两端吸附式爬壁机器人机械臂运动误差修正算法

Error correction algorithm for manipulator of wall climbing robot with both ends having magnetic adsorption

为了解决水轮机叶片坑内修焊空间加工作业需求,研制了适用于复杂曲面的两端吸附式爬壁机器人,该机器人由永磁间隙吸附式移动平台、多自由度机械臂(包括3个主动关节和3个被动关节)和永磁间隙吸附式末端作业单元组成。针对给定末端路径,这种结构的机器人需基于局部平面假设来完成主动关节的轨迹生成。但经仿真分析,在1.5m半径外球面上的简化造成的误差达到5mm以上,不满足修焊工艺要求精度。为此,提出在机械臂加工运动过程中,通过Jacobi矩阵将末端作业单元在Descartes坐标系下的误差转换为关节角修正量以完成动态修正的算法。仿真实验表明,该算法可有效降低运动路径误差至1mm以下。

A wall climbing robot with both ends using magnetic adsorption is developed for on-site hydraulic turbine blade repairs. The magnetic mobile platform has a multiple degrees of freedom （DOF） manipulator and an end operating unit. The manipulator has 3 active and 3 passive joints, so the trajectory planning method for a given working path assumes a local curve where the end effector of the manipulator works on a plane. However, simulations for a sphere with a 1.5 m curvature show that the path error due to this assumption is larger than 5 ram. A correction algorithm to reduce the error transforms the error from Cartesian space to the joint space through a Jaeobian matrix. Simulations show that the error can be reduced to less than 1 mm by this algorithm.