JPS624725B2 - - 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. As _shown in _{FIG .}
Starting from ₀ and changing the integral time T _I at a constant pitch while keeping it constant (T _I0 ), K 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. The value K _p1 of _p is set as the valley when searching with K _p , and then, while keeping K _p at this value K _p1 , change T _I at a constant pitch to find the valley T _I1 in the T _I direction in the same way. This is a means of finding the minimum point by repeating this search. However, with such a method, even in the case of a small number of parameters as shown in Figure 1, a considerable number of steps must be taken, 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 values ξ, λ,
η： η=1/ε ² dmax tmax∫ ^tmax ₀ ε ² dt The proportional band of the control device is calculated by inputting the output ξ of the first computing unit and the first, second and third computing units respectively outputting η=1/ε 2 dmax tmax∫ tmax 0 ε 2 dt. A fourth arithmetic unit outputs the evaluation function value γ ₁ to be evaluated, and the output λ of the second arithmetic unit is inputted, and the output γ ₁ of the fourth arithmetic unit is inputted to calculate the integration time of the control device. A fifth computing unit outputs the evaluation function value γ ₂ to be evaluated, and the output η of the third computing unit is inputted, and the output γ ₁ of the fourth computing unit is inputted to calculate the differential time of the control device. a sixth arithmetic unit that outputs the evaluation function value γ ₃ for evaluating the above-mentioned evaluation function values γ ₁ , γ ₂ , respectively;
γ ₃ is input, each input value is memorized, and the first, second, and third parameters are compared with the next input value and output by increasing or decreasing a preset parameter depending on the magnitude relationship. Inputting the outputs of the increase/decrease searcher and the first, second, and third parameter increase/decrease searchers, respectively, satisfies the condition of minimizing the sum of squares of the evaluation function values γ ₁ , γ ₂ , γ ₃ . If it is satisfied, the outputs of the first, second, and third parameter increase/decrease searchers are displayed; if not, the first, second, and third parameter increase/decrease searchers are displayed.
The present invention is characterized by comprising a circuit that can update the proportional band, integral time, and differential time of the control device according to the output of the parameter increase/decrease searcher. An embodiment of the present invention will be explained with reference to the drawings.
FIG. 2 is a block diagram thereof, and FIG. 3 is a diagram showing the input/output relationship of the fourth arithmetic unit in FIG. 2. First, in Fig. 2, 1 is a control device, and since the controlled variable Y deviates from the set value due to the disturbance D applied to the controlled object 2, it outputs the controlled variable U such that the control deviation ε becomes small. Give it to controlled object 2. 3
a, 3b, and 3c are first, second, and third arithmetic units, respectively, which input the control deviation ε of the control device 1, calculate the following ξ, λ, and η, and output these, respectively. . η=1/ε ² dmax tmax∫ ^tmax ₀ ε ² dt Here, t is time, tmax is the estimated value of the control system settling time, tmid is any time within the estimated value of the control system settling time, and εdmax is the control system settling time. This is the maximum allowable deviation. 5a inputs the output ξ of the first arithmetic unit 3a and outputs the evaluation function value γ ₁ , and the relationship between the input and output is such that when the input ξ is taken on the horizontal axis, there is a valley as shown in Figure 3. The fourth arithmetic unit 5b, in which the function is set, inputs the output λ of the second arithmetic unit 3b as well as the output γ ₁ of the fourth arithmetic unit, and calculates the evaluation function value γ ₂ = (1
+γ ₁ ) 5th arithmetic unit that outputs λ, 5c is the third
The output η of the arithmetic unit 3c is inputted, and the output γ ₁ of the fourth arithmetic unit 5a is inputted, and the evaluation function value γ ₃
A sixth arithmetic unit 6a that outputs =(1+γ ₁ )η
6b is a first parameter increase/decrease searcher which inputs the evaluation function value _γ1 output from the fourth arithmetic unit 5a, determines the value B _p of the proportional band of the control device, and outputs it; and 6b is the fifth arithmetic unit 5b. A second parameter increase/decrease searcher 6c inputs the evaluation function value γ ₂ outputted by the controller, determines the value of the integral time T _I of the control device, and outputs it.
A third parameter increase/decrease searcher 7 inputs the evaluation function value γ ₃ outputted from the computing unit 5c, determines the value of the differential time T _D of the control device, and outputs it. parameter increase/decrease searcher 6a,
Input the outputs of 6b and 6c and set the parameters of the control device, namely, proportional band B _p , integral time T _I , and differential time T _D
This is a selection circuit that outputs . Next, to describe the operation of such a device, first, a pattern of disturbance D such as a required load signal is determined. For example, if a step-like disturbance is used, the step width is determined, and the disturbance D is added in the same pattern during the search. Disturbance D with a determined pattern is controlled object 2
In addition, the difference between the set value and the controlled amount that results in the control device 1, that is, the control deviation ε, is expressed as the first, second,
Intermediate variables ξ, λ, and η for calculating the evaluation functions γ ₁ , γ ₂ , and γ ₃ are obtained by time-integrating by the third computing units 3 a, 3 b, and 3 c until a specified time. Since the output ξ of the first computing unit 3a accurately represents the damping ratio of the control deviation, the proportional band B _p is searched using this value. The output λ of the second arithmetic unit 3b is the absolute value of the control deviation amount at the maximum (0 to
Since it outputs the ratio of the value integrated up to approximately half of tmax) and the integrated value in the second half, this value represents the steady-state error. Therefore, the output of the second arithmetic unit 3b is used when searching for the value of the integration time T _I.
The output η of the third computing unit 3c means the root mean square 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, λ, and η, evaluation functions γ ₁ , γ ₂ , and γ ₃ are created in the next step.
The fourth calculator 5a receives the evaluation function value γ ₁ for setting the proportional band, the fifth calculator 5b receives the evaluation function value γ ₂ for setting the integral time, and the sixth calculator 5c receives the evaluation function value γ 2 for setting the differential time. Each of the evaluation function values γ ₃ is output, and the search for parameters such that each evaluation function value γ ₁ , γ ₂ , γ ₃ tends to the minimum is performed in the first, second, and third stages, respectively.
This is executed by parameter increase/decrease searchers 6a, 6b, and 6c. That is, each parameter increase/decrease searcher 6a, 6
b and 6c are the input evaluation function values γ _{1 and} 6c, respectively.
γ ₂ and γ ₃ are stored and compared with the next input, and preset parameters are sequentially increased or decreased and outputted so that each evaluation function value approaches the minimum.The rate of increase or decrease is, for example, an increase or μ when
If the value is multiplied or decreased, it is multiplied by 1/μ, and the value of μ can be specified arbitrarily. First, in the first search, disturbance D is applied to the controlled object 2 based on appropriately set parameters B _p0 , T _I0 , T _D0 .
Each evaluation function value γ ₁ , γ ₂ , γ obtained by adding
₃ is stored in the parameter increase/decrease searchers 6a, 6b, and 6c. For the second search, increase or decrease the parameters in the direction specified in advance, and similarly search for control target 2.
Disturbance D is added to , and each evaluation function value is determined. Then, the direction of increase/decrease in parameters from the third search is performed according to the following procedures (1) to (4). (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)|<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 limit value is adopted; if the evaluation function value has increased, the parameter returns to the value within the limit range. Increase or decrease. (4) When the evaluation function value has little variation and the parameter is held, the direction of parameter increase/decrease at the time of release of hold 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 it exceeds the 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, the selection circuit 7 monitors and judges whether the search results of the parameter increase/decrease searchers 6a, 6b, and 6c satisfy the following conditions, and if they do, the process is terminated in the satisfied state. That is, δ=γ ₁ ² + γ
The value of ₂ ² + γ ₃ ² is the minimum. Furthermore, the control device 1
If consists of n units, then

[Formula] is the minimum. In this way, when all the parameters have reached their optimal values, the iterative operation is terminated and the optimal values B _p ′, T
Display _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 band, integral time, Each parameter is determined simultaneously by making the differentiation times correspond to each other. In other words, one evaluation function value corresponds to one parameter of the control device, three types of parameters are searched in parallel and independently, and the results are changed simultaneously. As a result, the number of searches is greatly reduced, and the search time can be greatly shortened. In this embodiment, the selection circuit 7 determines whether or not all the parameters are at optimum values, and if not, the parameters at that time are directly fed back to the control device 1 to correct the parameters of the control device. The operation is automatically repeated in synchronization, and the judgment result of the selection circuit 7 is printed out.
The operator may repeatedly set the parameters of the control device 1 based on the printed values and apply a predetermined pattern of disturbance to the controlled object 2 again. In short, according to the present invention, the control deviation ε of the control device is inputted, and the following time integral values ξ, λ,
η; η=1/ε ² dmax tmax∫ ^tmax ₀ ε ² dt The proportional band of the control device is calculated by inputting the output ξ of the first computing unit and the first, second and third computing units respectively outputting η=1/ε 2 dmax tmax∫ tmax 0 ε 2 dt. A fourth arithmetic unit outputs the evaluation function value γ ₁ to be evaluated, and the output λ of the second arithmetic unit is inputted, and the output γ ₁ of the fourth arithmetic unit is inputted to calculate the integration time of the control device. A fifth computing unit outputs the evaluation function value γ ₂ to be evaluated, and the output η of the third computing unit is inputted, and the output γ ₁ of the fourth computing unit is inputted to calculate the differential time of the control device. a sixth arithmetic unit that outputs the evaluation function value γ ₃ for evaluating the above-mentioned evaluation function values γ ₁ , γ ₂ , respectively;
γ ₃ is input, each input value is memorized, and the first, second, and third parameters are compared with the next input value and output by increasing or decreasing a preset parameter depending on the magnitude relationship. Inputting the outputs of the increase/decrease searcher and the first, second, and third parameter increase/decrease searchers, respectively, satisfies the condition of minimizing the sum of squares of the evaluation function values γ ₁ , γ ₂ , γ ₃ . If it is satisfied, the outputs of the first, second, and third parameter increase/decrease searchers are displayed; if not, the first, second, and third parameter increase/decrease searchers are displayed.
The present invention provides an optimal parameter search device for a control device that greatly shortens the search time by including a circuit that can update the proportional band, integral time, and differential time of the control device according to the output of the parameter increase/decrease searcher. Therefore, the present invention is extremely useful industrially.

[Brief explanation of the drawing]

FIG. 1 is an explanatory diagram showing an optimal parameter search means of a conventional control device, FIG. 2 is a block diagram showing an embodiment of the present invention, and FIG. 3 is an input/output of the fourth arithmetic unit in FIG. It is a line diagram showing a relationship. DESCRIPTION OF SYMBOLS 1... Control device, 2... Controlled object, 3a... First computing unit, 3b... Second computing unit, 3c... Third computing unit, 5a... Fourth computing unit, 5b... ...Fifth arithmetic unit, 5c...Sixth arithmetic unit, 6a...First parameter increase/decrease searcher, 6b...Second parameter increase/decrease searcher, 6c...Third parameter increase/decrease searcher, 7 ...Selection circuit, D...Disturbance, U...
Manipulated amount, Y... Controlled amount, ε... Control deviation, B _p ...
...Proportional band, T _I ... Integral time, T _D ... Differential time.

Claims (1)

[Claims] 1. Input the control deviation ε of the control device and obtain the following time integral values ξ, λ, η: η=1/εd ² max tmax∫ ^tmax ₀ ε ² dt (where t is time, tmax is the estimated value of the control system settling time, tmid is any time within the estimated value of the control system settling time, and εdmax is the control deviation ), and an evaluation function value γ that inputs the output ξ of the first calculator and evaluates the proportional band of the control device. a fourth arithmetic unit that outputs ₁ ; the output λ of the second arithmetic unit is input; and the output γ of the fourth arithmetic unit is inputted;
a fifth arithmetic unit that inputs ₁ and outputs an evaluation function value _γ2 for evaluating the integration time of the control device; a sixth arithmetic unit that inputs γ ₁ and outputs _an evaluation function value γ ₃ for evaluating the differential time of the control device;
The first, second, and third inputs input γ ₂ and γ ₃ , store each input value, compare it with the next input value, increase or decrease a preset parameter according to the magnitude relationship, and output the respective values. The outputs of the parameter increase/decrease searcher and the first, second, and third parameter increase/decrease searchers are input, and each of the above evaluation function values γ is determined.
₁ , γ ₂ , γ ₃ to minimize the sum of squares. If the condition is satisfied, the outputs of the first, second, and third parameter increase/decrease searchers are displayed; if the condition is not satisfied, and a circuit that can update the proportional band, integral time, and differential time of the control device according to the outputs of the first, second, and third parameter increase/decrease searchers. Parameter search device.