flight envelope

fault tree

Reliability Engineering & System Safety

In this study, the reliability of the attitude control subsystem (ACS) of a flexible spacecraft in low earth orbit (LEO) is analyzed. Reaction wheels are considered actuators in tetrahedron configuration, whereas thrusters are adjusted as the redundant actuators to improve the reliability, as well as to de-saturate the reaction wheels. Based on the designed structure for ACS actuators, reliability block diagram (RBD) is proposed. A novel concept, Failure Assessment Logic Model (FALM), is proposed based on simulation methods. FALM can be employed to extract Failure Assessment Logic Table (FALT). FALT describes the relations between failure of components and the whole system failure. FALT enables the identification of critical components of the ACS for designers. By detecting these critical components and the system sensitivity to specific actuator failure, it is possible to optimize or find strategies to have a more robust design.

Failure assessment logic model (FALM): A new approach for reliability analysis of satellite attitude control subsystem