Model-invariant safety-preserving control

Employing viability techniques to preserve safety in safety-critical control applications has recently attracted much attention. The techniques rely on a conservative approximation of the viability kernel based on a state-space model of the system. However, in the case where the system's model is uncertain the safety concern has yet to be addressed in the literature. In this work, we are seeking a single control action preserving safety for a set-represented model uncertainty. We define the model-invariant viability kernel for a multi-model uncertainty description. Based on this kernel, we show that under some assumptions, the control action taken based on any model in the model set is capable of preserving safety for the entire set. We propose a model-invariant safety-preserving control input which is the same for all models in the set. We evaluate and discuss the performance of the proposed scheme by applying it to the closed-loop control of anesthesia in which safety is critical.