JP2009301258A - Control device - Google Patents

Abstract

<P>PROBLEM TO BE SOLVED: To provide a control device for synchronizing each process value of each control channel in a device having a plurality of control channels to change a target value. <P>SOLUTION: A master control part 1 performs PID control based on a target control value SVc1 from a temperature rise management part 9 and a measurement value PV1 from a master plant PR1. Slave control parts 3, 5 and 7 perform PID control based on target control values SVc2-SVc4 from the temperature rise management part 9 and measurement values PV2-PV4 from slave plants PR2-PR4. The temperature rise management part 9 performs temperature rise management by using, with respect to a master channel CH1, a set target value SV1 as the target control value SVc1, and adding, with respect to slave channels CH2-CH4, process values obtained by adding bias values to the process value PV1 of the master channel as the target control values SVc2-SVc4 for slave channels to the slave control parts 3 and 5 and 7. <P>COPYRIGHT: (C)2010,JPO&INPIT

Description

  The present invention relates to a control device, and more particularly to an improvement of a control device suitable for temperature increase control of a control target having a plurality of control channels.

  As an object to be controlled having a plurality of control channels, for example, there is a heating cylinder of a plastic molding machine having a plurality of heaters.

  In the heating cylinder of this type of plastic molding machine, there are a plurality of heaters that should be controlled in temperature rise. Therefore, in order to maintain good molding quality, when these heaters are started or the set temperature conditions are changed, these heaters are used. It is often necessary to synchronize the transient response of the process value (PV).

For example, the temperature control method of an injection molding machine disclosed in JP-A-2002-361705 (Patent Document 1) is a known example of this type.
JP 2002-361705 A

However, the conventional configuration described above has the following problems, and it has been difficult to sufficiently synchronize the process amount (PVn) of each control channel n in the temperature rising process.
(1) When one of a plurality of control channels n is a master channel and the rest are slave channels, PID control is performed with the process amount (PVm) of the master channel as the target value (SVs) of the slave channel. However, in this configuration, generally, as shown in FIG. 5A, the target value (SVm) to the PID control unit that controls the master channel is stepwise (type 1), while the slave channel that follows the master channel In the PID control unit, since the process amount (PVm) of the master channel becomes the target value (SVs) of the slave channel, the type of the target value does not become stepwise (type 1). In principle, in the PID controller, the slave channel process is set to the target value (SVs) of the slave channel in the temperature rising process. (PVs) can not match.

(2) In the slave channel that follows the master channel, the target value set in the slave channel's PID control unit is approximately assumed to be a tilt type (type 2), and an integrator is installed in the slave channel's PID control unit that follows. Even when one is added to form a type 2 PID controller, if the operation amount (MVs) of the slave channel is limited by the output limiter during the temperature rising process as shown in FIG. (SVs) may not be able to supply the operation amount necessary to match the process amount (PVs) of the slave channel, and the process amount (PVs) of the slave channel is set to the target value (SVs) of the slave channel in the temperature rising process. It may not be possible to match.

  The present invention has been made to solve such a problem, and an object of the present invention is to provide a control device capable of changing a target value by synchronizing each process amount of a device having a plurality of control channels.

  In order to solve such a problem, the control device according to the present invention uses the control channel with the slowest response speed when changing the target value in the device as the master channel, and calculates the process amount of the master channel from the predetermined master target value. A master control unit that performs feedback PID control and a slave control unit that performs feedback PID control of the process amount of the slave channel with respect to a predetermined slave target value using another channel as a slave channel. When changing the target value of the device, A temperature increase management unit configured to perform temperature increase management using a process amount obtained by adding a bias amount to the process amount of the master channel as a target value at the time of temperature increase of the slave channel.

  In the control device of the present invention, the temperature increase management unit subtracts the master channel target value from the master channel process amount and adds the set target value of each of the slave channels to the slave channel. Even if the set target values of the master channel and the slave channel are different by managing the temperature rise as a master process amount to be followed and adding the bias amount to this as a target value at the time of temperature rise It is also possible to raise the temperature in synchronization with each channel.

  In the control device of the present invention, when the target value of the device is changed, the temperature increase management unit obtains a deviation between the set target value of each slave channel and the process amount of the slave channel, and the deviation is When it is smaller than the proportional band setting value of the slave channel, the deviation amount is used as the bias amount of the slave channel, and when the deviation is equal to or larger than the proportional band setting value of the slave channel, the proportional band setting value of the channel is A configuration with a bias amount of is also possible.

  Further, in the control device according to the present invention, the temperature increase management unit, in each of the slave channels, sets the process amount of the slave channel to a value obtained by multiplying the proportional band set value by a predetermined constant. When the set target value is equal to or greater than the value subtracted from the set target value, feedback PID control is performed using the set target value as the target value of the slave channel, so that the process amount of each channel is satisfactorily set when the temperature rise is completed It is possible to converge to.

  Further, in the control device according to the present invention, the temperature increase management unit, in the process of reaching the target value of each process amount, exceeds the process amount of the master channel that each process amount of the slave channel should follow. In this case, the bias amount may be corrected and changed so as not to exceed the process amount of the master channel.

  Furthermore, in the control device of the present invention, a configuration is possible in which the bias amount is corrected and changed by a correction amount obtained by multiplying a value obtained by subtracting the process amount of the slave channel from the process amount of the master channel by a predetermined constant. It is.

  In such a control device according to the present invention, the control channel having the slowest response characteristic when changing the target value in the device is set as the master channel, and the master controller determines the process amount of the master channel from the predetermined master target value. Since feedback PID control is performed, the other control channel is set as a slave channel, and the process amount of the slave channel is feedback PID controlled with respect to a predetermined target value determined by the temperature increase management unit in the slave control unit. The following effects can be obtained in each set target value change of the control device that accompanies when the operation of the control target is started or when the operation conditions are changed.

(1) When each set target value of the control device is changed in order to change the operation start or operation condition of the control target, the temperature rise management unit sets the slave channel control target value to the master channel Since each slave channel performs PID control as a value obtained by adding a bias amount to the process amount, the process amount of each slave channel is not delayed by the process amount of the master channel without being affected by the output limit by the output limiter of each slave channel. Since it can be made to follow, it becomes possible to raise temperature in synchronization with a plurality of control channels well.

(2) Even when the set target values of the control targets are different from each other, the master channel target value should be subtracted from the master channel process amount and the set target values of the individual slave channels should be followed. As the master channel process amount, the value obtained by adding the bias amount to this is used as the target value for the temperature increase of the slave channel. Therefore, the temperature increase of each slave channel is synchronized with the master channel. Can be completed.

(3) The bias amount set for each slave channel at the time of temperature rise is the deviation amount between the set target value of each slave channel and the process amount of the slave channel, and the proportional band setting set for each slave channel. Since the configuration is determined based on the value, the temperature can be increased in synchronization with the master channel to be followed without being affected by the target value change amount of each channel.

(4) A target for performing PID control when the process amount of each slave channel that is being heated reaches a value obtained by multiplying the set target value of each channel by a predetermined constant for the proportional band set value. Since the value is switched from the value obtained by adding the bias amount to the process amount of the master channel to be followed to the set target value of each channel, the process amount of each channel can be successfully converged to the set target value when the temperature rise is completed. Is possible.

(5) When the process amount of each slave channel exceeds the master channel process amount to be followed in the temperature rising process, the bias amount added to the master channel process amount to be followed as the target value of each slave channel is corrected. Therefore, each slave channel can be heated up synchronously without overtaking the process amount of the master channel to be followed.

  The correction of the bias amount of each slave channel can be performed at a rate obtained by multiplying the value obtained by subtracting the slave process amount of the channel from the process amount of the master channel to be followed by each channel by a predetermined constant. The tracking characteristic for the master channel can be easily adjusted and improved.

  Hereinafter, embodiments of the present invention will be described with reference to the drawings.

  FIG. 1 is a block diagram showing an embodiment of a control apparatus according to the present invention. A case where the number of control channels is 4 will be described as an example.

  In FIG. 1, the control device according to the present invention includes three slave control units 3, 5, 7 in addition to a master channel CH 1 including one master control unit 1 and a master plant PR 1 connected to the master control unit 1. It is formed by three slave channels CH2, CH3, and CH4 including slave plants PR2, PR3, and PR4 connected thereto.

  The master controller 1 of the master channel CH1 selects the channel with the slowest response of the target value response characteristic among all the control channels.

  The master control unit 1 of the master channel CH1 includes a subtraction unit 1a that outputs a control deviation from a control target value SVc1 from a temperature increase management unit 9 described later and a measured value (process amount) PV1 from the master plant PR1, and this control. And a PID calculation unit 1b that outputs an operation amount MV1 as a PID control operator so that there is no deviation (deviation), and the PID calculation unit 1b is connected to the master plant PR1.

  The master plant PR1 is an operation unit a1 and a heater h1, which will be described later, heated by the operation amount MV1, and a measured value PV1 from the master plant PR1 is output to the subtraction unit 1a and the temperature increase management unit 9.

  The slave control unit 3 of the slave channel CH2 includes a subtraction unit 3a that outputs a control deviation from the control target value SVc2 from the temperature rise management unit 9 and the measured value PV2 from the slave plant PR2, and PID control so that this deviation is eliminated. And a PID calculation unit 3b that performs calculation and outputs an operation amount MV2. The PID calculation unit 3b is connected to the slave plant PR2.

  The slave plant PR2 is an operation unit a2 and a heater h2 that are heated by the operation amount MV2, and the measured value PV2 from the slave plant PR2 is output to the subtraction unit 2a and the temperature increase management unit 9.

  The configuration of the slave channels CH3 and CH4 is the same as that of the slave channel CH2.

  In the temperature rise management unit 9, set target values SV1, SV2, SV3, SV4 for the master channel CH1 and the slave channels CH2 to CH4, which specify the operation conditions to be controlled, are preset from the outside.

  The temperature increase management unit 9 outputs the set target value SV1 as the control target value SVc1 to the subtraction unit 1a for the master channel CH1, and the control target for the slave channels CH2 to CH4 is in a steady operation state. The set target values SV2 to SV4 are set as control target values SVc2 to SVc4, and when the control target is heated up or is in a temperature rising transient after the target value is changed, the temperature is raised in synchronization with the process amount of the master channel. Function target values are obtained and output as control target values SVc2 to SVc4 to the subtracting units 3a, 5a and 7a, respectively. Details of the temperature rise management unit 9 will be described later.

  FIG. 2 is a schematic configuration diagram showing a state in which the control device shown in FIG. 1 is applied to a heating cylinder of a plastic molding machine.

  In FIG. 2, the master plant PR1 and the slave plants PR2 to PR4 described above include operation units a1, a2, a3, a4 including solid state relays (SSR) operated by operation amounts MV1 to MV4, It is formed from a heated object (cylinder) 11 in which the heaters h1 to h4 are arranged.

  Temperature sensors s1, s2, s3, and s4 that measure the temperatures of the heated objects heated by the heaters h1 to h4 are arranged in the vicinity of the individual heaters h1 to h4 in the heated object 11, and the sensors s1 to s1 are arranged. The measured values PV1 to PV4 from s4 are output to the master PID control unit 1 and the subtraction units 1a, 3a, 5a, and 7a of the slave PID control units 2 to 4 and the temperature increase management unit 9 as described above.

  Next, the detail of the temperature rising management part 9 mentioned above is demonstrated.

  When the temperature of the apparatus is increased or the target value is changed, the temperature increase management unit 9 controls the slave channels CH2 to CH4 other than the master channel CH1 so as to follow the measured value PV1 of the master channel CH1. It has a function for obtaining each bias amount.

  This processing function operates only at the timing when the temperature of the apparatus is increased or the target value is changed, and does not operate at other timings.

Each bias amount for each of the slave channels CH2 to CH4 is obtained as follows, for example.
if (SVn-PVn <PBn)
then {BIASn = SVn−PVn} else {BIASn = PBn}

  Here, SVn is a set target value of channel n, PVn is a measured value (control amount) of channel n, PBn is a proportional band setting value of channel n, BIASn is a bias value of channel n, and the proportional band setting value is This is a quantity that represents the strength of proportional operation in PID control, and is a control deviation amount required for the operation output to change 100%. The subscript n is “n = 1” for the master channel and “n =” for the slave channel. 2-4 "(the same applies hereinafter).

  That is, when the deviation between the set target value SVn of each slave channel and the process amount PVn is smaller than the proportional band set value PBn of each channel in each of the slave channels CH2 to CH4, the temperature increase management unit 9 biases this deviation amount. When the deviation is equal to or larger than the proportional band set value PBn, the proportional band set value PBn is added as a bias quantity BIASn.

Moreover, the temperature increase management unit 9 obtains each of these bias amounts, and does not set the target values SV2 to SV4 for the individual slave channels CH2 to CH4 until the temperature increase processing for the slave channels CH2 to CH4 ends. The control target values SVc <b> 2 to SVc <b> 4 obtained by the following expression are continuously output.
SVcn = PV1 + BIASn ... Formula 2

  Here, SVcn is a control target value used for PID control calculation of channel n, PV1 is a measured value (control amount) of master channel CH1, and BIASn is a bias value of channel n.

Termination of the temperature raising process for the slave channels CH2 to CH4 is performed according to the following conditional expression, and an appropriate termination condition is set according to the control requirements of each slave plant PR2 to PR4.
PVn ≧ SVn−k1 × PBn Equation 3

  Here, PVn is a slave measured value (control amount) of channel n, SVn is a set target value of channel n, PBn is a proportional band set value of channel n, and k1 is a constant.

  In other words, the temperature increase management unit 9 sets the slave channel n setting target for the slave channel CH2 to CH4 by multiplying the proportional band set value PBn by the predetermined constant k1 for the process amount PVn of the slave channels CH2 to CH4. When the value subtracted from the value SVn is equal to or greater than the value, the control target value SVcn of each slave channel n is not the target value obtained by adding the bias amount BIASn to the process amount PV1 of the master channel, but the set target value of each slave channel n It has a function of switching to SVn.

  Therefore, the master control unit 1 performs PID calculation using the set target value SV1 as the control target value SVc1, and executes normal PID control for outputting the manipulated variable MV1 to the master plant PR1.

  When the temperature of the apparatus is increased or the target value is changed, the slave channels CH2 to CH4 are not for setting the set target values SV2 to SV4 but for the value obtained by adding the bias amount BAISn to the process amount PV1 of the master channel CH1. PID calculation is performed as target values SVc2 to SVc4, and follow-up control is executed. When the process amount PVn of each slave channel satisfies Equation 3, the set target values SV2 to SV4 are switched to the control target values SVc2 to SVc4 to follow. Control can be terminated.

  The above-described master control unit 1, slave control units 3, 5, and 7 and the temperature rise management unit 9 in the control device of the present invention are a CPU, a storage unit that stores an operation program for the CPU, and an interface unit (all not shown). ), And the operation is executed in accordance with the following processing procedure at every sampling time.

  That is, the flowchart of FIG. 3 is a process for setting the bias amount of each slave channel when the temperature of the apparatus is increased or the target value is changed, and starting the temperature increase process. The unit 9 determines whether or not the set target value SVn has been changed. If the target value has been changed and Step 1 is Yes, the process proceeds to Step 2.

  In Step 2, it is determined whether or not the channel whose target value has been changed is a slave channel. If the channel is a slave channel, Step 2 becomes Yes and the process proceeds to Step 3. In Step 3, the temperature increase management unit 9 biases the slave channels CH2 to CH4. While setting the amount, the temperature increase management unit 9 saves the state indicating that the temperature increase process is being performed in Step 4 and ends.

  If the target value is not changed and Step 1 is No, or if Step 2 is No instead of the slave channels CH2 to CH4, the process is terminated.

  Next, the flowchart of FIG. 4 is a process during the temperature rising process for each of the slave channels CH2 to CH4. In Step 10, the temperature rising management unit 9 determines whether or not the slave channel is CH2 to CH4. If Step 10 is Yes, the temperature rise management unit 9 determines whether or not the temperature raising process is being performed in Step 11. If the temperature raising process is being performed and Step 11 is Yes, the process proceeds to Step 12.

  That is, if the processing channel is not the slave channel CH2 to CH4 and Step 10 is No, or the slave channel CH2 to CH4 is not in the temperature increasing process and Step 11 is No, the process proceeds to Step 14, and Step 14 is performed. Then, the set target values SV1 to SV4 for the channel are set in the control target values SVc1 to SVc4 for performing PID control.

  When Step 11 is Yes and the process proceeds to Step 12, in Step 12, the temperature increase management unit 9 determines whether or not the temperature increase process corresponds to the end condition, and if the end condition is satisfied and Step 12 is Yes, the process proceeds to Step 13. At Step 13, the temperature rise management unit 9 clears the bias amount and proceeds to Step 14, and at Step 14, the set target values SV1 to SV4 are set as the control target values SVc1 to SVc4. If Step12 is No, it will move to Step15.

  By the way, as shown in FIG. 6, it is assumed that the measured values PV2 to PV4 of the slave channels CH2 to CH4 pass the measured value PV1 of the master channel CH1 in the temperature rising process accompanying the change of the target value.

  For the slave channels CH2 to CH4, a value obtained by adding a bias amount to the process amount PV1 of the master channel is used as the control target value in the temperature raising process. Depending on the added bias amount, the measured values of the slave channels CH2 to CH4 may be There is a case where the measured value PV1 of the master channel is overtaken.

  When follow-up control is performed using a PID controller for a type 2 target value that changes approximately in a ramp-like manner, a steady-state deviation called a speed deviation is generated. Therefore, it is added to the target values of the slave channels CH2 to CH4. If the bias amount is “0”, the control amount of the slave channels CH2 to CH4 does not overtake the control amount of the master channel CH1.

  Therefore, when the measured values PV2 to PV4 of the slave channels CH2 to CH4 overtake the measured value PV1 of the master channel CH1 during the temperature rising process, the bias amount set at the start of temperature rising of the device or when the target value is changed It is possible to correct the overtaking of the slave channels CH2 to CH4.

The temperature increase management unit 9 may be formed so as to correct the bias amount by the following process when overtaking is determined in the process.
BIASn = BIASn + k2 × (PV1-PVn) ... Formula 4

  Here, BIASn is a bias value of channel n, PV1 is a measured value (control amount) of the master channel, PVn is a measured value (control amount) of slave channels CH2 to CH4, and k2 is an adjustment constant.

The adjustment coefficient k2 for setting the degree of correction of the bias amount may be determined as follows using the set value Tin (seconds) of the integration time set for each slave channel CH2 to Ch4.
k2 = τ / Tin Equation 5

  Here, τ is a sampling period (second), and the integration time is a set value that determines the strength of the integration (I) operation of PID control.

  Therefore, in Step 15 of the flowchart shown in FIG. 4, the temperature increase management unit 9 determines whether or not the measured values PV2 to PV4 of the slave channel are larger than the measured value PV1 of the master channel, and the measured values PV2 to PV4 are larger than PV1. If Step 15 is Yes, the process proceeds to Step 16, and the temperature increase management unit 9 corrects the bias amount as described above and proceeds to Step 17 at Step 16.

  If the measured values PV2 to PV4 are smaller than the measured value PV1 and No in Step 15, go to Step 17.

  Step 17 is a process of calculating the control target values SVc1 to SVc4 of each slave channel during follow-up control by adding the bias amount BIASn to the control amount PV1 of the master channel.

  In Step 18, the PID control calculation is performed based on the control target values SVc1 to SVc4 of the master control unit 1 and slave control units 2 to 4 determined by the temperature increase management unit and the control amount PVn of each channel, and the process is terminated. .

  As described above, by controlling the apparatus having a plurality of control channels as described above, it becomes possible to raise the temperature by synchronizing the transient responses of a plurality of process amounts.

By the way, the control device according to the present invention is not limited to the case where the set target values SV1 to SV4 of the channels CH1 to CH4 are equal, and also when the set target values SV1 to SV4 of the channels CH1 to CH4 are different from each other. The measured value of the master channel CH1 used in the above-described formulas 2 and 4 can be effectively functioned by setting the measured value PV1n ′ below.
PV1n ′ = SVn−SV1 + PV1 Formula 6

  Here, the measured value PV1n ′ is a master PV value to be followed by each slave channel n, SVn is a set target value of the slave channel n, SV1 is a set target value of the master channel, and PV1 is a control amount (measurement amount of the master channel). Value).

  Furthermore, the present invention is not limited to a control device that processes with a digital signal, but can also be implemented with a control device that processes with an analog signal.

It is a block diagram which shows embodiment which concerns on the control apparatus of this invention. It is a schematic block diagram which shows the state which applied the control apparatus of FIG. 1 to the heating cylinder of the plastic molding machine. It is a flowchart explaining operation | movement of the control apparatus of this invention. It is a flowchart explaining operation | movement of the control apparatus of this invention. It is a chart explaining operation | movement of the conventional control apparatus. It is explanatory drawing when a slave channel overtakes a master channel in implementation of the control apparatus of this invention.

Explanation of symbols

DESCRIPTION OF SYMBOLS 1 Master control part 1a, 3a, 5a, 7a Subtraction part 1b, 3b, 5b, 7b PID calculating part 3, 5, 7 Slave control part 9 Temperature rising management part 11 To-be-heated object a1, a2, a3, a4 Operation part CH1 Master channel CH2, CH3, CH4 Slave channel h1, h2, h3, h4 Heater PR1 Master plant PR2, PR3, PR4 Slave plant s1, s2, s3, s4 Sensor

Claims (6)

A master control unit that performs the PID control of the process amount of the master channel with respect to a predetermined master target value, with the control channel having the slowest response speed when changing the target value in the device as a master channel;
A slave control unit that performs other PID control of the process amount of the slave channel with respect to a predetermined slave target value, with another channel as a slave channel;
When the target value of the device is changed, a temperature increase management unit that performs temperature increase management as a target value at the time of temperature increase of the slave channel, a process amount obtained by adding a bias amount to the process amount of the master channel;
A control device comprising: The temperature increase management unit subtracts the master channel target value from the master channel process amount and adds the set target value of each slave channel to the master channel process to be followed by the slave channel. 2. The control device according to claim 1, wherein the temperature rise management is performed using a value obtained by adding the bias amount to the process amount of the master channel to be followed as a target value at the time of temperature rise. The temperature increase management unit obtains a deviation between the set target value of each slave channel and the process amount of the slave channel when changing the target value of the device, and the deviation is larger than the proportional band set value of the slave channel. The deviation amount is set as the bias amount of the slave channel when the difference is small, and the proportional band setting value of the channel is set as the bias amount of the slave channel when the deviation is equal to or larger than the proportional band setting value of the slave channel. 2. The control device according to 2. The temperature increase management unit, in each of the slave channels, the process amount of the slave channel is equal to or greater than a value obtained by subtracting a value obtained by multiplying the proportional band set value by a predetermined constant from the set target value of the slave channel. 3. The control device according to claim 1, wherein feedback PID control is performed using the set target value as the target value of the slave channel. The temperature increase management unit corrects and changes the bias amount when the process amount of the slave channel exceeds the process amount of the master channel to be followed in the process of reaching the target value of the process amount. The control device according to claim 1, wherein control is performed so as not to exceed a process amount. 6. The temperature increase management unit corrects and changes the bias amount by a correction amount obtained by multiplying a value obtained by subtracting the process amount of the slave channel from the process amount of the master channel by a predetermined constant. Control device.

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