Attitude And Orbit Control Studies For Solar Sail Spacecraft

Solar sail spacecraft is a new type of spacecraft,which uses the particle nature of light and relies on the huge sail surface to reflect the sunlight to obtain the sunlight pressure as the orbital propulsion,which can get rid of the dependence of traditional spacecraft on limited fuel.It is a key research object in the field of deep space exploration and interstellar voyage.This thesis focuses on the design of the attitude and orbit control system of the solar sail.Focusing on the specific problems of the attitude actuator design,the attitude control law design,and the attitude-orbit couplings studies and controller design in the Earth-Moon-sail three body problem,this thesis proposes solutions and optimization strategy,and deeply studies the fast and effective schemes for the attitude and orbit control.The main contents and innovations are as follows:Aiming at the small control torque provided by the existing attitude control actuator of the roll axis,a new type of actuator is proposed,called Sliding Masses-Moving Panels(SMMP),which can offer the fast and large three-axis attitude control torque.The mathematical model of the proposed actuator is established and the performance analysis is carried out.The control effects of SMMP and the traditional sliding masses/scalable sail are compared and analyzed,which further shows the advantages of the proposed actuator In order to solve the problem of the changed inertia caused by SMMP,a robust adaptive control strategy is proposed in presence of the external disturbances due to solar radiation pressure torque and gravitational gradient torque.The numerical simulation shows that the attitude error of the solar sail can converge to the specified error band under the proposed control strategy.In order to serve the redundancy design of solar sail attitude control system in the future,the effective and fast attitude controllers are designed for two kinds of solar sail attitude control systems,which are equipped with the control boom and the sliding mass-roll axis stabilizer bar(RSB)actuator.An attitude control strategy utilizing a gimbal boom is studied for solar sail.The coupled rigid-flexible model for pitch axis is established with the dynamics of gimbal boom.Due to the difficult detection of flexible information,a novel attitude control law is proposed,where only the rigid state error and its integration are employed.And the asymptotical stabilization condition for the coupled rigid-flexible system is given as well.To suppress vibration of the flexible sail,a path planning method is designed associated with the attitude control law.The numerical simulation shows that the attitude error can quickly converge under the proposed control law.For the three-axis attitude control system of solar sail equipped with sliding masses and RSB,a state dependent equivalent constraint of torque saturation is proposed according to the couplings between attitude control torque and attitude angle as well as the actuator saturation.A finite time robust adaptive controller is proposed for the equivalent torque constraint,inertia uncertainty and unknown solar radiation pressure disturbance torque.The numerical simulation shows that the the proposed control strategy effectively increases the rapidity of the attitude control system of solar sail.The Earth-Moon-sail restricted circular 3-body problem(RC3BP)considering the attitudeorbit couplings of solar sail is studied to serve the special orbit mission of the Earth-Moon system.Aiming the time-dependent artificial Lagrangian points in the Earth-Moon-sail RC3 BP due to the non-autonomous characteristics of the orbit dynamics,the artificial Lagrangian points that only attitude-dependent are solved.For the periodic orbit around Lagrange point,the influence of the non-ideal attitude control performance on its orbital trajectory is analyzed,and the design idea of the attitude control specification is proposed.Finally,the coupled orbitattitude control system is introduced to further compare the differences of orbital trajectory deviations with and without control effort,which shows the necessity of the coupled attitudeorbit control of solar sail.Based on the analysis of the attitude-orbit couplings in Earth-Moon-sail RC3 BP,the condition of the restricted three body problem is relaxed by taking account of the inclination between Earth’s motion plane and Moon’ motion plane.The coupled orbit-attitude model of solar sail is established by selecting appropriate reference coordinate system.Focusing on the orbit-attitude couplings,a cascade triple-loop control structure is proposed.The complex orbit attitude coupling control problem is decomposed into three relatively independent control problems with the proposed control structure.Meanwhile,considering the torque saturation of attitude control,orbital modeling error,the matched and mismatched disturbances,and parametric uncertainties,an effective and fast robust adaptive control law is proposed.The numerical simulation shows that the solar sail spacecraft can track the desired orbit quickly under the proposed control scheme.