Research On On-orbit Assembly Sequence Planning Of Space Solar Power Station

With the rapid development of space technology,spacecraft required for space missions are gradually characterized by huge structures,huge scales and huge build sizes.Due to the limitation of launch vehicle thrust and loading space,it is difficult to launch large space structures into orbit and unfold them at one time.The way of multiple launches into orbit and robotic assembly in orbit has become one of the ideal construction methods for large space structures,which has gained extensive attention and research in academia.Assembly sequence planning is one of the key steps in the process of space in-orbit assembly.Large space structures are assembled in orbit with the structural characteristics of low intrinsic frequency,facing the complex space environment of microgravity and various space disturbances.A specific assembly sequence can help to increase the intrinsic frequency of the structure during the assembly process,avoid structure-control frequency coupling,and attenuate the structural vibration during the assembly process.Assembly sequence planning of large space structures is an important topic in in-orbit assembly research,and a reasonable assembly sequence can effectively improve the efficiency and accuracy of space in-orbit assembly.In this paper,we take the space solar power station transmitting antenna as the research object,and launch a study on the assembly sequence planning problem,which mainly includes the following aspects.(1)Taking the in-orbit assembly of multi-rotating joint space solar power station as an example,the basic process of space in-orbit assembly is described,and the research object of in-orbit assembly sequence planning in this paper is clarified.Several basic coordinate systems are established,and the general steps of finite element modeling are introduced.Considering the assembly characteristics that the antenna geometric configuration changes incrementally with the assembly and the structural dynamics model changes temporally with the assembly during the assembly process,a finite element modeling method based on raw and dead cells is proposed.Compared with other modeling methods,this method is simpler and eliminates the complicated process of repeated numbering of finite element nodes.(2)Combining the characteristics of ant colony algorithm and antenna structure assembly process,an assembly sequence planning method based on ant colony algorithm is proposed,and example simulation is carried out to verify the effectiveness of the sequence planning method.According to the discrete variation of the structure model in the antenna structure assembly process,the whole assembly task is decomposed by the number of assemblies and transformed into the optimization problem of the assembly position.According to the constant model and the optimization index from the perspective of the intrinsic frequency of the structure,several geometric constraints in the assembly are determined,and a complete mathematical model of the antenna structure assembly sequence planning based on the ant colony algorithm is given.The effectiveness of the proposed sequence planning method based on the ant colony algorithm is verified by a simulation example.(3)The characteristics of the ant colony algorithm for finding the optimum are analyzed,and an assembly sequence planning method based on the hybrid ant colony-clone immune algorithm is proposed by the hybrid clone-immune algorithm.The new optimization criterion is constructed by considering the two optimization objectives of maximizing the structural fundamental frequency and minimizing the structural attitude drift simultaneously with multiple objectives.The complete mathematical model of antenna structure assembly sequence planning based on the hybrid ant colony-clone immunity algorithm is given.The effectiveness and efficiency of the proposed new algorithm are verified by simulation examples and comparisons between different algorithms.