Applications of modern optimal control theory to environmental control of confined spaces and life support systems: Part 4—control of systems with inequality constraints imposed on state variables☆

Abstract The necessary conditions for optimum of a dynamic system whose state variables are constrained by certain inequality conditions are derived by applying a variational technique. The conditions are employed to determine the optimal policy for the room or cabin temperature control of a life support system. The system consisting of an air-conditioned cabin subject to an inpulse heat disturbance and a heat exchanger acting as a control element is again studied. The flow of air in the cabin is characterized by the two completely stirred tanks-in-series (2 CST's-in-series) model. A constraint is imposed on the room temperature which has to be higher than a certain value for some physical or biological reasons.