JPS6326401B2 - - Google Patents

Description

DETAILED DESCRIPTION OF THE INVENTION The present invention relates to an optimal parameter searching device for a control device.

2. Description of the Related Art Conventionally, as means for searching for optimal values of parameters (proportional gain, integral time, differential time, etc.) of a control device, there is a means for finding the extreme value of a value obtained by integrating the absolute value of a control deviation. For example, as shown in Figure 1, this means that the proportional gain K _P is set to the point marked X (K _P0
Starting from T _I0 ), the integral time T _I is kept constant (T _I0 ) and changed at a constant pitch, and when the value of the integral value G of the absolute value of the control deviation changes from a decreasing state to an increasing state. Let the value K _P1 of K _P be the valley when searching with K _P , then change T _I at a constant pitch while keeping K _P at this value K _P1 , and similarly find the valley T _I1 in the T _I direction. This is a means of finding the minimum point by repeating the search.

However, with such a method, a considerable number of steps must be taken even in the case of a decimal number of parameters as shown in Figure 1, and as the number of parameters increases, the number of steps also increases significantly, so it is far from practical. It's difficult to serve.

Incidentally, in recent years, digital simulation has been widely adopted for designing control systems and predicting control performance, but the current situation is that optimal adjustment of control systems requires a large amount of time and calculation costs. Furthermore, it takes a considerable number of days to search for optimal parameter values for the control device during the on-site trial run stage.

The present invention was proposed in view of the above circumstances, and aims to provide an optimal parameter search device for a control device that solves the problems of the prior art described above and greatly shortens the search time. Input the control deviation ε of the device and calculate the following time integral value ξ ₁ ,
ξ ₂ , λ, η; ξ ₁ =∫ ^{t max} / _{t nid} |ε|dt／∫ ^{t mid} / ₀ |ε|dt ,ξ ₂ =∫ ^{t max} ₀ |ε|dt λ=∫ ^{t max} _{t nid} | The first, second, third, and fourth arithmetic units that respectively output ε｜dt , η=∫ ^{t max} ₀ ε ² dt and the outputs ξ ₁ and ξ ₂ of the first and second arithmetic units are a fifth computing unit that inputs and outputs an evaluation function value γ ₁ for evaluating the proportional gain of the control device; and a fifth computing unit that inputs the output λ of the third computing unit and outputs the output γ ₁ of the fifth computing unit; a sixth input and output an evaluation function value γ ₂ for evaluating the integration time of the control device;
and an evaluation function value γ ₃ for evaluating the differential time of the control device by inputting the output η of the fourth computing unit and inputting the output γ ₁ of the fifth computing unit.
a seventh arithmetic unit that outputs
The outputs γ ₁ , γ ₂ , γ ₃ of the sixth and seventh arithmetic units are input, each input value is memorized and compared with the next input value, and the preset parameters are increased or decreased depending on the magnitude relationship. The outputs of the first, second, and third parameter increase/decrease searchers, respectively, are input as outputs, and the evaluation function values γ ₁ , γ ₂ , Determine whether or not the previous and current ratios of γ ₃ are all within the specified value. If the condition is met, display the output of each parameter increase/decrease searcher above and terminate the search. If not, The proportional gain of the control device is set to the value of the output of the first parameter increase/decrease searcher, and the second parameter increase/decrease searcher similarly controls the integral time, and the third parameter increase/decrease searcher controls the differential time. The present invention is characterized by comprising a selection circuit having a function of synchronizing the operation of setting values (where t is time, t max is an estimated value of the control system settling time, and t mid is a value within t max). any time).

An embodiment of the present invention will be explained with reference to the drawings.
FIG. 2 is a block diagram showing the circuit configuration.

In the figure above, 1 is a control device, and since the controlled variable 8 deviates from the set value due to the disturbance 7 applied to the controlled object 2, it controls this by outputting a manipulated variable 9 that reduces the control deviation ε. Give to target 2. 3,
4, 5, and 6 are first, second, third, and fourth computing units, respectively;
are input, and the following calculations are performed on ξ ₁ , ξ ₂ , λ, and η, respectively, and these are output.

ξ ₁ =∫ ^{t max} / _{t nid} |ε|dt／∫ ^{t mid} / ₀ |ε|dt ,ξ ₂ =∫ ^{t max} ₀ |ε|dt λ=∫ ^{t max} _{t nid} |ε|dt ,η=∫ ^{t max} ₀ ε ² dt Here, t is time, t max is the estimated value of the control system settling time, and t mid is any time within the estimated value of the control system settling time.

10 inputs the output ξ ₁ of the first arithmetic unit 3 and the output ξ ₂ of the second arithmetic unit 4, and calculates the evaluation function value γ ₁ = f(ξ ₁ )
or ξ ₂ , the output γ ₁ of the fifth calculator ₁₀ is a function value f(ξ ₁ ) or the output ξ ₂ of the second arithmetic unit 4 while monitoring ξ ₁ and outputs ξ ₂ when it becomes less than a specified value, otherwise outputs f(ξ ₁ ). 11 inputs the output λ of the third arithmetic unit 5 and the output γ ₁ of the fifth arithmetic unit 10, and calculates the evaluation function value γ ₂ =
The sixth arithmetic unit outputs (1+γ ₁ )λ, 12 is the fourth
The output η of the arithmetic unit 6 and the output γ ₁ of the fifth arithmetic unit 10
A seventh arithmetic unit inputs the evaluation function value γ ₃ = (1+γ ₁ )η and outputs the evaluation function value γ ₃ =(1+γ 1 )η. The first step that determines the amount and direction of increase in the value K _P
parameter increase/decrease searcher, 20 is the sixth arithmetic unit 1
A second parameter increase/decrease searcher inputs the evaluation function value γ ₂ outputted by the controller 1 and determines the amount and direction of increase in the integral time T ₁ of the control device; 21 is the seventh computing unit 12;
A third parameter increase/decrease searcher inputs the evaluation function value γ ₃ outputted by the controller and determines the amount and direction of increase in the differential time T _D of the control device; 22 is the first, second, and third parameter increase/decrease searcher 19 , 20, and 21, and outputs the parameters of the control device 1, that is, the proportional gain K _P , the integral time T _I , and the differential time T _D.

Next, to describe the operation of such a device, first, the disturbance 7 such as the required load signal is determined. For example, if a step-like disturbance is used, the step width is determined, and the disturbance 7 is added in the same pattern during the search. Adding a disturbance 7 of a determined pattern to the controlled object 2,
The resulting difference between the set value and the controlled amount, that is, the control deviation ε, is calculated by the first, second, third, and fourth computing units 3,
Intermediate variable ξ ₁ for integrating up to the time specified in 4, 5, and 6 and calculating the evaluation function values γ ₁ , γ ₂ , γ ₃ ,
Find ξ ₂ , λ, and η.

The output ξ ₁ of the first calculator 3 represents the damping ratio of the control deviation, and the output ξ 2 of the second calculator ₄ represents the absolute value of the error area of the control deviation, so these values are used to calculate the proportional gain. Search for K _P. The output λ of the third arithmetic unit 5 is the absolute value of the control deviation amount at t, which is approximately half of the maximum (0 to t max) of the integration interval.
The value integrated from mid to t max represents the steady-state deviation. Therefore, the output of the third arithmetic unit 5 is used when searching for the value of the integration time T _I.
The output η of the fourth arithmetic unit 6 represents the square area of the control deviation, and can be used as a comprehensive evaluation of control performance, and is used here to search for the differential time _TD .

Based on these integral values ξ ₁ , ξ ₂ , λ, η, evaluation function values γ ₁ , γ ₂ , γ ₃ are created in the next step.
The fifth calculator 10 calculates the evaluation function value γ ₁ for setting the proportional gain, the sixth calculator 11 calculates the evaluation function value γ ₂ for setting the integral time, and the seventh calculator 12 calculates the evaluation function value γ 2 for setting the differential time. The first, second, and third parameter increase/decrease searchers 19, 20, respectively output the evaluation function value γ ₃ and search for parameters such that each evaluation function value γ ₁ , γ ₂ , γ ₃ tends to the minimum. Execute on 21.

That is, each parameter increase/decrease searcher 19, 2
0 and 21 are the input evaluation function values γ ₁ and
γ ₂ and γ ₃ are memorized and compared with the next input, and the parameters are sequentially increased or decreased so that each evaluation function value approaches the minimum, and the output is output. is multiplied by μ, and when it decreases, it is multiplied by 1/μ, and the value of μ can be specified arbitrarily.

First, in the first search, each evaluation function value γ ₁ , γ ₂ , γ ₃ obtained by adding disturbance 7 to the controlled object 2 based on appropriately set parameters K _P0 , T _I0 , T _D0 is used as a parameter. It is stored in the increase/decrease searchers 19, 20, and 21. In the second search, the parameters are increased or decreased in the direction specified in advance, and disturbance 7 is applied to controlled object 2 in the same way.
and calculate each evaluation function value. The direction of increase/decrease in parameters from the third search is as follows (1) to (4)
Do this according to.

(1) If the evaluation function value is almost the same as the previous value, use the current value. That is, |1
- (Current evaluation function value)/(Previous evaluation function value) | If <α, the parameter is not changed (hereinafter, the state in which the parameter is not changed is referred to as hold). Here α represents accuracy.

(2) When the evaluation function value is decreasing, the direction of parameter increase/decrease is the same as last time. Further, when the evaluation function value increases, the direction of increase/decrease of the parameter is reversed.

(3) If the parameter is close to the specified limit value and the evaluation function value has decreased from the previous time, the control value is adopted, and if the evaluation function value has increased, the value returns to within the limit range and the parameter is changed. Increase or decrease.

(4) When the evaluation function value has little variation and the parameter is held, the direction of parameter increase/decrease when the hold is released is determined by remembering the direction of increase/decrease of the parameter immediately before the parameter was held, and keeping the evaluation function value within the hold range. If the value exceeds this value and is in a decreasing state, the next parameter change will follow the direction of increase or decrease immediately before the hold, and if the opposite is the case, it will be reversed.

Next, in the selection circuit 22, the parameter increase/decrease searchers 19, 20, and 21 monitor and judge whether the ratios of the previous and current evaluation functions γ ₁ , γ ₂ , and γ ₃ are all within specified values. However, if the parameters are satisfied, the search is terminated; if the parameters are not satisfied, the selection circuit 22 outputs the next parameter. It is also possible to synchronize between this device and the control device 1 every sampling period and automatically change the parameters of the control device 1.

In this way, when all parameters have reached their optimal values, the iterative operation is terminated and the optimal value K _P ′,
Display T _I ′ and T _D ′ on the display device.

In this way, in this device, three types of evaluation function values are set based on one value of control deviation by the parameter increase/decrease searcher and selection circuit, and three types of parameters of the control device, proportional gain, integral time, Each parameter is determined simultaneously by making the differentiation times correspond to each other. That is, one of the parameters of the control device
Since the method uses a method of associating one evaluation function value with one evaluation function value, searching three types of parameters in parallel and independently, and changing the results at the same time, the number of searches is significantly reduced compared to conventional methods. , the search time can be drastically reduced.

In this embodiment, the selection circuit 22 determines whether or not all parameters are at optimum values, and if not, the parameters at that time are fed back to the control device 1 as is, and the parameters of the control device are corrected. , the judgment result of the selection circuit 22 is printed out, the operator resets the parameters of the control device 1 based on the printed value, and then repeats the disturbance of the predetermined pattern again. You may repeatedly perform the operation of adding this to the controlled object 2.

In short, according to the present invention, the control deviation ε of the control device is inputted and the following time integral values ξ ₁ , ξ ₂ ,
λ, η; ξ ₁ =∫ ^{t max} / _{t nid} |ε|dt／∫ ^{t mid} / ₀ |ε|dt ,ξ ₂ =∫ ^{t max} ₀ |ε|dt λ=∫ ^{t max} _{t nid} |ε|dt , η=∫ ^{t max} ₀ ε ² dt , respectively, and the outputs ξ ₁ and ξ ₂ of the first and second arithmetic units are input, and the above a fifth computing unit that outputs an evaluation function value γ ₁ for evaluating the proportional gain of the control device; inputting the output λ of the third computing unit; and inputting the output γ ₁ of the fifth computing unit; A sixth device that outputs an evaluation function value γ ₂ for evaluating the integration time of the control device.
and an evaluation function value γ ₃ for evaluating the differential time of the control device by inputting the output η of the fourth computing unit and inputting the output γ ₁ of the fifth computing unit.
a seventh arithmetic unit that outputs
The outputs γ ₁ , γ ₂ , γ ₃ of the sixth and seventh arithmetic units are input, each input value is memorized and compared with the next input value, and the preset parameters are increased or decreased depending on the magnitude relationship. The outputs of the first, second, and third parameter increase/decrease searchers, respectively, are input as outputs, and the evaluation function values γ ₁ , γ ₂ , It is determined whether the ratios of the previous and current values of γ ₃ are all within the specified value, and if they are, the output of each parameter increase/decrease searcher is displayed and the search is terminated, and if not, the first Set the proportional gain of the control device to match the output value of the parameter increase/decrease searcher, similarly set the integral time value with the second parameter increase/decrease searcher, and set the value of the differential time with the third parameter increase/decrease searcher. (where t is time, t
max is the estimated value of the control system settling time, t mid is t
The present invention is industrially extremely useful because it provides an optimal parameter search device for a control device that greatly shortens the search time by (any time within max).

[Brief explanation of the drawing]

FIG. 1 is an explanatory diagram showing optimal parameter searching means of a conventional control device, and FIG. 2 is a block diagram showing a circuit configuration of an embodiment of the present invention. DESCRIPTION OF SYMBOLS 1... Control device, 2... Controlled object, 3... First computing unit, 4... Second computing unit, 5... Third computing unit, 6...
4th arithmetic unit, 7...disturbance, 8...controlled amount, 9...manipulated amount, 10...5th arithmetic unit, 11...6th arithmetic unit,
12... Seventh arithmetic unit, 19... First parameter increase/decrease searcher, 20... Second parameter increase/decrease searcher,
21... Third parameter increase/decrease searcher, 22... Selection circuit, ξ ₁ ... Output of first computing unit, ξ ₂ ... Output of second computing unit, λ... Output of third computing unit, η... Third computing unit. 4 arithmetic unit output, _γ1 ...5th arithmetic unit output, _γ2 ...6th arithmetic unit output, _γ3 ...7th arithmetic unit output,
K _P ...Proportional gain width, T _I ...Integral time, T _D ...Differential time, ε...Control deviation.

Claims (1)

[Claims] 1. Input the control deviation ε of the control device and obtain the following time integral values ξ ₁ , ξ ₂ , λ, η; ξ ₁ =∫ ^{t max} / _nid | ε | dt / ∫ ^{t max} / ₀ ^The _first ^{, second} _{, third} ^, _and ^{_ _} _{_} ^_ Output ξ ₁ of the fourth arithmetic unit and the first and second arithmetic units
and ξ ₂ and outputs an evaluation function value γ ₁ for evaluating the proportional gain of the control device;
a sixth computing unit that inputs the output λ of the third computing unit and inputs the output γ ₁ of the fifth computing unit and outputs an evaluation function value γ ₂ for evaluating the integration time of the control device; , an evaluation function value γ ₃ for evaluating the differential time of the control device by inputting the output η of the fourth computing unit and inputting the output γ ₁ of the fifth computing unit.
a seventh arithmetic unit that outputs
The outputs γ ₁ , γ ₂ , γ ₃ of the sixth and seventh arithmetic units are input, each input value is memorized and compared with the next input value, and the preset parameters are increased or decreased depending on the magnitude relationship. The outputs of the first, second, and third parameter increase/decrease searchers, respectively, are input as outputs, and the evaluation function values γ ₁ , γ ₂ , Determine whether or not the previous and current ratios of γ ₃ are all within the specified value. If the condition is met, display the output of each parameter increase/decrease searcher above and terminate the search. If not, The proportional gain of the control device is set to the value of the output of the first parameter increase/decrease searcher, and the second parameter increase/decrease searcher similarly controls the integral time, and the third parameter increase/decrease searcher controls the differential time. An optimal parameter search device for a control device, characterized by comprising a selection circuit having a function of synchronizing a value setting operation (where t is time, t max is an estimated value of control system settling time, t
mid is any time within tmax).