Characteristics of controllable stiffness for cable-driven parallel robots

Abstract

Human-robot interaction include some safety threats to people or products from the robots due to their stiffness. The characteristics of controllable stiffness for cable-driven parallel robots are studied using a static stiffness analysis and cable tension distribution method. The robot kinematics and statics equations are used for the force analysis with the three-dimensional Hessian matrix of the structural matrix to position differential is deduced by introducing a line vector and a differential transform. Then, the static stiffness model is derived for the relationship between the cable tension and the robot stiffness. The robots stiffness is then controlled by analyzing the cable tension polygon and the cable tension distribution. Simulations show that this method can effectively control the robot stiffness. 摘要 在机器人与人交互过程中, 机器人可能因刚度过大而对人或产品产生安全威胁。该文提出索驱动并联机器人静态刚度分析及索力分配方法, 研究其可控刚度特性问题。首先, 通过建立运动学和静力学方程对机器人进行受力分析, 并通过引入线矢量和微分变换的方式, 推导出结构矩阵对位姿微分的三维Hessian矩阵, 建立静态刚度模型, 分析索力与机器人刚度间的关系; 其次, 给出索力多边形计算算法, 并研究索力分配方法, 完成机器人刚度的有效控制; 最后, 通过计算实例验证该方法正确性与有效性。结果表明：该方法可以有效控制机器人的系统刚度。