面向在轨捕获的静电吸附式末端执行器设计理论与实验研究

There is a tremendous need for on-orbit capturing of space target. However, current end-effectors have deficiencies in versatility, misalignment tolerance and flexibility. Therefore, this project proposes a new idea to design the end-effector for on-orbit capturing by using the electrostatic adhesion force in place of the mechanical gripping force. By using a combination of means, such as theoretical analysis, optimization design, experimental studies and other technical means, we firstly attempt to reveal the mechanism of electrostatic adhesion under high vacuum and large temperature difference circumstances from the perspectives of microscopic and macroscopic polarization effect of the dielectrics. Then we establish a theoretical model of electrostatic adhesion considering the high vacuum and large temperature difference circumstances influence factors using the point matching method and the Maxwell stress tensor method. Based on the theoretical model, we attempt to explore a performance optimization method for the adhesion unit on the end-effector. In addition, we study the adaptive surface fitting mechanism between the end-effector and the space target from the two aspects of topology configuration and mechanism deformation. On the basis of the theoretical researches, we develop an electroadhesive end-effector prototype and conduct simulation capturing experiments with it on the ground, and the adhesive capturing performances of the end-effector prototype after adaptive and compliant surface fitting are tested and verified. Finally, a set of design theory and experimental methods of the electroadhesive end-effector for on-orbit capturing are established, which will provide the theoretical and technical support for independent research of the domestic space manipulator and rapid development of the on-orbit capturing technology.

面向空间目标在轨捕获的巨大需求，针对当前常见的末端执行器在通用性、容差性以及灵活性上存在的不足，提出利用静电吸附力取代机械夹持力设计在轨捕获用末端执行器的新思路。综合运用理论分析、优化设计、实验研究等技术手段，从电介质的微观和宏观极化效应两个角度揭示高真空大温差环境下静电吸附的机理，结合点匹配法和麦克斯韦应力张量法建立包含高真空大温差环境影响因素的静电吸附理论模型，以模型为基础探索末端执行器吸附单元的性能优化方法，从拓扑构型和机构变形两个方面研究末端执行器与空间目标之间的表面自适应柔顺贴合机制。在理论研究的基础上，研制静电吸附式末端执行器样机并进行地面模拟捕获实验，测试并验证末端执行器完成表面自适应柔顺贴合后的吸附捕获性能，最终建立一套面向在轨捕获的静电吸附式末端执行器设计理论与实验方法，为我国空间机械臂的自主研发和在轨捕获技术的快速发展提供理论和技术支撑。

本项目面向空间目标在轨捕获的应用需求，针对当前机械指爪类末端执行器在提升通用性、容差性以及灵活性上存在的问题，提出利用静电吸附力取代机械夹持力设计在轨捕获用末端执行器的新思路。基于此，研究高真空大温差环境下静电吸附的机理，考虑电介质材料的电导率，建立了静电吸附力随时间动态变化的吸附模型, 通过研究吸附模型在一个阶跃电压作用下的瞬态响应问题分析了电场和吸附力随时间的动态变化过程并进行了动态吸附实验验证了模型的正确性与计算结果的可靠性；建立了电极板转动时的吸附模型，从电场动态变化的角度探寻了引起吸附力减小的根本原因是电极板转动导致的夹层极化失效，并通过电极板转动时的动态吸附实验验证了理论分析的正确性；研究了吸附单元的性能优化方法与基于丝网印刷技术的静电吸附膜加工工艺方法，提出了一种机电一体化设计的正向静电吸附力测量平台，同时对两种新型柔性静电吸附膜还有传统吸附膜在玻璃平板表面上分别进行了实验测试与论证，矫正了之前通过切向静电吸附力与基底的摩擦系数进行简单换算而得到的正向吸附力的准确性；提出了仿鱼鳍结构的表面自适应柔顺贴合机制，并对物理模型进行了结构优化仿真与受力分析，得到了最利于弯曲变形的结构参数；研制了基于仿鱼鳍结构的静电吸附式末端执行器样机并进行了地面模拟捕获实验，验证了该结构对不同材质、不用表面结构目标物体的自适应柔顺贴合能力与吸附能力，量化了该结构的切向吸附力和最大球体抓取尺寸与重量。结果表明，在施加电压分别为0Kv和3Kv条件下，切向吸附力增大了69%，最大球体抓取尺寸从250mm增加到300mm且最大抓取球体质量（200mm尺寸下）增加了25%；最终形成了一套面向在轨捕获的静电吸附式末端执行器设计理论与实验方法，为我国空间机械臂的自主研发和在轨捕获技术的快速发展提供理论和技术支撑。