Point Targeting of Multisatellites via a Virtual Structure Formation Flight Scheme

This paper proposes a formation flight control scheme for spacecraft based on the virtual structure approach. The virtual structure approach treats the entire formation as a virtual rigid-body structure. With this approach, the geometric relationship among the spacecraft can be maintained during a maneuver. The information on the geometric relationships is used to complete the formation flight mission. Using rotational kinematics and rigid-body dynamics, the virtual structure formation algorithm calculates the reference position and attitude command to perform the synchronized maneuvers required to point to the desired target. The adaptive sliding mode control law is adopted to make the system track the reference command generated by the formation algorithm. An adaptive sliding mode controller, which combines the merits of the adaptive control scheme and the sliding mode control scheme, is proposed and used to make the spacecraft follow the specified position and attitude command. The stability of the proposed controller is analyzed by using the Lyapunov stability theorem, and a numerical simulation is performed to verify the effectiveness of the proposed formation algorithm and the adaptive sliding mode controller.