JP2020149112A - Control device, system with control device, control method and control program - Google Patents

Abstract

To provide a P control device in which the bumpless function for the operation amount is realized.SOLUTION: A control device 10 includes: control means 120 that P-controls a control target 30; difference calculating means 121 that calculates the difference between a start operation amount before the start of P-control and an initial operation amount at the start of P-control; correction amount calculation means 122 that calculates a correction amount related to an operation amount based on the difference and the number of times the correction is executed; and operation amount setting means 123 that sets the operation amount at the time of executing each correction based on the correction amount, where the control means 120 P-controls the control target based on the set operation amount.SELECTED DRAWING: Figure 2

Description

The present invention relates to a control device that proportionally controls a controlled object.

PID control is known as one of the feedback controls in control engineering. In PID control, the deviation between the current control amount, which is the output value from the controlled object, and the target value is controlled by performing proportional processing, integral processing, and differential processing. Controls the amount of operation that is the input value to the target. According to PID control, the transient characteristics of the controlled amount can be flexibly adjusted by three parameters of the proportional term, the integral term, and the differential term with respect to the deviation, so that the PID control is widely used in the industrial world.

Patent Document 1 shows an example of PID control in a vehicle cruise control device. Even in the PID control in the technique of Patent Document 1, in order to smoothly reach the target speed of the vehicle speed, which is the control amount, the proportional term, the integral term, and the differential term 3 are used according to the range of the target value. Two parameters have been adjusted.

Japanese Unexamined Patent Publication No. 2004-21309

With the diversification of consumer tastes and lifestyles in recent years, it is required to manufacture a wide variety of products with different specifications in small lots at the manufacturing site. Along with this, even in the production line of a factory where PID control devices, PI control devices, and P control devices are arranged in a mixed manner, it is required to improve the efficiency of step change. However, in PID control, since it is necessary to adjust the three parameters of the proportional term, the integral term, and the differential term at the same time, the adjustment becomes complicated, and a lot of time is required for the adjustment work associated with the step change.

A schematic diagram for explaining P control is shown in FIG. (A) is a schematic diagram showing an outline of P control, (B) is a schematic diagram showing a waveform of an operation amount, and (C) is a schematic diagram showing a waveform of a control amount. As shown in (C), it is possible to smoothly reach the target value by P control as well as PID control. However, as shown in (B), there is a problem that the operation amount suddenly fluctuates in P control. Sudden fluctuations in the amount of operation cause a problem that the yield of the workpiece manufactured by the molding machine decreases, for example, in the pressure control of the molding machine.

The function of suppressing sudden fluctuations in numerical values and switching numerical values smoothly is called the bump press function. For example, in the pressure control of a molding machine, PI control, which is P control plus I control, is applied in order to realize a bump press function. However, in PI control, another problem arises in which an overshoot phenomenon in which the control amount exceeds the target value is likely to occur when the parameters are not set appropriately. In a situation where overshoot occurs in PI control, if the parameters of PI control are left as they are and D control is further added, the possibility that overshoot increases rather increases. After all, in both PID control and PI control, if all parameters are not set properly in a well-balanced manner, various problems such as overshoot, hunting, and slow response occur.

Due to these circumstances, in a production line that is required to support small lot manufacturing, in order to realize the bump press function, the number of parameters required for adjustment is large and the adjustment work takes a lot of time, but PID control Or the reality is that PI control is used.

An object of the present invention is to provide a P control device in which a bumper function of an operation amount is realized.

The control device according to the present invention relates to a control means for P-controlling a control target, a difference calculation means for calculating a difference between a start operation amount before the start of P control and an initial operation amount at the start of P control, and an operation amount. It is provided with a correction amount calculating means for calculating the correction amount based on the difference and the number of times the correction is executed, and an operation amount setting means for setting the operation amount at the time of executing each correction based on the correction amount. The control means is characterized in that the control target is P-controlled based on the set operation amount.

Further, in the control device, it is preferable that the correction amount calculation means calculates the correction amount by dividing the difference by the number of times the correction is executed.

Further, in the control device, it is preferable that the operation amount setting means sets the operation amount at each correction execution time by adding or subtracting the correction amount to the operation amount at the time of the previous correction execution. ..

Further, in the control device, it is preferable that the control target is a servo mechanism.

Further, the system according to the present invention includes the above-mentioned control device, a control target controlled by the control device, a machine element driven by the control target, and a sensor for measuring a control amount in the machine element. It is characterized by being prepared.

Further, in the control method according to the present invention, a difference calculation step of calculating the difference between the start operation amount before the start of P control and the initial operation amount at the start of P control, and the correction amount related to the operation amount are corrected with the difference. A correction amount calculation step calculated based on the number of times of execution, an operation amount setting step of setting an operation amount at each correction execution time based on the correction amount, and control based on the set operation amount. It is characterized by including a control step of P-controlling an object.

Further, a program for operating a computer as the control device described above, the program for operating the computer as the control means, the difference calculation means, the correction amount calculation means, and the operation amount setting means, and the said. A computer-readable recording medium on which a program is recorded also belongs to the technical scope of the present invention.

According to the present invention, it is possible to provide a P control device in which a bumper function of an operation amount is realized.

It is a figure which shows typically the schematic structure of the control system which concerns on one Embodiment of this invention. It is a block diagram for demonstrating the function of the control device which concerns on one Embodiment of this invention. It is a schematic cross-sectional view for demonstrating the outline of the mechanical element which concerns on one Embodiment. It is a schematic diagram for demonstrating the outline of the control method which concerns on one Embodiment of this invention. It is a flowchart which shows the procedure of the data processing performed by the control device which concerns on one Embodiment of this invention. It is a graph for comparing the waveform by P control. It is a schematic diagram for demonstrating the outline of the control method which concerns on another Embodiment of this invention. It is a schematic diagram for demonstrating P control.

Hereinafter, embodiments of the present invention will be described in detail with reference to the accompanying drawings. In the following description and drawings, the same reference numerals indicate the same or similar components, and thus duplicate description of the same or similar components will be omitted.

In the embodiment of the present invention described below, as an example of control by the P control device in which the bumpless function of the operation amount is realized, the control device uses the injection shaft servomotor speed as the operation amount and the emission output as the control amount. , A case of controlling the injection operation of the injection molding machine will be described. The control device controls the injection molding machine via the servo mechanism, and the injection molding machine injects a material into a mold according to an instruction from the servo mechanism to manufacture a work which is a resin molded product. The emission output when the injection molding machine injects the resin material into the mold, which is the control amount in the injection molding machine, is measured by the load cell, and the emission output measured by the load cell is fed back input to the control device.

[System configuration]
FIG. 1 is a diagram schematically showing a schematic configuration of a control system according to an embodiment of the present invention.

The control system 100 according to one embodiment includes a control device 10, a servo mechanism 20 to be controlled by the control device, a machine element 30 driven by the servo mechanism 20, and a sensor 40 that measures a control amount in the machine element 30. And.

The control device 10 outputs a control signal regarding the operation amount for controlling the machine element 30 to the servo mechanism 20. The control amount of the machine element 30 measured by the sensor 40 is fed back to the control device 10. In one embodiment, the operating amount is the injection shaft servomotor speed (ie, the command speed to the servo driver 21), and the control amount is the firing output when the injection molding machine injects the resin material into the mold.

The servo mechanism 20 includes a servo driver 21, a servomotor 22, and an encoder 23. The servo driver 21 drives the servomotor 22 so as to follow the control signal input from the control device 10. The servomotor 22 drives the machine element 30 according to a drive instruction from the servo driver 21. The encoder 23 generates feedback regarding the position of the servomotor 22 and inputs it to the servo driver 21.

The mechanical element 30 is driven by the servo mechanism 20 to manufacture the work 90. In one embodiment, the machine element 30 is an injection molding machine and the work 90 is a resin molded product.

The sensor 40 is attached to the machine element 30 and measures the control amount in the machine element 30. The measured control amount is fed back to the control device 10. In one embodiment, the sensor 40 is a load cell, which measures the emission power when the injection molding machine injects the resin material into the mold.

[Device configuration]
FIG. 2 is a block diagram for explaining the function of the control device according to the embodiment of the present invention.

The control device 10 according to one embodiment includes a communication interface unit (I / F unit) 11 and an auxiliary recording unit 13 as a hardware configuration. Although not shown, the control device 10 further includes a processor such as a CPU that performs data processing and a memory that the processor uses for a work area of data processing as another hardware configuration.

The communication interface unit 11 transmits / receives data to / from an external device such as the servo mechanism 20 and the sensor 40. In one embodiment, the communication interface unit 11 transmits a control signal to the servo driver 21 and receives feedback from the sensor 40 on the control amount of the machine element 30.

The auxiliary recording unit 13 is a non-volatile storage device that stores an operating system (OS), various control programs, data generated by the programs, and the like. For example, an eMMC (embedded Multi Media Card) or an SSD (Solid State). Drive) etc.

In one embodiment, the auxiliary recording unit 13 records in advance an initial value 131 used for control and a P control program 132. In one embodiment, the target control amount SP and the number of times n of corrections are executed are recorded as initial values 131. The P control program 132 may be installed in the control device 10 via a network such as the Internet (not shown). Alternatively, the P control program 132 may be installed in the control device 10 by causing the control device 10 to read a computer-readable non-temporary tangible recording medium such as a memory card in which the P control program 132 is recorded. .. The initial value 131 is the same as that of the P control program 132.

Further, the control device 10 includes a calculation unit 12 as a software configuration. The arithmetic unit 12 is a functional block realized by the processor executing the P control program 132.

The calculation unit 12 includes a control unit 120, a difference calculation unit 121, a correction amount calculation unit 122, and an operation amount setting unit 123. In addition, each unit constituting the arithmetic unit 12 may be realized by hardware by a logic circuit formed on the integrated circuit.

The control unit 120 P-controls the control target with the control amount PV as the target value. The control amount of the machine element 30 measured by the sensor 40 is input to the control unit 120 via the communication interface unit 11. Each time the control amount is input, the control unit 120 determines the operation amount based on the input control amount and the P control parameter. The determined operation amount is output to the difference calculation unit 121 and the operation amount setting unit 123. The control unit 120 P-controls the control target based on the operation amount set by the operation amount setting unit 123.

At the start of the bumpless P control, the control unit 120 determines the start operation amount MVSta before the control start based on the input control amount before the control start, and outputs the determined start operation amount MVSta to the difference calculation unit 121. To do. Further, at the start of the bumpless P control, the control unit 120 reads the target control amount SP recorded in the auxiliary recording unit 13 as the initial value 131 from the auxiliary recording unit 13, and the read target control amount. Based on the SP, the initial operation amount MV1 at the start of control is determined, and the determined initial operation amount MV1 is output to the difference calculation unit 121. After that, in each cycle during P control, the control unit 120 determines the operation amount based on the input control amount, and outputs the determined operation amount to the operation amount setting unit 123.

The difference calculation unit 121 calculates the difference MVd between the start operation amount MVSta before the start of P control and the initial operation amount MV1 at the start of P control.

The correction amount calculation unit 122 calculates the correction amount related to the operation amount based on the difference calculated by the difference calculation unit 121 and the number of times n of the corrections are executed. Preferably, the correction amount calculation unit 122 calculates the correction amount related to the operation amount by dividing the difference calculated by the difference calculation unit 121 by the number of times the correction is executed.

The operation amount setting unit 123 sets the operation amounts MVr, MVr + 1, ... MVr + n at the time of each correction execution based on the correction amount calculated by the correction amount calculation unit 122. Preferably, the operation amount setting unit 123 sets the operation amount at each correction execution time by adding or subtracting the correction amount with respect to the operation amount at the time of the previous correction execution.

FIG. 3 is a schematic cross-sectional view for explaining the outline of the machine element according to the embodiment.

In one embodiment, the machine element 30 is an injection molding machine and the work 90 is a resin molded product. The mechanical element 30 according to one embodiment includes a hopper 31, a screw 32, a screw head 33, a cylinder 34, an injection drive cylinder 35, a nozzle 36, a mold 37, and a heater 38. ..

The material of the resin molded product, which is the work 90 manufactured by the machine element 30, is put into the hopper 31. The screw 32 and the screw head 33 are arranged in the cylinder 34 (34a, 34b) and are driven by the injection drive cylinder 35. The material supplied from the hopper 31 is conveyed toward the tip of the cylinder 34 by the screw 32 and the screw head 33, and is injected into the mold 37 from the nozzle 36 arranged at the tip of the cylinder 34b. Heaters 38 are arranged on the outer peripheral walls of the cylinders 34a and 34b and the nozzle 36, and the material is kept at a predetermined temperature.

In one embodiment, the servomotor 22 and the encoder 23 are integrated, and the injection drive cylinder 35 is driven by the servomotor 22. Further, in one embodiment, the injection drive cylinder 35 is provided with a load cell that functions as a sensor 40, and measures the emission output when the injection molding machine injects the resin material into the mold 37.

[Processing procedure]
FIG. 4 is a schematic diagram for explaining the outline of the control method according to the embodiment of the present invention, and FIG. 5 is a flowchart showing a procedure of data processing performed by the control device according to the embodiment of the present invention. is there.

In the control device 10 according to the present invention, in order to realize the bumpless function of the operation amount in P control, the difference MVd between the start operation amount MVSta before the start of P control and the initial operation amount MV1 at the start of P control is set in advance. By executing the process of distributing to the set period n and adding the distributed difference to the operation amount in each cycle during P control, a sudden fluctuation of the operation amount MV is suppressed.

First, at the start of the bumpless P control, the control unit 120 determines the start operation amount MVSta before the control start based on the input control amount before the control start, and determines the determined start operation amount MVSta as the difference calculation unit. The output is output to 121, the initial operation amount MV1 at the start of control is determined based on the target control amount SP read from the auxiliary recording unit 13, and the determined initial operation amount MV1 is output to the difference calculation unit 121.

In step S1, the difference calculation unit 121 calculates the difference MVd between the start operation amount MVSta before the start of P control and the initial operation amount MV1 at the start of P control.

In step S2, the correction amount calculation unit 122 calculates the correction amount CV related to the operation amount based on the difference MVd calculated in step S1 and the number of times n of corrections are executed. In one embodiment, the correction amount calculation unit 122 calculates the correction amount CV by CV = MVd / n.

In step S3, the operation amount setting unit 123 sets the operation amount MV at each correction execution time based on the correction amount CV calculated in step S2. In one embodiment, at the time of the first correction execution, the start operation amount MVSta before the start of control is used as the operation amount MV as it is. After that, in each cycle during P control, the operation amount MVr is calculated by adding the correction amount CV to the operation amount MVr-1 at the time of the previous correction execution. The operation amount MVr-1 in the previous cycle is determined by the control unit 120 based on the control amount PVr-1 in the previous cycle measured by the sensor 40.

In step S4, the control unit 120 controls the control target based on the set operation amount MV.

In step S5, the control unit 120 confirms the number of times the correction is executed. If the correction has not been executed a predetermined number of times (for example, n times), the processes of steps S3 to S4 are repeated. If the correction has been executed a predetermined number of times, the control is terminated.

FIG. 6 is a graph for comparing waveforms under P control. (A) is a waveform by conventional P control that does not realize the bump press function of the manipulated amount, and (B) is a waveform by P control according to the present invention that realizes the bump press function of the manipulated amount. The waveform shown in (B) is a waveform when correction for 10 times is performed in the P control according to the present invention. In the figure, the graph shown by the broken line is the emission output (control amount) when the injection molding machine injects the resin material into the mold, and the graph shown by the alternate long and short dash line is attached to the injection shaft of the injection molding machine. It is the speed (operation amount) of the servomotor, and the graph shown by the solid line is the torque of the servomotor.

As shown in (A), in the conventional P control that does not realize the bump press function, the emission output, which is the control amount, fluctuates relatively smoothly as shown by the broken line, but the servomotor shown by the alternate long and short dash line. The speed of the servo motor and the torque of the servo motor shown by the solid line fluctuate rapidly, and the torque value temporarily changes from a negative value to a positive value. This means that the torque fluctuates greatly because the speed of the servomotor changes abruptly, which puts a heavy burden on the manufacturing apparatus.

On the other hand, in the P control according to the present invention in which the bump press function is realized, as shown in (B), the speed of the servomotor shown by the one-point chain line and the torque of the servomotor shown by the solid line fluctuate smoothly. The emission output indicated by the broken line also fluctuates smoothly. This means that sudden changes in the speed and torque of the servomotor are suppressed.

Further, in the P control according to the present invention in which the bump press function is realized, the torque value of the servomotor does not change from a negative value to a positive value, and the torque is measured in each cycle in which the operation amount is corrected. The value is controlled so that it does not exceed 0. This means that control is realized in which the pressing force is released in each cycle while the material is injected into the mold and pressed.

[effect]
As described above, according to the present invention, it is possible to provide the P control device in which the bump press function of the operation amount is realized. In the present invention, the process of distributing the difference MVd between the operation amount MVSta before the start of P control and the initial operation amount MV1 at the start of P control in a preset period n and adding the distributed difference to the operation amount is performed by P. By executing it in each cycle during control, abrupt fluctuations in the operation amount MV are suppressed. As a result, the operation amount bumper function is realized in P control.

If the bumpless function of the operation amount is realized in P control, the sudden fluctuation of the operation amount, which has been a problem of P control so far, can be solved, and the control amount and the operation amount can be smoothly changed by P control. Can be made to. According to P control, the number of parameters required for adjustment is smaller than that for PID control and PI control, so the time required for adjustment work associated with step change can also be shortened, and the tact time required for manufacturing the product is guaranteed. be able to. Further, since the bumpless function of the manipulated amount is realized by the P control without the I control by the integral term, there is no possibility that the overshoot of the controlled amount occurs.

Further, according to the bumpless function of the operation amount in the P control according to the present invention, it is possible to control the fluctuation of the drive torque generated by the servomotor as shown in FIG. 6B. As a result, according to the bump press function of the operation amount in the P control according to the present invention, it is possible to perform a process in which torque and pressing pressure fluctuate, such as a process of injecting a material into a mold illustrated in one embodiment and pressing the material. On the other hand, the adjustment can be flexibly performed, and a sudden change in torque or pressing force can be suppressed to make a smooth fluctuation.

[Other forms]
Although the present invention has been described above by the specific embodiment, the present invention is not limited to the above-described embodiment.

In the above-described embodiment, the operation amount MVr at the time of each correction execution is set by adding the correction amount CV to the operation amount MVr-1 at the time of the previous correction execution, but the correction amount CV is added. Alternatively, the correction amount CV may be subtracted. In this case, whether to add or subtract the correction amount CV depends on the subtraction method when calculating the correction amount CV (that is, the magnitude of the start operation amount MVSta and the initial operation amount MV1 when calculating the difference MVd). Although it depends on the relationship), the calculation method of the correction amount CV may be changed as appropriate.

In the above-described embodiment, the operation amount MVr at each correction execution time is set by adding the correction amount CV to the operation amount MVr-1 at the time of the previous correction execution. As shown, the operation amount MVr at each correction execution is set by adding or subtracting the difference MVd updated each time each correction is executed with respect to the initial operation amount MV1 at the start of bumpless P control. May be done. In this case, the difference MVd is calculated by the difference between the operation amount MVSta before the start of control and the first operation amount MV1 at the start of control at the first time when the bumpless P control is started, and then each correction is executed for the difference MVd. It is updated by subtracting the correction amount CV from the difference MVd each time. Further, the method of updating the difference MVd is not limited to subtracting the correction amount CV from the difference MVd, and the difference MVd may be updated by adding the correction amount CV to the difference MVd.

That is, the process of setting the operation amounts MVr, MVr + 1, ... MVr + n at the time of each correction execution based on the correction amount calculated by the correction amount calculation unit 122 performed by the operation amount setting unit 123 is shown in FIG. As shown in 7 (B), the difference MVd, which is updated by the correction amount CV each time each correction is executed, is added or subtracted from the initial operation amount MV1 at the start of the bumpless P control. This is a concept that includes the process of setting the operation amount MVr at the time of correction execution.

In the above embodiment, the control device 10 is realized as an integrated device, but the control device 10 does not have to be an integrated device, and each part constituting the control device 10 is arranged in a different place, and these are networked with each other. It may be connected. Similarly, for each unit constituting the arithmetic unit 12 of the control device 10, each unit constituting the arithmetic unit 12 may be arranged in a different place, and these may be connected to each other by a network.

In the above embodiment, the case where the control device 10 controls the injection operation of the injection molding machine via the servo mechanism 20 is described as an example, but the control by the P control device in which the bump press function of the operation amount is realized is described. It is not limited to such a case. Instead of the injection operation of the injection molding machine, the control device 10 may control, for example, a molding step of pushing the material into the mold, a step of injecting the epoxy resin, or controlling the coating step of the coating machine. Good.

10 Control device 11 Communication interface unit 12 Calculation unit 13 Auxiliary recording unit 20 Servo mechanism 21 Servo driver 22 Servo motor 23 Encoder 30 Machine element 31 Hopper 32 Screw 33 Screw head 34 (34a, 34b) Cylinder 35 Injection drive cylinder 36 Nozzle 37 Gold Type 38 Heater 40 Sensor 90 Work 100 Control system 120 Control unit 121 Difference calculation unit 122 Correction amount calculation unit 123 Operation amount setting unit 131 Initial value 132 Control program

Claims (7)

A control means that P-controls the control target and
A difference calculation means for calculating the difference between the start operation amount before the start of P control and the initial operation amount at the start of P control, and
A correction amount calculation means for calculating a correction amount related to an operation amount based on the difference and the number of times the correction is executed.
An operation amount setting means for setting an operation amount at the time of executing each correction based on the correction amount, and
With
The control means is a control device that P-controls the control target based on the set operation amount. The control device according to claim 1, wherein the correction amount calculating means calculates the correction amount by dividing the difference by the number of times the correction is executed. The control according to claim 1 or 2, wherein the operation amount setting means sets the operation amount at each correction execution time by adding or subtracting the correction amount to the operation amount at the time of the previous correction execution. apparatus. The control device according to any one of claims 1 to 3, wherein the control target is a servo mechanism. The control device according to any one of claims 1 to 4,
The control target controlled by the control device and
The mechanical element driven by the controlled object and
A sensor that measures the amount of control in the machine element,
The system. A difference calculation process for calculating the difference between the start operation amount before the start of P control and the initial operation amount at the start of P control, and
A correction amount calculation step of calculating the correction amount related to the operation amount based on the difference and the number of times the correction is executed.
An operation amount setting step for setting an operation amount at the time of executing each correction based on the correction amount, and
A control process that P-controls the control target based on the set operation amount, and
Control methods, including. A program for operating a computer as the control means, the difference calculation means, the correction amount calculation means, and the operation amount setting means of the control device according to claim 1.

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