变刚度连续型机械臂设计与控制

针对空间机械臂碰撞过程中产生的冲击和破坏问题，提出一种能被动适应碰撞且能保证操作精度的可变刚度丝驱动连续型机械臂。在以超弹镍钛合金丝为支撑脊椎和驱动部件的基础结构上，设计了一种利用温控记忆合金改变关节内摩擦力的变刚度方法。通过运动学分析得到机械臂驱动空间、构型空间和工作空间之间的坐标映射及速度雅克比矩阵，并结合末端位置反馈设计了一个稳定的闭环运动控制器。在检测丝驱动力的基础上提出了一种碰撞识别方法和相应的变刚度控制策略。运动控制和变刚度控制的实验结果表明该连续型机械臂具有良好的运动控制精度和刚度调节能力。

Design and Control of a Continuum Arm with Variable Stiffness

 Considering the impact and damage resulted from the collision of the existing rigid space arms, a variable stiffness tendon-driven continuum arm that can passively adapt to the collisions and ensure the operation accuracy is proposed. Based on the structure with material of super-elastic NiTi alloy as the backbone and driving tendons, a variable stiffness method using the shape memory alloy (SMA) to change the internal friction is put forward. Through the kinematic analysis, the coordinate mappings from the joint space to configuration space and workspace, as well as the Jacobian matrixes are obtained, and a closed-loop controller is designed by integrating the end position feedback. Based on the measurement of the driving forces on the tendons, a collision detection method and a variable stiffness control strategy are established. The results show that the presented continuum arm has good tracking accuracy and capability of stiffness adjustment.