四自由度部分解耦并联机构运动学和性能分析

针对并联机构强耦合性导致的运动学分析复杂、控制难度大、工作空间小等问题,设计了一种新型四自由度并联机构。采用螺旋理论分析了机构的运动特性,得知该机构具有两转动两移动自由度,可由4个移动副驱动;建立了机构的位置数学模型,得到了位置反解表达式,分析了运动部分解耦特性;对机构进行了速度分析,推导了速度雅可比矩阵;基于雅可比矩阵对机构进行了奇异分析,得到了机构的奇异位形;分析了机构的条件数指标,通过添加冗余驱动分支消除了奇异位形,提升了机构的条件数性能,并验证了该机构具有较大的工作空间。

Kinematic and Performance Analysis of a Partially Decoupled Parallel Mechanism with Four Degrees of Freedom

A novel four DOF parallel mechanism was designed to solve the problems of complex kinematics analysis, difficult control and small working space caused by the strong coupling of parallel mechanism.The motion characteristics of the mechanism were analyzed by using the spiral theory, and it was known that the mechanism had two rotations and two moving DOF, and could be driven by four moving pairs.The position mathematical model of the mechanism was established, the expression of the inverse position solution was obtained, and the decoupling characteristic of the moving part was analyzed.The velocity of the mechanism was analyzed and the velocity Jacobian matrix was derived.The singular analysis of the mechanism was carried out based on the Jacobian matrix and the singular configuration of the mechanism was obtained.The conditional number index of the mechanism was analyzed, the singular configuration was eliminated by adding redundant driving branches, the conditional number performance of the mechanism was improved, and it was verified that the mechanism had a large working space.