Wu Changcheng, Song Tianci, Wu Zilong, Cao Qingqing, Fei Fei, Yang Dehua, Xu Baoguo, Song Aiguo
College of Automation Engineering, Nanjing University of Aeronautics and Astronautics, Nanjing 211100, China.
School of Instrument Science and Engineering, Southeast University, Nanjing 210096, China.
Micromachines (Basel). 2020 Dec 30;12(1):33. doi: 10.3390/mi12010033.
To realize the adaptive grasping of objects with diverse shapes and to capture the joint angles of the finger, a multi degree of freedom (DOF) adaptive finger for prosthetic hand is proposed in this paper. The fingers are designed with three joints. The maximum rotation angle of the finger joints is 90°. The angle at which the finger joints bend can be captured. Firstly, the prototype design, forward kinematics and force analysis of phalanges are described in detail. In order to achieve an adaptive motion pattern similar to that of the human hand, this paper investigates the optimization of the torsion spring stiffness coefficient so that the metacarpophalangeal (MCP) joints, proximal interphalangeal (PIP) joints, and distal interphalangeal (DIP) joints of the bionic finger meet a motion ratio of approximately 3:3:1. Then, in order to realize the joint angle measurement in the process of grasping an object, the mechanical-sensor integrated finger joint is designed, and the composition, angle measurement principle and measurement circuit are introduced in detail. Finally, joint angle measurement, movement law evaluation and object grasping experiments are performed to verify the validity of the designed finger. The experimental results show that the root-mean-square (RMS) of the DIP, PIP and MCP angle measurement errors are 0.36°, 0.59° and 0.32°, respectively. The designed finger is able to grasp objects with different shapes stably.
为实现对不同形状物体的自适应抓取并获取手指关节角度，本文提出了一种用于假肢手的多自由度自适应手指。手指设计有三个关节，手指关节的最大旋转角度为90°，能够获取手指关节弯曲的角度。首先，详细描述了指骨的原型设计、正向运动学和受力分析。为实现类似于人手的自适应运动模式，本文研究了扭簧刚度系数的优化，以使仿生手指的掌指关节、近端指间关节和远端指间关节满足约3:3:1的运动比例。然后，为实现抓取物体过程中的关节角度测量，设计了机械-传感器集成手指关节，并详细介绍了其组成、角度测量原理和测量电路。最后，进行了关节角度测量、运动规律评估和物体抓取实验，以验证所设计手指的有效性。实验结果表明，远端指间关节、近端指间关节和掌指关节角度测量误差的均方根分别为0.36°、0.59°和0.32°。所设计的手指能够稳定地抓取不同形状的物体。
