JPH05143105A - Automatic control device - Google Patents

Abstract

PURPOSE:To prevent the generation of a large wind-up phonomenon by preventing the excess execution of integrating operation in an automatic control device for PI operation. CONSTITUTION:In the automatic control device for PI operation, a manupilated variable U including a proportional operation a component and an integrating operation component is determined based upon a control deviation (e) to be a difference between an objective value R and a control variable Y and applied to a controlled system 7 to control the operation of the controlled system 7. The device is provided with an objective value holding means 13 to hold the objective value R at a current value when the variable U to be applied to the control target 7 reaches a hold value determined in accordance with the upper limit value of the variable U for the target 7. Consequently the deviation (e) is not increased until the variable U is saturated, so that the variable U is not saturated in any status and the generation of excess integration operation during the saturation of the variable U can be previously prevented.

Description

Detailed Description of the Invention

[0001]

BACKGROUND OF THE INVENTION 1. Field of the Invention The present invention relates to an automatic control device,
In particular, the present invention relates to an automatic control device that linearly controls the operation of a controlled object by PI operation.

[0002]

2. Description of the Related Art As an automatic control device for linearly controlling the operation of a controlled object such as a servo mechanism and various processes, a target value (command value) and values of controlled variables such as speed, position and force which are outputs of the controlled object Of the so-called PI operation, in which the manipulated variable including the proportional motion component and the integral motion component is determined based on the difference of the control deviations, and the manipulated variable is given to the controlled object which is the controlled object to control the operation of the controlled object. Automatic control devices are well known.

In the automatic control device as described above, the operation amount increases with the lapse of time due to the integral motion component increasing in an integrating manner even if the control deviation is very small, so that not only the proportional motion is achieved. However, the steady deviation approaches zero, and control is performed to eliminate the offset and maintain the controlled variable near the target value.

[0004]

In the automatic control device as described above, for example, in the position control, the load becomes large, which causes the control deviation which is the difference between the target value and the value of the control amount. As the size increases, the operation amount that is the input of the controlled object also increases.

However, the maximum output of the servo motor,
Since the input of the controlled object always has an upper limit like the maximum speed, it may be saturated when the operation amount becomes large. When the manipulated variable is saturated, the integral action component continues to increase over time, even if the control deviation does not decrease due to saturation,
An excessive integral motion component is generated, and due to the digestion of the excessive integral motion component, a so-called windup phenomenon occurs in which a large overshoot occurs when the control deviation becomes zero and positioning is completed. This wind-up phenomenon becomes a big problem especially in positioning control.

The present invention has been made by paying attention to the above-mentioned problems in the conventional PI operation automatic control device, and prevents the integral operation from being excessively performed, thereby causing a large wind-up phenomenon. It is an object of the present invention to provide an automatic control device improved so as not to do so.

[0007]

According to the present invention, the above object is to provide an operation amount including a proportional operation component and an integral operation component based on a control deviation which is a difference between a target value and a value of the control amount. In the automatic control device for controlling the operation of the controlled object, the operation amount given to the controlled object is determined according to the upper limit value of the operated amount for the controlled object. This is achieved by an automatic control device characterized by having target value holding means for maintaining the target value at the present value when the hold value is reached.

[0008]

According to the above construction, when the manipulated variable reaches the hold value, that is, when the manipulated variable increases near the upper limit value of the manipulated variable, the target value hold means maintains the target value at the current value and the target value. The value is prohibited from increasing more than this, and the control deviation, which is the difference between the target value and the value of the controlled variable, does not become large until the manipulated variable is saturated. The manipulated variable is no longer saturated, and the occurrence of an over-integral motion component during the saturation of the manipulated variable is avoided in advance.

[0009]

Embodiments of the present invention will be described in detail below with reference to the drawings.

FIG. 1 shows an embodiment of an automatic control device according to the present invention. In FIG. 1, the automatic control device includes a proportional operation component operation unit 1 with a predetermined proportional gain, an integral operation component operation unit 3 with an integrator, an amplifier 5, and a servo mechanism.
Alternatively, the control target 7 is formed by various processes.

The proportional motion component computing unit 1 is given a control deviation e due to the difference between the target value R and the control amount Y due to the output of the controlled object 7 from the summing point 9 and is proportional based on a predetermined proportional gain. It is designed to calculate motion components.

The integral action component calculator 3 is configured to calculate the integral action component which is given from the summing point 9 by adding the above-mentioned control deviation e and increases with the passage of time.

The proportional motion component calculated by the proportional motion component calculator 1 and the integral motion component calculated by the integral motion component calculator 3 are added to each other at a summing point 11, and a manipulated variable U is passed through an amplifier 5. Are given to the controlled object 7.

As a result, the controlled object 7 is actuated and controlled according to the manipulated variable U, and the controlled variable Y is output.

The automatic control apparatus according to this embodiment includes a target value holding unit 13 in addition to the basic configuration of the automatic PI operation control apparatus as described above. The target value hold unit 13
When the operation amount U is input and the operation amount U is going to increase beyond the hold threshold A which is slightly smaller than the upper limit value of the operation amount for the controlled object 7, the target value R given to the addition point 9 is maintained at the current value. Then, the target value R is prohibited from increasing above the present value, and this state is maintained until the manipulated variable U becomes equal to or less than the hold release threshold B which is smaller than the hold threshold A by a predetermined systematic level. In other cases, the target value R input to the control system is added to the summing point 9 and given in real time.

The upper limit value of the manipulated variable for the controlled object 7 is a known value, whereby the hold threshold value A and the hold release threshold value B are set to appropriate values in advance according to the controlled object 7.

The target value hold unit 13 includes hardware,
It may be configured by any of software.

According to the above-mentioned structure, when the operation amount U given to the controlled object 7 reaches the hold threshold A, in other words, when the operation amount U given to the controlled object 7 is about to be saturated, the target value is held. The target value R given to the addition point 9 by the unit 13 is maintained, that is, held at the current value. As a result, the target value R given to the addition point 9 is maintained at the current value and is prohibited from increasing above the current value regardless of the input target value at this time.

As a result, the control deviation e due to the difference between the target value R and the value of the control amount Y does not increase until the operation amount U is saturated, and the saturation of the operation amount U is avoided in advance. As a result, it is possible to prevent the integral motion component calculation unit 3 from performing a useless calculation of the integral motion component during the saturation of the manipulated variable U, and to avoid the occurrence of overintegration motion. As a result, the occurrence of a large overshoot is avoided, and a large windup phenomenon does not occur.

If the manipulated variable U applied to the controlled object 7 is reduced below the hold release threshold value B, that is, the manipulated variable U is decreased until there is no danger that the operated amount U applied to the controlled object 7 will be saturated, the target value is reduced. The hold of the target value R by the hold unit 13 is released, and thereby the increase change of the target value R given to the addition point 9 is allowed, and thereafter, the operation amount U given to the controlled object 7 reaches the hold threshold A. This state is maintained until

2 (a) and 2 (b) show an example of changes over time in the manipulated variable U and the target value R given to the addition point 9 in the automatic controller of the present invention having the above-mentioned structure. .. 2 (a) and 2 (b), the manipulated variable U reaches the hold threshold value A at the time point T1, and then the manipulated variable U decreases below the hold release threshold value B at the time point T2. The operation amount U reaches the hold threshold value A again at T3, and the operation amount U is reduced to the hold release threshold value B or less at the subsequent time point T4. The target value R is held between time T2 and between time T3 and time T4, and saturation of the manipulated variable U given to the controlled object 7 is avoided.

In the above, the present invention has been described in detail with respect to a specific embodiment, but the present invention is not limited to this, and various embodiments are possible within the scope of the present invention. It will be apparent to those skilled in the art.

[0023]

As can be understood from the above description, according to the automatic control apparatus of the present invention, when the manipulated variable increases near the upper limit of the manipulated variable with respect to the controlled object, the target value hold means causes the target value to change to the current value. It is prohibited to increase the target value further than this by maintaining the control value, and the control deviation, which is the difference between the target value and the value of the control amount, does not become large until the manipulated variable is saturated, that is, the input follows The target value will not be forcibly increased for the output that does not exist. As a result, the manipulated variable does not saturate under any condition, the occurrence of the wind-up phenomenon due to the integration operation during the saturated manipulated variable is avoided, and the settling property is improved.

[Brief description of drawings]

FIG. 1 is a block diagram showing an embodiment of an automatic control device according to the present invention.

2 (a) and 2 (b) are graphs showing an example of changes with time of a manipulated variable and a target value given to an addition point in the automatic control device of the present invention.

[Explanation of symbols]

 1 Proportional Motion Component Calculation Unit 3 Integration Motion Component Calculation Unit 5 Amplifier 7 Servo Mechanism 9, 11 Addition Point 13 Target Value Hold Unit

Claims (1)

[Claims] 1. An operation amount including a proportional movement component and an integral movement component is determined based on a control deviation, which is a difference between a target value and a value of a control amount, and this operation amount is given to a control target to control the control target. In an automatic control device for controlling the operation, a target value for maintaining the target value at the present value when the operation amount given to the control target reaches a hold value determined according to the upper limit value of the operation amount for the control target. An automatic control device having holding means.