Control Design for a Hybrid Dynamic System: A NASA Life Support System

We consider the control problem of a Variable Configuration CO2 Removal system (VCCR), which exhibits a hybrid dynamical character due to the various configurations/modes in which one could operate the system. The VCCR is part of an overall Air Recovery System of an intended human life-support system for space exploration. The objective of the control problem is to track a desired concentration profile of CO2 in a crew cabin while also ensuring safety in terms of keeping the CO2 and O2 concentrations in the crew cabin within permissible bounds. We present a mathematical programming based control synthesis formulation, as well as a simulation-based hybrid feedback controller. We exploit the problem structure and map the hybrid optimization problem onto a continuous nonlinear program with the aid of an appropriate representation of time and set definitions. We also discuss case studies showing the performance of these controllers during off-nominal and failure conditions.