在轨组装空间结构面向主动控制的动力学建模

在轨组装是未来超大型空间结构最有发展潜力的构建方式之一, 组装过程中空间结构尺寸逐渐增长、动力学特性也随之改变, 给结构主动控制任务带来了新的挑战. 针对这一问题, 提出一种在轨组装空间结构面向主动控制的动力学建模方法. 首先, 建立不同类别组装模块的基础模型库, 以用于后续直接调用; 然后, 定义模块的邻接关系矩阵以描述在轨组装过程中空间结构的变化, 并根据在轨组装任务特点, 设计了面向分布式控制的智能组件结构形式; 在有限元建模方法的基础上提出"节点自由度加载"方法, 利用模块的基础模型库与邻接关系矩阵, 分别建立智能组件和空间结构整体的动力学模型, 该模型可随组装的进行同步自适应更新; 最后, 以在轨组装桁架结构为例, 给出组装碰撞冲击下动力学建模与分布式主动控制数值仿真. 结果表明, 在轨组装过程中桁架结构整体的动力学特性有明显的变化, 主动控制非常必要; 基于提出的建模方法, 可高效地建立构型多样的在轨组装空间结构动力学模型; 智能组件的动力学模型在组装过程中可进一步根据邻接关系矩阵限定更新范围, 适用于在轨组装过程中的分布式主动控制系统设计. 

ACTIVE-CONTROL-ORIENTED DYNAMIC MODELLING FOR ON-ORBIT ASSEMBLY SPACE STRUCTURE1)

Subject to carrying capacity of a launch vehicle, on-orbit assembly technology has become one of the most promising solutions for building ultra-large space structures in the future. The size of the space structure is gradually increasing, and the dynamic characteristics are changing during the assembly process, which brings new challenge to the dynamic modelling and structural active control. Aiming at this issue, an active-control-oriented dynamic modelling method for the on-orbit assembly space structure is proposed in this paper. As the on-orbit assembly mission possess high regularity and repeatability, the basic model database is firstly established for different modules to improve the modelling efficiency, including the module type, the assembly interface, etc. In order to describe the varying on-orbit assembly space structure, the adjacent matrices of modules are defined. The form of intelligent component (IC) oriented to distributed control are then designed, taking the characteristics of the assembly task into consideration. Based upon the finite element modelling method, the 'node freedom degree loading' method is proposed to develop the dynamic models of the IC and the whole space structure, which are adaptively updated along with assembly. Finally, the numerical simulation are carried out on the truss structure under the assembly impact, including the dynamics analysis and the distributed vibration control. The simulation results show that the dynamic characteristics of truss structure experience obvious changes during the process, and the active vibration control is necessary; the modelling method proposed in this paper, with the established basic model database and the 'node freedom degree loading', applies to various on-orbit assembly space structure; According to the adjacency relation matrix, the active-control-oriented dynamic models of the IC can be updated in a limited range during the assembly process, which reduces the complexity of control system and is suitable for distributed active control of on-orbit assembly structure.