JPH06274203A - Imc controller - Google Patents

Abstract

PURPOSE:To provide an IMC controller capable of attaining both of objective value followup ability and disturbance suppression ability and having high generality. CONSTITUTION:An objective value is inputted to an objective value filtering part 2 and a feedback amout is subtracted from the output of the filtering part 2 by the 1st subtracting processing part 3. The subtracted output is inputted to an objective value/disturbance filtering part in a manipulated variable computing part 4 and a manipulated variable (u) is computed from the output of the filtering part by an operation part in the computing part 4 and outputted to a controlled process. The 2nd subtracting processing part 8 subtracts a reference controlled variable ym outputted from an internal model output computing part 6b for computing an internal model arithmetically expressing the controlled process from the controlled variable (y) of the controlled process to obtain a feedback amount (e). Since disturbance is adjusted by the objective value/ disturbance filtering part and the objective value is adjusted by an objective value filtering part, both of objective value followup ability and disturbance suppression ability can be attained.

Description

Detailed Description of the Invention

[0001]

BACKGROUND OF THE INVENTION 1. Field of the Invention The present invention relates to a general-purpose controller, and more particularly to a controller using a control algorithm having an IMC (Internal Model Control) structure.

[0002]

2. Description of the Related Art Conventionally, a PID has been used as a general-purpose controller.
The one using control is generally used. FIG. 8 is a block diagram of a control system using a conventional PID controller. Reference numeral 23 denotes a subtraction processing unit that subtracts a control amount (indoor temperature), which is the control result, from a target value (for example, if the PID controller is an indoor air conditioner, it corresponds to an indoor temperature set value), and 24 denotes a subtraction processing unit 23. An operation unit that calculates an operation amount (temperature of hot air or cold air from the indoor air conditioner) based on the output, 30 is a control target process (indoor environment).
Further, Gc and Gp are transfer functions of the operation unit 24 and the controlled process 30, respectively, r is a target value, u is an operation amount, d is disturbance (outdoor environment with respect to indoor environment, etc.), and y is a control amount.

To briefly explain the operation of such a PID controller, the operation section 24 includes a P-operation section whose gain is K in a proportional operation section (not shown) and an I-operation whose integration time is TI in the integral operation section. Section, similarly, there is a D operation section in the differentiating operation section whose differentiation time is TD, and the transfer function Gc of this operating section 24 is given by the following equation. Gc = K × (1 + 1 / (TI × s) + TD × s) (1) where s is a Laplace operator. Therefore, the operation unit 2
The manipulated variable u, which is the output of 4, is obtained by the following equation. u = Gc × (r−y) = K × (1 + 1 / (TI × s) + TD × s) × (r−y) (2)

That is, in the PID controller, the operation amount u is calculated from the output of the subtraction processing unit 23 by the operation unit 24 that performs the operation of adding the proportional operation P, the integral operation I, and the differential operation D, and the control target process 30 The influence of the disturbance d can be monitored by configuring a feedback control system that outputs the control amount y from the controlled object process 30 to the subtraction processing unit 23. But,
Time from when the manipulated variable u is output to the PID controller until the control amount y in the controlled process 30 changes (for example, in the case of an indoor air conditioner, the time from when hot air comes out until when the indoor temperature rises) When the dead time is large, the operation amount u that is larger than the original operation is output, and the control amount y overshoots or vibrates, which makes it difficult to deal with the dead time. It was

Therefore, there has been proposed a controller using an IMC structure control algorithm for performing control by incorporating an internal model in which a process to be controlled is expressed by a mathematical expression. FIG. 9 is a block diagram of a control system using this IMC controller. Reference numeral 33 is a first subtraction processing unit that subtracts a feedback amount described later from the target value r, 32 is a filter unit for preventing sudden changes in the output of the first subtraction processing unit 33, and 34 is a filter unit. An operation unit that calculates and outputs a manipulated variable u based on the output of 32, and 36 is an approximation of the controlled object process 30 by a mathematical expression, and outputs a reference controlled variable corresponding to the controlled variable y of the controlled object process 30. An internal model, 38 is a second for outputting a feedback amount by subtracting the reference control amount from the internal model 36 from the control amount y
Is a subtraction processing unit. Further, F and Gm are transfer functions of the filter unit 32 and the internal model 36, ym is a reference control amount, and e is a feedback amount.

Next, the operation of such an IMC controller will be described. First, the first subtraction processing unit 33 subtracts the feedback amount e from the target value r, and the result is output to the filter unit 32 for preventing a rapid change in the target value r from being transmitted. Next, the operation amount u is calculated by the operation unit 34 from the output of the filter unit 32, and is output to the control target process 30 and the internal model 36 of the controller. Then, the second subtraction processing unit 38 subtracts the reference control amount ym from the internal model 36 that approximates the control target process 30 from the control amount y of the control target process 30, and the result is the feedback amount e. A feedback control system that is fed back to the first subtraction processing unit 33 is configured as.

Ideally, the internal model 36 of such an IMC controller is expressed mathematically so as to be exactly the same as the controlled process 30, and the operating section 34 is also used.
Is ideally the inverse characteristic (1 / Gm) of the transfer function of the internal model 36, but since the elements of the dead time in the internal model 36 cannot be reciprocal, normally the elements of the dead time are Ignore. Therefore, the control amount y can be obtained by the following equation from the target value r and the disturbance d with such a configuration. y = F * Gp * Gc * r / {1 + F * Gc * (Gp-Gm)} + (1-F * Gm * Gc) * d / {1 + F * Gc * (Gp-Gm)} ... (3 Here, the transfer function Gm of the internal model 36 is equal to the transfer function Gp of the control target process 30, and the transfer function Gc of the operating unit 34 is the reciprocal of the transfer function of the internal model 36 (1 / Gm =
Assuming an ideal state equal to 1 / Gp), equation (3) becomes: y = F × r + (1−F) × d (4)

Further, under ideal conditions where the target value r does not change suddenly, the filter unit 32 is unnecessary and F = 1 can be set, so that the control amount y becomes equal to the target value r (y =
r), it is possible to realize the control without any influence of the disturbance d. Further, focusing on the disturbance d in the control system of FIG. 9, even if there is a large dead time in the controlled process 30 and the internal model 36, both exhibit the same characteristics with respect to the manipulated variable u, so the second subtraction It can be seen that the feedback amount e that is the output of the processing unit 38 is only the disturbance d, and the disturbance d can be suppressed. Such an IMC controller usually has robust stability indicating stability when the error between the controlled process 30 and the internal model 36 becomes large, and similarly robust performance indicating performance when the error becomes large. It is designed based on design conditions. Further, the filter unit 32 is adjusted based on the model identification accuracy of the internal model 36 and the controlled process 30 after the internal model 36 is determined by such a model identification technique.

However, the transfer function F of the filter section 32 is
Is the first term on the right side [F × Gp × Gc × r / {1 + F × Gc × (Gp−G
m)}], and the second term on the right side of the disturbance d [(1-F ×
Gm × Gc) × d / {1 + F × Gc × (Gp−G
m)}]. That is, the first term on the right side,
The second term on the right-hand side, that is, the characteristics related to the target value r,
When the characteristics relating to the disturbance d are adjusted by the filter unit 32, they cannot be adjusted independently. Therefore, it is difficult to achieve both the target value followability indicating how the control amount y follows the target value r and the disturbance suppressing ability indicating how much the disturbance d can be suppressed. In addition, a design method of a two-degree-of-freedom IMC that achieves both target value tracking performance and disturbance suppression performance has been proposed. However, it is intended to obtain optimum control performance and is used as a versatile controller. Has not been realized.

[0010]

Since the conventional IMC controller is configured as described above, it is unsuitable as a controller that can be used for general purposes, and it is premised on achieving both target value tracking performance and disturbance suppression performance. There is a problem in that a general-purpose controller that takes advantage of the IMC structure has not been realized. Moreover, the conventional general-purpose PID controller has a problem that it cannot effectively control a control target process having a long dead time. An object of the present invention is to provide a highly versatile IMC controller that achieves both target value tracking performance and disturbance suppression performance in order to solve the above problems.

[0011]

According to the present invention, a target value filter unit for outputting an input target value of control with a characteristic of a first-order delay in a transfer function, and a feedback amount is subtracted from an output of the target value filter unit. The first subtraction processing unit, the target value / disturbance filter unit that outputs the output of the first subtraction processing unit with the characteristic of a first-order lag in the transfer function, and the target value / disturbance filter unit based on the parameters of the internal model. Reference is made from the operation amount output part from the operation amount operation part based on the parameters of the internal model and the internal model storage part that stores the parameters of the internal model An internal model output calculation unit that calculates a control amount, and a second subtraction that outputs a feedback amount by subtracting the reference control amount output from the internal model output calculation unit from the control amount of the control target process Those having a processing section.

Also, a first subtraction processing unit for subtracting the feedback amount from the signal based on the input target value, and a side for performing IMC control and PID control for the output of the first subtraction processing unit by the switching signal. Of the internal model, and a first operation amount calculation unit that calculates an operation amount from the output of the signal transmission switching unit as IMC control based on the parameters of the internal model. An internal model storage unit to store, an internal model output calculation unit that calculates a reference control amount from the operation amount output from the first operation amount calculation unit based on the parameters of the internal model, and a PID that stores PID control parameters. A second operation amount for calculating an operation amount from the output of the signal transmission switching unit as PID control based on the storage unit and the parameter output from the PID storage unit In the calculation unit and the IMC control, the reference control amount output from the internal model output calculation unit is subtracted from the control amount of the control target process to output as a feedback amount, and in the PID control, the control amount of the control target process is output. A second subtraction processing unit that outputs as a feedback amount, a settling state determination unit that determines the settling state of the control target process based on the target value and the control amount, and outputs the result as a determination signal, and a settling state determination unit Based on the determination signal output from the internal model storage unit and the parameter output from the internal model storage unit, a switching control unit that determines which of IMC control and PID control is suitable for the state of the control target process and outputs a switching signal is provided. I have.

[0013]

According to the present invention, the target value is input to the target value filter unit, the feedback amount is subtracted from the output of the target value filter unit in the first subtraction processing unit, and the result is output to the operation amount calculation unit. To be done. Then, the manipulated variable computing unit computes the manipulated variable from the output of the first subtraction processing unit, and outputs it to the controlled object process and the internal model output computing unit. And
The second subtraction processing unit subtracts the reference control amount from the internal model output operation unit from the control amount of the control target process, and the result is fed back to the first subtraction processing unit as a feedback amount. Has been done. Further, the settling state determination section determines the settling state of the controlled process based on the target value and the control amount, and the switching control section outputs the determination signal output from the settling state determination section and the parameter output from the internal model storage section. Based on the above, it is determined which of the IMC control and the PID control is more suitable for the state of the controlled process, and the switching signal is output. Then, by this switching signal, it is possible to switch between which of the first manipulated variable calculation unit that performs IMC control and the second manipulated variable calculation unit that performs PID control outputs the signal based on the target value from the signal transmission switching unit. Done.

[0014]

DESCRIPTION OF THE PREFERRED EMBODIMENTS FIG. 1 is a block diagram of a two-degree-of-freedom IMC controller that achieves both target value tracking and disturbance suppression, showing an embodiment of the present invention. FIG. 2 is a block diagram of a control system using this IMC controller. It is a figure. In FIG. 1, reference numeral 1 is a target value input section for inputting a target value r set by an operator (not shown) to this controller, and 2 is a target value r from the target value input section 1 for which the transfer function has a first-order lag characteristic. The target value filter unit 3, the first subtraction processing unit 4 for subtracting the feedback amount e from the output of the target value filter unit 2,
Is a manipulated variable calculation unit that calculates a manipulated variable u from the output of the first subtraction processing unit 3 based on a parameter from an internal model storage unit, which will be described later, and 5 represents the manipulated variable u output from the manipulated variable calculation unit 4. 1 is a signal output unit for outputting to a control target process (not shown).

Further, 6a is an internal model storage section for storing the parameters of the internal model of this IMC controller, 6a
b is a reference control amount ym that is calculated as an internal model based on the parameters output from the internal model storage unit 6a.
, An internal model output operation unit for outputting the control amount y from the controlled object process to the IMC controller, and an internal model output operation for the control amount y output from the control amount input unit 7. The second subtraction processing unit subtracts the reference control amount ym output from the unit 6b and outputs the feedback amount e.

In FIG. 2, reference numeral 4a is inside the manipulated variable calculating unit 4 and the transfer function of the output of the first subtraction processing unit 3 is 1
Target value / disturbance filter unit that outputs with the characteristics of the next delay, 4b
Is also inside the target value / disturbance filter unit 4a.
An operation unit for calculating the manipulated variable u from the output of F, an internal model 6 including an internal model storage unit 6a and an internal model output operation unit 6b, F1 a transfer function of the target value filter unit 2, and F2 a target value / disturbance filter unit. 4a is a transfer function. In addition,
FIG. 2 shows the IMC controller of FIG.
This is rewritten as a control system including 0 and the disturbance d.

Next, the operation of such an IMC controller will be described. The target value r is set by the operator or the like of this IMC controller, and is input to the target value filter unit 2 via the target value input unit 1. The target value filter unit 2 outputs the target value r with the characteristic of the transfer function F1 as shown in the following equation, the time constant of which is T1. F1 = 1 / (1 + T1 × s) (5) Next, the first subtraction processing unit 3 uses the target value filter unit 2
The feedback amount e output from the second subtraction processing unit 8 is subtracted from the output of.

Then, the target value / disturbance filter unit 4a in the manipulated variable calculation unit 4 outputs the output of the first subtraction processing unit 3 with the characteristic of the transfer function F2 such that the time constant is T2. . F2 = 1 / (1 + T2 × s) (6) Similarly, the operation unit 4b therein also calculates the operation amount u from the output of the target value / disturbance filter unit 4a, but its transfer function Gc is The following expression is obtained by the gain and time constant of the internal model 6 output from the model storage unit 6a, which is the reciprocal of the transfer function Gm of the internal model 6 excluding the elements of the dead time Lm as in the example of FIG. Gc = (1 + Tm × s) / Km (7) where Km and Tm are gains of the internal model 6, respectively.
It is a time constant. Therefore, the transfer function of the operation amount calculation unit 4 as a whole is given by the following equation. F2 × Gc = (1 + Tm × s) / {Km × (1 + T2 × s)} (8) In this way, the manipulated variable u is calculated from the output of the first subtraction processing unit 3 and the signal output unit It is output to the control target process 30 via 5 and is also output to the internal model output calculation unit 6b.

Next, the internal model 6 uses the gain Km, the dead time Lm, and the time constant Tm stored in the internal model storage unit 6a as the parameters, which are the first-order lag and the dead time. This is a mathematical expression expressed as having elements, and the reference control amount ym is calculated from the operation amount u output from the operation amount operation unit 4 in the internal model output operation unit 6b. The transfer function Gm is given by the following equation. Gm = Km × exp (−Lm × s) / (1 + Tm × s) (9) Next, the second subtraction processing unit 8 receives the control target process 30 input via the control amount input unit 7. The reference control amount ym from the internal model output calculation unit 6b is subtracted from the control amount y from the above, and the feedback amount e is output. Then, this feedback amount e is input to the first subtraction processing unit 3 as described above. This completes the feedback control system consisting of this IMC controller.

In this control system, in the control system of the example of FIG. 9, the filter unit 32 is set to the target value / disturbance filter unit 4
It corresponds to a control system in which the target value r is set to a and the target value filter unit 2 is added to the target value r. y = F1 * F2 * Gp * Gc * r / {1 + F2 * Gc * (Gp-Gm)} + (1-F2 * Gm * Gc) * d / {1 + F2 * Gc * (Gp-Gm)} ... (10) That is, as shown in Expression (10), the second term on the right side of the disturbance d [(1-F2 × Gm × Gc) × d / {1 + F2 ×
Since only the transfer function F2 of the target value / disturbance filter unit 4a is related to Gc × (Gp−Gm)}], the disturbance d is adjusted by the target value / disturbance filter unit 4a. Also, the first term on the right side [F1 × F2 × Gp × Gc × r / {1+
F2 × Gc × (Gp−Gm)}], the target value r is calculated by the transfer function F after adjustment of the target value / disturbance filter unit 4a.
The target value filter unit 2 of 1 is adjusted.

Therefore, after the internal model 6 is determined, the target value filter unit 2 and the target value / disturbance filter unit 4a having necessary and sufficient characteristics can be adjusted by setting a small number of parameters as shown in equations (5) and (6). By doing so, it is possible to realize a controller having an IMC structure that can achieve both the target value following property and the disturbance suppressing property and that can be generally used for a general plant. The two-degree-of-freedom IMC of this embodiment
The controller has a target value / disturbance filter unit 4a having a first-order lag characteristic of a transfer function F2 for the disturbance d, and a target value filter unit 2 and a target value / displacement unit for the target value r.
The disturbance filter unit 4a uses the transfer function F1 × F2, which is 2
It becomes the characteristic of the next delay.

FIG. 3 is a diagram showing the target value followability when the IMC controller of this embodiment is used for controlling the height of the liquid level in the tank, and FIG. 4 is a diagram showing the disturbance suppression property.
In FIGS. 3 and 4, the vertical axis represents the height of the liquid surface (control amount y), the horizontal axis represents time, and yp represents the control amount when controlled by the conventional PID controller. Fig. 3 shows the target value r at 0 seconds.
(One-dot chain line) is input as the liquid level height of 4 cm, and the control amount y (solid line), which is the liquid level height as a result of control by the IMC controller of the present embodiment, and the control amount yp (, similarly by the conventional PID controller. (Broken line) is the simulation result.

Here, assuming that the gain of the controlled object process 30 which is the liquid in the tank is 4.0, the dead time is 50 seconds, and the time constant is 10 seconds, the gain Km of the internal model 6 of this embodiment and the dead time are set. Lm and time constant Tm are the same as those of the control target process 30, and the time constant T of the target value filter unit 2 is set.
1 for 15 seconds, the time constant T2 of the target value / disturbance filter unit 4a
Is set to 15 seconds. Further, the gain K of the PID controller is 0.03, the integration time TI of the I operation is 10 seconds, and the differential time TD of the D operation is 25 seconds. As shown in FIG. 3, it can be seen that the target value followability of the present embodiment is improved without exceeding the target value r unlike the control amount yp of the conventional PID controller.

In FIG. 4, when a manipulated variable u = 0 and a controlled variable y = 0 are stable and a disturbance d (dashed-dotted line) suddenly rises at a height of 1 cm at 0 seconds. The results are compared in the same manner as in FIG. Also, the internal model 6
And the parameters of the controlled process 30 are the same as those in FIG. 3, but the gain K of the PID controller is 0.047.
5. The integration time TI is 120 seconds and the differential time TD is 20 seconds. As shown in FIG. 4, the conventional PID controller does not completely suppress the disturbance d with respect to the control target process 30 having a long dead time, whereas the IMC controller of the present embodiment improves the disturbance suppression property. I understand that.

As described above, the IMC controller can easily cope with the case where the controlled object process has a large dead time, but the PID optimally adjusted is limited to the disturbance suppressing property for the controlled object process having a small dead time. IMC is inferior to IMC. Therefore, by using the advantages of IMC and PID properly, it is possible to cope with a control target process with a short dead time.

FIG. 5 is a block diagram of an IMC controller showing another embodiment of the present invention. The same parts as those in the example of FIG. 1 are designated by the same reference numerals. Reference numeral 9 is a signal transmission switching unit for switching between the output of the first subtraction processing unit 3 based on a switching signal, which is to be output to a later-described first operation amount calculation unit or a second operation amount calculation unit, and 10a is a PID. A PID storage unit 10b that stores control parameters, and a PID storage unit 10a
A second manipulated variable calculation unit that calculates the manipulated variable u from the output of the signal transmission switching unit 9 as the operating unit of the PID controller based on the parameters output from the target value input unit 1 and the target value r from the target value input unit 1. A settling state determination unit that determines the settling state of the control target process based on the control amount y from the control amount input unit 7 and outputs the result as a determination signal; Model storage unit 6
A switching control unit that outputs a switching signal based on the parameter from a, 14 is a first operation amount calculation unit similar to the operation amount calculation unit 4 of the embodiment of FIG.

In the present embodiment, the signal transmission switching unit 9 switches the output of the first subtraction processing unit 3 based on the switching signal output from the switching control unit 12, and the first operation amount calculation unit 14 is switched. If switched to output, the configuration and operation including the first manipulated variable calculating unit 14 corresponding to the manipulated variable calculating unit 4 in FIG. 1 are similar to those in the example of FIG. Further, if the output of the first subtraction processing unit 3 is switched to be output to the second manipulated variable calculation unit 10b, the internal model output calculation unit 6b.
Since the reference control amount ym from is not output, the feedback amount e that is the subtraction result of the second subtraction processing unit 8 is only the control amount y, and the PID corresponding to the operation unit 24 in FIG.
The configuration and operation including the storage unit 10a and the second manipulated variable calculation unit 10b are similar to those in the example of FIG. As will be described later, switching to the second manipulated variable calculation unit 10b side is equivalent to no target value filter unit 2 at this time because the target value r does not change in the settling state.

Next, as such a switching algorithm, the operation of the settling state determination section 11 will be described first. The settling state determination unit 11 determines whether the control target process is in the settling state based on the target value r from the target value input unit 1 and the control amount y from the control amount input unit 7, and outputs the result as a determination signal. To do. First, when the target value r output from the target value input unit 1 changes, it is determined that the settling state is not established, and the value of the determination signal is set to "1".

Next, the amount of change d when the target value r changes
A difference h = y−r between r, the target value r and the controlled variable y is calculated for each sampling time of this control system. Further, the control amount before one sampling is y2, and the difference from the current control amount y is dy =
y-y2 is calculated for each sampling. Then, when the determination signal is "1" and the condition of the following equation is satisfied at the same time, the process to be controlled is determined to be in the settling state and the value of the determination signal is set to "0". | H | <X1 × | dr | (11) | dy | <X2 × | dr | / dt (12) where dt is a sampling time of 1.0 second, for example, The values X1 and X2 are each 0.0, for example.
It is set to 2, 0.01.

Next, the operation of the switching control unit 12 determines the switching condition based on the determination signal output from the settling state determination unit 11 and the dead time Lm and the time constant Tm output from the internal model storage unit 6a. And outputs a switching signal. At this time, the determination signal is "1", or the switching signal is set to "0" when the following expression is satisfied. Lm / Tm ≧ X3 (13) That is, whether the settling state determination unit 11 has determined that the control target process is not in the settling state, or the dead time Lm / time constant Tm is equal to or greater than the threshold value X3, When it is determined that the dead time is long, the switching signal is set to “0” because the IMC control is more suitable. In addition,
The threshold value X3 is, for example, 0.25. Therefore, the signal transmission switching unit 9 outputs the output of the first subtraction processing unit 3 to the first manipulated variable calculation unit 14 according to the switching signal output from the switching control unit 12, and the controller of the present embodiment is It operates exactly the same as the two-degree-of-freedom IMC controller of the first example.

Further, the switching control section 12 sets the switching signal to "1" when the judgment signal output from the settling state judging section 11 is "0" and the following expression is satisfied. Lm / Tm <X3 (14) That is, the settling state determination unit 11 determines that the control target process is in the settling state, and the dead time Lm / time constant Tm is smaller than the threshold value X3. When it is determined that the dead time is short, the switching signal is set to "1" because the PID control is more suitable. Therefore,
The signal transmission switching unit 9 outputs the output of the first subtraction processing unit 3 to the second manipulated variable calculation unit 10b in response to the switching signal output from the switching control unit 12, and the controller of the present embodiment has the configuration shown in FIG. It operates similarly to the example PID controller.

Therefore, when the control is not in the settling state or the dead time of the controlled process is long, the IMC
It operates as a structure controller, and when the control is in the settling state and the dead time of the control target process is small, it operates as a PID structure controller, thereby achieving both target value tracking performance and disturbance suppression performance, and a small dead time. It can also be used as a general-purpose controller for control target processes. The IMC controller of this embodiment has the same IMC structure as that of the example of FIG. 1, but may have another IMC structure.

FIG. 6 is a diagram showing the target value followability when the IMC controller of this embodiment is used for controlling the height of the liquid level in the tank as in FIG. 3, and FIG. 7 is also the same as FIG. It is a figure which shows a disturbance suppression property. Similar to FIG. 3, in FIG. 6, the target value r (dashed line) is input as the liquid level height of 4 cm at 0 seconds, and the control amount y (solid line) by the IMC controller of the present embodiment and the conventional PID controller are input. Controlled variable yp
(Dashed line).

Here, the gain of the controlled process is set to 4.
Assuming that the dead time is 0, the dead time is 1.0 second, and the time constant is 22.3607 seconds, the gain K of the internal model storage unit 6a of this embodiment is K.
m, the dead time Lm, and the time constant Tm are the same as those of the controlled process, and the time constant T1 of the target value filter unit 2 is 1.0 second. The first manipulated variable calculating unit 14 not shown in FIG.
The time constant T2 of the target value / disturbance filter section is set to 1.0 second. In addition, the PI stored in the PID storage unit 10a
The gain K2 of the D controller is 5.311, the integration time TI2 of the I operation is 2.4 seconds, and the differential time TD2 of the D operation is 0.4 seconds. Further, the gain K of the conventional PID controller is 3.354, and the integration time TI of the I operation is 2
2.3607 seconds and the differential time TD of the D operation is 0.5 seconds. In FIG. 6, the IMC controller of the present embodiment operates as IMC control with respect to a change in the target value r from 0 seconds, and shifts to the PID control after the control amount y stabilizes, thereby tracking the target value. The nature is improving.

Similar to FIG. 4, FIG. 7 shows a state in which the manipulated variable u = 0 and the controlled variable y = 0 are stable, and the height 1c is suddenly increased at 0 seconds.
This is the result when a disturbance d (not shown), which is a rise in the liquid level of m, occurs, and the disturbance suppression property is the same as that of the conventional PID. Therefore, it is compared with the control amount yi by the conventional IMC controller. ing. In FIG. 7, the process to be controlled is in the settling state before the disturbance d occurs, and the target value r does not change even after the disturbance d occurs. Therefore, the IMC controller of this embodiment performs the PID operation. It can be seen that the disturbance suppression property is improved as compared with the conventional IMC controller.

[0036]

According to the present invention, by providing the target value filter section and the target value / disturbance filter section having the necessary and sufficient characteristics with the minimum parameter setting, both the target value following ability and the disturbance suppressing ability are compatible. Therefore, it is possible to realize a controller having an IMC structure which can be generally used for general plants. When the control target process is not in the settling state or when the control target process has a long dead time, it operates as a controller of the IMC structure, and when the control target process is in the settling state and the control target process has a small dead time, it operates in the PID structure. By operating as a controller, it is possible to achieve both target value tracking performance and disturbance suppression performance, and it is possible to handle as a general-purpose controller even for a control target process with a short dead time.

[Brief description of drawings]

FIG. 1 is a block diagram of a two-degree-of-freedom IMC controller showing an embodiment of the present invention.

FIG. 2 is a block diagram of a control system using the IMC controller of FIG.

FIG. 3 is a diagram showing target value followability of the IMC controller of FIG. 1.

FIG. 4 is a diagram showing a disturbance suppressing property of the IMC controller of FIG. 1.

FIG. 5 is a block diagram of an IMC controller showing another embodiment of the present invention.

FIG. 6 is a diagram showing a target value followability of the IMC controller of FIG.

FIG. 7 is a diagram showing the disturbance suppressing property of the IMC controller of FIG.

FIG. 8 is a block diagram of a control system using a conventional PID controller.

FIG. 9 is a block diagram of a control system using a conventional IMC controller.

[Explanation of symbols]

 2 target value filter unit 3 first subtraction processing unit 4 manipulated variable calculation unit 4a target value / disturbance filter unit 4b operation unit 6a internal model storage unit 6b internal model output calculation unit 8 second subtraction processing unit 9 signal transmission switching unit 10a PID storage unit 10b Second operation amount calculation unit 11 Settling state determination unit 12 Switching control unit 14 First operation amount calculation unit e Feedback amount r Target value u Manipulation amount y Control amount ym Reference control amount

Claims (2)

[Claims] 1. A reference control amount corresponding to a control amount of a control target process, which is a control result, is calculated by calculating an operation amount to be output to a control target process from a control target value, and using an internal model expressing the control target process by a mathematical expression. Control is performed by calculating and feeding back the difference between the control amount and the reference control amount I
In the MC controller, a target value filter unit that outputs the input target value of the control with a characteristic of a first-order lag in the transfer function, a first subtraction processing unit that subtracts a feedback amount from the output of the target value filter unit, A target value / disturbance filter unit that outputs the output of the first subtraction processing unit with a characteristic of a first-order delay in the transfer function, and an operation amount is calculated from the output of the target value / disturbance filter unit based on the parameters of the internal model. And a reference control amount from an operation amount output from the operation amount calculation unit based on the parameters of the internal model, and an internal model storage unit that stores parameters of the internal model. The internal model output calculation unit for calculation, and the reference control amount output from the internal model output calculation unit from the control amount of the process to be controlled are subtracted from the feedback amount. IMC controller; and a second subtraction processing section for outputting the amount. 2. A reference control amount corresponding to the control amount of the control target process, which is a control result, is calculated by calculating an operation amount to be output to the control target process from a control target value and using an internal model expressing the control target process by a mathematical expression. Control is performed by calculating and feeding back the difference between the control amount and the reference control amount I
In the MC controller, a first subtraction processing unit that subtracts a feedback amount from a signal based on an input target value, and an output of the first subtraction processing unit according to a switching signal IMC.
A signal transmission switching unit that switches between a control side and a PID control side, and a first operation for calculating an operation amount from the output of the signal transmission switching unit as the IMC control based on an internal model parameter.
Of the operation amount, an internal model storage unit for storing the parameters of the internal model, and a reference control amount from the operation amount output from the first operation amount calculation unit based on the parameters of the internal model. An internal model output operation unit, a PID storage unit that stores the parameters of the PID control, and an operation amount calculated from the output of the signal transmission switching unit as the PID control based on the parameters output from the PID storage unit And a reference control amount output from the internal model output calculation unit from the control amount of the process to be controlled during the IMC control, and outputs the feedback control amount as the feedback amount.
In the case of D control, the second subtraction processing unit that outputs the control amount of the control target process as the feedback amount, and the settling state of the control target process is determined based on the target value and the control amount, and the result is determined. I based on the settling state determination section that outputs as a determination signal, the determination signal output from the settling state determination section, and the parameters output from the internal model storage section.
An IMC controller comprising: a switching control unit that determines which of MC control and PID control is suitable for the state of a control target process and outputs the switching signal.