Servotracking for a class of multivariable systems with parasitics

In this paper we show that the reduced-order controllers obtained by Porter (1976) and Porter and Tsingas (1978) for asymptotic tracking of constant reference inputs and polynomial-type reference inputs respectively for a class of singularly perturbed multivariable linear lime-invariant plants are special cases of a more general controller derived from multivariable servomechanism theory. These controllers essentially consist of a servocompensator, a stabilizing control law and a reduced-order observer.