Controller design for Unstable FOPTD Plants based on Sensitivity

Abstract

Abstract This paper presents a new method for designing PID controller for unstable first order plus time delay (FOPTD) plant models. The controller design problem is solved by pole zero cancellation and keeping the minimum distance of the Nyquist curve of the open loop transfer function from the critical point to a specified value. Analytical expressions correlating the controller parameters and the plant model parameters are also provided for ease of use. Simulation results are given to show the performance that can be achieved.