Specifications

Design Controller Using the Design Tool
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In general, if your plant model includes unmeasured disturbance inputs, the toolbox
default strategy will assume that they are dominant and sustained, as in the above
example. This forces the controller to include an integrating mode, intended to eliminate
steady-state error.
If the plant model contains no unmeasured input disturbances, the toolbox assumes
sustained (integrated white noise) disturbances at the measured plant outputs.
If there are more measured outputs than unmeasured input disturbances, it assumes
sustained disturbances in both locations according to an algorithm described in the
product's online documentation.
In any case, the design tool displays the assumptions being used.
To modify the estimation strategy in the OutputSteps controller, do the following:
• Click the Input Disturbances tab. Set the disturbance Type to White, and its
Magnitude to 0.
• Click the Output Disturbances tab. For the T output, set the disturbance Type to
Steps, and its magnitude to 1.
This reverses the default assumptions, i.e., the OutputSteps controller assumes that
sustained disturbances enter at the plant output rather than at the unmeasured
disturbance input. The InputSteps controller is still using the original (default)
assumptions.
Next, select the first scenario in the tree. Rename it Disturbance 1, set its Duration
to 30, define all setpoints as constant zero values, and define a unit-step disturbance in
the unmeasured input, C_A_i. If necessary, set its Controller option to InputSteps .
CSTR Disturbance 1 Scenario shows the final Disturbance 1 scenario.