绳索牵引康复机器人运动误差及仿真分析

The simulation and movement errors analysis of wire-driven rehabilitative robots

绳索牵引康复训练机器人具有柔顺性好的特性,满足人与机器人在同一物理空间时安全性的要求.通过绳索牵引控制骨盆的运动规律,使其与下肢步态运动相协调,同时提高受训者稳定能力.为满足训练效果,需保证骨盆运动精度,由此分析了绳索牵引康复机器人影响骨盆运动精度的因素,即绳索本身的弹性和绳索过轮的半径.依建立的绳索牵引康复机器人模型,得到绳索拉力的表达式,导出系统正逆运动学和动力学方程.分析了在弹性范围内绳索具有的拉伸刚度,明确其对骨盆运动精度的影响;通过不同位置时绳索变化量的方法证明了绳索过轮半径对骨盆运动精度的影响.利用MATLAB的建模仿真,分析了2个因素对骨盆运动精度的不同影响规律,提出了改进方法,得出减重外力对垂直轴加速度误差的影响.该分析为骨盆的控制做准备,同时具有普遍性,可为其他绳索牵引系统提供参考作用.

Wire-driven rehabilitative robots have good compliance and meet safety requirements in man-machine cooperation systems. Through wire traction control, pelvic motion is coordinated with the movement of the lower gait, improving the robotic trainer＇s stability. To effectively produce the training effect, the system needs to ensure accu- racy of pelvis movement. So the factors affecting the motion accuracy were analyzed, including wire elasticity and the radius of wire-across-wheel. According to the wire-driven rehabilitative robot model, the expression of wire tension was built up, both the forward and inverse kinematics and dynamics equations were derived. The influence of wire tensile stiffness on the accuracy of movement of the pelvis was analyzed. The influence of the wire-acrosswheel radius on the movement accuracy of the pelvis was shown through wire changes in various positions using MATLAB modeling simulation. Two factors that affect the motion accuracy were analyzed and the corresponding method for improving the accuracy was proposed. It was found that the acceleration error on the vertical axis is influenced by the outside force. The analysis gives an engineering basis for control and is universally applicable to other wire-driven systems.