Parameter Analysis of DDE-Based PID Controller Tuning Method

The PID controller tuning method based on desired dynamic equation is analyzed on its close-loop control performance and stability. The stable region calculation method for DDE-based PID controller is proposed based on Nyquist stability criterion and open-loop frequency response. Then the influence of tunable parameter k on set point tracking error is analyzed when the order of controller does not consist with the relative degree of process. Simulation indicates that for the linear system with relative degree unknown or higher than two, the tracking error decreases with the growth of parameter k initially and increases afterwards, so an optimal parameter k exists, but the scaling factor l could expand the feasible scope of k largely.