Rockwell Automation Arena OptQuest Users Guide - Manual (Page 30)

A RENA O PT Q UEST U SER ’ S G UIDE
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logic would simply increase the value from that starting point. As long as this is taken into
consideration when viewing the results, this is perfectly correct.
However, if the control is set by OptQuest then immediately changed by the control logic,
then OptQuest is expecting responses based on the control values it supplied, but the
actual responses will reflect the changed control values.
For resources, OptQuest establishes the initial capacity. Keep the following considerations
in mind:
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If your resource follows a schedule (instead of a fixed capacity) and you want it to be
an optimization control, then you should use a variable to identify the maximum
capacity of the resource. The schedule would then set the resource capacity by multi-
plying quantities by this variable.
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Logic that adjusts the resource capacity in the model should make relative adjustments
from the maximum resource capacity (again, stored in a variable), rather than setting
absolute capacities, since the optimization will establish different values of the
capacity.
Remember also that controls can be either discrete or continuous.
E
XCLUDING VARIABLES
Any variable in an Arena model can be used as a control in an optimization model. The
list of variables and resources appears in OptQuest’s Controls tree node. However, the
model may contain many variables that will not be selected for optimization and having
all these appear in the Controls node is unnecessary. Excluding them from this window
makes the resulting list more concise.
To exclude a variable, go to the Variables element (or the user-created module where the
variable was originally defined). In the Control Category field, type Exclude. (There is
also a field called Response Category; typing Exclude in this field excludes the variable
from OptQuest’s Responses tree node.) The default is Include.
Responses
The objective function and constraints may depend on outputs of the simulation, and
therefore, they are based on responses. These responses—including tallies, outputs,
Cstats, Dstats, counters, and variables—are defined in the Arena simulation model.
E XCLUDING RESPONSES
Any variable in an Arena model can be used to create an objective function or a constraint
expression in an optimization model. The list of variables and other responses appears in
OptQuest’s Responses tree node. However, the model may contain many variables that