Disturbance observer-based finite-time attitude maneuver control for micro satellite under actuator deviation fault

Precise and fast attitude maneuvers are a requirement in many future space missions. However, the actuator deviation fault of micro satellite is inevitable, which affects the precision of spacecraft pointing. To overcome this difficulty, this paper presents a novel attitude control scheme to compensate the actuator deviation fault and achieve the finite-time attitude maneuver. Moreover, the proposed control scheme is constituted by an outer attitude tracking loop and an inner angular velocity tracking loop according to dynamic features of micro satellite. In the outer loop, a novel virtual control law, namely a desired angular velocity command, is developed, under which the finite-time attitude tracking can be achieved. Furthermore, in the inner loop, an effective composite controller which consists of a terminal sliding mode controller and a finite-time disturbance observer (FTDO) is proposed. The aim of composite controller is to ensure that the angular velocity can track the virtual control law in finite time, where the FTDO is designed to estimate and compensate the actuator deviation fault in the feed-forward channel. Finally, simulation results are conducted to demonstrate the effectiveness of the proposed control scheme.