Comparison of robustness between adaptive control and PID control

This paper quantitatively compares adaptive control schemes with PID control scheme from the robustness point of view for parameter variation of a controlled system. The adaptive schemes are model reference adaptive control (MRAC) and adaptive pole placement control (APPC). All the controllers are of discrete-time with and without saturation limit in the control input. The transfer function of the controlled system is taken to be K/[s(1+sT/sub c/)]. It is shown that the adaptive has extremely wider stable range for parameters of K and T/sub c/ than the PID. Adaptive control gives shorter settling time than PID control when the parameters of controlled system varies apart considerably from their nominal values. Moreover, adequate sampling period exists in the adaptive schemes when the control input is limited.<>