Abstract: To synthesize decoupled Three-Translational (3T) and Two-Rotational (2R) hybrid mechanisms,a methodology of structural synthesis was proposed based on screw theory.All possible configuration types of 3T2R hybrid mechanism were proposed on the basis of kinematic element's combination and distribution.A method of type synthesis for fully-decoupled parallel mechanisms was proposed in accordance with the screw theory and the driven-chain principle,and the method was applied to accomplish the type synthesis for fully-decoupled lower-mobility parallel mechanisms.The type synthesis of fully-decoupled hybrid mechanism could be carried out by substituting the parallel mechanism with decoupling characteristic into hybrid mechanism,and was used to synthesize 3T2R hybrid mechanism.The instantaneity and kinematics of a synthesized 3T2R hybrid mechanism were analyzed based on method of geometric constraint analysis and the decoupling characteristic of hybrid mechanism was verified by the deduced Jacobian matrix.

Key words: structural synthesis, decoupled, hybrid mechanism, screw theory

摘要： 针对3T2R混联解耦机构的构型综合问题,提出一种基于螺旋理论的混联解耦机构构型综合方法。首先基于运动基组合分配理论,给出3T2R五自由度混联机构所有可能的结构类型;然后基于螺旋理论和支链独立驱动原则提出完全解耦并联机构构型综合方法,运用该方法可以实现各类少自由度完全解耦并联机构的构型综合;再将综合的完全解耦并联单元构型到已有的混联构型中,得到解耦混联机构构型,并用该方法完成了3T2R类五自由度混联解耦机构构型综合;最后根据约束几何分析法分析了所综合的一种混联机构的瞬时特性,给出了运动学分析,推导了机构的雅可比矩阵,验证了机构的解耦特性。

关键词: 型综合, 解耦, 混联机构, 螺旋理论