Applying Active Diagnosis to Space Systems by On-Board Control Procedures

The instrumentation of real systems is often designed for control purposes and control inputs are designed to achieve nominal control objectives. Hence, the available measurements may not be sufficient to isolate faults with certainty and diagnoses are ambiguous. Active diagnosis formulates a planning problem to generate a sequence of actions that, applied to the system, enforces diagnosability and allows to iteratively refine ambiguous diagnoses. This paper analyzes the requirements for applying active diagnosis to space systems and proposes ActHyDiag as an effective framework to solve this problem. It presents the results of applying ActHyDiag to a real-space case study and of implementing the generated plans in the form of on-board control procedures. The case study is a redundant SpaceWire network where up to six instruments, monitored and controlled by the on-board software hosted in the satellite management unit, are transferring science data to a mass memory unit through SpaceWire routers. Experiments have been conducted on a real physical benchmark developed by Thales Alenia Space and demonstrate the effectiveness of the plans proposed by ActHyDiag.