Rockwell Automation Arena OptQuest Users Guide - Manual (Page 35)

4 • S ETTING U P AND O PTIMIZING A M ODEL
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A constraint is non-linear if the mathematical expression contains a response or a non-
linear term. Non-linear constraints require a simulation to be run to determine constraint
feasibility.
Constraints Editor
The Constraint Editor lets you build a constraint expression to use in your optimization.
When added, the Constraints node of the OptQuest tree will contain a node for each
constraint you define. Selecting the Constraints node displays the defined Constraints
Summary grid in the right-hand window.
To add each new constraint:
1. Right-click on the Constraints node and choose Add New. The Constraints Editor will
display the Controls and Responses that have been included in the optimization.
2. In the fields at the bottom of the edit window, enter a Constraint Name,
Description (optional), and an Expression, which can combine controls and
responses that are in the tree.
When you click a Control or Response from the edit window tree, it will be added
automatically to the expression. The keypad on the right shows all the functions that
can be used to create a constraint expression. When you roll your pointer over a
function, the appropriate syntax and a function description are displayed. If a control
or response doesn’t appear in the tree, go back to the Control or Response Summary
grid and check the item as included.
The Sum All Controls button creates an expression that is the sum of all control
variables.
The logical operator “or” can be used to combine two or more expressions in a single
constraint.
3. Click Check Expression to verify the validity of the expression. Errors are reported in
a message box and an error indicator will appear next to the expression box. You can
see the error text by letting your pointer hover over the error indicator.
4. Click OK to accept the constraint edits. The expression will be checked for validity
when OK is clicked. If the expression is invalid, it will appear in yellow in the
Constraint Summary grid.
If you do not want to add constraints to your optimization model, then just leave the
Constraints Editor empty.