JPH04209003A - Digital controller - Google Patents

Abstract

PURPOSE:To eliminate the need to operate an automatic tuning key manually by an operator by performing automatic tuning when program control is started at the time of program data setting. CONSTITUTION:When a step for performing the automatic tuning is specified and inputted at a setting input part 2 together with program data, those data are stored in a storage part 3 through a program control part 4. The control part 4 performs the program control according to the program data in the storage part 3. An automatic tuning control part 6, on the other hand, controls a PID arithmetic part 5 in the step where the automatic tuning is performed to vary a manipulated variable, calculates the best PID control parameter corresponding to the characteristics of a controlled object according to a feedback quantity from a detection part 7, and stores it in the storage part 3. Consequently, PID control is performed according to the setting contents and the automatic tuning is performed.

Description

[Detailed description of the invention]

[00011

FIELD OF THE INVENTION The present invention relates to a digital controller with a program function, such as a temperature controller with a built-in program function. [0002] Generally, in program control, the target setting value is varied over a wide range, and the characteristics of the controlled object may also vary greatly, so digital controllers that perform such program control , is configured to be able to store multiple sets of control parameters (for example, multiple sets of PID control parameters consisting of proportional bands, integral time, differential time, etc.), and in each step of the program, any set of control parameters can be stored. It is now possible to specify whether to use parameters. [0003] In order to set the optimum value of each set of control parameters, so-called auto-tuning (AT) is performed.
For digital controllers equipped with this function, by performing a test run and operating the auto-tuning key during this test run, the manipulated variable is automatically changed inside the controller, and the characteristics of the controlled object are measured and the characteristics are determined. Control parameters are calculated and determined according to the set, and stored in the memory as the optimum control parameters for each set. During actual operation, control is performed using these optimum control parameters. [00041 FIG. 4 is a diagram showing an example of a program pattern of such a digital controller, in which the vertical axis shows the target setting value (SP) and the horizontal axis shows time. [0005] Table 1 also shows the setting contents of the program pattern in FIG. Note that in Table 1, the group number indicates the number of each of the plurality of control parameter groups described above. [0006] [0007] As mentioned above, the optimum value of the control parameters of each set (numbered 1 to 3 in Table 1) used in the program is set by auto-tuning after a trial run. However, this auto-tuning must be started at the step that is desired to be executed, and is generally performed in the soak zone where the target setting value shown in FIG. 4 is constant. [0008] Therefore, in this program,
Regarding the control parameters of group number 1 used in steps 1 and 2, as shown in FIG.
T) is started to calculate the optimal control parameters and stored in memory, and for the control parameters of group number 2 used in steps 3 to 5, auto-tuning is started in step 4 to calculate the optimal control parameters. The control parameters of group number 3 are calculated and stored in the memory.Furthermore, in step 6, auto-tuning is started to calculate the optimal control parameters and stored in the memory.During actual operation, In this way, control is achieved using optimal control parameters stored in memory. In addition, in FIG. 5, the fluctuation of the control amount accompanying the execution of auto-tuning is shown by a broken line, and the point in time when the auto-tuning (AT) key is operated is shown by an arrow. [0009]

[Problems to be Solved by the Invention] In such conventional digital controllers, the operator must monitor the steps and operate the auto-tuning key when the step that should activate auto-tuning is reached. ,Moreover,
A drawback is that this autotuning must be activated for each of the plurality of control parameter sets in use. [00101 The present invention has been made in view of the above-mentioned points, and the present invention has been made in view of the above-mentioned points. The purpose is to enable tuning to be activated. [0011]

[Means for Solving the Problems] In order to achieve the above-mentioned object, the digital controller of the present invention is constructed as follows. [0012] That is, the present invention provides a digital controller that is equipped with a program function and an auto-tuning function that automatically calculates and sets optimal control parameters, and is equipped with a setting input section and an auto-tuning control section, The setting input section is for setting program data and specifying the step at which auto-tuning is to be executed, and the auto-tuning control section is for performing auto-tuning each time the program progresses to the specified step. configured to run. [0013]

[Operation] According to the above configuration, when setting the program data, it is possible to specify the step at which auto-tuning is to be executed, and when program control is started and the program advances to the specified step, the auto-tuning is automatically performed. Therefore, there is no need for the operator to manually operate the auto-tuning key when it comes to a step where auto-tuning should be executed by monitoring the progress of the program, as in the conventional example. There will be no. [0014]

Embodiments Hereinafter, embodiments of the present invention will be explained in detail with reference to the drawings. [0015] FIG. 1 is a block diagram of an embodiment of the present invention, and this embodiment is a digital controller 1 having a program function for performing PID control. [00161 In the figure, 2 is a setting input section for setting and inputting program data such as the arrival set value (SP) and the arrival time, 3 is a storage section in which the program data from the setting input section is stored, and 4 is a storage section. This is a program control unit that performs program control based on program data, and this program control unit 4 outputs target set values and
PID control parameters such as proportional band, integral time, and differential time are outputted to control the PID calculation section 5 and the like. [0017] 6 controls the PID calculation unit 6 based on the output of the program control unit 4 to vary the operation amount, and based on the feedback amount from the detection unit 7, determines the optimum value according to the characteristics of the controlled object 8. This is an auto-tuning control unit that calculates PID control parameters and stores them in the storage unit 3, and the auto-tuning operation itself is similar to the conventional example. [0018] In the digital controller 1 of this embodiment, the operator does not have to monitor the progress of the program and operate the auto-tuning key each time to start auto-tuning during a trial run to determine the optimal PID control parameters. It is configured as follows. [0019] That is, in the setting input section 2, as in the conventional example described above, it is possible to specify and input the step at which auto-tuning should be executed, along with program data such as the set value reached, the time reached, and the set number of the PID control parameter. It has become. [00201 Table 2 shows the settings of the program input from the setting input section 2 in accordance with the program pattern of FIG. 4, and is a table corresponding to Table 1 of the conventional example. [00211 [0022] In Table 2, the code rA4 added to a group number indicates that auto-tuning for determining the PID control parameter of that group number is executed at that step. [0023] That is, in this embodiment, auto-tuning for determining the PID control parameters of set number 1 used in step 1.2 is performed in step 2, and the auto-tuning for determining the PID control parameters of set number 1 used in step 1. Autotuning to determine the PID control parameter number 2 is performed in step 4, and set number 3 used in step 6.
It is shown that auto-tuning for determining the PID control parameters of is executed in step 6. [0024] Note that until the optimum PID control parameters are determined by auto-tuning, appropriately set PID control parameters are used. [0025] In this way, in the setting input section 2, it is possible to specify and input the step at which auto-tuning should be executed, as well as program data as in the past, and these data are input via the program control section 4. and stored in the storage unit 3. [00261 The program control unit 4 performs program control based on the program data in the storage unit 3, and -
On the other hand, when it comes to the step in which auto-tuning should be executed, the auto-tuning control section 6 controls the PID calculation section 5 to vary the operation amount and determine the characteristics of the controlled object based on the amount of feedback from the detection section 7. The optimum PID control parameters are calculated and stored in the storage unit 3. [00271 FIG. 2 is a diagram corresponding to FIG. 5 showing the state of execution of auto-tuning based on the settings in Table 2. [0028] In this embodiment, a distinction is made between a trial run during which auto-tuning should be performed to determine the optimal PID control parameters, and an actual operation during which PID control is performed using the determined optimal PID control parameters. To do this, during a trial run, operate the auto-tuning key at the beginning of control. [0029] As a result, P according to the settings in Table 1
When TD control is performed and Step 2 is reached, auto-tuning is automatically performed and the optimum PID control parameters of group number 1 are calculated and stored in the storage unit 3, as shown by the broken line in FIG. , Further, when the program progresses and reaches step 4, auto-tuning is automatically performed and the optimum PID control parameters of group number 2 are calculated and set and stored in the storage unit 3. , auto-tuning is automatically performed, and the optimum PID control parameters of group number 3 are calculated and set and stored in the storage unit 3. [00301 FIG. 3 is a flowchart corresponding to such control. (00311 First, n indicates the step number of the program.
, an initial value of 1 is set (51), and this step n
P
ID control is started, tl, (S2), and at the same time, a built-in timer is activated (S3). [0032] Next, it is determined whether or not the auto-tuning key has been operated (S4), and when the auto-tuning key has been operated, it is assumed that this is a trial run, and step n executes auto-tuning based on the program data. (S5)
, when the step is one in which auto-tuning should be executed, auto-tuning is performed (S6), and the optimal PID control parameters calculated by this auto-tuning are stored as a set of PID control parameters corresponding to step n (S7). . [0033] After that, it is determined whether step n is completed or not (S8), and when it is completed, it is determined whether this step n is the final step or not (S9), and if it is not the final step, the step of the program is Add 1 to the number n to create a new step number n (510), and based on the program data such as the arrival set value, arrival time, and PID control parameter set number corresponding to this new step n, It is changed (Sll) and returns to S5. [0034] In S5, if the step does not require auto-tuning, the process moves to S8. Also, S9
In the final step, PID control is stopped (S16). [0035] In S4, when the auto-tuning key is not operated, it is assumed that the operation is not a test run but an actual run, and it is determined whether step n is completed (512), and when it is completed, this step n is the final one. 513), and if it is not the final step, the step number n of the program is set to 1.
514), and change to PID control based on program data such as the arrival set value, arrival time, and PID control meter set number corresponding to this new step n. Then, the process returns to 312 (S15). [0036] In this embodiment, auto-tuning at the time when control is started determines whether it is a trial run in which auto-tuning should be performed or an actual operation after the optimum PID control parameters have been determined by the trial run. Although we tried to differentiate based on whether or not a key was pressed,
As another embodiment of the present invention, "rAIJ, rA2" in Table 2 specifying that auto-tuning is automatically performed.
, "A3", etc., after auto-tuning is performed once in each corresponding step, the setting contents such as "1
”, “2”, or “3” so that auto-tuning is not automatically performed during actual driving. [0037] In the above embodiment, auto-tuning during trial operation was explained, but the present invention
This is not limited to test runs; for example, if the characteristics of the controlled object change depending on the operating day conditions, the specific steps may be automatically set automatically during actual operation. It may be configured such that tuning is performed. [0038]

As described above, according to the present invention, it is possible to specify the step at which auto-tuning is to be executed when setting program data, and the step at which the program control is started and the program is specified. Therefore, as in the conventional example, when the program progress is monitored and the step where auto-tuning should be executed is reached, the operator manually presses the auto-tuning key. There is no need to operate it frequently.

[Brief explanation of the drawing]

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

FIG. 2 is a diagram showing an execution state of auto-tuning in the embodiment of FIG. 1;

FIG. 3 is a flowchart for explaining the operation.

FIG. 4 is a diagram showing a program pattern.

FIG. 5 is a diagram showing a state of execution of auto-tuning in a conventional example.

[Explanation of symbols]

1 Digital controller 2 Setting input section 6 Auto tuning control section

Claims (1)

[Claims] 1. A digital controller equipped with a program function and an auto-tuning function for automatically calculating and setting optimal control parameters, comprising a setting input section and an auto-tuning control section, the setting input section being , the program data is set, and the step at which auto-tuning is to be executed is specified, and the auto-tuning control unit executes auto-tuning every time the program progresses to the specified step. A digital controller characterized by: