A partial model matching design of robust 2DOF PID controller for time-delay systems

This paper presents a design method of robust PID controller with two degrees of freedom (2DOF PID controller) for SISO plants with a time-delay and parametric uncertainty based on the partial model matching (PMM) approach. It is assumed that the adjustable parameters of the 2DOF PID controller are chosen so as to minimize the two performance indices for step reference and disturbance responses which maximized by the plant parameters belonging to a given bounded set. Thus the design problem is for mulated as a multi-objective minimax optimization problem, which is solved by new genetic algorithm (GA). A novel feature of the present paper lies in the exact robust stability check for time-delay systems without using approximant. Numerical examples show the effectiveness of the present approach.