一种含闭环支链的新型并联机构设计与分析

为满足航天飞行器壳体套装过程中位姿调整机构刚度大、精度高的要求，对传统的支链结构进行有针对性的改进，设计了一种支链为闭环结构的新型5-U（RRP）S/（8U）PU并联机构，并进行了分析研究。应用螺旋理论计算机构的自由度；建立封闭矢量方程，进行运动学正反解；应用螺旋理论求解机构的全雅可比矩阵；利用杆长约束条件绘制机构的定姿态工作空间；通过求解静刚度矩阵分析机构的刚度随位姿的变化情况；利用软件进行仿真，并与一般机构进行对比。通过分析，验证了该机构的可行性和实际应用价值，为实现航天飞行器壳体套装的自动化奠定基础。 

Design and analysis of a novel parallel mechanism with closed-loop limbs

In order to meet the requirements of high stiffness and accuracy of the position and posture adjusting mechanism in the assembly process of spacecraft shell, a novel 5-U(RRP)S/(8U)PU parallel mechanism with closed-loop limbs, which are improved from conventional limb structure, is proposed and analyzed. The degree of freedom of the mechanism is calculated by screw theory. The positional positive and negative solutions are figured out through establishing the seal vector constraints equation. The complete Jacobian matrix is calculated by screw theory. The fixed posture workspace is drawn by the restrained link length. The changes of mechanism stiffness with the position and posture are analyzed by solving the static stiffness matrix. The software is used to simulate and compare with the general mechanism. Through the above analysis, the feasibility and practical application value are verified, which lays the foundation for the automatic assembly process of spacecraft shell.