An optimized relation between Ti and Td in Modified Ziegler Nichols PID controller tuning

This paper suggests an optimized tuning strategy for PID controller by selecting a factor α which relates integral time with derivative time. Modified Zeigler Nichols Method (MZN), Bode-integrals and Iso-damping are well known methods for tuning of PID parameters in meeting the desirable objectives. All these methods make use of different relationship between T_i and T_d instead of using the relationship T_i = 4T_d as suggested in Modified Ziegler Nichols method. The new control strategy suggests a methodology for proper selection of α. Here the selection of was optimally carried out by minimizing ITAE using Particle Swarm Optimization (PSO) and Genetic Algorithm (GA). The effectiveness of the scheme has been illustrated by considering some typical systems.