低耦合度半对称三平移并联机构拓扑设计与运动学分析  

Topological Design and Kinematics Analysis of Novel Asymmetric 3-Translation Parallel Manipulator with Low Coupling Degree

作　　者：沈惠平[1] 赵一楠 许正骁 李菊[1] 杨廷力[1] SHEN Huiping;ZHAO Yi nan;XU Zhengxiao;LI Ju;YANG Tingli(Research Center of Advanced Mechanism, Changzhou University, Changzhou 213016, China)

机构地区：[1]常州大学现代机构学研究中心,常州213016

出　　处：《农业机械学报》2019年第3期404-411,357,共9页Transactions of the Chinese Society for Agricultural Machinery

基　　金：国家自然科学基金项目(51475050);江苏省科技成果转化专项资金项目(BA2015098);江苏省绿色过程装备重点实验室项目

摘　　要：根据基于方位特征(POC)方程的并联机构拓扑设计理论与方法,提出一种三自由度3Pa+2RSS并联机构,并对该机构的方位特征集、自由度、耦合度等主要拓扑特征进行分析计算,证明分析了其耦合度κ=1;建立了基于序单开链法运动学建模原理的位置正解求解模型,并应用一维搜索方法求解了该并联机构的位置正解;导出机构位置逆解的公式,并据此分析计算了该机构奇异发生的条件;在自由度、输出和运动学分析不变的前提下,为了增大工作空间,将两条RSS支链替换为RUU支链,分析求解了机构工作空间和工作空间内部的奇异性特征。结果表明:该机构工作空间形状规则,且内部的无奇异工作空间较大。According to the topological design theory of parallel mechanism(PM)based on position and orientation characteristic(POC)equations,a three degrees-of-freedom(DOF)3 Pa+2 RSS PM was designed.The main topological characteristics such as the POC set,DOF and coupling degree(κ)were calculated.It was proved that the coupling degree of the PM equaled to 1(κ=1)by using the formula of coupling degree.Afterward,a forward solution model for the kinematics modeling principle based on ordered single open chain(SOC)units method was established.Then the forward kinematics was solved by using one-dimensional search method.The inverse kinematic formulas were derived by establishing the relationship between the input variables and output variables.Meanwhile,the Jacobian matrices were derived by inverse kinematic formulas which were used to analyze the geometric conditions of three kinds of singular positions for the PM.In order to enlarge the workspace of the mechanism,two RSS chains were replaced by using RUU chains under the premise of constant degrees-of-freedom,output characteristic and kinematics analysis.The workspace boundary and singularities inside the workspace of the mechanism were analyzed by using the discretization method and calculated in Matlab.The result turned out that the shape of workspace boundary of the mechanism was regular and large.Also the free singularities area inside the workspace was large.The research laid a theoretical foundation for the stiffness,dynamics investigation and prototype design of the PM in the future.

关 键 词：并联机构 耦合度 运动学分析 工作空间 奇异位形 

分 类 号：TH112[机械工程—机械设计及理论]