An analysis package comparing PID anti-windup strategies

Abstract

This article describes software developed in SIMULINK that enables the behavior of feedback control systems with actuator saturation and PID controllers to be evaluated. The software, which is part command- and part menu-driven, allows a choice of four PID controllers using different integral wind-up strategies and transfer function entry of the actuator and plant dynamics. Most realistic control systems contain nonlinearities of some form. One nonlinearity commonly found in control systems is a saturating element. If integral control is applied to such a system to eliminate steady state error, an undesired side effect known as integrator windup may occur when large setpoint changes are made. This effect leads to a characteristic step response with a large overshoot and a very high settling time. To avoid this situation, many different anti-windup strategies have been suggested. This article discusses a software package that has been developed in the SIMULINK/MATLAB environment to investigate and compare the performance of four different anti-windup implementations for PI or PID controllers. The software is partially menu-driven and enables the user to easily enter his own actuator and plant transfer functions to study the performance with the different controllers. >