7自由度冗余绳驱动机械臂运动分析及仿真

针对传统机械臂负载自重比小、臂身惯量大、人机交互安全性弱等问题,对绳驱动机械臂的结构、绳驱关节耦合、冗余运动学等方面进行了研究,创新设计了一种新型7自由度冗余绳驱动机械臂。采用绳索间接驱动前端4个关节自由度,作为位置控制;采用电机直接驱动腕部关节3个自由度,作为姿态控制。利用绳索将驱动力从基座电机传递至机械臂关节处,实现驱动机构后置;对绳驱关节耦合问题进行分析,建立了电机-关节耦合映射关系;利用位姿分离方式,结合加权最小范数法,进行机械臂逆运动学冗余位置求解。仿真结果表明:耦合映射关系建立正确,冗余运动学求解准确高效,为绳驱机械臂结构优化、动力学建模奠定了基础。

Kinematics analysis and simulation of the 7 DOF redundant cable-driven manipulator

Aiming at the problems of low load-to-weight ratio, high inertia, and weak physical human-robot interaction for the tradi-tional manipulator, cable-driven manipulator was researched on structure, joints coupling and redundant kinematics. A novel 7 DOF redundant cable-driven manipulator was designed. The first 4 DOF were driven indirectly by cables for the position control. The distal 3 DOF of the wrist joint were directly driven by motors for the pose control. Motion and force were transmitted by cables from actuators on the base to joints, which achieved the postposition of driving system. A mapping between motor angle and joint angle was established after analyzing the effect of cable coupling in the kinematics. A method, combining the position-pose separation and the weighted least-norm solution, was used to solve the redundant inverse kinematics. The simulation results indicate that the cou-pling mapping is correctness and the kinematics solution is accurate and efficient, which lays the foundation of structural optimiza-tion and dynamics modeling of the cable manipulator.