Controlled hybrid system safety verification: advanced life support system testbed

In this paper we demonstrate the use of Barrier Certificates as a method to verify safe performance of a hybrid Variable Configuration CO_2 Removal (VCCR) system. We designed a simple nonlinear feedback controller that tracks a desired CO_2 profile, while ensuring that the CO_2 and O_2 concentrations stay within acceptable limits. Though the controller and its switching rules are simple, we do not have a closed form expression for the equilibrium sets of the closed loop hybrid system, and hence Lyapunov stability analysis and computation of region of attraction are impossible. We used Sum-Of-Squares programming approach to construct and verify that our control law provides safe functionality of VCCR system