A simple procedure for improving performance of PID controllers

Proportional-integral derivative (PID) controllers are still extensively used in industrial systems. In the literature, many publications can be found considering PID controller design for processes with resonances, integrators and unstable transfer functions. However, due to structural limitations of PID controllers, good closed loop performance cannot be achieved with a PID controller, good closed loop performance cannot be achieved with a PID controller for the aforementioned processes and usually a step response with a high overshoot and oscillation is obtained. The PI-PD controller has been shown to provide very satisfactory closed loop performance for controlling processes with resonances, integrators and unstable transfer functions. This paper introduces a simple approach to get parameters of a PI-PD controller from parameters of a PID controller so that a good closed loop system performance is obtained. Extensive simulation examples are given to illustrate the value of the approach proposed.