Anti-Windup PID Example

This is an example of PID control of a 1/s plant. The concept of anti-windup integration and its importance is brought out here. It is mandatory that all integrators in safety critical control systems have anti-windup protection. This is taken from the best practices (https://www.cso.nato.int/pubs/rdp.asp?RDP=RTO-TR-029). This example brings out the reason why this is required. It compares the PID performance with and without anti-windup. There is an example where the anti-windup integrator is implemented incorrectly as an integrator followed by a saturation block. The correct implementation is the integrator output being limited and this limited output fed back as a state. However, it is seen that the mistake in implementation is done very often.