摘要
根据基于方位特征方程(POC)的并联机构拓扑结构设计理论及方法,设计了一种低耦合度三平移一转动(3T1R)并联机构,对该机构进行了拓扑结构分析,包括方位特征、自由度及耦合度计算,该机构具有部分运动解耦性。但耦合度k=1只能求得位置正解的数值解,不利于后续的尺度优化、误差分析及动力学分析,为此对其进行拓扑降耦优化设计,即在基本功能(DOF、POC)以及部分运动解耦性不变的情况下,使其耦合度k=0并具有符号式位置正解。运用基于拓扑特征的运动学建模原理求解该优化机构的符号式位置正解,基于导出的雅可比矩阵进一步分析了机构发生奇异的条件,分别基于位置逆解和位置正解求解机构的工作空间,研究表明,基于位置正解的机构工作空间分析具有计算过程简单、计算精确、计算量少等优点。本研究为该机构后续的尺度优化、误差分析及动力学分析奠定了基础。
According to the theory and method of topological structure design of parallel mechanism(PM)based on position and orientation characteristic(POC)equation,firstly,a low coupling parallel mechanism of three translation and one rotation(3T1R)was designed,and its topological structures were analyzed,including POC,degrees of freedom and coupling degree.It was shown that the PM had partial motion decoupling,but the coupling degree of the PM was one(k=1).That meant only the numerical solutions of direct position solution can be obtained,which was not conducive to the subsequent scale optimization,error analysis and dynamic analysis.Therefore,the topology decoupling optimization design was carried out,that was,the coupling degree k=0 and the symbolic direct position solution can be obtained under the condition that the basic functions(DOF,POC)and partial motion decoupling remained unchanged.Secondly,using the kinematics modeling principle based on topology characteristics,the symbolic direct position solution of the optimal mechanism was solved.Furthermore,based on the derived Jacobian,the conditions for singularity of the mechanism were analyzed.Finally,based on the inverse position solution and the direct position solution,the workspace of the mechanism was solved.It showed that the workspace analysis based on the direct position solution had the advantages of simple calculation process and less calculation amount.The work can lay a foundation for the subsequent scale optimization,error analysis and dynamic analysis of the mechanism.
作者
沈惠平
顾晓阳
李菊
邓嘉鸣
SHEN Huiping;GU Xiaoyang;LI Ju;DENG Jiaming(Research Center of Advanced Mechanism, Changzhou University, Changzhou 213016, China)
出处
《农业机械学报》
EI
CAS
CSCD
北大核心
2021年第8期406-415,共10页
Transactions of the Chinese Society for Agricultural Machinery
基金
国家自然科学基金项目(51975062)。
关键词
并联机构
耦合度
拓扑降耦设计
运动学分析
parallel mechanism
coupling degree
topological coupling-reducing design
kinematic analysis