中文摘要：

并联机构拓扑信息的符号描述方法对于计算机辅助机构拓扑结构分析和机构型综合等研究具有重要意义。基于并联机构的SOC组成原理,遵循机构学领域符号表达习惯,提出了具有代数运算功能的并联机构符号描述系统,将并联机构拓扑结构表示为一种符号多项式,其中每一项代表一条支路;分析了运动副方位关系的传递性,提出了方位关系组的概念,给出了运动副方位关系的符号描述方法。在此基础上给出了POC集的符号推导方法,将支路的POC集表示为所含运动副POC集的加法运算,将整个并联机构的POC集表示为各支路POC集的乘法运算。该符号描述系统在一定程度上具有符号语言的代数特征,便于进行并联机构拓扑不变量的自动分析,为计算机辅助并联机构型综合提供了理论基础和有效工具。

英文摘要：

Kinematic and dynamic performance of a parallel mechanism is,to some extent,determined by its topological structure,so topological structure analysis and synthesis is very important to research and application of parallel mechanisms,especially the parallel robot mechanisms. In order to achieve computer aided topological structure analysis and synthesis of parallel mechanisms, the topological structure of parallel mechanism must first be represented symbolically. An algebraic symbolic description system was proposed for parallel mechanisms on the basis of SOC-based mechanism composition principle. With this symbolic description system,topological structure of any parallel mechanism can be expressed as a symbolic polynomial,each item of the polynomial represents a branch of the parallel mechanism. The transitivity of kinematic pair orientation relations was discussed and symbolic representations of different kinematic pair relations were introduced. Based on this symbolic description system,position and orientation characteristic（ POC） set of parallel mechanisms can be derived easily with the help of a computer program,i. e. POC set of a branch was sum of the POC set of each kinematic pair in this branch and POC set of the complete parallel mechanism was product of the POC set of each branch. The proposed symbolic description system features the algebraic property of a symbolic computer language,so it can be used reliably in computer aided mechanism studies. Work in this paper provided atheoretic basis and an effective method for computer aided analysis and automatic generation of parallel mechanisms.