Design And Optimization Of Solar Sail Spacecraft Coupled Orbit-attitude

With its non-propellant, infinite specific impulse, rich tasks and other advantages, solar sail most likely to become the main force in the deep space exploration. Design and optimization of solar sail coupled orbit-attitude have a vital significance and practical engineering value for the design of solar sail system. In this dissertation, the solar sail coupled orbit-attitude was considered based on a systematic study of the displaced orbit design and contro l, the transfer orbit design and optimization, flexible solar sail dynamics and control, and a tool software was developed. The main contents are as follows:Firstly, solar sail heliocentric displaced orbit and attitude coupled design and control were studied. Based on displaced orbit stability condition, the passive control law of constant attitude was designed and it meets the stability condition. The simulation result shows that the control law makes all the displaced orbits stable, but the radius and height of the displaced orbit varies periodically within the vicinity of the design values. As a comparison, LQR was applied to active displaced orbit control. The simulation result shows that the control law can achieve a higher orbit control accuracy. Expressions between orbital elements of displaced orbit and Kepler orbit were given based on spatial relationship, together with patched displaced orbits conditions.Solar sail transfer orbit and attitude coupled design and optimization were studied. The control law of maximum energy change rate was applied to sail escape Earth’s orbit. The effect of non- ideal sail and shadow of Earth to orbit and time was studied. Minimum- time interplanetary orbit transfers for solar sail base on genetic algorithm were explored. Then the effectiveness of the algorithm was validated by the transfer from Earth to Mars. For transfer orbit flying to heliocentric displaced orbit, the control angles and the transfer time were parameterized by dividing the control angles into several segments. The genetic algorithm was used to obtain initial guess, and then taken it into the SQP. The simulation result shows that the method can give the transfer orbit to displaced orbit quickly and meet the constraints. Global optimization method of solar sail gravity assist and solar photonic assist trajectory for interstellar mission was proposed. The simulation result shows that plenty of time could be saved by adding Jupiter gravity assist, though solar sail gains a large velocity with solar photonic assist. In order to enhance the visualization of the solar sail transfer orbit mission scene and improve research efficiency, the sail control forces calculated by the control strategy were added into the STK orbit propagator, which is realized through the STK plug- in coded in MATLAB.Flexible solar sail dynamics and control problems were studied. Sensor configuration, attitude control actuators and controller solutions of sail attitude control system were designed. Sailcraft finite element simulation indicates that the solar sail can be seen as a rigid spacecraft hub plus a flexible attachment model to calculate the coupling coefficient. Hub plus flexible attachment model of flexible solar sail attitude dynamics have a relatively simple dynamic model that can be used for large-scale solar sail flexible attitude dynamics simulation analysis. The simulation result has certain engineering value for the actuator design. Full flexible solar sail coupled orbit-attitude-vibration dynamics model embodies all the characteristics. The simulation results shows the full three-axis model of flexible solar sail position and attitude angles errors are much larger than the rigid model of the solar sail, and reflect the long-term effects of flexible solar sail vibration fo r the mission.Finally, a series of software tools for orbit and attitude coupled solar sail design and optimization are developed, respectively named ―Solar sail spacecraft orbit design and control software‖, ―Solar sail spacecraft attitude control simulation system‖ and ―Global optimization of solar sail gravity assist and solar photonic assist trajectory for interstellar mission software‖. These softwares were introduced in the dissertation, including software function, software architecture and operating instructions. Then part of mission examples were given appropriate instructions. Architecture design, user interface and related operations of the upgrade version of the software, solar sail spacecraft orbit and attitude coupled simulation software were completed.