Research On Attitude Control And Fuel Sloshing Suppression Of Liquid Filled Spacecraft

As a kind of widely used aerospace energy, the sloshing of liquid fuel inevitably exerts negative impact on the stability of spacecraft attitude. Liquid-filled spacecraft is a kind of solid-liquid mutual coupling system, the dynamics modeling research relates to fluid mechanics and classical mechanics, the liquid-filled spacecraft is a class of complex nonlinear, strong coupling and non-minimum phase system, these characteristics are always the keys and difficulties in control research.Firstly, this paper introduces the research background and significance, and summarizes the state-of-the-art of the dynamics modeling research and attitude control technology of liquid-filled spacecraft.Secondly, for a class of liquid-filled spacecraft maneuvers in the two-dimensional plane, based on the simplified model which adopts the equivalent control inputs, a sliding mode observer design approach is proposed to estimate the angle of fuel slosh effectively, the observer indirectly estimates the angle of fuel slosh based on the measurement of attitude angle, therefore the states of sloshing can get close to the real value within a certain error range based on boundary theorems and error analysis. This method effectively solves the problem that liquid sloshing states in actual cannot be measured, which has a certain engineering significance.Thirdly, this paper directly designs a sliding mode controller of liquid-filled spacecraft system. By compared with the simplified model which uses equivalent control inputs, there are no conversion errors between equivalent controller and actual controller. Therefore, the sliding mode controller is able to stable the attitude of liquid-filled spacecraft quickly, and the system also has strong robustness. Then, in view of the actual control inputs of spacecraft, which are the thrust and torque appears unknown faults, this paper adopts adaptive method to estimate the unknown faults information, in the meantime, the fault-tolerant sliding mode controller is also designed to stable spacecraft attitude.Finally, the purpose of the last part is to establish a mathematical model of the three-axis liquid-filled spacecraft in the three-dimensional surface. First of all, the research is based on the coordinate systems of global inertia, orbit, spacecraft body and the single pendulum model, in these frames of references, the moment of momentum of spacecraft system with respect to the center of mass can be calculated by using angular momentum theorem. Based on the theorem and the Lagrange equations, the paper derives the whole dynamic equations and completes the modeling research.Finally, a sliding mode attitude control method is designed for the three-axis liquid-filled spacecraft, and it can ensure the on-orbit stability of the three-axis liquid-filled spacecraft...