空间4R冗余度机械臂容错空间分析

针对空间4R冗余度机械臂活动关节工作空间进行了定量研究,并且对其容错空间做了进一步探讨。首先推导出空间4R冗余度机械臂不同关节锁定时工作空间的解析表达式,并且根据表达式对工作空间进行了三维造型;然后,进一步分析了机械臂的D-H参数对工作空间的影响;最后,给出3 sigm a型机械臂容错空间的计算方法及三维造型,分析了其容错空间的影响因素。研究结果表明:当机械臂结构参数一定时,一个活动关节(关节2)在一定范围内锁定,工作空间不变,并且此锁定范围与结构参数一一对应;机械臂的臂长之和一定时,各机械臂长度越接近,机械臂的工作空间越大;机械臂关节2偏置的存在使机械臂工作空间不会出现薄壳,另一活动活动关节(关节3)的偏置的存在也可以增大工作空间;关节工作空间增大,容错空间也会相应增大。

Analysis of Fault Tolerant Workspace of a Spatial 4R Redundant Manipulator

The paper carried out the quantitive study of the workspace of a spatial 4R redundant manipulator and explored its fault tolerant workspace.First,the analytical expressions of the workspace when the manipulator′s different joints had been locked were derived,whereby the workspace was 3D modeled.Then,the manipulator′s D-H parameters′ influence on workspace was analyzed.Finally,the calculation method and 3D models for the 3-sigma type of manipulator′s fault tolerant workspace were presented,and its influence factors were analyzed.The study results indicate that when the manipulator′s structural parameters are given,its workspace is constant if an active joint(Joint 2) is locked within a certain range and if the range corresponds with each structural parameter of the manipulator.For the manipulator with a fixed total of arm length,the smaller the distance between the arm lengths is,the larger its workspace is.The offset of Joint 2 is helpful to avoiding the appearance of the thin shell of its workspace.The offset of Joint 3 can also increase the workspace.As the workspace increases,so does the fault tolerant workspace.