Simulink Control Design™ - MathWorks

• If you have configured the start/stop signal to begin and end the tuning process at
  specific times, allow the simulation to run long enough to begin the experiment.

Step 6. Stop Experiment and Examine Tuned Gains

The frequency-response estimation experiment ends when the start/stop signal falls.

• If you have configured a manual start/stop signal, end the experiment when the
  signal at the % conv output stabilizes near 100%.


• If you have configured the start/stop signal to begin and end the tuning process at
  specific times, allow the simulation to run through the end of the experiment.

In either case, a conservative estimate for the experiment time is 200/ωc for closed-loop

tuning or 100/ωc for open-loop tuning, where ωc is your target bandwidth.

When you stop experiment, the block computes new PID gains based on the estimated

frequency response of the system and your specified tuning goals. Examine them for

reasonableness. For instance, if you have an initial PID controller, you might expect the

tuned gains to be roughly the same magnitude as the gains of the initial design. There are

several ways to see the tuned gains:

• View the output of the pid gains port of the autotuner block. One way to view this
  output is to connect the output to a Simulink Display block.


• In the block, in the Block tab, click Export to MATLAB. The block creates a
  structure in the MATLAB workspace, OnlinePIDTuningResult. For more
  information about the contents of this structure, see the Closed-Loop PID Autotuner or
  Open-Loop PID Autotuner block reference pages.

Step 7. Update PID Controller with Tuned Gains

The autotuner block can write tuned controller parameters directly to the PID controller

block, if your PID controller is either:

• A Simulink PID Controller block.


• A custom PID controller for which the following conditions are both true:
  
  
  • The custom controller is a masked subsystem.
  
  
  • The PID gains are mask parameters named P, I, D, and N. (You do not need to use
    all four parameters. For example, if you use a custom PI controller, then you only
    need mask parameters P and I.)
  
  
  
  

8 PID Autotuning