PID/spl times/(n-2) stage PD cascade controller for SISO systems

Presents a design technique for a two degree of freedom (2-DOF) control system using PID (proportional-integral-derivative)/spl times/(n-2) stage PD as a cascade controller for an n/sup th/ order plant. It is intended to satisfy both transient and steady state response specifications based on the root locus approach. This controller can be used instead of a conventional PID controller to obtain better performance without relying upon any tuning methods. The overall system is approximated as a stable and robust second order system. The cascade controller gain can be adjusted to meet faster responses with a little or no overshoot. The simulation results show that the desired performances are achieved. The merit of this approach for a plant with uncertain parameters is also shown.