Use the PID Tuner to tune two-degree-of-freedom PID Controller (2DOF) blocks to achieve both good setpoint tracking and good disturbance rejection.
A two-degree-of-freedom PID compensator, commonly known as an ISA-PID compensator, is equivalent to a feedforward compensator and a feedback compensator, as shown in the following figure.
The feedforward compensator is PD and the feedback compensator
is PID. In the PID Controller (2DOF) block, the setpoint
c determine the
strength of the proportional and derivative action in the feedforward
compensator. See the PID Controller (2DOF) block
reference page for more information.
PID Tuner tunes the PID gains
N. For the PID Controller (2DOF) block,
the tuner also automatically tunes the setpoint weights
You can use the same techniques to refine and analyze the design that
you use for tuning one-degree-of-freedom PID controllers.
To tune a PID Controller (2DOF) block in a Simulink® model:
Double-click the block. In the block parameters dialog box, click Tune.
PID Tuner opens, linearizes the model at the model initial conditions,
and automatically computes an initial controller design that balances
performance and robustness. In this design, PID Tuner adjusts the
necessary, as well as the PID gains. To see the tuned values of all
Analyze and refine the initial design, described in Analyze Design in PID Tuner. All the same response plots, design adjustments, and options are available for tuning 2DOF PID controllers as in the single-degree-of-freedom case.
Verify the controller design, as described in Verify the PID Design in Your Simulink Model.