Research on fault diagnosis approach for spacecrafts based on fuzzy SDG model

The fault diagnosis method based-on signed directed graph (SDG) has better completeness and detailed explanation facility, but lower resolution lowers efficiency of diagnosis, because the cause-effect relationship only by positive and negative influence of directed edge is insufficient, so the novel qualitative model based on integration of the advantage of SDG and fuzzy reasoning is given. The algorithm is presented to search the set of failure source candidates with fuzzy consistent branch by fuzzy reasoning. Furthermore, the candidates in the set is ranked according to the possibility rate defined as the product value of the failure propagation weight and failure rate of the failure source candidates. The primary power system of some satellites was modeled with the approach, the simulation diagnosis results show that the reason algorithm was validated and the diagnosis result improved diagnostic resolution. The approach is feasible to be applied for on-board diagnosis for spacecrafts.