JP2949849B2 - Digital controller - Google Patents

Description

DETAILED DESCRIPTION OF THE INVENTION

[0001]

BACKGROUND OF THE INVENTION 1. Field of the Invention The present invention relates to a digital controller having a program function such as a temperature controller having a program function.

[0002]

2. Description of the Related Art In a digital controller of this type, a program pattern of a polygonal line indicating a target set value with respect to an execution time as shown by a solid line in FIG. 5 can be set only by inputting an arrival time and an arrival set value. It has become.

When the control of the program pattern set in this way, for example, PID control, is performed, the rate of change of the target set value, that is, the transition portion where the slope of the program pattern changes, for example, from the ramp band to the soak band In a portion where the control shifts to, a phenomenon in which the control amount exceeds the target set value as shown by a broken line, that is, a so-called overshoot occurs.

[0004]

Therefore, in order to prevent the occurrence of such overshoot or the like, conventionally, a program pattern is changed between a ramp band and a soak band as shown in FIG. One step is inserted in

[0005] However, in the case where the program pattern is changed by inserting one step between the ramp band and the soak band, the setting input is troublesome and the step which can be set from the relation of the memory capacity is required. There is a disadvantage that the number of steps is wasted because the number is limited.

SUMMARY OF THE INVENTION The present invention has been made in view of the above points, and eliminates the need to insert a step to prevent overshoot or undershoot, thereby facilitating the operation of setting program data. With
The purpose is to enable the steps to be used effectively.

[0007]

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

That is, according to the present invention, a program function in which a program pattern indicating a target set value with respect to an execution time is set by inputting an arrival time and an arrival set value of each step, and control according to the program pattern is performed. In the digital controller provided with, a transition portion where the rate of change of the target set value changes is detected from among the set program patterns, and the program pattern is corrected so that the control amount does not deviate from the target set value at the transition portion. The program pattern correction unit corrects the target set values so as to linearly connect the target set values at both time points before and after the transition part of the set program pattern. Is what you do.

[0009]

According to the above configuration, of the program pattern set in the same manner as in the conventional example, a portion where an overshoot or an undershoot occurs, that is, a portion where the rate of change of the target set value changes, for example, from a ramp band. Since the transition to the soak zone is detected and the target set value is corrected so as to linearly connect between the two target set values at the two points before and after the transition, one step is substantially added to the transition. Insertion means that overshoot and the like can be prevented, and there is no need to perform setting input for inserting the one step, and it is possible to avoid wasting a limited number of steps and to use the steps effectively. become.

[0010]

DESCRIPTION OF THE PREFERRED EMBODIMENTS Embodiments of the present invention will be described below in detail with reference to the drawings.

FIG. 1 is a block diagram of one embodiment of the present invention. This embodiment is a digital controller 1 having a program function for performing PID control.

In FIG. 1, reference numeral 2 denotes a setting input unit for setting and inputting program data such as an arrival set value and an arrival time of each step, as in the prior art; and 3, a storage unit for storing program data from the setting input unit 2. Reference numeral 4 denotes a program control unit that obtains a program pattern indicating a target set value for the execution time based on the program data, performs control according to the program pattern, and stores the program pattern in the storage unit 3. The control unit 4 outputs a target set value and outputs a PID control parameter to control the PID calculation unit 5 and the like. In addition, 6 is a control object, and 7 is a detection unit.

In the digital controller 1 of this embodiment, it is not necessary to insert a step for preventing overshoot or the like between the ramp band and the soak band. In order to enable the effective use of the program pattern, a transition portion from the ramp band to the soak band in the set program pattern is detected, and the program pattern is controlled so that the control amount does not deviate from the target set value at the transition portion. Is provided.

The program pattern correcting unit 8 is configured to execute, for example, based on the program data from the setting input unit 2,
When the program pattern indicated by the solid line in FIG. 2 is set, the transition from the ramp zone to the soak zone is detected, and the program pattern is calculated and corrected as indicated by the imaginary line T time before the transition. The program control section 4 performs control according to the corrected program pattern in the transition portion.

The modification of the program pattern of this embodiment is such that points at the same time T before and after the transition point A from the ramp band to the soak band are connected as shown in FIG. The correction has been made so that there is a linear connection between the two target setpoints at both times before and after the transition to the band, thereby essentially inserting one step into the transition.

That is, in the digital controller of the present invention,
As in the conventional example, at the transition between the lamp zone and the soak zone,
Even if one step is not inserted, the transition from the ramp band to the soak band is automatically detected, the program pattern of the transition is corrected, and control is performed according to the corrected program pattern. It is not necessary to set and input a step for preventing overshoot or undershoot, and the step can be used effectively.

FIG. 3 is a flowchart of PID control after a program pattern is set.

First, n indicating the step number of the program
Is set to an initial value 1 (S1), and this step n
Is started in accordance with the program pattern corresponding to (2) (S2).

Next, it is determined whether or not the time T before the shift to the step n + 1 has been reached (S3). When the time has reached, it is determined from the step n to the step n based on the program pattern.
It is determined whether the shift to +1 is a shift from the ramp zone to the soak zone (S4). If the shift to the +1 zone is a shift from the ramp zone to the soak zone, as shown by a virtual line in FIG. The program pattern is modified to connect the same time T before and after the change point from the band to the soak band (S5).

Then, PID control is performed over a period 2T according to the corrected program pattern (S
6) Then, 1 is added to the step number n of the program to obtain a new step number n (S7), and PID control according to the program pattern corresponding to the new step n is started (S8). It is determined whether or not step n has been completed (S9).
Is determined as the last step (S10), and if not the last step, 1 is added to the step number n of the program to obtain a new step number n (S1).
1) Return to S2.

As described above, at the time of transition from the ramp band to the soak band, the program pattern is corrected and controlled so as to prevent overshoot and undershoot.

In the embodiment described above, the program pattern was modified to connect points at equal times T before and after the transition from ramp to soak as shown in FIG. In another embodiment, for example, as shown by a virtual line in FIG. 4, an isosceles triangle is formed by the original program pattern and the corrected program pattern from the time T before the transition from the ramp band to the soak band. May be modified so that

The time T may be set from the setting input unit 2, but may be configured to be a time proportional to the integration time of the PID control parameter.

In the above-described embodiment, the transition from the ramp zone to the soak zone has been described. However, the present invention is not limited to this, and any transition where the rate of change of the target set value greatly changes may be used. Of course, the present invention can be similarly applied to the transition from the ramp band to the ramp band or from the soak band to the ramp band.

[0025]

As described above, according to the present invention, a transition portion where the rate of change of the target set value changes is detected from among the program patterns set in the same manner as in the prior art, and both before and after the transition portion are detected. Since the target set values are corrected so as to be linearly connected between the two target set values at the time, one step is substantially inserted in the transition portion, and the occurrence of overshoot and the like can be prevented, and There is no need to input settings for inserting one step, and the step can be used effectively.

[Brief description of the drawings]

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

FIG. 2 is a diagram showing a program pattern according to the embodiment of FIG. 1;

FIG. 3 is a flowchart for explaining an operation;

FIG. 4 is a diagram showing a program pattern according to another embodiment of the present invention.

FIG. 5 is a diagram showing the occurrence of overshoot.

FIG. 6 is a diagram showing a program pattern of a conventional example.

[Explanation of symbols]

 1 digital controller 2 setting input section 4 program control section 8 program pattern correction section

Claims (1)

(57) [Claims] 1. A digital adjustment having a program function in which a program pattern indicating a target set value with respect to an execution time is set by inputting an arrival time and an arrival set value of each step, and control according to the program pattern is performed. A program pattern correction for detecting a transition portion where a change rate of a target set value changes in the set program pattern, and correcting the program pattern so that the control amount does not deviate from the target set value at the transition portion. A program setting unit, wherein the program pattern correction unit corrects the target set values so as to linearly connect the target set values at both time points before and after the transition part of the set program pattern. Digital controller.