WO2018100670A1

WO2018100670A1 - Automatic tuning device

Info

Publication number: WO2018100670A1
Application number: PCT/JP2016/085543
Authority: WO
Inventors: 木原　健; 隆廣間瀬; 貴司新井; 洸太高橋; 健太郎山下
Original assignee: 理化工業株式会社
Priority date: 2016-11-30
Filing date: 2016-11-30
Publication date: 2018-06-07
Also published as: JP6751244B2; JPWO2018100670A1

Abstract

For a cascade control, the present invention is provided with: an elapsed time measurement unit 6 which performs a process of monitoring the temperature of a control target and detecting a timing at which the temperature of the control target passes a set temperature, and measures an elapsed time from a previous passing timing to a current passing timing; and a time calculation unit 7 which calculates an end time of automatic tuning by using the elapsed time measured by the elapsed time measurement unit 6, wherein a time presenting unit 8 displays the end time of automatic tuning calculated by the time calculation unit 7. Accordingly, for the cascade control, a user can know the end time of automatic tuning.

Description

Auto tuning device

The present invention relates to an auto-tuning device having an auto-tuning function for adjusting control parameters in a cascade control system.

Conventionally, a PID control device that calculates PID parameters in a cascade control system and performs auto-tuning has been proposed. Patent Document 1 below discloses a PID control device that calculates a PID parameter of a master PID controller by approximating a slave-side closed loop transfer function with a first order delay + dead time model.

On the other hand, in a single loop PID control device, there was a request to know the end time of PID auto-tuning in order to set up the process until PID control is started. Patent Document 2 below discloses a PID control device that can predict the end time of PID auto-tuning by a single loop.

JP 2012-89004 A International Publication No. WO2014 / 088705

However, in the cascade control system, it was difficult to predict the auto-tuning end time of the control parameter due to the complexity of the control.

The present invention has been made to solve the above-described problems, and an object of the present invention is to provide an auto-tuning device that can predict the auto-tuning end time of a control parameter in a cascade control system.

(Configuration 1)
Used in a cascade control system in which a master controller that performs PID control and at least a slave controller that performs P control are cascade-connected, a master parameter that is a control parameter of the master controller and a slave parameter that is a control parameter of the slave controller An auto tuning apparatus having an auto tuning function for performing auto tuning to be adjusted,
An auto tuning management unit that receives an effective command of auto tuning;
Before starting control of the temperature of the control target, in a period in which the temperature of the control target is lower than a set temperature, a heater that applies heat to the control target is set to an on state, and the temperature of the control target is set to the set temperature In the above period, by setting the heater to an off state, a temperature control unit that controls the temperature of the control target;
A control parameter calculation unit for calculating the master parameter and the slave parameter from the measured value of the temperature of the controlled object controlled by the temperature control unit;
The process of monitoring the measured value of the temperature of the control object, detecting the timing at which the temperature of the control object passes the set temperature is performed, and the process from the previous passage timing to the current passage timing An elapsed time measuring unit for measuring time;
Using the elapsed time measured by the elapsed time measuring unit, a time calculating unit that calculates the end time of auto-tuning,
A time presentation unit for presenting the end time of auto-tuning calculated by the time calculation unit;
Auto tuning device with

(Configuration 2)
The elapsed time measurement unit measures the elapsed time from the previous passage timing to the current passage timing each time the passage timing is detected,
The time calculation unit calculates an end time of auto-tuning using the elapsed time every time the elapsed time is measured by the elapsed time measurement unit,
2. The auto tuning apparatus according to claim 1, wherein the time presentation unit presents the end time every time the end time of auto tuning is calculated by the time calculation unit.

(Configuration 3)
The time presentation unit sets the time from the current time to the end time every time the auto-tuning end time is calculated by the time calculation unit, and sets the timer count value to reduce the count value. The auto-tuning device according to Configuration 2, wherein the processing is started and a count value during reduction processing is presented.

(Configuration 4)
When using the limit cycle method in the auto tuning function,
4. The auto tuning apparatus according to claim 1, wherein the elapsed time calculation unit performs correction based on the elapsed time before switching the set temperature with respect to the end time of the auto tuning.

(Configuration 5)
When using the limit cycle method in the auto tuning function,
4. The auto-tuning device according to claim 1, wherein the elapsed time calculation unit predicts a time required for switching the set temperature based on the elapsed time before the set temperature switching.

(Configuration 6)
When using the limit cycle method in the auto tuning function,
The elapsed time calculation unit calculates the end time of the auto-tuning based on the time taken until the set temperature is switched after the set temperature is switched and the elapsed time. The auto-tuning device according to any one of the above.

According to this invention, it is possible to obtain an auto-tuning device that can predict the end time of auto-tuning in a cascade control system.

1 is a schematic diagram illustrating an auto-tuning device according to an embodiment of the present invention. It is a flowchart which shows the outline | summary of the auto tuning operation | movement at the time of the cascade connection by embodiment of this invention. It is a flowchart which shows the auto tuning remaining time prediction method at the time of cascade connection by embodiment of this invention. It is a flowchart which shows the detail of the auto tuning remaining time prediction method at the time of cascade connection by embodiment of this invention. It is the conceptual diagram which showed the relationship between the measured value in master AT at the time of the cascade connection by embodiment of this invention, and time. It is a figure which shows the simulation result of the set temperature of a master control object, a measured value, the set temperature of a slave control object, a measured value, and the remaining auto-tuning time at the time of auto-tuning at the time of cascade connection by embodiment of this invention.

Embodiment FIG. 1 is a block diagram showing an auto-tuning apparatus according to an embodiment of the present invention.
1 has an auto tuning function for calculating control parameters in the master controller 9 and the slave controller 10 in a cascade control system. Further, the auto tuning apparatus 100 has a function of predicting the end time of the auto tuning. The cascade control system refers to the master controller 9, the slave controller 10, the temperature controller 4, the heater 2, the master control target 1_1, the slave control target 1_2, the slave temperature measurement unit 3_2, the master temperature measurement unit 3_1, and the like in FIG. Refers to a control loop constituted by

The auto tuning management unit 11 starts the operation of the auto tuning device 100 based on an auto tuning command input from an input unit (not shown) or the like.

The master controller 9 is a control controller composed of, for example, a semiconductor integrated circuit on which a CPU is mounted, a one-chip microcomputer, or the like, and a set temperature input from an input unit (not shown) and a master input from the master temperature measurement unit 3_1. Based on the measured value PVm and the master parameter input from the control parameter calculation unit 5, the slave set temperature SVs is output to the slave controller 10.

The slave controller 10 is a control controller composed of, for example, a semiconductor integrated circuit mounted with a CPU or a one-chip microcomputer, and is input from the slave set temperature SVs input from the master controller 9 and the slave temperature measuring unit 3_2. The manipulated variable MV is output to the temperature control unit 4 based on the slave measurement value PVs and the slave parameter input from the control parameter calculation unit 5.

The temperature control unit 4 includes, for example, a semiconductor integrated circuit on which a CPU is mounted, a one-chip microcomputer, and the like, and the slave measurement value output from the slave temperature measurement unit 3_2 before the temperature control of the control target 1 is started. When the temperature of the slave control target 1_2 indicated by PVs is lower than the slave set temperature SVs of the slave controller 10, the heater 2 is set to the on state, and when the temperature of the slave control target 1_2 is equal to or higher than the slave set temperature SVs, heating is performed. This is a temperature regulator that controls the temperature of the slave control object 1_2 by setting the device 2 to the OFF state. Hereinafter, the operation performed by the temperature control unit 4 is also referred to as ONOFF control.
Here, setting the heater 2 to the on state means that the operation amount of the heating to the heater 2 is set to 100%, for example, and setting the heater 2 to the off state means that the heater 2 is set to the off state. It means that the operation amount of heating with respect to is set to 0%, for example.
The heater 2 is a device such as a heater that applies heat to the controlled object 1.

The master temperature measurement unit 3_1 is a temperature sensor that measures the temperature of the master control target 1_1 and outputs the measured value (PVm).
The slave temperature measuring unit 3_2 is a temperature sensor that measures the temperature of the slave control target 1_2 and outputs the measured value (PVs).

The control target 1 is, for example, a chemical temperature control system, the master control target 1_1 is a chemical temperature, the slave control target 1_2 is a chemical bath temperature, and heat is applied to the slave control target 1_2 by the heater 2 to perform master control. The temperature of the object 1_1 is controlled to the master set temperature SVm set by the master controller 9.

The control parameter calculation unit 5 includes, for example, a semiconductor integrated circuit on which a CPU is mounted, a one-chip microcomputer, or a computer including a multiplier or an adder. Then, a master parameter that is a control parameter in the master controller 9 and a slave parameter that is a control parameter in the slave controller 10 are calculated and output to the master controller 9 and the slave controller 10, respectively.

The elapsed time measuring unit 6 is composed of, for example, a semiconductor integrated circuit on which a CPU is mounted, a one-chip microcomputer, or a computer having a timer, and is input from the master temperature measuring unit 3_1 and the slave temperature measuring unit 3_2. The measured value is monitored, and the process of detecting the timing at which the temperature of the master control target 1_1 passes the master set temperature SVm is performed, and each time the passage timing is detected, the current passage time is detected from the previous passage timing. A process of measuring the elapsed time until the timing is reached.

The time calculation unit 7 includes, for example, a semiconductor integrated circuit on which a CPU is mounted, a one-chip microcomputer, or a computer including a multiplier or an adder. The elapsed time measurement unit 6 measures the elapsed time. Every time, the elapsed time is used to calculate the remaining time until the end of auto-tuning.

The time presentation unit 8 includes, for example, a 7-segment display, a timer, and the like, and performs processing for displaying the end time each time the time calculation unit 7 calculates the remaining time of auto-tuning.
Further, every time the time calculation unit 7 calculates the remaining time of auto-tuning, the time presentation unit 8 sets the remaining time to the count value of the timer and starts the count value reduction process. The process of displaying the count value of the timer is implemented.

Next, the auto tuning operation in the cascade control of the auto tuning device 100 will be described.
Hereinafter, auto-tuning is also simply referred to as AT.
Here, an example is described in which both the master controller 9 and the slave controller 10 execute PID control, and the master parameter and the slave parameter, which are the respective control parameters, are also referred to as a master PID parameter and a slave PID parameter, respectively. .

FIG. 2 is a flowchart showing an outline of AT operation of PID control according to the embodiment of the present invention.
Here, an example will be described in which the limit cycle operation (steps S201 and S202) is executed twice in the slave controller 10, and the control parameter calculation unit obtains the PID parameter of the slave controller 10. Hereinafter, this operation is also referred to as a slave AT.
In addition, an example will be described in which the master controller 9 performs two limit cycle operations (steps S203 and S204) to obtain the PID parameter of the master controller 9. Hereinafter, this operation is also referred to as a master AT.
First, AT is started by an AT effective command input to the auto-tuning management unit 11.

First, the first slave AT is executed (step S201). The slave controller 10 performs ON / OFF control of the slave control object 1_2 through the temperature control unit 4 based on the slave measurement value PVs and the slave set temperature SVs set in advance during the first slave AT operation. Each time the slave measurement value PVs reaches the slave set temperature SVs, the heater 2 is switched ON / OFF, and ONOFF control is performed until the preset number of switching times is reached.
Here, the number of times of switching is six.
The control parameter calculation unit 5 monitors the slave measurement value PVs. When the ON / OFF control for a preset number of times is completed, the control parameter calculation unit 5 records the limit cycle waveform generated as a result of the control and ends the AT. When the first slave AT is completed, the process proceeds to step S202.

Next, the second slave AT is executed (step S202). In the second slave AT, a value that is a preset constant k times larger than the amplitude of the limit cycle waveform obtained by the first slave AT is set as the second slave set temperature SVs. Then, similarly to the first slave AT, ON / OFF control is performed for the number of times of switching. As a result, the control parameter calculation unit 5 identifies the slave-side control target using the first order delay + dead time approximation model, and obtains the slave PID parameter expressed by the following equations 1 to 3.

However, Gs is the transfer function of the slave control target 1_2, _{K s} is the steady gain of the slave control target 1_2, _{T s} is equivalent time constant, _{L s} is equivalent dead time, _{SV s1} is the target value in the first slave AT, theta _s1 is an on / off duty ratio in the first slave AT, SV _s2 is a target value in the second slave AT, and θ _s2 is an on / off duty ratio in the second slave AT.

Further, the limit gain: K _cs and limit period: T _cs of the slave side control target are calculated from the limit cycle waveform at AT, and the equivalent time constant: T _s and the dead time equivalent to T _s : L _s are calculated by the following equation (3). .

When the slave PID parameter is calculated in this way, the slave AT is terminated and the process proceeds to step S203.

Next, the first master AT is executed (S203). Based on the AT effective command, the master controller 9 performs ON / OFF control for controlling the temperature of the master control target 1_1 through the slave controller 10 and the temperature control unit 4 based on the preset master set temperature SVm. Each time PVm reaches SVm, the heater 2 is switched ON / OFF, and ON / OFF control is performed until the preset number of switching times is reached.
Similar to the slave AT, the preset number of times of switching is six.
The control parameter calculation unit 5 monitors the master measurement value PVm and the slave measurement value PVs, and when the ON / OFF control for a preset number of times is completed, the limit cycle waveform generated as a result of the control is recorded. When the ON / OFF control of the preset number of times is finished and the first master slave AT is finished, the process proceeds to step S204.

Next, the second master AT is executed (step S205). In the second master AT, a value that is a constant set k times larger than the amplitude of the limit cycle waveform obtained by the first master AT is set as the second set temperature SVm.
Then, similarly to the first master AT, the ON / OFF control is performed until the preset number of switching times is reached. The control parameter calculation unit 5 obtains a mathematical model of the transfer function of the master control object 1_1 from the limit cycle waveform of the master measurement value PVm and the slave measurement value PVs generated by the control. When the transfer function of the master control target 1_1 is approximated by the dead time + temporary delay model in the same manner as the slave control target 1_2, the master PID parameters represented by the following equations 4 to 6 are obtained.

However, K _m is the steady gain of the master-side controlled object 1_1, T _m is the equivalent time constant, L _m is the equivalent dead time, SV _m1 and θ _m1 are the target value and on / off duty ratio of the first master AT, SV _m2 , Θ _m2 are the target value and on / off duty ratio of the second master AT, and K _s is the steady gain of the slave-side control target 1_2 obtained from Equation 1.

Further, the control parameter calculation unit 5 calculates a limit gain: K _cm and a limit period: T _cm of the master-side controlled object 1_1, and obtains an equivalent time constant: T _m and an equivalent dead time: L _m by the following formula: Master PID parameter Get.

Where T _cm is the limit cycle period, X _s is the amplitude of the limit cycle waveform of PV _s , X _m is the amplitude of the limit cycle waveform of PV _m , and φ is the phase difference between the limit cycle waveforms of PV _s and PV _m .
In this way, the master PID parameter is calculated, and the AT operation in the present embodiment ends.

Next, the function for predicting the time until the end of auto-tuning in the auto-tuning apparatus 100 in the present embodiment will be described. Hereinafter, this function is also referred to as an AT end time prediction function.

FIG. 5 is a conceptual diagram showing the relationship between the master measurement value PVm and the elapsed time at the master AT according to the embodiment of the present invention.

FIG. 3 is a flowchart showing an outline of the AT end time prediction function according to the embodiment of the present invention. The AT end time prediction function operates in parallel with the AT operation. Therefore, in FIG. 3, in order to collate with the timing of the AT operation in the present embodiment, the flowchart of the AT operation in FIG. 2 is also shown.

First, an AT operation is started by an AT effective command input to the auto-tuning management unit 11 and an AT end time prediction operation is started.
Simultaneously with the start of the AT, the elapsed time measuring unit 6 counts the actual time from the start of the AT and records it as Treal.
First, until the first and second slave ATs are completed, the time presenting unit 8 displays “CALC” indicating that the PID parameter is being calculated (step S301). When the second slave AT is completed, the process proceeds to step S302.
The detailed operation of step S302 will be described with reference to FIG.

<Master AT 1st time>
In step S302, the remaining AT time during execution of the first master AT is predicted.
The elapsed time measurement unit 6 monitors the master measurement value PVm input from the master temperature measurement unit 3_1 during execution of the first master AT, and performs processing to detect the timing when PVm passes the master set temperature SVm. To do. Hereinafter, the detection target point is referred to as an AT point, and the timing thereof is also referred to as a timing passing through the AT point.
As described above, the preset number of times of switching is six.
When the elapsed time measuring unit 6 detects passage of the first AT point in the first master AT (step ST3: Yes), it specifies the passage time t1_1 of the first AT point in the first master AT. The elapsed time Tela12 starts to be measured from the passage time t1_1 (step ST4).
When the elapsed time measuring unit 6 detects the passage of the second AT point (step ST5: Yes), it specifies the second AT point passage time t1_2 in the first master AT, and the following equation (7) As described above, the measurement of the elapsed time Tela12 from the passage of the first AT point in the first master AT to the passage of the second AT point in the first master AT is ended (step ST6).
Tela12 = t1_2−t1_1 (7)

When the elapsed time measurement unit 6 measures Tela 12, the time calculation unit 7 calculates Tend1_2, which is a predicted value of the remaining time until the end of only the AT at the time of the second AT point in the first master AT. (Step ST7).
Note that “the end of only the AT” means the end time of the AT when the switching time of the first and second master ATs is not considered, and the same applies hereinafter.

In step ST7, the AT end time at the second AT point in the first master AT is predicted.

Here, it is necessary to consider the following points when predicting the AT end time in cascade control.
One is that it takes time to change the SV when shifting from the end of the first AT to the second AT.
The other is that, compared to the first AT, the second AT is likely to take longer than the first AT due to the reduced load factor.
In order to deal with these points, the end time is predicted as follows.

The SV change time is predicted based on the time required for the first master AT to pass the AT point. Here, the time Tsleep required for the SV change is calculated as shown in the following formula (8), for example, for 1.5 periods of the AT point passing period.
Tsleep = 1.5 × Tela12 (8)

Further, for the point that the second AT takes longer than the first AT, correction is performed to bias the remaining AT time based on the time required for the first master AT. Here, the bias is treated as a constant term Tbuff and is calculated as the following equation (9) as a half period of the AT point passing period.
Tbuff = 0.5 × Tela12 (9)
In this way, Tend1_2 is calculated as in the following equation (10) in consideration of the characteristics of AT in cascade control.
Tend1_2 = 4.5 × Tela12 (10)
Then, Trest1_2, which is an estimated time until the actual end of the AT at the second AT point time in the first master AT, is calculated as follows.
Trest1_2 = Tend1_2 + Tbuff (11)
Note that “the actual end of the AT” means the end time of the AT in consideration of the switching time of the first and second master ATs, and so on.
Further, Tleft, which is a predicted end time of the entire auto tuning process until the end of the second master AT, is calculated as follows.
Tleft = 2 × Trest1_2 + Treal + Tsleep (12)

Usually, the first elapsed time Tela 12 required for the first cycle of the control start is longer than the subsequent elapsed time. Therefore, the actual AT end time is expected to be smaller than the Tleft calculated as described above, but a rough AT remaining time can be calculated.

When the time calculating unit 7 calculates Tend1_2, the time presenting unit 8 displays the expected time at which the AT ends based on the current time and the Tleft at that time.
In addition, the time presentation unit 8 sets Tleft at the time to the count value of the timer, and starts the count value reduction process.
Furthermore, the time presentation unit 8 displays the count value of the timer during the reduction process (step ST8).
The timer count value reduction process and the count value display process during the reduction process are repeated until Tend1_3 is calculated in step ST12, which will be described later.

Next, the elapsed time measuring unit 6 starts measuring the elapsed time Tela13 from the passing time t1_2 of the second AT point in the first master AT (step ST9).
When the elapsed time measuring unit 6 detects the passage of the third AT point in the first master AT (step ST10: Yes), it specifies the passage time t1_3 of the third AT point in the first master AT. Then, the measurement of the elapsed time Tela13 from the passage of the second AT point in the first master AT to the passage of the third AT point in the first master AT is ended as shown in the following equation (13) ( Step ST11).
Tela13 = t1_3-t1_2 (13)

When the elapsed time measuring unit 6 measures Tela 13, the time calculating unit 7 calculates Tend1_3, which is a predicted value of the remaining time until the end of only the AT at the third AT point in the first master AT, using the following formula ( 14) (step ST12).
Tend1_3 = 2.0 × Tela12 + 1.5 × Tela13 (14)
Then, Trest1_3, which is the time until the actual end of the AT at the time of the third AT point in the first master AT, is calculated by the following equation.
Trest1_3 = Tend1_3 + Tbuff (15)
Further, Tleft, which is the estimated end time of the entire auto tuning process until the end of the second master AT, is calculated as in the following equation.
Tleft = 2 × Trest1_3 + Treal + Tsleep (16)
Further, in the AT point switching after the third time, the current predicted value is recalculated and calculated as described above only when the predicted value is larger than the estimated value temp_left based on the actual time taken until now. Replace Tleft with temp_left calculated as in the following equation.
temp_left = Treal + (6-n) × Tend1_n + Tsleep (17)
Note that n is the number of remaining AT point switchings in the master AT, and here, n = 3.

When the time calculating unit 7 calculates Tend1_3, the time presenting unit 8 calculates the expected time when the AT ends based on the current time and the Tleft at the time.
When the time calculating unit 7 calculates Tleft at the time, the time presenting unit 8 deletes the previously displayed predicted end time and count and displays a new predicted end time.
In addition, the time presentation unit 8 sets Tleft as a new count value of the timer and starts the count value reduction process.
Furthermore, the time presentation unit 8 displays the count value of the timer during the reduction process (step ST13).
The timer count value reduction process and the count value display process during the reduction process are repeated until Tend1_4 is calculated in step ST17, which will be described later.

Here, in Tend1_3, since the calculation process of the PID parameter by the control parameter calculation unit 5 is more advanced than the stage in which Tend1_2 is calculated, it is assumed that the error included in Tend1_3 is reduced as compared with Tend1_2. .

So far, regarding the AT end time prediction function, the operation up to the third AT point passing in the first master AT has been described. Thereafter, the operation (step S15 to step S29) in the 4th to 6th AT point passing in the first master AT is the same as the operation in the 3rd AT point passing except for the calculation of the predicted AT end time. Therefore, explanation is omitted.

The following formulas (18) to (20) are used to calculate Tend1_4 to Tend1_6 when passing through each AT point in the first master AT.
Tend1_4 = 1.5 × Tela13 + Tela14 (18) (step S17)
Tend1_5 = Tela14 + 0.5 × Tela15 (19) (step S22)
Tend1_6 = 0.5 × Tela15 (20) (Step S27)
Based on the above equations, Trest1_4 to Trest1_6 are calculated, and Tleft, which is an AT end time prediction value at each time point, is calculated as follows.
Trest1_4 = Tend1_4 + Tbuff (21)
Tleft = 2 × Trest1_4 + Treal + Tsleep (22)
Trest1_5 = Tend1_5 + Tbuff (23)
Tleft = 2 × Trest1_5 + Treal + Tsleep (24)
Trest1_6 = Tend1_6 + Tbuff (25)
Tleft = 2 × Trest1 — 6 + Treal + Tsleep (26)

<Master AT second time>
After starting the measurement of Tela 16 in step ST24, the first master AT is completed, the new master set temperature SVm calculated by the control parameter calculation unit 5 is input to the master controller 9, and the master set temperature SVm is newly set. Can be switched to the correct master set temperature. Thereafter, the second master AT is started, and the process proceeds to an AT end time prediction operation in the second master AT (step S303).

During the transition from step S302 to step S303, the time presentation unit 8 displays the estimated end time calculated when the sixth AT point passes in the first master AT, and the timer count value reduction process and the reduction process are in progress. The display processing of the count value is continued.

In step S302, a predicted time from the first master AT to the end of the master AT during the second master AT is predicted. The detailed operation of step S303 will be described with reference to FIG.

The elapsed time measurement unit 6 monitors the master measurement value PVm input from the master temperature measurement unit 3_1 during the execution of the second master AT, and the timing at which PVm passes the master set temperature SVm (passes the AT point). (Timing) is detected. Also for the second master AT, the number of times of switching set in advance is six.
When the elapsed time measuring unit 6 detects passage of the first AT point in the second master AT (step ST33: Yes), the elapsed time measuring unit 6 specifies the passage time t2_1 of the first AT point in the second master AT. Then, measurement of the elapsed time Tela22 from the passage time t2_1 is started (step ST34).

During the transition from step ST33 to step ST35, the time presentation unit 8 displays the estimated end time calculated when the master AT passes the sixth AT point, and the timer count value reduction process and the reduction process are in progress. The display processing of the count value is continued.

When the elapsed time measuring unit 6 detects passage of the second AT point in the second master AT (step ST35: Yes), the elapsed time measuring unit 6 specifies the passage time t2_2 of the second AT point in the second master AT. Then, the measurement of the elapsed time Tela22 from the passage of the first AT point in the second master AT to the passage of the second AT point in the second master AT is finished as shown in the following equation (27) (step ST36). ).
Tela22 = t2_2-t2_1 (27)

In the time calculation unit 7, the elapsed time Tela 22 from the passage of the first AT point in the second master AT to the passage of the second AT point in the second master AT is measured by the elapsed time measurement unit 6. Then, Tend2_2, which is the predicted value of the AT remaining time at the second AT point in the second master AT, is calculated as in the following equation (28) (step ST37).
Tend2_2 = 4.5 × Tela22 (28)
Then, Tleft, which is the predicted end time of the full auto tuning process in the second master AT, is calculated as follows.
Tleft = Tend2_2 (29)

When the time calculating unit 7 calculates Tend2_2, the time presenting unit 8 calculates the expected time when the AT ends based on the current time and the Tleft at the time.
When the time calculating unit 7 calculates Tleft, the time presenting unit 8 displays the predicted end time and remaining time Tleft previously displayed (here, estimated end time and remaining time based on Tend1_6 in the first master AT) ) And display the new estimated end time. In addition, the time presentation unit 8 sets Tleft as the count value of the timer and starts the count value reduction process.
Furthermore, the time presentation unit 8 displays the count value of the timer during the reduction process (step ST38).
The timer count value reduction process and the count value display process during the reduction process are repeated until Tend2_3 is calculated in step ST42 described later.

So far, regarding the AT end time prediction function, the operation up to the second AT point passing in the second master AT has been described. Thereafter, regarding the operation (step S40 to step S58) in the third to sixth AT point passages in the second master AT, the second AT point passage in the second master AT is performed except for the calculation of the predicted AT end time. Since this is the same operation as in FIG.

The calculation methods of the predicted AT end time values Tend2_3 to Tend2_6 at each AT point passage in the second master AT are as shown in the following equations (30) to (33).
Tend2_3 = 2.0 × Tela22 + 2.5 × Tela23 (30) (step S42)
Tend2_4 = 1.5 × Tela23 + Tela24 (31) (step S47)
Tend2_5 = Tela24 + 0.5 × Tela25 (32) (step S52)
Tend2 — 6 = 0.5 × Tela25 (33) (step S57)
Further, as shown in the following expression, Tleft, which is an AT end time prediction value at each time point, is calculated.
Tleft = Tend2_3 (34)
Tleft = Tend2_4 (35)
Tleft = Tend2_5 (36)
Tleft = Tend2_6 (37)

The control parameter calculation unit 5 outputs the calculated PID parameter to the master controller 9 and the slave controller 10 when the passage of the sixth AT point of the second master AT is detected.
Then, when the timer count in the time calculation unit 7, that is, the reduction process of Tend2_6 becomes 0, the ON / OFF control of the heater 2 is terminated and the PID control of the control target 1 is started based on the calculated PID parameter. .

In FIG. 6, the transfer function of the master control target is 1 / (1 + 8s) (1 + 8s) (1 + 253s), the transfer function of the slave control target is 1 / (1 + 32s), and the SV values of the master and slave are 50%. The simulation result using the auto-tuning apparatus 100 of this embodiment is shown.
It can be seen that the AT remaining expected time is close to linear, and the AT remaining time can be accurately predicted.

As described above, according to this embodiment, it is possible to obtain an auto tuning apparatus that can predict the end time of auto tuning in a cascade control system.
For this reason, for example, even when the calculation time of the PID parameter by the auto tuning function becomes long because the load capacity of the control target 1 is large and the response is slow, the setup until the start of PID control can be easily set up. .
In addition, since the end time is corrected based on the elapsed time between AT points in the first master AT, the accuracy of AT end time prediction in cascade control can be increased.
In addition, since the time for switching SVm between the first master AT and the second master AT is predicted based on the elapsed time between AT points in the first master AT, the AT in cascade control is The accuracy of the end time prediction can be increased.
In addition, since the first AT effective time is used to estimate the second AT remaining time, the accuracy of AT end time prediction in cascade control can be improved.

Further, according to this embodiment, every time the elapsed time measuring unit 6 detects the passage timing, the elapsed time from the previous passage timing to the current passage timing is measured, and the time calculation unit 7 However, every time the elapsed time is measured by the elapsed time measuring unit 6, the remaining AT time is calculated using the elapsed time, and every time the time presenting unit 8 calculates the remaining AT time by the time calculating unit 7, Since it is configured to display the count of the end time and the remaining time, the AT remaining time with high calculation accuracy can be displayed as the auto-tuning process approaches.

In this embodiment, the example in which the calculation process of the PID parameter is completed when the timing of the sixth passage is detected is merely an example, and the timing of the sixth or more passage is detected. In some cases, the calculation process of the PID parameter may be completed at the time point, or the calculation process of the PID parameter may be completed when the timing of the fourth or subsequent passage is detected. Hereinafter, the operation at the AT point is also referred to as AT switching.
In such a case, the remaining time Tleft is calculated as follows.
Remaining AT switching count: remain_cycle_count = total switching count−current switching count.
The number of remaining AT switching cycles: remain_cyc = remain_cycle_count / 2 (much rounded down).
Then, the calculation method is changed depending on the number of AT switching times at the time of calculating the remaining time.
In the second AT switching, the time corresponding to a half period of the AT switching cycle measured in the first AT switching (time_count) × the number of remaining switching (remain_cycle_count) + the end time which is a time corresponding to ¼ period from the previous AT point ( at_xtime).
In addition, after the third AT switching, first, it is confirmed whether or not there is a “less” half cycle in the remaining cycle. “Too much” in a half cycle is too much obtained by dividing the remaining switching count (remain_cycle_count) by 2. In the calculation, if the remaining switching is one time, “too much” becomes zero.
And if there is "too much",
Tleft = (ct_cyc) × (remain_cyc) which is the time of the previous one cycle + (ct_old) + (at_xtime) which is the time of a half cycle before one cycle.
If you do n’t have “too much”,
Tleft = immediately preceding one cycle time (ct_cyc) × (remain_cyc) + calculated as (xt_old) which is a time corresponding to a quarter cycle before one cycle.

In this embodiment, an example in which the master loop and the slave loop are configured in two stages has been described. However, the present invention is not limited to this and may be configured by a plurality of slave loops. In that case, as many slave controllers as slave loops are required.
Moreover, although the time presentation part 8 described about the example comprised by a 7 segment display etc., it is not restricted to this, For example, you may present by outputting audio | voice the end time and remaining time. .
FIG. 1 shows an example in which the heater 2, the master temperature measurement unit 3_1, and the slave temperature measurement unit 3_2 are provided outside the auto tuning apparatus 100. However, all or any combination thereof is auto tuning. It may be provided inside the apparatus 100.
In the example of FIG. 1, each of the temperature control unit 4, the control parameter calculation unit 5, the elapsed time measurement unit 6, the time calculation unit 7, and the time presentation unit 8 that are components of the PID control device is dedicated hardware. Although what is comprised is assumed, all or any combination may be comprised by software.
Moreover, although the case where the slave controller 10 performs PID control has been described in the present embodiment, similar processing may be performed when performing control such as P control and PI control instead of PID control.
In addition, although the time Tsleep required for the SV change is set to 1.5 periods of the AT point passing period, an appropriate numerical value may be used according to the device characteristics and the like. Moreover, it may be updated every time the AT point passes by a coefficient (for example, 1.5) times the latest cycle time.
In addition, as for Tbuff, an appropriate numerical value may be used as a half period of the AT point passing period in accordance with the device characteristics and the like as in Tsleeep. Further, it may be updated by a factor (for example, 0.5) times of the latest cycle time every time the AT point passes.

As described above, the content of the present invention has been described based on the embodiment. However, the content of the present invention is not limited only to the content of the embodiment, but within the content described in the claims and the equivalent scope thereof. Of course, it can be changed.

DESCRIPTION OF SYMBOLS 1 Control object 2 Heater 3_1 Master temperature measurement part 3_2 Slave temperature measurement part 4 Temperature control part 5 Control parameter calculation part 6 Elapsed time measurement part 7 Time calculation part 8 Time presentation part 9 Master controller 10 Slave controller 11 Auto tuning management part 100 Auto tuning device

Claims

Used in a cascade control system in which a master controller that performs PID control and at least a slave controller that performs P control are cascade-connected, a master parameter that is a control parameter of the master controller and a slave parameter that is a control parameter of the slave controller An auto tuning apparatus having an auto tuning function for performing auto tuning to be adjusted,
An auto tuning management unit that receives an effective command of auto tuning;
Before starting control of the temperature of the control target, in a period in which the temperature of the control target is lower than a set temperature, a heater that applies heat to the control target is set to an on state, and the temperature of the control target is set to the set temperature In the above period, by setting the heater to an off state, a temperature control unit that controls the temperature of the control target;
A control parameter calculation unit that calculates the master parameter and the slave parameter from the measured value of the temperature of the controlled object controlled by the temperature control unit;
The process of monitoring the measured value of the temperature of the control object, detecting the timing at which the temperature of the control object passes the set temperature is performed, and the process from the previous passage timing to the current passage timing An elapsed time measuring unit for measuring time;
Using the elapsed time measured by the elapsed time measuring unit, a time calculating unit that calculates the end time of auto-tuning,
A time presentation unit for presenting the end time of auto-tuning calculated by the time calculation unit;
Auto tuning device with
The elapsed time measurement unit measures the elapsed time from the previous passage timing to the current passage timing each time the passage timing is detected,
The time calculation unit calculates an end time of auto-tuning using the elapsed time every time the elapsed time is measured by the elapsed time measurement unit,
2. The auto tuning apparatus according to claim 1, wherein the time presentation unit presents the end time each time the end time of auto tuning is calculated by the time calculation unit.
The time presentation unit sets the time from the current time to the end time every time the auto-tuning end time is calculated by the time calculation unit, and sets the timer count value to reduce the count value. 3. The auto-tuning apparatus according to claim 2, wherein processing is started and a count value during reduction processing is presented.
When using the limit cycle method in the auto tuning function,
4. The auto tuning apparatus according to claim 1, wherein the elapsed time calculation unit performs correction based on the elapsed time before switching the set temperature with respect to the end time of the auto tuning. .
When using the limit cycle method in the auto tuning function,
The auto-tuning device according to any one of claims 1 to 3, wherein the elapsed time calculation unit predicts a time required for switching the set temperature based on the elapsed time before the set temperature switching.
When using the limit cycle method in the auto tuning function,
2. The elapsed time calculation unit calculates an end time of the auto-tuning based on the time taken until the set temperature is switched after the set temperature is switched and the elapsed time. 4. The auto-tuning device according to any one of 3.