Simulink Control Design™ - MathWorks

Simulated Response Does Not Match PID Tuner

Response

When you run your Simulink model using the PID gains computed by PID Tuner, the

simulation output differs from the PID Tuner response plot.

There are several reasons why the simulated model can differ from the PID Tuner

response plot. If the simulated result meets your design requirements (despite differing

from the PID Tuner response), you do not need to refine the design further. If the

simulated result does not meet your design requirements, see “Cannot Find Acceptable

PID Design in Simulated Model” on page 7-213.

Some causes for a difference between the simulated and PID Tuner responses include:

• The reference signals or disturbance signals in your Simulink model differ from the
  step signals that PID Tuner uses. If you need step signals to evaluate the performance
  of the PID controller in your model, change the reference signals in your model to step
  signals.


• The structure of your model differs from the loop structure that PID Tuner designs
  for. PID Tuner assumes the loop configuration shown in the following figure.

As the figure illustrates, PID Tuner designs for a PID controller in the feedforward

path of a unity-gain feedback loop. If your Simulink model differs from this structure,

or injects a disturbance signal in a different location, your simulated response differs

from the PID Tuner response.

• You have enabled nonlinear features in the PID Controller block in your model, such as
  saturation limits or anti-windup circuitry. PID Tuner ignores nonlinear settings in the

Simulated Response Does Not Match PID Tuner Response