A Robust Approach to Multirate Controller Design using Eigenstructure Assignment

This paper presents a new method for the design of constant gain digital controllers for multirate systems with a multiple input/fixed output sampling rate configuration. The technique is based on full-state feedback pole placement. Two main problems are addressed; the adverse effects of intersample cross-coupling and the high amplitude control signals that normally result from a multirate feedback structure. The trade-off between these two factors is outlined and a method for minimising each as a design parameter is considered. An example demonstrates the conflicting design objectives of the multirate feedback control problem.