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

doi:10.3901/JME.2022.23.001

Abstract

Abstract: 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.

Key words: parallel mechanism, bifurcation of motion, atlas method, type synthesis

CLC Number:

TH112

LI Yongquan, ZHENG Tianyu, JIANG Hongsheng, ZHANG Duo, ZHANG Lijie. Type Synthesis of New Kinematic Bifurcation Parallel Mechanism Based on Atlas Method[J]. Journal of Mechanical Engineering, 2022, 58(23): 1-17.

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