The attitude maneuver dynamics and control strategy for a fuel-filled spacecraft with uncertain inertia and external disturbances are studied. The mathematical model of a three-axis stabilized spacecraft is established based on the law of conservation of momentum, and the liquid fuel inside the partially-filled fuel tank is represented by an equivalent two-mode spring-mass model. The adaptive sliding mode control law is designed for this kind of underactuated system, and the Lyapunov stability analysis guarantees that all system trajectories reach and remain on the sliding surface. Then, the multiple mode input shapers are used to suppress the sloshing of the fluid fuel. The numerical results show good performance and effectiveness of the control strategy.

The problem of robust, angular velocity-free control and fault-tolerant control for liquid-filled flexible spacecraft attitude maneuver subject to unknown external disturbances is investigated. Moreover, state variables measurement uncertainty and actuator failures are explored. The liquid sloshing effect of spacecraft fuel is equivalent to a two-order spring-mass model, and the flexible attachments are equivalent to the Euler–Bernoulli beams. The external disturbance, multiple failures of the output actuator, and the coupled interference caused by liquid sloshing and vibrations of flexible attachments are distinguished as continuous and percussive disturbances. First, a fault-tolerant control method against the percussive disturbances is proposed, and the robustness performance and characteristics of this method are analyzed. Then, both continuous and percussive disturbances are considered to propose a new fault-tolerant control method based on a nonlinear disturbance observer, which is used to estimate the integrated disturbance. The Lyapunov stability theory proves that the proposed control strategy can make the state variables converge to a small neighborhood of the origin in finite time. Finally, the numerical simulation is used to verify the effectiveness and robustness of the proposed control strategy.

The attitude tracking form quaternion measurements for a three-axis stabilized liquid-filled spacecraft are studied under uncertain parametric and external disturbances. The sloshing liquid inside the partially filled liquid tank is equivalent to a spherical pendulum model; thus, coupled dynamic equations are derived using the conservation of moment of momentum. Considering the failure of acceleration sensors, when the angular velocity information cannot be obtained, an adaptive robust backstepping control algorithm is proposed by combining the adaptive backstepping control technique with a passive control algorithm. A nonlinear damping algorithm is introduced to enhance the disturbance attenuation ability and robustness performance against lumped disturbances. Globally uniformly ultimately bounded (GUUB) stability of the entire closed-loop system is guaranteed based on the Lyapunov approach. The comparative simulations show that the control strategy is robust and effective for the spacecraft attitude maneuvers.