The 4-parameter controller: a linear, time-varying treatment

An extension of the 4-parameter controller configuration given by Nett (1986) to the case of linear, time-varying systems is given. These results include a complete parameterization of all stabilizing controllers for a given linear, time-varying plant. The results, while not limited to the lumped parameter case, are illustrated by considering linear, finite dimensional, time-varying systems with state space representations {A(t), B(t), C(t), D(t)}. In addition, a controller design example is provided.