少自由度并联机构型综合问题一直是国际上的研究热点和难点，其中一个很重要的原因就是机构存在同性异构现象。本项目以少自由度并联机构为研究对象，以螺旋理论为主要工具，根据机构拓扑变换原理，建立系统结构约束特性模型，研究少自由度并联机构同性异构现象的产生机理以及其对系统运动学、动力学等操作性能的影响。在此基础上，通过揭示系统拓扑特征对分支链结构约束的影响关系，总结出少自由度并联机构产生同性异构变化的结构约束条件，建立统筹拓扑构型的机构运动学及动力学性能评价指标，进而为少自由度并联机构的拓扑构型优化提供理论依据。本项目研究成果对丰富和完善少自由度并联机器人机构学理论，发明创造出新型且有实用价值的少自由度并联机构具有重要的理论及现实意义。

Type synthesis of lower-mobility parallel mechanisms has been a hot subject and a hard point to crack in international academic, one of the main causes is that there exist isomerism phenomenon for mechanisms. This project focuses on the isomerism generating mechanism of lower-mobility parallel mechanisms and aims to clear its effects on kinematics performances and dynamics properties of the mechanisms and to design new architectures of lower-mobility parallel mechanisms with independent knowledge properties. The main contributions are as follows:.Based on screw theory and mechanism topology, the characteristic model of system structural constraint will be proposed and the corresponding constrained motion will be obtained by reciprocal relations between twists and wrenches. Further, the constraint effect of the limb acting on the moving platform will be described by limb constrain system and the combined effect of all limb constraints is going to described by mechanism constraint system. The constraint conditions for generating isomerism will be summarized though the relationship between all limb constraints and mechanism constraint system..On the basis of the above work, the performance indexes including topological configuration information and kinematics performances and dynamics properties of the mechanisms will be established for the configuration optimization. .The fruits of the project wii be good for enriching and developing the theory of lower-mobility parallel mechanisms, and of theoretical and practical values for designing new and substantive lower-mobility parallel mechanisms.