JP3307515B2 - Method and apparatus for continuously switching a plurality of controllers - Google Patents

Description

DETAILED DESCRIPTION OF THE INVENTION

[0001]

BACKGROUND OF THE INVENTION 1. Field of the Invention The present invention relates to an automatic control system that uses a plurality of controllers having control functions such as PI, PD, and PID to provide a common operation amount to a controlled object. The present invention relates to a method and an apparatus for switching a controller.

[0002]

2. Description of the Related Art A conventional controller switching method is shown in FIG. In the figure, 1 is an automatic controller A including a PID controller A, 2 is an automatic controller B including a PID controller B, and ab3 and ab4 are contacts for switching between the controller A and the controller B. Actual values of each automatic control device 11, 21
Represents a detection signal of a process corresponding to each control mode, and a signal selected at the contacts ab3 and ab4, that is, a command output to the drive system is an operation amount for the target drive device. Next, the configuration of the automatic control devices A and B will be described. 10 and 20 are set values corresponding to the control amounts of the respective automatic control devices, 11 and 21 are the above-described actual values, 12 and 22
Is a subtractor, 13 and 23 are zero setting units, 14 and 24 are proportional amplifiers, 15 and 25 are I processing units (integration processing units),
26 is a D processing unit (differential processing unit), and 17 and 27 are adders. In the figure, when the output signals of the controllers A and B are switched so as to be continuous signals as the manipulated variables of the control target, the automatic control device A which was in charge of the control before the switching was performed.
Of the I (integral) and D (differential) components of the PID controller A
1 and D1 are replaced by I2 and D2 of the I and D components of the PID controller B of the automatic control device B which is in charge of the control after the switching. That is, the values of the I and D components of the controller generated due to the process of the control up to the present time are replaced with the corresponding I and D components of the controller after switching, and are continued. At the same time, switch 3 is switched from automatic control device A to automatic control device B.
To suppress the change in the output value to the drive system at the moment, that is, the change in the operation amount.

[0003]

However, in the prior art, when the shapes of the controllers A and B are different, for example, the PID
As for the component (for example, the D component) in which the correspondence cannot be obtained as in the control and the PI control, the above-described switching process cannot be performed, so that the value of D1 decreases after the switching. Further, since the controller B before the switching is in the non-control state, the actual value immediately after the switching is not necessarily a near value of the set value,
There is no fixed relationship with the values of P1 and D1 before switching. For this reason, the total output (P1
+ I1 + D2) and the total output (P
2 + I2) usually do not match. Furthermore, between the controller and the final output to the drive system, conversion processing such as correction of the operation characteristics of the drive system is separately performed between the controller A and the controller B (for example, a non-linear If X (command) → Y (actual) conversion processing when approximation is required is included, the inverse conversion of correction (for example, Y (actual) in the hydraulic device → X (command) conversion processing) is required. As a result, at the moment when the controller is switched, the output value almost always changes in a step-like manner, which adversely affects the material being processed in the process, for example, the steel plate. Also in the adjustment of the controller, if the characteristic adjustment of the conversion processing before the switching is performed, it is necessary to perform the adjustment again to the inverse conversion coefficient of switching the I and D components to the controller after the switching. The present invention proposes to solve such a problem, and is not limited to the shape of the controller (PID, PI, etc.), and prevents a sudden change in the output value at the moment of switching. It is an object of the present invention to provide a method and an apparatus capable of continuously switching a controller.

[0004]

SUMMARY OF THE INVENTION A method according to the present invention is directed to an automatic control system in which a plurality of controllers having different target control amounts are switched and the output of the selected controller is used as an operation amount of a common control target. In a method of switching between a plurality of controllers, a first linear commander that receives a set value of the control amount as an input, sets a result value of the control amount as an initial value, and outputs a set value that is directly compared with the result value, The ON / OFF of the input signals of the second linear commander, the first and second zero setting devices, and the first linear commander with the zero set value as an input and the output value of the controller as an initial value. A first switch and a second switch for turning on / off an initial value input signal of the first linear commander, and a deviation signal which is a difference between the set value of the control amount and the actual value, turned on / off. Turn on the signal of the third switch and the first zero setter And the fourth switch to OFF,
A fifth switch for turning on / off the initial value input signal of the second linear commander, and an ON / O output for the second linear commander.
7th switch to flip-flop and output ON / OF of the controller
F, a plurality of automatic control devices each including a sixth switch, and a sixth switch and a seventh
An analog OR element which takes an analog OR of each signal of the automatic control device selected by ON / OFF of the switch, and uses the output as an operation amount of the controlled object,
When switching from the first automatic control device to the second automatic control device, (1) First, the fifth switch of the first automatic control device is turned on to set the initial value of the second linear commander, At the same time, the second switch of the second automatic control device is turned on.
N and set the initial value of the first linear commander, (2)
Next, the first, third and sixth switches of the first automatic control device are turned off, and the fourth and seventh switches are turned on. (3) The first, third and sixth switches of the second automatic control device are then turned on. Switch ON
Then, the fourth and seventh switches are turned off. Further, the device according to the present invention is a switching device for a plurality of controllers in an automatic control system in which a plurality of controllers having different target control amounts are switched and an output of the selected controller is used as an operation amount of a common control target. A first linear commander that receives a set value of the control amount as an input, outputs a set value that is directly compared with the actual value, with the actual value of the control amount as an initial value,
The ON / OFF of the input signals of the second linear commander, the first and second zero setting devices, and the first linear commander with the zero set value as an input and the output value of the controller as an initial value. ON / O the initial value input signal of the first switch and the first linear commander
A second switch for flip-flop, a third switch for turning on / off a deviation signal which is a difference between the set value of the control amount and the actual value, and a fourth switch for turning on / off a signal of the first zero setting device. , A fifth switch for turning on / off the initial value input signal of the second linear commander, a seventh switch for turning on / off the output of the second linear commander, and the output of the controller. A plurality of automatic control devices each including a sixth switch that is turned on and off, and separately from the automatic control devices,
An analog OR element which takes an analog OR of each signal of the automatic control device selected by ON / OFF of the sixth switch and the seventh switch and uses the output as an operation amount of the control object. is there.

[0005]

According to the above means, the controller (P, PI, PI)
D), the output of the controller that takes charge of the control before switching is gradually reduced to zero, and the output of the controller that takes charge of the control after switching is from zero to the actual value. Since the value is increased to a value required to approach the set value, the two outputs can be continuously switched without instantaneous stepwise change of the value via the analog OR element.

[0006]

DETAILED DESCRIPTION OF THE PREFERRED EMBODIMENTS An embodiment of the present invention will be described below with reference to the drawings. FIG. 1 is a diagram showing an embodiment of the present invention, and is a control block diagram of a dancer roll device that controls by switching between position control by a PID controller and tension control by a PI controller.
In the figure, 41 is the material processed in the process line,
In this example, steel material, 42 is an annealing furnace, 43 is a dancer roll,
44 is a rope winder for raising and lowering the dancer roll, 45
Is a motor for driving the winder, 46 is a position detector of a dancer roll provided on the motor shaft, and 47 is a tension detector of steel material. The automatic control device A has a PID controller, and takes charge of a detection signal of the position detector 46 as an actual value to control the position of the dancer roll. On the other hand, automatic control device B
Has a PID controller, takes in the detection signal of the tension detector 47 as an actual value, and takes charge of the tension control of the steel material. The output signals of both automatic control devices become the operation amount of the motor 45 via the analog OR circuit 70. Next, the configuration of each automatic control device will be described. 50 and 60 are set values corresponding to the control process amount of each automatic control device, 51 and 61 are actual values, the former is a detection signal of the position detector 46, and the latter is a detection signal of the tension detector 47. 52 and 62 are delay elements (for example, linear commanders), 53 and 63 are subtractors, 54 and 64 are zero setting devices, 55 and 65 are controllers, and the former controls PID and the latter controls PI. Further, 56 and 66 are zero setting devices, 57 and 67 are delay elements (for example, linear command devices),
A1 to A7 and B1 to B7 are contact points. Next, the operation will be described. Hereinafter, switching from position control to tension control will be described as an example. Switching from position control to tension control is performed in four steps including before and after switching as described below. Here, step (1) represents each state before switching, steps (2) and (3) represent switching, and step (4) represents each state after switching. FIG. 2 shows ON / OFF states of the contacts A1 to A7 and B1 to B7 corresponding to each step. Step (1) State before switching: When the automatic control device A is selected to perform position control, the ON / OFF states of the contacts A1 to A7 and B1 to B7 are as in step (1) in FIG. ing. In this state, the PID control is performed by the controller 55 which receives the output of the linear accelerator 52 to which the position set value 50 is input (the output already matches the input position set value) and the deviation of the actual position value 51 as input. Done,
An output of the analog OR circuit 70 is used as an output of the position control.
, The amount of operation of the motor 45. On the other hand, in the automatic control device B in charge of the tension control,
The I controller 65 does not function and the I component output is set to a value of zero.
Output of tension control is set to zero. As a result, the sum of the output of the automatic control device A and the output of the automatic control device B, that is, the output of the analog OR circuit 70 becomes the output value of the PID controller 55 for position control. Step (2) First stage during switching from position control to tension control: In this step, contacts A1 to A7 and B1 to
The ON / OFF state of B7 is as shown in (2) of FIG. The position control sets the current output of the PID controller 55 as an initial value of the linear commander 57 in addition to the state of step (1). In the tension control, in addition to the state of step (1), the output of the actual value 61 is set in the linear command unit 62 as an initial value. The output of the analog OR element at this time is the same as in step (1). Step (3) Second stage during switching from position control to tension control: In this step, contacts A1 to A7 and B1 to
The ON / OFF state of B7 is as shown in (3) of FIG. On the position control side, the input value is set to zero in the linear accelerator 57 using the output value of the PID controller 55 as an initial value in step (2), and the output value is reduced to zero with time. On the tension control side, the output value of the linear accelerator 62 approaches the original tension set value with time starting from the actual value at the moment of switching, and sets the actual tension value by operating the PI controller 65. Control to approach the value. During this time, the output of the automatic control device A, the output of the automatic control device B, and the analog O
The output of the R circuit 70 changes as shown in FIG. First, the output of the automatic control device A gradually decreases from the output value immediately before the switching of the position control to the value 0 (zero) (the upper diagram in FIG. 3). Next, the output of the automatic control device B is 0 (zero) immediately after switching between the output of the linear accelerator 62 in which the tension result is initially set (that is, the same as the tension result value) and the tension result value.
And the output of the PI controller 65 is also 0. Next, the action of gradually bringing the output of the linear accelerator 62, which is the set value, from the initially set actual value to the original set value, and the P
The operation of the I controller 65 is performed in parallel. For this reason, the output of the automatic control device B changes from the value 0 (zero) to a value necessary for bringing the actual value closer to the original set value (the middle diagram in FIG. 3). The effect of the output of the position control is absorbed by the function of the PI controller 65 of the tension control. Step (4) State after switching: In this step,
The ON / OFF states of the contacts A1 to A7 and B1 to B7 are as shown in (4) of FIG. The PID controller 55 does not function by the zero setting unit 54, and the P, I, and D component outputs are set to zero, and the output of the position control is set to zero. In the tension control, the control of the tension by the function of the PI controller 65 is continued similarly to the step (3). The above steps (1) to (4)
FIG. 3 shows the output of each controller up to and the change in the total output. It can be seen that the total output changes continuously before and after the switching. In addition, although the Example showed the example which has two controllers, the present invention can be applied to three or more controllers.

[0007]

As described above, according to the present invention, the controller can be easily adjusted without being limited to the form of the controller, and the controller can be continuously switched without causing a change in the instantaneous output value. Therefore, there is a great effect that the occurrence of defective portions is eliminated in the material to be controlled and the productivity is improved.

[Brief description of the drawings]

FIG. 1 is a block diagram illustrating a configuration example of a dancer roll control system to which the present invention has been applied.

FIG. 2 is a contact operation table of FIG.

FIG. 3 is a graph showing an output change of each controller to which the present invention is applied.

FIG. 4 is an explanatory diagram of switching of PID control according to a conventional technique.

[Explanation of symbols]

 1, 3 Automatic controller A 2, 4 Automatic controller B 18, 28 Controller 55 PID controller 65 PI controller 52, 57, 62, 67 Linear accelerator 41 Steel material 42 Annealing furnace 43 Dancer roll 45 Motor for up and down dancer roll 46 Position detector 47 Tension detector

Claims (2)

(57) [Claims] 1. A method for switching a plurality of controllers in an automatic control system in which a plurality of controllers having different target control amounts are switched and an output of the selected controller is used as an operation amount of a common control target. A first linear commander that receives a set value of a control amount as an input, outputs the set value directly compared with the actual value with the actual value of the control amount as an initial value, and the controller that receives a zero set value as an input, A second linear commander and a first and a second zero setting device having initial values as output values, a first switch for turning ON / OFF an input signal of the first linear commander, and a first linear command Turn on the initial value input signal of the
A second switch for turning off, a third switch for turning on / off a deviation signal representing a difference between the set value of the control amount and the actual value, and a second switch for turning on / off a signal of the first zero setting device. A fourth switch, a fifth switch for turning on / off the initial value input signal of the second linear commander, a seventh switch for turning on / off the output of the second linear commander, and the output of the controller. A plurality of automatic control devices each including a sixth switch that is turned on and off; and separately from the automatic control device, each signal of the automatic control device that is selected by turning on and off the sixth switch and the seventh switch. An analog OR element that performs an OR operation in an analog manner and uses the output as an operation amount of the control object, and when switching from the first automatic control device to the second automatic control device, (1) first Of automatic control equipment The fifth switch is turned ON to set the initial value of the second linear commander and, simultaneously, the second switch of the second automatic control device O
N and set the initial value of the first linear commander, (2)
Next, the first, third and sixth switches of the first automatic control device are turned off, and the fourth and seventh switches are turned on. (3) The first, third and sixth switches of the second automatic control device are then turned on. Switch ON
And a method for continuously switching a plurality of controllers, wherein the fourth and seventh switches are turned off. 2. A switching device for a plurality of controllers in an automatic control system in which a plurality of controllers having different target control amounts are switched and an output of the selected controller is used as an operation amount of a common control target. A first linear commander that receives a set value of a control amount as an input, outputs the set value directly compared with the actual value with the actual value of the control amount as an initial value, and the controller that receives a zero set value as an input, A second linear commander and a first and a second zero setting device having initial values as output values, a first switch for turning ON / OFF an input signal of the first linear commander, and a first linear command Turn on the initial value input signal of the
A second switch for turning off, a third switch for turning on / off a deviation signal representing a difference between the set value of the control amount and the actual value, and a fourth switch for turning on / off a signal of the first zero setting device. , A fifth switch for turning on / off the initial value input signal of the second linear commander, a seventh switch for turning on / off the output of the second linear commander, and the output of the controller. A plurality of automatic control devices each including a sixth switch that is turned on and off; and, separately from the automatic control device, analog signals of the automatic control devices selected by turning on and off the sixth switch and the seventh switch. And an analog OR element whose output is an operation amount of the controlled object.