Sliding-mode adaptive attitude controller design for spacecrafts with thrusters

In this study, the authors propose two non-linear attitude controllers, mainly consisting of the sliding-mode attitude tracking controller and the sliding-mode adaptive attitude tracking controller, for spacecrafts with thrusters to follow the predetermined trajectory in outer space by use of employing the spacecraft´s attitude control. First, the attitude model and non-linear controllers of the attitude control system of a spacecraft are established and derived, considering the external forces suffering from the gradient torque in a gravitational field because of universal gravitation, the optical torque because of solar shining and so on, to utilise the sliding-mode and/or adaptive control theory for designing the non-linear attitude controllers. Also, we consider the variation of moment inertia matrix of a spacecraft during the whole flying course to analyse their influences for the practical controller design as the conditions of limitation and correction. Simultaneously, the authors use both the adaptive control theory and the sliding-mode control to estimate parameters and eliminate disturbances of the attitude control system. Accordingly, the non-linear attitude controllers of a spacecraft are designed while the spacecraft is flying. Finally, the authors employ the Lyapunov stability theory to fulfil the stability analysis of two non-linear controllers for the overall non-linear attitude control system. Extensive simulation results are obtained to validate the effectiveness of the proposed attitude controllers.