Output-feedback safety-preserving control

Safety verification of control systems is mostly discussed for full-state measurable systems and there are scant results on safety analysis of output-feedback control systems in which the states are partially measurable. This paper proposes a safety-preserving control scheme for output-feedback control systems. We specify a viable tube for the states of an observer (estimated states) based on constraints on the actual states. Furthermore, we discuss the existence of a control input which maintains trajectories of the observer within the viable tube. We prove that a control action which keeps the estimated states inside the specified tube also maintains the actual states within the original set of constraints. Finally, we compare the proposed approach in this paper with a recent technique proposed by Lesser and Abate [1] and show that our approach reduces conservatism.