小天体附着装置地形被动自适应机构设计与优化

Design and Optimization of Terrain Passive Adaptive Mechanism for Small Celestial Body Attachment Device

面向在小天体非确知、非结构性表面安全稳定附着的技术需求,设计了一种可同时在偏移和扭转共6个自由度上实现对抓附区域星表地形被动自适应的串并混联机构,并完成了其工作空间优化。首先,针对附着过程中附着装置与星表拟合球面不居中问题,提出了一种3-RSPS串并混联被动自适应机构设计方案;进而,采用修正的G-K公式计算了该机构的自由度,基于空间位置矢量法推导出其逆运动学模型,并通过虚拟样机仿真验证了逆运动学模型的正确性;最后,采用数值搜索方法完成了该机构的定姿态工作空间分析和基于NSGA-II算法的多目标优化。结果表明:相较于目前广泛应用的3-SPS并联机构,本文所设计的星表地形自适应机构的全局工作空间提高了40.9%,优化后,又进一步提高了21.3%,可适应更加崎岖陡峭的小天体星表地形,具有较好的工程价值。

Aiming at the technical requirements of non-ascertained and non-structural surface safe and stable attachment of small celestial bodies,a series-parallel hybrid mechanism is designed,which can realize passive self-adaptation to the terrain of the star catalog in the grasping area on a total of six degrees of freedom of offset and torsion at the same time,and its workspace optimization is completed.Firstly,a design scheme of 3-RSPS serial-parallel hybrid passive adaptive mechanism is proposed to solve the problem that the attachment device and the star table fitting sphere are not centered during the attachment process.Furthermore,the modified G-K formula is used to calculate the degree of freedom of the mechanism,and the inverse kinematics model is derived based on the spatial position vector method.The correctness of the inverse kinematics model is verified by virtual prototype simulation.Finally,the numerical search method is used to complete the fixed attitude workspace analysis and multi-objective optimization based on NSGA-II algorithm.The results show that compared with the widely used 3-SPS parallel mechanism,the global workspace of the star terrain adaptive mechanism designed in this paper is improved by 40.9%.After optimization,it is further improved by 21.3%.It can adapt to the more rugged and steep small celestial terrain and has good engineering value.