Distributed 6-DOF Coordination Control for Spacecraft Formation With Disturbance, Unmeasurable Velocity, and Communication Delays

In this paper, the problem of distributed 6-DOF coordinated control for spacecraft formation is investigated. The dynamics of each spacecraft consisting of relative attitude and position motions are modeled into a unified Euler-Lagrange formulation. The formation consists of one virtual leader and n spacecrafts, and the information switching among the formation members is described by a directed graph. A distributed coordination control protocol is proposed to guarantee the stability of the spacecraft formation in the presence of external disturbances, unmeasurable attitude angular and position velocities, and time-varying communication delays based on the backstepping technique using time-delayed information. Further, to decrease the communication frequency of the spacecraft formation flying system, an event-triggered distributed coordination strategy is also developed to solve the 6-DOF coordinated control problem for spacecraft formation. The stability analyses of the obtained control algorithms are conducted through the Lyapunov method. Finally, the effectiveness and the ability of massive reducing the frequency of communication times of the proposed control scheme are illustrated through numerical simulations.