Distributed Fixed-Time Attitude Tracking Consensus for Rigid Spacecraft Systems under Directed Graphs

Distributed fixed-time attitude tracking consensus is investigated in this letter for rigid spacecraft systems, with a directed communication graph containing a single leader which is the root of a directed spanning tree. The evolution of each follower is subject to unknown but bounded disturbances. First, a distributed fixed-time observer with heterogeneous coefficients is presented for each follower allowing cooperative estimation of the state of the leader at each follower. Then an observer-based fixed-time tracking protocol is designed to make the state of each spacecraft exactly track the state of the leader by the aid of backstepping technique. Finally, a simulation example is conducted to verify the analytical results.