Augmented system approach to measurement-based robust tracking

This paper considers the robust tracking problem using an augmented system approach. Our results extend previous full-state results to observer-based feedback. The system matrix is assumed to contain time-invariant uncertainty. Two cases are considered. In the first, the tracked output is available for feedback and a controller can be obtained by considering a robust stabilization problem. The resulting control law can be applied to polynomial reference signals of known order and results in zero steady-state error. In the second case, where the tracked output is not available for feedback, our approach is restricted to step references, and the steady-state error is nan-zero, although bounded by a prescribed value. To obtain the controller, a robust H-infinity problem must be solved rather than a robust stabilization problem.