Attitude Dynamics and Control of Spacecraft with Multiple Liquid Propellant Tanks

This paper focuses on the dynamics and control of spacecraft with multiple liquid propellant tanks. The liquid slosh dynamics are included by using an improved moving pulsating ball model. The moving pulsating ball model is an equivalent mechanical model that is capable of imitating the liquid reorientation process, especially for large-amplitude slosh. This model is improved by incorporating a static capillary force and an effective mass factor. The improvements are validated with previously published experiment results. The spacecraft attitude maneuver is implemented by the momentum transfer technique. The designed feedback control strategy is demonstrated to be efficient and robust for the coupled liquid-filled spacecraft system. For the two-tank system, two eccentric cases of concern are an asymmetric tank arrangement and an unbalanced propellant mass distribution in the two tanks. The effects of the two eccentric cases on sloshing torque and control torque are investigated. Some conclusions obtained are useful in the overall design of liquid-filled spacecraft.