绳索驱动腕部并联康复机构设计与逆运动学分析

Design and Inverse Kinematics Analysis of Wrist Parallel Rehabilitation Mechanism:A Rope Driven-based Method

针对现有腕部康复机构运动范围小,存在柔顺性和舒适性差等问题,提出一种新型绳索驱动、压缩弹簧支撑的柔性并联腕部康复机构。机构定平台、动平台由三根绳索和压缩弹簧连接,弹簧用来模拟腕骨与韧带复合体,起支撑并限制与掌骨相对应的动平台运动;动平台模拟掌骨末端,定平台模拟桡骨和尺骨末端;三根绳索模拟肌肉来驱动并联机构。考虑弹簧轴向位移以及柔性问题,基于有限转动张量法和力与力矩平衡分析方法,构建系统逆运动学数学模型,得到运动学和静力学联合求解的非线性方程组。通过对机构模型分析,完成0~75°下各绳索长度和拉力的数值求解。通过仿真与试验得到人体腕部生理运动空间和机构有效工作空间,验证了机构的合理性和分析方法的正确性。所提出的求解方法对康复机器人和绳索驱动并联机构设计具有积极的促进作用。

To tackle the problem of small moving range, poor compliance and comfort level in human wrist joint rehabilitation mechanism, this paper proposes a novel cable-driven and compression spring supported flexible parallel wrist rehabilitation mechanism. The fixed platform and the moving platform of the mechanism are connected via three ropes and a compression spring,the spring is used to simulate the carpal and ligament complex to support and limit the movement of the moving platform corresponding to the metacarpal bone. The mobile platform serves to simulate the end of the metacarpal bone of the wrist joint, the static platform is used to simulate the end of the radius and the ulna. Then, the three ropes serve to simulate wrist muscles to realize the driving control of the parallel mechanism. Considering the axial displacement and flexibility of the spring, based on the finite rotation tensor method and the force and moment balance analysis method, construct the inverse kinematics mathematical model of the system, obtain a system of nonlinear equations jointly solved by kinematics and statics. Through the analysis of the mechanism model, the numerical solution of the length and tension of each rope under 0-75°is completed. Through simulation and experiment,the physiological movement space of human wrist and the effective working space of the mechanism are obtained, then the rationality of the mechanism and the correctness of the analysis method are verified. The proposed solution method has a positive effect on the design of rehabilitation robots and cable-driven parallel mechanisms.