Specifications

Test Controller Robustness
3-49
Copy Accurate Model. Rename the copy Perturbed Model, and set its Plant option to
CSTRp. Thus, both scenarios use the same controller, which is based on the CSTR model,
but the Perturbed Model scenario uses a different model to represent the “real” plant.
This tests the controller's robustness to a change in plant parameters.
Robustness Test, Accurate Plant Model Scenario
Simulate the two scenarios. Robustness Test, Accurate Model (1) and Perturbed Model
(2) shows the output responses. As expected, setpoint tracking degrades when the model
is inaccurate, but performance is still acceptable.
The disturbance rejection appears to improve with the perturbed model. This is a
consequence of the perturbations used. The gain for the T/C
Ai
output/input pair is about
15% smaller in the CSTRp model, which has two beneficial effects: the actual impact of
the disturbance is reduced, and the controller is aggressive because it expects a larger
impact.