Research On The Coupled Attitude-Orbit Dynamic And Control Of The Large Flexible Solar Sail Spacecraft

A solar sail is a new type of spacecraft that is propelled by solar radiation pressure.Because the lowest fuel consumption, the solar sail is widely used in the deep spaceexploration and some other missions which are difficult for the ordinary spacecraft.To reduce the launch cost and achieve the highest thrust, the solar sail must employlarge-scale, lightweight structures, which cause the solar sail to be large moment ofinertia and highly flexible. The thrust of the solar sail could change with its attitude, sothere is strongly coupled effect of orbit and attitude for the solar sail. Considering theout-plane deformation and the deduced foreshortening deformation of the solar sail, acoupled and reduced dynamic model is established with hybrid coordinate method andvirtual power principle. Base on this dynamic model, the coupled effect of orbit, attitudeand elastic vibration for the solar sail is analyzed through the dynamic analysis in thegeosynchronous orbit and large-eccentricity elliptical orbit.When the flexible structures are in motion, the vibration of the structure influencesthe dynamic characteristics of the entire structure and the control, and the influence issignificant, especially when the structure undergoes large-angle maneuvering. So thecoupled effect of attitude and elastic vibration is studied when the solar sail has singledegree of freedom and large-angle maneuvering. The large-amplitude vibration offlexible structure and the sustained vibration of attitude can be eliminated with the inputshaper. And it also can be achieved by the control of tip-mounted vanes.With the coupling effect of the orbit and the attitude included, a displaced solarorbit is designed for the solar sail. Including the additional influence of the flexibility,the coupled orbit-attitude control with the orbital and attitude feedback for the solar sailis researched.The solar polar orbit is presented by NASA, which is used for the observation ofthe sun. Based on the coupling effect of the orbit and the attitude, a transfer trajectoryfrom an earth-centric orbit to a solar polar orbit is designed. With theory oftime-optimal control, the transfer mission can be achieved by the design of the attitudeangles, but it is based on an assumption of the attitude changing transiently. Thesequences of attitude angles are generated by the time-optimal control and PD control is used to achieve attitude tracking control. The influence of attitude control and theflexibility of the solar sail in the mission are studied. In the long-term mission, theimportance of the solar pressure disturbance torques is also studied. At last, the controlof tip-mounted vanes is compared with centric torque control.