A parametric frequency domain approach to decoupling with coupled rows

This contribution considers the incomplete decoupling of non-minimum phase and non-decouplable systems by static state feedback, where a stable diagonal decoupling is not possible. By introducing a coupled row in the reference transfer matrix, so that one output is affected by several reference inputs, an incompletely decoupled but internally stable closed loop system is obtained. This decoupling problem is solved using a parametric approach to the design of state feedback controllers in the frequency domain. Explicit expressions are derived for the design parameters of the state feedback controller achieving the decoupled reference transfer matrix. A simple example demonstrates the proposed design procedure.