连杆驱动的欠驱动机器人手指研究与样机研制

The robotic hand design with underactuated finger mechanism (UFM) has the feature of easy-control and easy-operation, and has the ability of adapting its shape by wrapping grasped objects with various shapes and sizes. However, Tendon-actuated mechanisms can be easily built with compact architectures but they can exert only small grasping forces. Underactuated hands with linkage mechanism currently reported in some papers and patents have the disadvantages of complex, big volume and difficult on built and maintain. On the other hand, the methods on analysis and design for UFM still mainly belong to bio-inspired or trial and error methods. Although some literatures are presented on the aspect of design, grasp stability, contact force characteristics, grasp characteristics, etc. of the underactuated finger, the theoretical methods on analysis and design is deficient. For developing underactated finger with compact structure and big grasping force, on the basis of some preliminary works, the project focus on the research of deduce method of equivalent mechanism of underactuated mechanism, and then proposes the analysis and design methods of UFM based on the equivalent mechanisms. The project also researches on the complete analysis methods of grasping stability, and then proposes the rules and methods on designing elastic elements of UFM. Besides, the project should develop and build a novel kind of linkage UFM. The researches of this project has important theoretical significant on the aspect of theoretical analysis and design methods for UFM. The planned novel kind of underactuated finger should has the feature of compact structure, big grasping force, and easy operation, and has broad application prospect in the field of industrial manipulator, humanoid robot, prosthetic limbs, and space robot, etc.

采用欠驱动手指机构的灵巧手控制与操作简单，能自适应抓取不同形状和尺寸的物体，但腱驱动等方式实现的欠驱动手指较难实现大的抓持力。目前见诸文献的各种连杆式欠驱动多指手又存在机构复杂、体积大、制造维护难等缺点。而且欠驱动手指机构的设计与分析主要还是通过仿生或试凑，分析与设计理论有所研究但还很欠缺。为实现结构紧凑、大抓持力的欠驱动拟人手指，本项目在前期研究的基础之上，研究推导欠驱动机构等效机构的方法，并提出基于等效机构的欠驱动手指机构分析与设计方法。研究考虑欠驱动手指机构本身稳定性的抓持稳定性全面分析方法，提出欠驱动手指机构弹性元件的参数设计理论与方法。提出并研制一种新型的连杆式欠驱动机器人手指机构。项目研究在欠驱动手指机构的分析与设计方法方面具有重要的理论研究意义。所实现的结构紧凑、抓持力大、操作简单的新型欠驱动机器人手指，在工业机器人、拟人机器人、人体假肢及航天机器人等领域都有广泛的应用前景。

腱驱动等方式实现的欠驱动手指较难实现大的抓持力，各种连杆式欠驱动多指手存在机构复杂、体积大、制造维护难等缺点。为实现结构紧凑、大抓持力的欠驱动拟人手指，本项目完成了以下研究。（1）提出了一种新型的全转动关节欠驱动手指机构。所提出的8连杆全转动关节欠驱动手指机构，包括1个电机及其减速器、8个连杆、8个旋转关节、2个弹簧。（2）提出了一种基于最小阻尼原理推导欠驱动手指机构在不同阶段下的等效机构，进而基于等效机构实现运动学分析的方法，可以方便地求解欠驱动手指机构的运动学，手指机构有较大的运动空间和平滑均匀的抓物轨迹。（3）完成了欠驱动手指机构详细的运动学与静力学仿真分析。设计的全转动关节欠驱动手指可实现均匀且连贯的抓取。其抓取物体的直径范围是手指直径的0.106到0.851倍之间，手指用一般的小型电机进行驱动可产生5倍于人手的抓持力，可以产生较大的抓持力，具有较大的抓取范围。（4）提出了一种欠驱动手指机构尺寸的优化设计方法，采用拉格朗日乘子法进行优化问题求解，完成机构尺寸的优化设计。（5）提出了一种弹性系数的设计指标与设计方法，实现了弹簧的优化设计，并对设计方法和设计结果进行了仿真分析和验证。（6）完成了一个欠驱动手指的机加工样机和一个3D打印样机。形成了图纸一套，并完成了一台手指样机的加工和装配制作。为降低成本和提高制作效率，对所设计的手指零件进行了适用于3D打印的重新设计，并按照2：1的比例，采用3D打印机打印零件，装配完成了一个尺寸放大了的手指样机。项目研究在欠驱动手指机构的分析与设计方法方面具有重要的理论研究意义。所实现的结构紧凑、抓持力大、操作简单的新型欠驱动机器人手指，在工业机器人、拟人机器人、人体假肢及航天机器人等领域都有广泛的应用前景。