The Livingstone Model of a Spacecraft Power System

Livingstone is a qualitative, discrete, propositional logic-based, reusable inference engine. The model built in this paper is used by Livingstone in order to implement a diagnostic system for integrated vehicle health management (IVHM) for spacecraft power system. We couple compositional constraint-based modeling with the concurrent transition systems used to model reactive software. The model is composed of component transition systems and some connections between component transition systems. Component transition system consists of a set of modes with explicit transitions between modes. Each mode is associated with a set of constraints that describe the component´s behavior in that mode. This model not only includes static information, but also provides dynamic information, and can be computed with efficiently in real time. Some experiments done on spacecrafts have demonstrated that this qualitative model can be used for diagnosis of a real-world system with continuous sensor values.