中文摘要：

针对三自由度移动多环耦合机构开展构型综合,提出了通过添加耦合支链将并联机构向等自由度多环耦合机构转变的2个基本原则.根据这2个基本原则,基于三自由度移动并联机构3-（RRR）RR综合出有等自由度性质的一类对称多环耦合机构.首先,根据单闭环自由度公式确定耦合支链上运动副的个数.然后,为避免出现瞬时机构,分析耦合支链上运动副的种类.最后,通过对耦合支链的组装,综合出了一类具有一、二级耦合节点的对称三自由度移动多环耦合机构.

英文摘要：

Two basic principles for the transformation from parallel mechanisms to multi-loop coupled mechanisms with equal mobility are proposed by adding coupled branches. According to the two basic principles,the 3-DOF parallel mechanism 3-（ RRR） RR was transformed into a class of symmetrical multi-loop coupled mechanisms with equal mobility. First,the number of kinematic pairs on the coupled branch was determined according to the mobility formula for single-closed loop. Then,to avoid the occurrence of instantaneous mechanisms,the types of kinematic pair on the coupled branches were analyzed. Finally,through the assembly of the coupled branches,a class of three-dof mobile multi-loop coupled mechanisms with first-or second-level coupled nodes was synthesized.