基于图谱法的新型运动分岔并联机构型综合

多模式并联机构在航空航天、机械加工、医疗康复等领域均极具应用前景，但目前能够实现多模式的运动分岔并联机构类型较少，绝大多数运动分岔并联机构中含有变自由度性质的RER支链，为此基于图谱法综合了一类新型运动分岔并联机构且机构中含有4类变自由度性质支链与已有的RER支链不同。首先基于图谱法以机构初始位置两瞬时转动自由度线非共面且相互垂直为例对2T1R运动分岔并联机构进行综合，随后将机构含有的URR支链中和定平台相连接的R副轴线方向改变，使其具有2R2T和3R1T两种自由度性质。将改进后的URR支链配置方案应用到部分4自由度和5自由度支链中，提出另外三类变自由度支链，每种类别支链分别有4、12、32种。以机构中含有4类不同变自由度性质的支链为分类依据，综合出四大类同时具有2T1R+2R1T两模式新型运动分岔并联机构，共包括12种子类别；以第4类变自由度支链为例，将其引入到并联机构中，通过图谱法综合出具有3T1R+2R2T两模式新型运动分岔并联机构。

Type Synthesis of New Kinematic Bifurcation Parallel Mechanism Based on Atlas Method

The multi-mode parallel mechanism (PM) has great application prospects in aerospace, machining, medical rehabilitation and other fields. However, there are few types of kinematic bifurcation PMs that can realize multi-mode, and most kinematic bifurcation PMs contain RER branches with variable DOF. Therefore, a new type of kinematic bifurcation PM is synthesized based on the atlas method, and the mechanism contains four types of branch chains with variable DOF, which are different from the existing RER branches. Firstly, based on the atlas method, the 2T1R motion bifurcation PM is synthesized by taking the two instantaneous DOF lines at the initial position of the mechanism as an example, which are not coplanar and perpendicular to each other. Then, the direction of the R pair connected to the fixed platform by the URR branch neutralizing mechanism is changed, which made it have two DOFs properties of 2R2T and 3R1T. The improved URR branch chain configuration scheme is applied to some 4-DOF and 5-DOF chains. Three other types of variable DOF chains are proposed, with 4, 12 and 32 chains in each type. Based on the classification of four types of branch chains with different variable DOF in the mechanism, four types of new kinematic bifurcation PMs with 2T1R+2R1T two modes are synthesized, including 12 subcategories in total. Taking the fourth type of branched chain with variable DOF as an example, it is introduced into the PM, and a new type of kinematic bifurcation PM with 3T1R+2R2T two modes is synthesized by the atlas method.