Spacecraft formation control in 6DOF based on finite-time control and disturbance observer

In this paper, a composite control method, consisting of a feedforward compensation part based on disturbance observer (DOB) and a feedback regulation part based on finite time controller, is proposed for 6DOF spacecraft formation control. The design of the composite controller can be divided into two steps: firstly, a continuous finite time controller is designed to stabilize the closed-loop spacecraft formation control system to a set of two equilibria in finite time in the absence of disturbances; secondly, considering the presence of external disturbances, a DOB is introduced to estimate unknown disturbances. The dynamic and disturbance rejection performances of the closed-loop spacecraft formation control system can be improved. A numerical example is provided to demonstrate the effectiveness of the proposed approach.