 handled by the present invention
is a pro-7 system controlled object and assumes a first-order delay system with dead time. Therefore, the transfer function of the controlled object is G(sl= Kp * exp (-Ls) y (
t-4-sTp). Here, L is dead time and Tp is a time constant.

The method of determining the constant from P of the controlled object is Ziegler
Methods such as Nichols' limit sensitivity method are known, and the integral amplification factor and the differential amplification factor may be controlled by P at a constant ratio. If the proportional amplification factor is too large, the controlled signal will repeatedly oscillate around the target value, and if the proportional amplification factor is too small, the controlled signal will not reach the target value easily.

FIG. 1 is an explanatory diagram of a method for automatically adjusting the P constant in the P control device according to the present invention. When the deviation signal between the controlled signal and the target value is outside the range of the standard deviation value, the manipulated variable outputs a sufficiently large output so that the controlled signal approaches the target value as quickly as possible. By doing so, the deviation signal between the controlled signal and the target value will quickly fall within the range of the standard deviation value. If the deviation signal comes out after entering the range of the standard deviation value, it is either a case where the controlled signal continues to reach the target value as shown in graph A, or B
This is the case when the repulsive force that causes the controlled signal to return to the target value is too strong, as shown in the graph below. In either case, by increasing the proportional amplification factor, it is possible to adjust the controlled signal so that it almost oscillates within the range of the standard deviation value, as in C and D.

In addition, if the controlled signal oscillates within the standard deviation value range, as in D, by lowering the proportional amplification factor, it can be caused to oscillate at a high damping ratio, as in C, and stably converge to the target value. Can be done.

Therefore, the proportional amplification factor can be automatically adjusted using the following algorithm.

[1] If the deviation signal between the controlled signal and the target value falls within the standard deviation value range and then exits, increase the proportional amplification factor.

[2] If the vibration amplitude of the deviation signal within the range of the standard deviation value is greater than or equal to the standard amplitude value, the proportional amplification factor is lowered.

Also, according to the Ziegler-Nichols limit sensitivity method, the stability limit vibration period when only proportional amplification is operated is Tu
Then, the integral amplification factor and the differential amplification factor are respectively T
It is known that it is good to set u/2%'l"uy4. By developing this known knowledge, we can calculate the general vibration period around the target value as in the case of D in Figure 1. Based on Tv, it can be found that it is sufficient to increase or decrease the integral amplification factor and differential amplification factor in proportion to Tv.For this reason,
The estimated oscillation period, which is the basis for determining the integral amplification factor and the differential amplification factor, may be increased or decreased based on the general oscillation period Tv as follows.

[1] Every time the period of vibration of the deviation signal within the range of the standard deviation value is measured, the measured value is compared with the estimated value of the vibration period, and if the measured value is larger than the estimated value of the vibration period, the estimated value of the vibration period is determined. Increase the size accordingly.

[2] In the above comparison, if Tv is smaller than the estimated vibration period, the estimated vibration period is reduced accordingly.

Next, FIG. 2 is a block diagram of a PID control device according to the present invention.

A deviation signal of the difference between the controlled signal and the target value is obtained, and the proportional amplification section (2) amplifies and adds the value of the deviation signal to the manipulated variable. The absolute value of the deviation signal is compared with the reference deviation value in the comparison/judgment section @, and when it moves from within the pupil circumference of the reference deviation value to outside the direct position, the amplification factor of the proportional amplification section (2) is increased. If the biased amplitude is larger than the reference amplitude value, the amplification factor of the proportional amplification section (2) is decreased.

Next, the integral processing section (2) integrates the deviation signal, and the integral amplification section (2), which changes according to the vibration period estimated value storage section (2), amplifies and adds it to the manipulated variable. The differential processing section (■) differentiates the deviation signal, and the differential amplification section (■) changes according to the vibration period estimated value storage section (■).
It is compared with the dynamic period estimated value storage unit [phase] which is amplified and added to the manipulated variable, and if it is larger than the value of [phase], the vibration period estimated value storage unit Q3
The order of is increased, and if it is smaller than the value of [phase], the value of [phase] is decreased.

FIG. 3 is an explanatory diagram of an embodiment of a method for detecting the amplitude and period of vibration of a control device according to the present invention. The proportional amplification factor, integral amplification factor, and differential amplification factor are adjusted at each timing shown in this figure. In this way, since adjustment is performed once with - times of vibration, the controlled signal can be rapidly approached to the target adjustment value. Therefore, even if an unexpected disturbance occurs, the disturbance in the PXD parameters due to it can be suppressed to a small level.

Further, such arithmetic processing of the control device using P can be easily realized by using a microcomputer.

〔Effect of the invention〕

By doing so, the following effects unique to the present invention can be obtained.

(1) Is it a controlled object whose temperature characteristics change quickly? (2) It is possible to quickly follow up even when controlling and control with appropriate P.
Appropriate Pl:D control can be performed while automatically adjusting control parameters from P without causing disturbance to the control system.

(8) It is easy to determine the standard deviation value, the standard vibration@ value, and the initial estimated value of the vibration period, and there is no particular need for adjustment work to obtain a constant from the optimum P.

(4) Even if an unexpected disturbance occurs, the disturbance in the parameters can be suppressed to be smaller than P due to it.

(5) According to P of the present invention, the control device can be implemented at low cost by utilizing a microprocessor.

Note that the present invention is not limited to the above embodiments.

For example, small improvements in implementation, such as adding a hysteresis characteristic to the comparison of two values or using 172 cycles as the vibration cycle, are within the scope of the present invention. In short, the present invention can be implemented with various modifications without departing from the gist thereof.

[Brief explanation of drawings]

Fig. 1 is an explanatory diagram of a method for automatically adjusting the constant from P in the control device of the present invention, and Fig. 2 is an explanatory diagram of a method for automatically adjusting the constant from P of the present invention.
FIG. 3 is a block diagram of the leg device; FIG. 3 is a timing explanatory diagram of the vibration amplitude and period detection method of the P control device according to the present invention; FIG. 4 is a block diagram of the conventional P control device; FIG. 1 is an overall diagram when controlling a controlled signal to a target ff value using a PID control device. ■・-Differential amplification section @-PID control device@...-Controlled object @, [phase], [phase]...Comparison judgment section 0.-
Vibration period estimated value storage unit

Claims (2)

[Claims] (1) In a PID control device that obtains an operation signal by proportionally amplifying, integrally amplifying, and differentially amplifying and adding a deviation signal between a controlled signal and a target value, a comparison determination unit determines whether the deviation signal is within the range of a reference deviation value. (21), and a comparison/judgment unit (22) for comparing the vibration amplitude of the deviation signal with a reference amplitude value, and increases the proportional amplification factor when the deviation signal moves from within the range of the reference deviation value to outside the range; A PID control device characterized in that the proportional amplification factor is lowered if the vibration amplitude of the deviation signal within the range of the standard deviation value is greater than or equal to the standard amplitude value. (2) In the PID control device, an oscillation period estimated value storage section (24), a deviation signal oscillation period detection section (23),
and a comparison determination unit (25) for comparing the vibration period of the deviation signal with the vibration period estimated value storage unit, and if the vibration period of the deviation signal within the range of the standard deviation value is equal to or greater than the vibration period estimated value, the vibration period is It is configured to increase the estimated value and increase the integral amplification factor and differential amplification factor, and if the oscillation period of the deviation signal is less than the oscillation period estimated value, the oscillation period estimated value is lowered and the integral amplification factor and differential amplification factor are lowered. A PID control device characterized by: