Most Simulink® Control Design™ PID tuning tools design PID gains based on a linearized plant model. When your plant model does not linearize or linearizes to zero, one option is to design a PID controller based on simulated frequency-response data. Simulink Control Design gives you several ways to do so.
Use Frequency Response Based PID Tuner to design a PID controller using estimated plant frequency responses near the target open-loop bandwidth. Advantages of this approach include:
Frequency Response Based PID Tuner works even if disturbances are present in the plant model.
You can configure the estimation and tuning in one dialog box, making tuning less
complex than using frestimate or Model Linearizer to
estimate the frequency response.
For more information about using Frequency Response Based PID Tuner, see Frequency-Response Based Tuning.
frestimate or Model LinearizerUse the frestimate command or the frequency-response estimation
workflow in Model Linearizer to estimate the plant frequency response over a
range of frequencies that you specify. This approach results in a frequency-response data
(frd) model object that you then import into PID Tuner.
Advantages of this approach include:
You do not have to specify a control bandwidth ahead of time. PID Tuner chooses an initial control bandwidth, which you can adjust to achieve the desired balance between performance and robustness.
You can use the interactive tuning and analysis tools of PID Tuner to
examine the estimated linear response of the tuned system in the frequency domain.
Also, you can use the frd model of the plant for other analysis
tasks.
Depending on the particulars of your model, this approach can be faster, because Frequency Response Based PID Tuner simulates your model twice.
For more information, see: