Dynamics And Control Of Solar Sail Spacecraft

The development of space technology has been pushing the steps of aerospace ex-ploration. The manned space flight has been gradually entering the space station stage in our country, the deep space detection has realized the mission of "flying around the moon-falling on the moon-returning to the Earth", and the Mars exploration has been already in steady progress. With the expansion of deep space detection range, fuel consumption has become the restricted factor of the development of traditional space-craft which relies on chemical propulsion. Therefore, some novel propulsion, such as electric propulsion, nuclear propulsion, laser propulsion, solar sail propulsion and mi-cropropulsion, arise at the historic moment. Solar sails, propelled by sunlight pressure can provide a continuous low-thrust for the spacecraft. With the advantages of less fuel consumption continuous thrust and higher payload mass ratio, the solar sail becomes an ideal spacecraft for deep space exploration. The study of solar sails abroad is as-cendant. In 2010, the Japanese IKAROS realized the accelerated flyby of Venus for the first time in the world, which deeply pushed the engineering application of solar sailing. Focusing on the application research requirement in China, the dynamics and control of solar sail is the theoretical basis for research on China’s solar sail application, which has great significance.Compared with conventional spacecraft, the features of solar sail spacecraft in-clude the intense coupling and nonlinear relationship between the attitude dynamics and its flexible structure such as the large-scale sail film and booms. Namely atti-tude adjustment will induce flexible structural vibration, thereby affect the spacecraft’s thrust magnitude and direction. While most of the research of attitude dynamics in existing works is based on rigid model, this paper is mainly focused on rigid-flexible coupling attitude dynamics modeling and control of solar sail spacecraft, an attitude robust a-controller was designed, the asymptotic tracking of the target attitude angle and the robust vibration suppression of flexible structures were achieved with the output saturation constraints.In recent years, the research and application of libration point orbit are growing rapidly. Represented by solar sail spacecraft and solar electric propulsion spacecraft, the orbital dynamics of libration point of continuous small thrust spacecraft has the non-affine, nonlinear character, combined with the complexity of the deep space environ- ment, the orbit of the controller robustness, reliability and anti-interference ability put forward higher requirements. Existing research shows that it is difficult to achieve high precision, long time station-keeping and formation flight through pulse control. This paper studied the artificial libration point orbital dynamics of solar electric propulsion, and put forward an active disturbance rejection station-keeping control and an active disturbance rejection formation flight control of unstable orbits around libration points for the first time. This method was designed by using the system input and output rather than the model and was adequate for station-keeping and formation flight of unstable orbits in the presence of system uncertainties, initial injection errors, solar radiation pressure and perturbations of the eccentric nature of the Earth’s orbit.Compared with the libration point station-keeping control of solar electric propul-sion spacecraft, the control of solar sail is achieved by adjusting the two attitude angles and sails’reflectivity to indirectly realize the light pressure three axis component con-trol, so the design of station-keeping controller is more difficult. This paper studied the solar sail artificial libration point orbital dynamics, and put forward an active distur-bance rejection station-keeping control of unstable orbits around libration points. By using the system input and output rather than the model, through the design of dif-ferential trackers, extended state observers and nonlinear closed loop feedback control laws and by adjusting the two attitude angles and sails’reflectivity, an active distur-bance rejection station-keeping controller is proposed. This method is adequate for station-keeping of unstable orbits in the presence of system uncertainties, initial in-jection errors, solar radiation pressure and perturbations of the eccentric nature of the Earth’s orbit.However, there is a strong constraint relationship between the solar sail light pres-sure and solar sail attitude, solar sail can’t get sun pressure from opposite direction of incident light, objects covered cases is also unable to obtain pressure acceleration. Therefore, solar sail is faced with great challenges to perform more complex space ap-plications. For example, the relay satellite of artificial L2 point Halo orbit to the moon of China’s Chang’ e-4 tasks, solar sail can’t get sun pressure from lunar occultation area, the orbit will be easily out of control. Hybrid solar sail propulsion is the fusion of solar sail propulsion and solar electric propulsion, which gives full play to the ad-vantages of the two kinds of propulsion. This paper studied the sail libration point station-keeping and formation flight of hybrid solar sail propulsion, and put forward an active disturbance rejection station-keeping control and an active disturbance rejec-tion formation flight control of unstable orbits around libration points for hybrid solar sail propulsion, which achieved the independent problem of dynamics model, and real-ized high precision libration point station-keeping and formation flight with unknown model.