Dynamic Characteristics Analysis And Control Of A Flexible Space Solar Power Satellite

With the development of the aerospace industry,space missions are increasingly complicated,and spacecraft sizes are getting larger and larger.Large space structure spacecraft is huge in size,flexible in structure,exhibiting more complex dynamics,and has complex attitude / orbital / structure coupling effects.In this paper,a large-scale flexible space solar power satellite is taken as the research object,a high-precision dynamic model is established and the system dynamics characteristics are analyzed.The orbital,attitude,vibration motion evolution under high-order gravitational forces,as well as the attitude and vibration control of the space solar power satellite are simulated.Firstly,for the flexible space solar power satellite with a central flexible body and flexible appendixes,the hybrid coordinate method and the assumed modal method are used to describe the flexible system.The dynamic model of the flexible multi-body system is established based on the Kane’ equation.Secondly,the high-order gravitational forces and dynamic evolution of large flexible space solar power satellite are analyzed.In order to obtain an accurate model of such system,the analytical expressions of the gravitational force,gravity gradient torque and modal force are investigated.They are expanded to the fourth order in a Taylor series with the elastic displacements considered.It is assumed that the deformation of the structure is relatively small compared with its characteristic length,so that the assumed mode method is applicable.In this paper,the higher-order moments of inertia and flexibility coefficients are given,and a method of obtaining high-order invariants to speed up the computational efficiency is proposed.The comprehensive dynamics of a large flexible SPS and its orbital,attitude and vibration evolutions with different order gravitational forces,gravity gradient torques and modal forces in geosynchronous Earth orbit are performed.Then,the classic direct adaptive control theory including linear simple adaptive control(SAC)method,and nonlinear simple adaptive control method are studied.Under the effect of adaptive control law,the closed-loop system is globally asymptotically stable.Finally,the problem of simple adaptive control about attitude stabilization and vibration suppression of a flexible space solar power plant is studied.For the flexible space solar power satellite that satisfies the small-angle and the circular orbit assumption,the almost strictly positive real(ASPR)of the spacecraft system is verified when the spacecraft velocity plus the scaled displacement term are as the output of the controlled plant.The nonlinear simple adaptive attitude stabilization and vibration suppression controller is proposed,and system is perfect output tracking of the ideal trajectory which validates the correctness of the model.