Abstract

Stringent precision requirements, communication limitations and automated fault accommodation are three important considerations that need to be taken into account in design of formation control of satellites. In this work a more accurate relative state modeling for the attitude dynamics is developed and a semi-decentralized control strategy is proposed that is accomplished by the model predictive control (MPC) scheme. The proposed MPC incorporates the effects of the actuator constraints in design of the control laws. Furthermore, a semi-decentralized active system recovery scheme is proposed that uses on-line fault information to compensate for the identified characteristics losses under actuator fault conditions.

Simulation results for a team of four satellites in formation are presented and the formation precision is compared with the centralized scheme. The results verify that the proposed semi-decentralized strategy yields a quite satisfactory formation performance in a sense that the team behaves similar to a centralized MPC control scheme, however without imposing significant computational complexity that is associated with solving the problem of high dimension with stringent communication requirement as in the centralized scheme.

Moreover, the performance of our proposed semi-decentralized recovery scheme is compared with the centralized recovery scheme subject to the reaction wheel (RW) faults in the attitude control subsystem (ACS) of the formation flying satellites. The proposed semi-decentralized recovery scheme satisfies the formation recovery specifications and also imposes lower fault compensation control effort cost as compared with the centralized recovery scheme. It has been validated through multiple fault severity scenarios.