Main

Main.ControllerTuning History

May 25, 2018, at 07:48 PM by 10.5.113.123 -
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May 25, 2018, at 07:48 PM by 10.5.113.123 -
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* Application tuning
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* [[http://apmonitor.com/wiki/index.php/Main/DbsGlobal|Application tuning]]
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* Manipulated Variable (MV) tuning
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* [[http://apmonitor.com/wiki/index.php/Main/DbsVariable|Manipulated Variable (MV) tuning]]
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* Controlled Variable (CV) tuning
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* [[http://apmonitor.com/wiki/index.php/Main/DbsVariable|Controlled Variable (CV) tuning]]
May 25, 2018, at 07:44 PM by 10.5.113.123 -
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May 25, 2018, at 07:43 PM by 10.5.113.123 -

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August 16, 2017, at 04:14 PM by 173.117.178.94 -

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August 10, 2017, at 05:56 AM by 10.5.113.229 -
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August 10, 2017, at 05:56 AM by 10.5.113.229 -

April 05, 2017, at 08:45 PM by 10.5.113.121 -
** SOLVER
*** 0=Try all available solvers
*** 1=APOPT (MINLP, Active Set SQP)
*** 2=BPOPT (NLP, Interior Point, SQP)
*** 3=IPOPT (NLP, Interior Point, SQP)
July 16, 2016, at 11:34 AM by 66.87.137.245 -
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** COST = (+) minimize MV, (-) maximize MV
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** COST = (+) minimize CV, (-) maximize CV
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** STATUS = turn on (1) or off (0) MV
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** STATUS = turn on (1) or off (0) CV
May 29, 2015, at 02:04 PM by 45.56.3.184 -
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May 29, 2015, at 01:21 PM by 45.56.3.184 -
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In this case, the parameter ''u'' is the manipulated variable and ''x'' and ''y'' are the controlled variables. It is desired to maximize ''x'' and maintain values between 9 and 10. It is desired to maintain values of ''y'' between 2 and 5. For the first 10 minutes, the priority is to maintain the range for ''y'' and following this time period, it is desired to track the range for ''x''. Tune the controller to meet these objectives while minimizing MV movement.
to:
In this case, the parameter ''u'' is the manipulated variable and ''x'' and ''y'' are the controlled variables. It is desired to maximize ''x'' and maintain values between 9 and 10. It is desired to maintain values of ''y'' between 2 and 7. For the first 10 minutes, the priority is to maintain the range for ''y'' and following this time period, it is desired to track the range for ''x''. Tune the controller to meet these objectives while minimizing MV movement.
May 29, 2015, at 01:20 PM by 45.56.3.184 -

May 29, 2015, at 01:18 PM by 45.56.3.184 -
** CV_TYPE = CV type with 1=l_1-norm, 2=squared error
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** CV_TYPE = 1 for l'_1_'-norm and 2 for squared error
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** CV_TYPE = CV type with 1=l_1-norm, 2=squared error
May 29, 2015, at 01:07 PM by 45.56.3.184 -

!!!! Exercise

'''Objective:''' Design a model predictive controller with one manipulated variable and two controlled variables with competing objectives that cannot be simultaneously satisfied. Tune the controller to achieve best performance. ''Estimated time: 2 hours.''

Use the following system of linear differential equations for this exercise by placing the model definition in the file ''myModel.apm''.

Parameters
u
Variables
x
y
Equations
5 * $x = -x + 1.5 * u 15 *$y = -y + 3.0 * u

In this case, the parameter ''u'' is the manipulated variable and ''x'' and ''y'' are the controlled variables. It is desired to maximize ''x'' and maintain values between 9 and 10. It is desired to maintain values of ''y'' between 2 and 5. For the first 10 minutes, the priority is to maintain the range for ''y'' and following this time period, it is desired to track the range for ''x''. Tune the controller to meet these objectives while minimizing MV movement.

!!!! Solution

(:html:)
<iframe width="560" height="315" src="https://www.youtube.com/embed/yw_a9ektOqc?rel=0" frameborder="0" allowfullscreen></iframe>
(:htmlend:)
May 11, 2015, at 02:07 PM by 45.56.3.184 -
** CV_TYPE = 1 for l'_1_'-norm and 2 for squared error
May 11, 2015, at 02:03 PM by 45.56.3.184 -
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** SP = setpoint with CV_TYPE = 2
** SPLO = lower setpoint with CV_TYPE = 1
** SPHI = upper setpoint with CV_TYPE = 1
to:
** SP = set point with CV_TYPE = 2
** SPLO = lower set point with CV_TYPE = 1
** SPHI = upper set point with CV_TYPE = 1
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** TR_OPEN = opening at initial point of traj compared to end
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** TR_OPEN = opening at initial point of trajectory compared to end
May 11, 2015, at 02:01 PM by 45.56.3.184 -

!!!! Common Tuning Parameters for MPC

Tuning typically involves adjustment of objective function terms or constraints that limit the rate of change (DMAX), penalize the rate of change (DCOST), or set absolute bounds (LOWER and UPPER). Measurement availability is indicated by the parameter (FSTATUS). The optimizer can also include (1=on) or exclude (0=off) a certain manipulated variable (MV) or controlled variable with STATUS. Below are common application, MV, and CV tuning constants that are adjusted to achieve desired model predictive control performance.

* Application tuning
** IMODE = 6 or 9 for model predictive control
** DIAGLEVEL = diagnostic level (0-10) for solution information
** MAX_ITER = maximum iterations
** MAX_TIME = maximum time before stopping
** MV_TYPE = Set default MV type with 0=zero-order hold, 1=linear interpolation

* Manipulated Variable (MV) tuning
** COST = (+) minimize MV, (-) maximize MV
** DCOST = penalty for MV movement
** DMAX = maximum that MV can move each cycle
** FSTATUS = feedback status with 1=measured, 0=off
** LOWER = lower MV bound
** MV_TYPE = MV type with 0=zero-order hold, 1=linear interpolation
** STATUS = turn on (1) or off (0) MV
** UPPER = upper MV bound

* Controlled Variable (CV) tuning
** COST = (+) minimize MV, (-) maximize MV
** CV_TYPE = CV type with 1=l_1-norm, 2=squared error
** FSTATUS = feedback status with 1=measured, 0=off
** SP = setpoint with CV_TYPE = 2
** SPLO = lower setpoint with CV_TYPE = 1
** SPHI = upper setpoint with CV_TYPE = 1
** STATUS = turn on (1) or off (0) MV
** TAU = reference trajectory time-constant
** TR_INIT = trajectory type, 0=dead-band, 1,2=trajectory
** TR_OPEN = opening at initial point of traj compared to end

There are several ways to change the tuning values. Tuning values can either be specified before an application is initialized or while an application is running. To change a tuning value before the application is loaded, use the ''apm_option()'' function such as the following example to change the lower bound in MATLAB or Python for the MV named ''u''.

apm_option(server,app,'u.LOWER',0)

The upper and lower deadband targets for a CV named ''y'' are set to values around a desired set point of 10.0. In this case, an acceptable range for this CV is between 9.5 and 10.5.

sp = 10.0
apm_option(server,app,'y.SPHI',sp+0.5)
apm_option(server,app,'y.SPHI',sp-0.5)

Application constants are modified by indicating that the constant belongs to the group ''nlc''. IMODE is adjusted to either solve the MPC problem with a simultaneous (6) or sequential (9) method. In the case below, the application IMODE is changed to simultaneous mode.

apm_option(server,app,'nlc.IMODE',6)