中文摘要：

含方位特征支链的并联机构是一类特殊结构的刚度好、承载大的少自由度并联机构。首先,提出了含方位特征支链并联机构的构型组成原理,简化了该类机构的方位特征方程、自由度、耦合度等拓扑特征的计算公式,以及拓扑结构综合步骤;其次,根据方位特征方程,综合了2~5自由度方位特征支链以及无约束主动支链的拓扑结构型式,以4自由度并联机构为例,给出了该类机构结构综合的原则和方法。再次,根据方位特征支链中的驱动副数目（0、1、2）对机构进行分类,并给出具体结构设计案例。最后,针对部分机构存在的力学性能不好的问题,提出了支链结构优化和对称性结构优化2种拓扑结构优化方法及其相应案例。本文工作为含方位特征支链并联机构的拓扑结构综合提供了较系统的理论基础和设计方法。

英文摘要：

The parallel mechanism with position and orientation characteristics limb（ POL） is a kind of special low mobility mechanism which consists of 2 ~ 5 identical active unconstrained limbs and a passive POL. The motion characteristics of the mechanism are determined by POL,thus it was referred to as motion constraint generator by some literatures. This parallel mechanism with POL has many excellent characteristics,such as high rigidity,high control accuracy and bearing capacity,and the synthesis process is simpler than the other mechanism. Firstly,principle of composition of parallel mechanism with POL was proposed,and some formula of topological structure characteristics were simplified,including its position and orientation characteristics equation（ POC）,degree of freedom（ DOF） and coupling degree,meanwhile,synthesis process of topological structure was listed. Secondly,topological structures of POL with 2 ~ 5 DOF and unconstrained active limbs were synthesized according to POC theory. Type synthesis of 4-DOF parallel mechanism was used as an example to illuminate the principles and methods of designing this kind of mechanism. In this section,the concept of generalized POL is mentioned,which contained not only traditional precisely constrained passive chains,but also some active branched chains.Thirdly,the mechanism was classified on the basis of the number of driving pairs in POL,and several cases were designed of each type. Lastly,two ways of structure optimization for chain structure and mechanism symmetric were presented to improve mechanical properties of partial examples. The research provided a more systemic theory and design methodology for topological structure synthesis of the parallel mechanism with POL than previous literatures.