When you open PID Tuner, the following actions occur:
- PID Tuner automatically linearizes the plant at the operating point specified by the
model initial conditions, as described in “What Plant Does PID Tuner See?” on page 7-
4. If you want to design a controller for a different operating point, see “Tune at a
Different Operating Point” on page 7-19.
NoteIf the plant model in the PID loop linearizes to zero, PID Tuner provides the
Obtain plant model dialog box. This dialog box allows you to obtain a new plant
model by either:- Linearizing at a different operating point (see “Tune at a Different Operating Point”
on page 7-19). - Importing an LTI model object representing the plant. For example, you can import
frequency response data (frd model) obtained by frequency response estimation.
For more information, see “Design PID Controller Using Estimated Frequency
Response” on page 7-159. - Identifying a linear plant model from simulated or measured response data
(requires System Identification Toolbox software). PID Tuner uses system
identification to estimate a linear plant model from the time-domain response of
your plant to an applied input. For an example, see “Interactively Estimate Plant
from Measured or Simulated Response Data” on page 7-73.
As an alternative, you can exit PID Tuner and use the Frequency Response Based
PID Tuner, which runs simulations to perturb the plant and estimate frequency
responses at frequencies near the control bandwidth. See “Frequency-Response Based
Tuning” on page 7-51.- PID Tuner computes an initial compensator design for the linearized plant model
using the algorithm described in “PID Tuning Algorithm” on page 7-4. - PID Tuner displays the closed-loop step reference tracking response for the initial
compensator design. For comparison, the display also includes the closed-loop
response for the gains specified in the PID controller block, if that closed loop is
stable, as shown in the following figure.
Open PID Tuner