Rockwell Automation Arena OptQuest Users Guide - Manual (Page 36)

A RENA O PT Q UEST U SER ’ S G UIDE
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V ARIABLE BOUNDS
In many situations, it can be useful to know what effect a constraint has on the optimal
solution and what would happen if the constraint were relaxed or tightened.
OptQuest allows you to define one constraint with varying bounds. The bounds are listed
as a comma-separated list, and any number of bounds can be specified. The bounds do not
need to be even increments. For example:
Var1*3*Var2 >= 600, 800, 1200
The optimization begins with the bound set to the first value and a number of simulations
are run to determine a good solution given this bound. Then, OptQuest uses the next
bound and runs more simulations to determine a new best solution. OptQuest continues in
this manner until all bounds have been checked.
Selecting the objective
You define the goal of the optimization by setting the objective function. OptQuest for
Arena will allow you to define more than one objective, but only one objective can be
used for an optimization. The other objectives are ignored and have no impact on the
optimization.
The Objectives node of the OptQuest tree will contain a sub-node for each objective you
define.
1. To set an objective, you must first be sure that you have checked the Included box of
any desired controls or responses in the respective Controls and Responses edit grids.
2. Then select Add > Objective from the menu or right-click on the Objectives node to
select Add New.
3. When the Objective Editor opens, you may build an objective to be used in your
optimization. The edit fields include Name (to assign a meaningful name to the
objective) and Description (to add optional comments to be saved with the objective).
The tree in the edit window lists all the controls and responses that you checked as
Included in the Control or Response Summary grids. If a needed control or response
doesn’t appear in the tree, go back to the Control or Response Summary grids and
check the item to be included.
To complete the Expression field, click a control or response from the edit tree; it will
be added automatically to the expression. The keypad on the right shows all the
functions that can be used to create an objective expression. The Sum All Controls
button creates an expression that is the sum of all control variables.