五面体可展桁架单元展开特性分析

为满足大型空间桁架结构太空在轨装配的需要，根据五面体可展桁架单元可以组合成多种类桁架结构的特点，设计了一种五面体可展桁架单元，发射到太空后用于桁架结构的组装。为分析五面体可展桁架单元的运动特性，利用螺旋理论对该五面体可展桁架单元进行了自由度分析；采用了D-H坐标变换方法对该五面体可展桁架单元进行了运动学分析，并推导了展开过程的运动学方程；采用拉格朗日法对五面体可展桁架单元进行了动力学分析，给出了展开过程的动力学方程。分析结果表明，该五面体可展桁架单元展开过程中自由度为1；推导的运动学公式曲线结果与Adams仿真软件的仿真结果高度吻合，能很好地描述该结构的展开运动过程；增大扭簧的刚度对展开的运动参数变化趋势没有明显影响；节点的加速度不仅与扭簧的驱动力有关，还和节点位置和速度有关。在展开后期，节点位置和节点速度对节点加速度的影响比较明显。

Unfolding characteristics analysis of pentahedral deployable truss unit

According to the characteristic that pentahedral deployable truss units can be combined into various types of truss structures, a pentahedral deployable truss unit was designed to solve the space on orbit assembly of large space truss structures. The pentahedral deployable truss units were used for truss structure assembly after launching into space. In order to analyze the kinematic characteristics of pentahedral deployable truss unit, the degree of freedom of pentahedral structure was analyzed based on the constrained screw theory. Kinematics analysis on the pentahedral structure was carried out by using D-H coordinate transformation method, and the kinematics equation for the deployment process was acquired. The Lagrange method was used to analyze the structure dynamics and the dynamics equation for the deployment process was obtained. Analysis results show that the degree of freedom of the pentahedral deployable unit is 1. The deduced kinematics equation result is highly consistent with the simulation results of Adams simulation software, which can fully describe the structure deployment movement process. Increasing the torsion spring stiffness has less effect on the changing trend of the parameters. The joint acceleration is related not only to the driving force of the torsion spring, but also to the joint position and the joint speed. In the late stages of deployment, the influence of position and velocity on acceleration is obvious.