JPH0651805A - Adaptive control method for plant and device for realizing the same - Google Patents

Abstract

PURPOSE:To exactly identify the dynamic characteristics of a plant by providing a step to adjust only a proportional gain as the control parameter of a controller based on a step for identifying the gain in the state of excluding disturbance operated upon the plant while using an observer. CONSTITUTION:An operating signal subtracting a plant output Y from a command U by a subtracter 12 is multiplied a proportional gain Kp by a controller 11, supplied to an adder 13, added an identifying signal and supplied to an adder 14. Estimated disturbance TL is calculated from a plant input and the plant output Y by an observer 16 and outputted to the adder 14. A discrete model 17a simulates a plant 10 with the output of the adder 13 as an identifying input X and outputs the model output Y. An identification unit 18 estimates the discrete system 17a minimizing error between the model output Y and the plant output Y, the discrete system model 17a is converted to a continuous system by a discrete system/continuous system converter 19, and a tuning unit 20 automatically tunes the proportional gain Kp and an estimated coefficient Tmm of the observer 16.

Description

Detailed Description of the Invention

[0001]

BACKGROUND OF THE INVENTION 1. Field of the Invention The present invention relates to a method for identifying a dynamic characteristic of a plant, automatically tuning a control parameter of a controller based on the identification result, and adaptively controlling the plant, and an apparatus for realizing the method. .

[0002]

2. Description of the Related Art A machine, a process, a system or the like can be considered as a controlled object, but here, a case where the controlled object is a plant will be described in particular. However, it is not necessary to limit the control target to the plant, and it can be applied to a system that needs to perform process control whose main purpose is to suppress disturbance.

As is well known, control of such a plant is performed by using a controller (also called a controller). In such a case, it is necessary to adjust the control parameters of the controller so that the best control performance can be expected.

As is well known in the art, there are various types of such controllers, but there are three types: proportional action (P action), integral action (I action), and integral action (D action). One is basic, and these are used alone or in combination. That is, a) Only the P operation is performed and only the proportional gain K _P is used as the control parameter. Such a controller is called a P controller.

B) Only the I operation is performed, and only the integral term gain K _I is used as a control parameter. Such a controller is called an I controller.

C) A combination of P operation and I operation, which has a proportional gain K _P and an integral term gain K _I as control parameters. Such a controller is called a PI controller.

D) A combination of P operation and D operation, which has a proportional gain K _P and a differential term gain K _D as control parameters. Such a controller is called a PD controller.

E) A combination of P, I, and D operations, having proportional gain K _P , integral term gain K _I , and derivative term gain K _D as control parameters. Such a controller is called a PID controller.

Which controller is adopted depends on what kind of response is given to the plant. In general,
Any one of the P controller, the PI controller, and the PID controller is used, and among them, the PID controller is often used. This is because the PID controller can improve the steady state characteristic and the quick response at the same time.

In any case, the plant is controlled by using the controller, but it is necessary to know the state (dynamic characteristic) of the plant in order to adjust the control parameter of the controller. That is, when modeling a plant, a model (mathematic model) that is usually obtained contains uncertainty such as unknown parameters, and using information that can be observed from the outside, such as input / output data of the plant, The model needs to be deterministic. In this way, eliminating the uncertainty of the mathematical model by externally observing the plant to be modeled is called identification. In this technical field, identification is defined as obtaining a mathematical model that can be regarded as equivalent to the input-output relationship of a plant from a given class of mathematical model.

There are two types of this identification. One of them is identification when a plant is described by a mathematical model with a known number of parameters by a priori information and these are uniquely determined from input / output, and such identification is called parameter identification. The other is identification when the number of parameters that characterize the model to be identified is not known in advance, and such identification is called non-parameter identification.

The plant targeted by the present invention is described by a mathematical model with a known number of parameters, and therefore parameter identification is performed.

In any case, the control parameter of the controller is automatically tuned based on the identification result to adaptively control the plant.

Various adaptive control devices for such a plant have already been proposed. For example, Japanese Patent Laid-Open No. 59-1602
See Japanese Patent Publication No. 05 and Japanese Patent Laid-Open No. 60-069702.

As is well known in this technical field, a disturbance is generally applied to the plant. In a conventional plant adaptive controller, a PID controller is used as a controller, an identification signal is injected into the control system during closed loop control, and the plant dynamic characteristics are identified in the state where disturbance is applied to the plant. By automatically tuning to a control system with a response shape of, the response and the suppression of disturbance are improved.

[0016]

As described above, in the conventional adaptive control system for a plant, the dynamic characteristics of the plant are identified in the state where the disturbance is applied to the plant. Therefore, the dynamic characteristics of the plant can be accurately identified. It had the drawback of not being able to do it.

Further, since the conventional adaptive controller of the plant uses the PID controller as the controller, the proportional gain K _P , the integral term gain K _I , and the derivative term gain K are used.
_It is necessary to adjust the three control parameters of _D , and there is a drawback in that the control parameter adjustment becomes complicated.

Therefore, an object of the present invention is to provide an adaptive control device for a plant including an identification means capable of accurately identifying the dynamic characteristics of the plant.

Another object of the present invention is to provide an adaptive control device for a plant, which can easily adjust control parameters.

Still another object of the present invention is to provide an adaptive control device for a plant, which can easily identify the dynamic characteristics of the plant.

[0021]

An adaptive control method for a plant according to the present invention identifies a dynamic characteristic of a plant, automatically tunes a control parameter of a controller based on the identification result, and adaptively controls the plant. The method for controlling includes the step of adjusting only the proportional gain that is the control parameter of the controller, based on the step of identifying with the observer in a state where the disturbance acting on the plant is removed.

In the adaptive control method for the plant described above, the step of removing the disturbance in the identifying step includes:
The method includes the steps of estimating the disturbance from a plant input supplied to the plant and a plant output output from the plant to obtain an estimated disturbance, and adding the estimated disturbance to the plant input.

In the adaptive control method for the plant described above, it is desirable that the control parameter is only a proportional gain.

The adaptive control system for a plant according to the present invention is
It is an apparatus for identifying the dynamic characteristics of a plant, automatically tuning the control parameters of a controller based on the identification result, and adaptively controlling the plant.

The adaptive control system for a plant according to the first aspect of the present invention subtracts the plant output from the command, outputs a motion signal indicating a deviation, and multiplies the motion signal by a variable proportional gain. , A controller that outputs a control signal,
Acts on the plant based on a first adder that adds the control signal and the identification signal and outputs a first addition result signal, and a plant input and the plant output supplied to the plant A disturbance estimating means for estimating a disturbance and outputting the estimated disturbance; and adding the first addition result signal and the estimated disturbance to supply a second addition result signal to the plant as the plant input And a model that outputs the model output by simulating the plant by using the first addition result signal as a model input, and the dynamic characteristics of the plant are identified based on the model output and the plant output. And estimating the model, and supplying an identification result to the model such that an error between the model output and the plant output is minimized, and the proportional gate based on the identification result. And having a an automatic tuning tuning means down.

In the adaptive control device for a plant according to the first aspect, the plant is modeled as an integral element having a plant coefficient, and the disturbance estimating means is represented as a first-order lag element having a filter time constant. An element in which first filter means for outputting a first filter output in response to an input, a first-order lag element having the filter time constant and a differential element having an estimated coefficient for estimating the plant coefficient are connected in series. Second filter means for outputting a second filter output in response to the plant output, and a subtractor for subtracting the second filter output from the first filter output and outputting the estimated disturbance When,
The tuning means also automatically tunes the estimation coefficient.

An adaptive control apparatus for a plant according to a second aspect of the present invention subtracts the plant output from a command, outputs a motion signal representing a deviation, and multiplies the motion signal by a variable proportional gain. , A controller that outputs a control signal,
Acts on the plant based on a first adder that adds the control signal and the identification signal and outputs a first addition result signal, and a plant input and the plant output supplied to the plant A disturbance estimating means for estimating a disturbance and outputting the estimated disturbance; and adding the first addition result signal and the estimated disturbance to supply a second addition result signal to the plant as the plant input And a model for simulating the plant by using the plant input as a model input and outputting a model output, and based on the model output and the plant output, the dynamic characteristics of the plant are identified to identify the model. And an identification means for supplying an identification result to the model such that an error between the model output and the plant output is minimized, and the proportional gain based on the identification result. And having a kinematic tuning tuning means.

In the adaptive control system for a plant according to the second aspect, the plant is modeled as an integral element having a plant coefficient, the plant output is detected with a detection delay, and the disturbance estimating means is the plant. A detection delay compensating means for compensating the detection delay with respect to the input and outputting a compensated plant input, and a first-order delay element having a filter time constant, which are expressed in response to the compensated plant input. The first filter means for outputting the first filter output, a first-order lag element having the filter time constant, and a differential element having an estimation coefficient for estimating the plant coefficient are represented by elements connected in series. In response to the second filter means for outputting a second filter output, and from the first filter output to the second filter means.
And a subtracter that outputs the estimated disturbance by subtracting the filter output of the above, and the tuning means also automatically tunes the estimated coefficient.

[0029]

Embodiments of the present invention will now be described with reference to the drawings.

FIG. 1 shows an adaptive control system for a plant according to a first embodiment of the present invention. The adaptive controller of the plant is
This is an apparatus for adaptively controlling the plant 10 by identifying the dynamic characteristics of the plant 10 and automatically tuning the control parameters of the controller 11 based on the identification result.

As will be apparent from the following description, in the adaptive control system for a plant of this embodiment, the dynamic characteristics of the plant 10 are identified in a state in which the disturbance TL acting on this plant is removed, and Based on this, the proportional gain which is the control parameter of the controller 11 is adjusted.

In order to eliminate the disturbance TL when performing identification,
Plant input supplied to the plant 10 and the plant 10
The estimated disturbance TL ∧ (in the drawing, ∧ is attached to the TL) is obtained by estimating the disturbance TL from the plant output Y output from the above, and this estimated disturbance TL ∧ is added to the plant input. The controller 11 of this embodiment is a P controller and has a proportional gain K _P as a control parameter.

The adaptive control device of the illustrated plant has a command U
From the plant output Y, and outputs a motion signal representing the deviation. This operation signal is supplied to the P controller 11. The P controller 11 multiplies the operation signal by a variable proportional gain K _P and outputs a control signal.

This control signal is supplied to the first adder 13. An identification signal for identifying a model, which will be described later, is also supplied to the first adder 13. First adder 13
Outputs the first addition result signal by adding the control signal and the identification signal. The first addition result signal is supplied to the second adder 14. An estimated disturbance TL ∧ is supplied to the second adder 14 from an observer 16 described later. Second
Of the first addition result signal and the estimated disturbance TL ∧
And are added, and the second addition result signal is supplied to the plant 10 as a plant input. In the actual case, this plant input is supplied to the plant 10 with the disturbance TL removed by the subtractor 15.

The plant input and the plant output Y are supplied to the observer 16. As will be described later in detail, the observer 16 estimates the disturbance TL acting on the plant 10 based on the plant input and the plant output Y, and outputs the estimated disturbance TL ∧. That is, the observer 16 acts as a disturbance estimation unit.

The first addition result signal is also supplied to the discrete system model 17 as the model input X. The discrete system model 17 simulates the plant 10 and outputs a model output Y∧. This model output Y∧ is supplied to the identification unit 18. The plant output Y is also supplied to the identification unit 18. The identification unit 18 identifies the dynamic characteristics of the plant 10 based on the model output Y∧ and the plant output Y. That is, the identification unit 18 uses the discrete system model 17
And the identification result that minimizes the error between the model output Y∧ and the plant output Y is supplied to the discrete system model 17. Here, although there are various identification methods in the identification unit 18, the least square method is adopted in the present embodiment. The identification unit 18 identifies the discrete system model 17 in which the error between the model output Y∧ and the plant output Y is minimized.

The identification result is supplied to the discrete system / continuous system converter 19, where the discrete system value is converted into the continuous system value and then supplied to the tuning unit 20. The tuning unit 20 automatically tunes the proportional gain K _P and an estimation coefficient (observer coefficient) Tmm described later based on the identification result.

In this embodiment, as shown in FIG. 1, the plant 10 is modeled as an integral element having a plant coefficient Tm. That is, the transfer function Gp of the plant 10
(S) is expressed by Equation 1 below.

[0039]

[Equation 1]

The plant 10 has such a transfer function Gp
In the case of being represented by (S), the observer 16 operating as the disturbance estimation unit has a configuration as described below.
That is, the observer 16 uses the first and second filters 2
1 and 22 and a subtractor 23.

The first filter 21 has a filter time constant T
Represented as a first-order lag element with f. In other words, the transfer function Gf1 (S) of the first filter 21 is expressed by Equation 2 below.

[0042]

[Equation 2]

The plant input is supplied to the first filter 21. In response to this plant input, the first filter 21 outputs a first filter output.

The second filter 22 is represented by an element in which a first-order lag element having a filter time constant Tf and a differential element having an estimated coefficient Tmm for estimating the plant coefficient Tm are connected in series. That is, the transfer function Gf2 (S) of the second filter 22 is expressed by the following mathematical formula 3.

[0045]

[Equation 3]

The plant output Y is supplied to the second filter 22.
Is supplied. In response to this plant output Y, the second filter 22 outputs the second filter output.

The first filter output and the second filter output are supplied to the subtractor 23. The subtractor 23 subtracts the second filter output from the first filter output and outputs the estimated disturbance TL∧.

As described in detail below, by converting the discrete system model 17 identified by the identification unit 18 into a continuous system model by the discrete system / continuous system converter 19,
The plant coefficient Tm can be estimated. Then, the tuning unit 20 can adjust the observer coefficient Tmm with this estimated (identified) plant coefficient Tm. Furthermore, the tuning unit 20 can adjust the proportional gain K _P from the identified plant coefficient Tm to obtain the desired response.

First, the estimation of the plant coefficient Tm will be described.

As a target of the discrete system model 17, the identification unit 18 uses the estimated disturbance TL ∧, the disturbance TL, and the transfer function Gp.
(S) is modeled and identified with the plant 10 represented by Formula 1 above.

When the model input X to the plant output Y are displayed in a continuous system, the plant output Y is expressed by the following equation 4.

[0052]

[Equation 4]

If the filter time constant Tf of the observer 16 is set to be much smaller than the plant coefficient Tm and the observer coefficient Tmm, the second side on the right side of the above equation 4
The term, that is, the term including the disturbance (load torque) TL can be ignored. Therefore, the above formula 4 is approximately represented by the following formula 5.

[0054]

[Equation 5]

By the way, when the discrete system model 17 identified by the identification unit 18 is converted into a continuous system model by the discrete system / continuous system converter 19, the model output Y∧ output from the discrete system model 17 is expressed by the following equation 6 It is represented by.

[0056]

[Equation 6]

As is clear from the comparison between the above equations 5 and 6, if the attention is paid only to the first-order coefficient a of the numerator on the right side of equation 6, the plant coefficient Tm is represented by the following equation 7, The plant coefficient Tm can be identified.

[0058]

[Equation 7]

Next, the setting of the proportional gain K _P of the P controller 11 will be described.

Assume that the observer 16 has completely canceled the disturbance TL. In this case, the entire system shown in FIG. 1 is as shown in FIG. That is, the transfer function Gs (S) of the entire system is represented by the following formula 8.

[0061]

[Equation 8]

In other words, the entire system is (Tm /
It can be in the form of a first-order lag whose time constant is K _P ). Therefore, by adjusting the proportional gain K _P from the plant coefficient Tm identified by the identification unit 18, it becomes possible to provide the target responsiveness. Specifically, to make the 63% response 0.5S,
(Tm / K _P ) = 0.5, that is, K _P = Tm / 0.5.

As described above, in the first embodiment, the disturbance TL acting on the plant 10 can be canceled by using the observer 16, so that the dynamic characteristic of the plant 10 is reduced to the disturbance T.
It can be identified without L. Also, based on this identification result, the optimum proportional gain K of the P controller 11
You can ask for _P. Further, since the P controller 11 is adopted as the controller, there is also an advantage that the control parameter, that is, the proportional gain K _P can be easily adjusted.

In the first embodiment described above, as is apparent from FIG. 1, the input X for identifying the plant 10 is supplied to the second adder 1 whose estimated disturbance TL ∧ which is the output of the observer 16.
I've taken it in before it was added in 4. In this way, the target to be identified by the identification unit 18 is the combined portion of the plant 10 and the observer 16. As a result, the discrete system model 17 to be estimated by the identification unit 18 must be expressed by a high-order transfer function.
Therefore, the calculation amount in the identification unit 18 increases, and the problem remains that the identification unit 18 needs to perform complicated calculation.

In the second embodiment described next, in order to solve this problem, the input for identification (identification input) is provided not in front of the second adder 14 to which the estimated disturbance TL∧ is added. The object to be identified is only the plant 10 by incorporating it from then on. As a result, the discrete system model can be expressed by a low-order transfer function, and the calculation in the identification unit becomes easy.

FIG. 3 shows an adaptive control system for a plant according to the second embodiment of the present invention. The adaptive control device for a plant according to the second embodiment takes in the identification input X after the second adder 14 to which the estimated disturbance TL ∧ is added.
The plant output Y has the same configuration as that shown in FIG. 1 except that the plant output Y is detected with a detection delay by the detection delay element 24. Therefore, components having the same configurations as those shown in FIG. 1 are designated by the same reference numerals, and description thereof will be omitted for simplification of the description.

Since the plant output Y is detected with a detection delay, in order to compensate for this, the observer 16a of the present embodiment, in addition to the first and second filters 21 and 22 and the subtractor 23, Further, a detection delay compensator 25 is provided. The detection delay compensator 25 compensates the plant input for the detection delay by the detection delay element 24 and outputs the compensated plant input. This compensated plant input is fed to the first filter 21.

Since the identification input X is taken in after the second adder 14 to which the estimated disturbance TL∧ is added, the transfer function of the discrete system model 17a of this embodiment is more discrete than that shown in FIG. It can be expressed in a lower order than that of the system model 17. Therefore, the identification unit 18a of the present embodiment is
The unit calculation is much simpler than the identification unit 18 shown in FIG.

[0069]

As described above, according to the present invention, the dynamic characteristics of the plant are identified with the disturbance acting on the plant removed, so that the dynamic characteristics of the plant can be accurately identified. Further, since the P controller is used as the controller, there is an advantage that the control parameter can be easily adjusted. Furthermore, there is an advantage that the dynamic characteristics of the plant can be easily identified by using the plant input to which the estimated disturbance is added as the identification input.

[Brief description of drawings]

FIG. 1 is a block diagram showing an adaptive control device for a plant according to a first embodiment of the present invention.

FIG. 2 is a diagram showing an adaptive control device for the plant shown in FIG.
FIG. 3 is a block diagram showing the entire system when the disturbance is completely canceled.

FIG. 3 is a block diagram showing an adaptive control device for a plant according to a second embodiment of the present invention.

[Explanation of symbols]

 10 ... Plant 11 ... P controller 12 ... Subtractor 13,14 ... Adder 15 ... Subtractor 16,16a ... Observer 17,17a ... Identification unit 18,18a ... Discrete system model 19 ... Discrete system / continuous system converter 20 Tuning unit 21, 22 ... Filter 23 ... Subtractor 24 ... Detection delay element 25 ... Detection delay compensator

Claims (5)

[Claims] 1. A method of adaptively controlling a plant by identifying a dynamic characteristic of the plant, automatically tuning a control parameter of a controller based on the identification result, and using an observer to control the plant. A method for adaptively controlling a plant, comprising: adjusting only a proportional gain, which is the control parameter of the controller, based on the step of identifying in a state in which a disturbance that acts is removed. 2. The step of removing the disturbance in the identifying step includes a step of estimating the disturbance from a plant input supplied to the plant and a plant output output from the plant to obtain an estimated disturbance. The adaptive control method for a plant according to claim 1, further comprising: applying the estimated disturbance to the plant input. 3. An apparatus for realizing the adaptive control method according to claim 1, wherein: a subtracter that subtracts a plant output from a command and outputs an operation signal representing a deviation; and a proportional gain variable to the operation signal. And a controller for outputting a control signal, a first adder for adding the control signal and the identification signal and outputting a first addition result signal, and a plant input supplied to the plant. Based on the plant output, the disturbance estimating means for estimating the disturbance acting on the plant and outputting the estimated disturbance, and adding the first addition result signal and the estimated disturbance,
A second adder that supplies a second addition result signal to the plant as the plant input; a model that simulates the plant and outputs a model output by using the first addition result signal as a model input; Based on the model output and the plant output, the dynamic characteristics of the plant are identified to estimate the model, and an identification result that minimizes the error between the model output and the plant output is supplied to the model. An adaptive control device for a plant, comprising: an identification unit; and a tuning unit that automatically tunes the proportional gain based on the identification result. 4. An apparatus for realizing the adaptive control method according to claim 1, wherein a subtracter that subtracts a plant output from a command and outputs an operation signal representing a deviation, and a proportional gain variable to the operation signal. And a controller for outputting a control signal, a first adder for adding the control signal and the identification signal and outputting a first addition result signal, and a plant input supplied to the plant. Based on the plant output, the disturbance estimating means for estimating the disturbance acting on the plant and outputting the estimated disturbance, and adding the first addition result signal and the estimated disturbance,
A second adder for supplying a second addition result signal to the plant as the plant input; and a second addition result signal for simulating the plant using the plant input as a model input and outputting a model output. A model, based on the model output and the plant output, the dynamic characteristics of the plant are identified to estimate the model, and an identification result that minimizes the error between the model output and the plant output is obtained by the model. An adaptive control device for a plant, comprising: an identification unit that supplies the proportional gain to the unit; and a tuning unit that automatically tunes the proportional gain based on the identification result. 5. The plant is modeled as an integral element having a plant coefficient, the plant output is detected with a detection delay, and the disturbance estimating means compensates the detection delay for the plant input. And a detection delay compensating means for outputting a compensated plant input, and a first filter which is represented as a first-order lag element having a filter time constant and which outputs a first filter output in response to the compensated plant input. Means, a first-order lag element having the filter time constant, and a differential element having an estimation coefficient that estimates the plant coefficient are connected in series, and outputs a second filter output in response to the plant output. And a subtractor that subtracts the second filter output from the first filter output and outputs the estimated disturbance. Serial tuning means plant adaptive control apparatus according to claim 4, characterized in that automatic tuning is also the estimation coefficient.