Abstract
Singular perturbation methods are used to exhibit the asymptotic structure of the transfer function matrices of discrete-time tracking systems incorporating linear multivariate plants which are amenable to fast-sampling error-actuated digital control. It is shown that these results greatly facilitate the determination of controller matrices which ensure that the closed-loop behaviour of Buch discrete-time tracking systems becomes increasingly ‘ tight ’ and non-interacting as the sampling frequency is increased. These general results are illustrated by designing a fast-sampling error-actuated digital controller for a chemical reactor.