JPH05127704A - Controller - Google Patents

Abstract

PURPOSE:To set a control parameter as desired a user against external disturbance in normal operation by estimating the strength of the applied disturbance and setting the control parameter according to the strength of the disturbance and the characteristics of a controlled system. CONSTITUTION:In a PID temperature controller 1, a PID control means 3 outputs a manipulated variable (u) corresponding to set control parameter to the controlled system 2 for the disturbance in stationary operation according to the deviation between a controlled variable (y) and a desired value (r) so that a desired response waveform can be obtained. A disturbance estimating means 4 estimates the strength of the applied disturbance according to the controlled variable (y), manipulated variable (u), and desired value (r). Then PID control parameter setting means 5 sets the control parameter corresponding to the desired response characteristics for the disturbance in the normal state in the PID control means 3 according to the estimated strength of the disturbance and the previously identified characteristics of the controlled system 2. The desired response characteristics are set by the user through a requested specification setting part 6.

Description

Detailed Description of the Invention

[0001]

BACKGROUND OF THE INVENTION 1. Field of the Invention The present invention relates to a control device such as a PID controller, and more particularly to a self-adjusting control device for setting a control parameter to an optimum value in accordance with the characteristics of a controlled object.

[0002]

2. Description of the Related Art In a control device of this type, for example, a PID controller, overshoot is suppressed as much as possible with respect to disturbance during steady operation, or even if overshoot occurs, the settling time is made as short as possible. It has been difficult to obtain a response waveform that meets the user's wishes such as.

[0003]

SUMMARY OF THE INVENTION The present invention has been made in view of the above-mentioned points, and it is possible to set an appropriate control parameter according to a user's desire with respect to a disturbance during steady operation. The purpose is to do.

[0004]

In order to achieve the above object, the present invention is configured as follows.

That is, according to the present invention, the control means for outputting the manipulated variable corresponding to the set control parameter to the controlled object based on the deviation between the controlled variable and the target value, and the controlled variable, the manipulated variable, and the target value. Based on the disturbance estimation means for estimating the magnitude of the applied disturbance based on the estimated disturbance magnitude and the characteristics of the control target previously identified, the desired response characteristic to the steady-state disturbance is supported. Control parameter setting means for setting control parameters in the control means.

[0006]

According to the above configuration, the magnitude of the applied disturbance is estimated, and the control corresponding to the desired response characteristic is performed on the basis of the estimated magnitude of the disturbance and the characteristic of the control target previously identified. Since the parameters are set, it is possible to obtain a disturbance response waveform according to the user's request with respect to the disturbance during steady operation.

[0007]

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

FIG. 1 is a functional block diagram of an embodiment of the present invention, and this embodiment will be described by applying it to a PID temperature controller.

The PID temperature controller 1 of this embodiment is a self-adjusting controller that sets the PID control parameter to an optimum value in accordance with the characteristics of the controlled object 2. In this embodiment, the controlled object 2 is stepped. Is used to identify the characteristic of the controlled object from the response waveform, set the PID control parameters, and then perform the conventional closed-loop control by the conventional step response method.

The PID temperature controller 1 uses a set control parameter based on a deviation between a control amount and a target value so as to obtain a desired response waveform with respect to a disturbance during steady operation. P that outputs the corresponding manipulated variable to the controlled object
The ID control unit 3, the disturbance estimation unit 4 that estimates the magnitude of the applied disturbance based on the control amount, the operation amount, and the target value, and the estimated magnitude of the disturbance and the control target 2 that is identified in advance. Based on the characteristic, the PID control parameter corresponding to the desired response characteristic to the steady-state disturbance is set to the P
The PID control means 3 includes a PID control parameter setting means 5 to be set in the ID control means 3 and a required specification setting section 6 for the user to set the desired response characteristic.
Identifies the characteristic of the controlled object 2 in advance by the above step response method.

The PID control means 3, the disturbance estimation means 4 and the PID control parameter setting means 5 of this embodiment are composed of a microcomputer.

Here, the estimation of the magnitude of the disturbance by the disturbance estimating means 4 will be described.

For example, the pulse disturbance shown in FIG. 2 (A) has exactly the same magnitude and a step disturbance shown in FIG. 2 (C) in the opposite direction after a certain period of time from the step disturbance shown in FIG. 2 (B). You can think of it as having entered.

(1) Discrimination of Kind of Disturbance Therefore, as shown in FIG. 3, the integrated manipulated variables U _I (A) and U _I (B) before and after the control amount is disturbed in a steady state are used.
When U _I (A) −U _I (B) ≈0, it is determined to be a pulse disturbance, and otherwise, it is determined to be a step disturbance.

(2) Step Disturbance The magnitude of the step disturbance is obtained by the following equation as a difference between the integrated operation amounts.

Magnitude of Disturbance = U _I (A) −U _I (B) (3) Case of Pulse Disturbance As described above, the pulse disturbance shown in FIG. 2 (A) has the steps of FIG. 2 (B). It can be considered that the disturbance and the step disturbance of FIG. 2C are combined, and FIGS. 2D and 2E are response waveforms of the step disturbance of FIGS.
If (F) is the response waveform of the pulse disturbance in FIG. 2 (A),
The time of disturbance can be measured as the time between the extreme values of the response waveform of FIG. 2 (F), and in FIG.
Area, I + J area, W + X time and Y + Z time can also be measured.

Therefore, the time of the disturbance measured as the time between the extreme values is equal to W (= Z), so that the time of X + Y and the area of G can be known.

In this area of G, as shown in FIG.
FIG. 2 shows the addition of the area (estimating this area) of the portion surrounded by the waveform indicated by the broken line at the time of X + Y.
It becomes the area of A + B + C in (D), and this area becomes the change amount of the integrated operation amount, and by dividing this by the time, the magnitude of the disturbance is obtained.

Next, the estimation of the magnitude of the disturbance of the present embodiment based on the above concept will be described more specifically with reference to FIG.

(1) Processing at the time of settling The sampling cycle is, for example, 0.5 second, and the past 10
The sum ΣU _I of the integral operation amounts of times is stored.

(2) The control waveform is a settling band width, for example,
When it deviates from 0.5 ° C, the time at this time is set to t ₀ ,
The sum ΣU of the past 10 integrated operations until t ₀
Store _I (t ₀ ).

After time t ₀ , until the control waveform enters the settling band width, for example, continuously until the settling determination time, the time is t.
_{If 0} + t _m , the integrated manipulated variable U _{I for} each sampling period
(T ₀ + t) is stored, the deviation e (t ₀ + t) for each sampling cycle is stored, and the time t ₀ + t is stored.
_m to calculate the past 10 times integration operation amount of the sum _{ΣU I (t 0 + t m} ) of.

(3) Whether the disturbance is a step disturbance,
The determination as to whether or not it is a pulse disturbance is performed as follows.

That is, when the following expression is satisfied, it is judged as pulse disturbance, and when it is not satisfied, it is judged as step disturbance.

| ΣU _I (t ₀ ) −ΣU _I (t ₀ + t _m ) | <1% (4) When it is determined that the disturbance is a step disturbance, the magnitude of the disturbance is calculated as follows.

Magnitude of disturbance = (1/10) · {ΣU
_I (t ₀ ) −ΣU _I (t ₀ + t _m )} (5) When it is determined that the pulse disturbance is generated, the following processing is performed.

First, at times t ₀ + t _max , t from the extreme values e _max , e _min of the deviation e in the period from time t ₀ to t ₀ + t _m .
₀ + t _min is calculated, and the disturbance time τ is calculated according to the following equation.

Τ = │t _max -t _min │ As described above, it is considered that the pulse disturbance includes step disturbances of the same magnitude and opposite directions after a certain period of time of the step disturbance. The settling time τ _s for is calculated according to the following equation.

Τ _s = t _m -2τ Then, considering that there is a disturbance that enters for a very long time and a disturbance that enters for a very short time, the magnitude of the disturbance is classified into the following two cases. To estimate.

In the case of 2τ> τ _{s In} this case, as shown in FIG. 6 (A), an area G ₀ corresponding to the above-mentioned area G and an area N excluding a portion partially overlapping this G ₀ Then, the magnitude of the disturbance is estimated as follows.

G ₀ = U _I (t ₀ ) −U _I (t ₀ + τ) N = U _I (t ₀ + t _m −τ _s + τ) −U _I (t ₀ + t _m ) Disturbance magnitude = | G ₀ | + | N | When sign = t _max > t _min Negative t _max <t _min Positive 2τ <τ _{s In} this case, the disturbance is very short, and the disturbance reaches the first extreme value. The case is divided into the case where there is an influence and the case where the influence of the disturbance disappears before reaching the first extreme value.

When -1 τ> min (t _max , t _min ) At this time, as shown in FIG. 6B, the area G ₁ corresponding to the above-mentioned area G, the area P, and the area Q are Estimate the magnitude of the disturbance from.

G ₁ = U _I (t ₀ ) −U _I (t ₀ + τ) Q = U _I (t ₀ + t _m −τ) −U _I (t ₀ + t _m ) Mean deviation e in P = {│ e (t ₀ + τ) | + | e
Time at (t ₀ + t _m −τ) |} / 2 P = integral at τ _s −2 τ P, that is, area P = K _I · [{| e (t ₀
+ Τ) | + | e (t ₀ + t _m −τ) |} / 2] · (τ _s −
2τ) Therefore, the magnitude of disturbance = | G ₁ | + | Q | + P sign = t _max > t _min , negative t _max <t _min , positive −2 τ <min (t _max , t _min ). At this time, as shown in FIG. 6C, the magnitude of the disturbance is estimated from the area G ₂ corresponding to the area G, the areas P ₁ and P _2, and the area Q ₁ .

G ₂ = U _I (t ₀ ) −U _I (t ₀ + τ) Q ₁ = U _I (t ₀ + t _m −τ) −U _I (t ₀ + t _m ) min (t _max , t _min ). deviation e ^m in ^{is, e m = | e (t} 0 + min (t max, t min)) | - | e
(T ₀ + min (t _max , t _min ) −τ | Average of deviation e in P ₁ = {| e (t ₀ + τ) | +
e ^m } / 2 P ₁ time = min (t _max , t _min ) −τ P ₁ integral, that is, area P ₁ = K _I · [{| e
(T ₀ + τ) | + e ^m } / 2] · {min (t _max ,
t _min ) −τ} Mean of deviation e in P ₂ = {e ^m + | e (t ₀ + t _m −
τ) |} / 2 Time at P ₂ = τ _s −τ−min (t _max , t _min ) Integration at P ₂ , that is, area P ₂ = K _I · [{e ^m +
| E (t ₀ + t _m −τ) |} / 2] · {τ _s −τ−min
(T _max , t _min )} Therefore, the magnitude of the disturbance = | G ₂ | + | Q ₁ | + P ₁ + P ₂ sign = t _max > t _min is negative, and t _max <t _min is positive.

Based on the disturbance response waveform as described above,
The magnitude of the disturbance is estimated.

Next, based on the estimated magnitude of the disturbance and the characteristic of the controlled object previously identified by the step response method, the PID control parameter corresponding to the desired response characteristic to the steady-state disturbance is set to the PID control means. The operation of the PID control parameter setting means 5 set to 3 will be described. The PID control parameter setting means 5 has a PID
The maximum slope R, the dead time L, and the steady gain K are given from the control means 3.

Here, the characteristic of the control amount in the case of the target value response and the characteristic of the deviation integral in the case of the disturbance response are the same,
That is, the overshoot and settling time at the target value response have the same characteristics as the overshoot and the settling time of the deviation integration at the disturbance response.

The relationship between the deviation integral overshoot and the settling time characteristic and the disturbance response characteristic is that the settling time of the deviation integral represents the settling time during the disturbance response, and the deviation integral overshoot and As shown in FIG. 7, if the overshoot of the deviation integral ∫e is n%, the area of the positive / negative part of the deviation e is (100 + n)% and n%. If the deviation integral has no overshoot, the deviation also has no overshoot.

Therefore, the PID control parameter setting means 5
Then, the response characteristic of the deviation integral for each control target that is identified in advance is obtained as follows.

That is, the transfer function of the secondary vibration system is G (s) = ω _n ² / (s ² + 2ξω _n s + ω _n ² ) (1), and the overshoot OS and settling at this time are set. Time ST and decay rate are

[0041]

[Equation 1]

It becomes

Therefore, when the controlled object represented by the first-order lag + dead time and the loop transfer function of the PID control system are quadratic-approximated by using the partial model matching method, the following equation is obtained.

G (s) = 1 / (1 + b ₁ s + b ₂ s ² ) (4) ω _n = 1 / (b ₂ ) ^1/2 (5) ξ = b ₁ / {2 · (b ₂ ) ^{1 / 2} } (6) b ₁ = {(g ₀ · Ti) / Kp} + α · Ti (7) b ₂ = (Ti / Kp) · {g ₁ − (1-α) · g ₀ · Ti} + Ti · Td-α (1-α) Ti ² (8) g ₀ = 1 / K (9) g ₁ = (T + L) / K (10) However, the control system is FF: G _F (s) = Kp (α + T _D s) (11) PID: Gc (s) = Kp {1 + 1 / (T _I s) + T _D s} (12) The control target is Gp (s) = {K / (1 + Ts)} e ^{− This is LS} (13).

Therefore, ω obtained by the equations (4) to (13)
By substituting _n and ξ into the equations (2) and (3), the overshoot and the settling time can be obtained.

For example, the controlled object Gp (s) = 1 / {(1 + 37s) (1 + 508s)}
8 to FIG.
Shown in.

Here, FIG. 8 shows the relationship between the proportional gain Kp and the overshoot and settling time when the integral time Ti and the derivative time Td are fixed to the present values, and FIG. 9 shows the proportional gain Kp and the derivative time. FIG. 10 shows the relationship between the integration time Ti and the overshoot and settling time when Td is fixed to the current value. Further, FIG. 10 shows the derivative time T when the proportional gain Kp and the integration time Ti are fixed to the current values.
The relationship between d, overshoot, and settling time is shown.

The overshoot and settling time obtained from FIGS. 8 to 10 and the actual measurement value at the current value of the PID control parameter may deviate from the model error, but the PID control parameter and the overshoot and settling time may differ. Since the relationship with the
It is possible to know how many times the PID control parameter should be multiplied in order to multiply by / 2.

The PID control parameter setting means 5 uses such a relationship to control what percentage of the user's request set in the required use setting section 6, for example, overshoot, or settling time within a few seconds. The PID control parameter is calculated so as to correspond to the request such as
It is set in the ID control means 3.

As a result, it becomes possible to obtain a response waveform according to the wish of the user with respect to the disturbance during the steady operation.

FIG. 11 is a flow chart showing an outline of the above processing.

First, it is judged whether or not it has been set for the first time (step n1), and if it has been set for the first time, the steady gain K is calculated (step n6) and the process proceeds to step n2. Otherwise, the process proceeds to step n2. ..

In step n2, it is judged whether or not it is in the settling band, and when it is not in the settling band, it is judged whether or not the steady gain K has been calculated (step n7). If it has not been settled yet and is in the middle of rising, the process returns to step n1. If it has been calculated, the deviation and the deviation integral are calculated as disturbances, the data are stored in time series, and the process returns to step n2.

When it is determined in step n2 that the settling zone is present, it is determined whether or not the settling zone is entered for the first time after the disturbance is applied (step n3). In this way, the magnitude of the disturbance is estimated (step n4), and the PID control parameter is set according to the estimated magnitude of the disturbance (step n5). If it is not the first time to enter the settling band in step n3, the process returns to step n2.

Although the control object is identified by the conventional step response method in the above-mentioned embodiment, as another embodiment of the present invention, the applicant of the present invention filed a patent application (September 20, 1991). In Japanese Patent Application No. 3-241443) "PID controller", the control target may be identified by the proposed method. That is, when rising, for example, 100%
The dead time and the slope may be sequentially calculated from the response waveform by applying the step operation amount of, and the control target may be identified by the dead time and the maximum slope obtained until they reach a predetermined condition.

[0056]

As described above, according to the present invention, the magnitude of the applied disturbance is estimated, and based on the estimated magnitude of the disturbance and the characteristic of the control target that has been identified in advance,
Since the control parameter corresponding to the desired response characteristic is set, the overshoot is suppressed as much as possible with respect to the disturbance during the steady operation, or the settling time is shortened as much as possible even if the overshoot occurs. It is possible to obtain a desired disturbance response waveform.

[Brief description of drawings]

FIG. 1 is a functional block diagram of an embodiment of the present invention.

FIG. 2 is a waveform diagram for explaining a method of estimating the magnitude of disturbance.

FIG. 3 is a response waveform diagram for explaining the determination of the type of disturbance.

FIG. 4 is a waveform diagram for explaining a method of estimating the magnitude of disturbance.

FIG. 5 is a response waveform diagram for explaining a method of estimating the magnitude of disturbance.

FIG. 6 is a waveform diagram for explaining a method of estimating the magnitude of disturbance.

FIG. 7 is a waveform chart showing the relationship between deviation integration and deviation.

FIG. 8 is a diagram showing a relationship between a proportional gain Kp, overshoot, and settling time.

FIG. 9 is a diagram showing the relationship between integration time Ti and overshoot / settling time.

FIG. 10 is a diagram showing a relationship between a differential time Td and overshoot and settling time.

FIG. 11 is a flowchart for explaining the operation.

[Explanation of symbols]

 2 controlled object 3 PID control means 4 disturbance estimation means 5 PID control parameter setting means

Front Page Continuation (72) Inventor Yoshihiro Nagami 10 Odoron-cho, Hanazono, Ukyo-ku, Kyoto Omron Corporation

Claims (1)

[Claims] Claim: What is claimed is: 1. Control means for outputting an operation amount corresponding to a set control parameter to a control target based on a deviation between the control amount and the target value, and an application based on the control amount, the operation amount and the target value. The disturbance estimation means for estimating the magnitude of the disturbed disturbance, and the control parameter corresponding to the desired response characteristic to the steady-state disturbance based on the estimated magnitude of the disturbance and the characteristics of the control target previously identified, A control device comprising: a control parameter setting unit that is set in the control unit.