A New PSO-PID Tuning Method for Time-delay Processes

A novel method is proposed to design PID controllers for stable first order and high order systems with time delay. Using a first-order Pade approximation for the transport delay, this method is based on developing a certain relationship between the coefficients of corresponding powers of s in the numerator and those in the denominator of the closed loop transfer function for FOPTD processes. Such relationship between these coefficients is searched using particle swarm optimization (PSO) algorithm. Then, the approach is applied to high order systems by approximating them to FOPDT models. The proposed method originates from processes with small time delay; however, it is still effective even if the time delay is quite large. Simulation results show that the proposed method gives significantly better dynamic performances than IMC-PID method and the formula proposed by Smith, C.A. et al.