Application of fractional pid controller to single and multi-variable non-minimum phase systems

Abstract

A non-minimum phase system has the unique characteristic of undershoot or over and undershoot based on the number of zeros and the location of zeros in the systems. A fractional PID controller has the ability to capture more dynamics, as there are two more parameters to tune compared to a traditional PID controller. In this paper, a fractional PID controller is designed for single and multi-variable non-minimum phase systems. A simple optimization method for the tuning of a fractional PID controller has been applied. Six different single variable plants were simulated covering different cases of non-minimum phase systems. Simulation results showed that zero crossing is reduced to a greater extent by fractional PID controller as compared to traditional PID controller for single variable systems. This paper also provides experimental validations for design and tuning of a fractional PID controller for a multi-variable non-minimum phase quadruple-tank system. Fine tuned experimental results agree well with simulation results, thereby validating the applicability of the fractional PID controller for multi variable non-minimum phase systems.