Control systems perspective on safety critical systems

In this paper we examine the connection between safety critical systems and their `loss-of-control´. Varied factors can lead to unsafe situations and traditional approaches to design of safety critical systems using real or analytical redundancy are not sufficient to examine possible recovery mechanisms. We make an argument that it is important to link the `loss of control´ mechanism to underlying dynamics. We provide a perspective which links analysis of such systems to the regulator theory. We then illustrate a practical approach for control of such systems under nominal and off-nominal operation. We take examples from switched, nonlinear systems to make the case that while it may not be possible to eliminate all the causes of `loss-of-control´ a better understanding of underlying mechanisms can lead to better protection schemes and automated recovery techniques for safety critical systems.