Tracking and disturbance rejection for an uncertain system using fast output sampling

Abstract

It is shown how a recently proposed sampled-data, multi-rate output feedback controller can be designed to realise the effect of robust state feedback, so that when applied simultaneously to a family of linear plants, the closed-loop eigenvalues are retained. This is not possible when a Luenberger observer is used to realise state feedback. The multi-rate control law proposed here is useful because it allows to utilise previously developed LMI methods for robust state feedback design when the full state is not available for feedback. A practical design example is presented, and experimental results show that, using the same state feedback design, the multi-rate controller gives performance superior to that achieved with an observer.