An observer based controller design with disturbance feedforward framework for formation control of satellites

In this paper, a bespoke sliding mode nonlinear observer and a linear controller framework is proposed for achieving robust formation control of a cluster of satellites in the case of a circular reference orbit. Exploiting the structure of the satellite dynamics, a nonlinear observer is proposed based on super-twist sliding mode ideas. The observer estimates the states and any unknown bounded disturbances in finite time. The stability properties of the observers are demonstrated using Lyapunov techniques. A distributed controller, based on the estimated states and the relative position output information, depending on the underlying communication topology, is proposed. A polytopic representation of the collective dynamics which depends on the eigenvalues of the Laplacian matrix associated with the communication topology is used to synthesize the gains of the proposed control laws. A simulation example is used to demonstrate the efficacy of the proposed approach.