How to prevent integration windup when actuators are saturated using anti-windup methods

I have a model implementing a PID controller that exhibits a lot of overshoot. I have already specified the upper and lower saturation output limits. I used the PID Tuner app to calculate controller gains that are supposed to produce a controlled signal with minimal overshoot. Why does my model continue to exhibit higher overshoot than predicted?

Answer 1

[MathWorks Support Team]

When you specify saturation output limits and the controller calculation exceeds the specified output limits, the PID controller block will hold the output at the specified limit. However, the integrator output can continue to grow (integrator windup), increasing the difference between the block output and the sum of the block components. Even though the PID controller block's output is bounded, the integral output remains unbounded.

If the sign of the input signal never changes, the integrator continues to integrate until it overflows. The overflow value is the maximum or minimum value for the data type of the integrator output.

To combat these effects an anti-windup method should be used. The PID controller block offers two methods, back calculation, and clamping. Documentation on these two methods can be found below:

https://www.mathworks.com/help/simulink/slref/pidcontroller.html#mw_8008046a-81c5-4ae0-9fd7-3834478483b3_sep_mw_5efedc1d-6cb6-4ad6-ab2f-d4d47d933c70

An example of when to implement an anti-windup method is provided below:

https://www.mathworks.com/help/simulink/slref/anti-windup-control-using-a-pid-controller.html