Abstract Flexible actuators composed of twisted and coiled polymers (TCPs) can provide excellent performance such as high power-to-weight ratios for robotic hands. This paper presents a systematic methodology for the kinematic design of the TCP-actuated finger mechanism. The finger mechanism has a redundant serial-parallel hybrid topology, which is designed for grasping in space. The local and global performance evaluation indices concerning the dexterity and the extreme value of the velocity are first proposed for the optimal design of mechanism dimensions. Moreover, the flexibility matrix, mapping the stiffnesses of flexible elements including active TCP actuators and passive springs into the end-effector's stiffness, is established, and thus the extreme value of the deformation is obtained as the optimization objective function. Therefore, optimal passive stiffness coefficients are achieved by the genetic algorithm. Finally, the prototype of three-fingered robotic hand with the proposed finger mechanism and the control strategy based on TCP power-strain model were developed. Comparisons of experimental and theoretical data validated the kinematic design of the finger mechanism.

中文翻译：

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由扭曲和盘绕聚合物驱动的串并联混合指机构的运动学设计

摘要 由扭曲和卷曲聚合物 (TCP) 组成的柔性致动器可以为机械手提供出色的性能，例如高功率重量比。本文提出了 TCP 驱动手指机构运动学设计的系统方法。手指机构具有冗余串并联混合拓扑结构，专为空间抓取而设计。针对机构尺寸的优化设计，首次提出了关于灵巧性和速度极值的局部和全局性能评价指标。此外，建立了柔性矩阵，将包括主动 TCP 执行器和被动弹簧在内的柔性元件的刚度映射到末端执行器的刚度，从而获得变形的极值作为优化目标函数。所以，最佳被动刚度系数是通过遗传算法实现的。最后，开发了具有所提出的手指机构的三指机械手原型和基于 TCP 功率-应变模型的控制策略。实验和理论数据的比较验证了手指机构的运动学设计。