Position and Attitude Model-Based Thruster Fault Diagnosis: A Comparison Study

International audienceThis paper deals with performance and reliability evaluation of a fault diagnosis scheme based on two distinct models to detect and isolate a single thruster fault affecting a chasing spacecraft during rendezvous with a passive target in a circular orbit. The analysis is conducted in the frame of a terminal rendezvous sequence of the Mars Sample Return mission. A complete description of a robust residual generation design approach based on eigenstructure assignment is presented. Unknown time-varying delays, induced by the thruster drive electronics and uncertainties on thruster rise times, are considered as unknown inputs. Particular novelty of the work is a new method for estimating the unknown input directions used to enhance the robustness properties of the diagnosis scheme. Monte Carlo results from a high-fidelity industrial simulator and carefully selected performance and reliability indices allows us to evaluate the effectiveness of both schemes. The obtained results reveal that the proposed fault diagnosis scheme based on a position model is a justified competitor to the conventionally used attitude model-based scheme