Robust Compensation of Discrete-Time Plants using 2-Degrees-of-freedom 2-Periodic Controller

摘要

It has been observed in literature that a 2-periodic controller assumed in a (controller) canonical form may achieve, by virtue of its loop-zero placement capability, improved loop robustness in respect of compensating an unstable, discrete-linear-time-invariant, non-minimum-phase, SISO plant. Unfortunately, outputs thus yielded contains unacceptable amount of ripples that persists even at steady-state. This paper revisits the 2-periodic compensation problem by considering a 2-degree-of-freedom configuration and shows that such controllers can be used to eliminate the steady-state output ripples. A generalized two stage algorithm involving only linear algebraic steps to obtain the controller parameters is also presented.