Abstract: The hazardavoidance control for a liquidfilled lunar lander is considered in this paper. A threedimensional spherical pendulum is used for the mechanical equivalent model of the liquid sloshing. Considering the threedimensional dynamics combined of spherical pendulum and rigid body of spacecraft, the vector dynamics equations are given as well as the projected coordinates of each vector variables. With these equations, a combined position and attitude controller is designed, which can stabilize the position and attitude of the rigid body. Moreover, this controller only depends on the position and attitude of rigid body, and independent of liquid sloshing angle or sloshing dynamics. It thus leads to the convenience for the practical applications. The stability of closedloop system is given via LaSalle invariance principle, and the control parameters are suggested for the asymptotical stability of the system when the reference vertical attitude is chosen. Finally the effectiveness of the proposed control is validated via numerical simulations.

Key words: liquid sloshing, combined position and attitude control, spherical pendulum, liquidfilled spacecraft