线驱动柔性机械臂的运动学分析

The Kinematics Analysis of A Cable-driven Soft Robotic Manipulator

与传统的由连杆和关节构成的刚性机械臂不同,设计的柔性机械臂无任何刚性结构,外围驱动装置通过嵌在机械臂内部的拉线与柔性机械臂相联系,控制拉线长度的变化量即可调整柔性机械臂末端执行器的位置和姿态。柔性机械臂由弹性材料制作而成,拥有无穷多个自由度,在确保了高安全性、高灵活性的同时,随之也带来运动学和动力学建模复杂、控制难度大等问题。基于分段常曲率的假设,提出了一种运动学建模方法,通过建立3个空间,即驱动空间、虚拟关节空间、任务空间,以及两个映射,即驱动空间-虚拟关节空间映射、虚拟关节空间-任务空间映射,将拉线长度的变化量和柔性机械臂末端执行器的位置和姿态关联起来。仿真结果表明,提出的线驱动柔性机械臂的运动学模型,能较为真实地模拟柔性机械臂在拉线长度变化时的形态,计算末端执行器的位置和姿态。

Differ from traditional rigid manipulators which consist of links and joints, the soft robotic manipulator designed in this paper has no any rigid structure. The peripheral actuation system connects with the soft robotic manipulator by the cables embedded in the manipulator, and the position and orientation of the end-effector of the soft robotic manipulator can be adjusted by controlling the length variables of the cables. The soft robotic manipulator is made of elastic materials and has infinite degree of freedom, which make it to be highly safe and dexterous. However, at the same time, some difficulties rise such as building kinematic and dynamic models and motion control. Based on piecewise constant curva^are hypothesis, a kinematic model is proposed. In this method, three spaces namely actuation space, virtual joint space, task space and two mappings namely actuation space-virtual joint space mapping, virtual joint space-task space mapping are established to obtain the relationship betw^e,a th ~ length variables of the cables and the position and orientation of the end-effector of the soft robotic manipulator. The simulation results demonstrate that the kinematic model of the cable-driven soft robotic manipulator can truly simulate the shape of the ＇manipulator and compute the position and orientation of the end-effector when cable lengths vary.