A New Method for Type Synthesis of 2R1T and 2T1R 3-DOF Redundant Actuated Parallel Mechanisms with Closed Loop Units

Chinese Journal of Mechanical Engineering

Lijie Zhang¹  Yongquan Li²  Yang Zhang³ 

[1] Key Laboratory of Advanced Forging & Stamping Technology and Science, Ministry of Education of China, Yanshan University, 066004, Qinhuangdao, China;Hebei Provincial Key Laboratory of Heavy Machinery Fluid Power Transmission and Control, Yanshan University, 066004, Qinhuangdao, China;Parallel Robot and Mechatronic System Laboratory of Hebei Province, Yanshan University, 066004, Qinhuangdao, China;Key Laboratory of Advanced Forging & Stamping Technology and Science, Ministry of Education of China, Yanshan University, 066004, Qinhuangdao, China;School of Mechanical Engineering and Automation, Harbin Institute of Technology, 518052, Shenzhen, China;

关键词: Redundant actuated;    Parallel mechanisms;    Type synthesis;    Atlas method;    Instantaneous analysis;   

DOI  :  10.1186/s10033-020-00487-7

来源: Springer

【 摘 要 】

The current type synthesis of the redundant actuated parallel mechanisms is adding active-actuated kinematic branches on the basis of the traditional parallel mechanisms, or using screw theory to perform multiple getting intersection and union to complete type synthesis. The number of redundant parallel mechanisms obtained by these two methods is limited. In this paper, based on Grassmann line geometry and Atlas method, a novel and effective method for type synthesis of redundant actuated parallel mechanisms (PMs) with closed-loop units is proposed. Firstly, the degree of freedom (DOF) and constraint line graph of the moving platform are determined successively, and redundant lines are added in constraint line graph to obtain the redundant constraint line graph and their equivalent line graph, and a branch constraint allocation scheme is formulated based on the allocation criteria. Secondly, a scheme is selected and redundant lines are added in the branch chains DOF graph to construct the redundant actuated branch chains with closed-loop units. Finally, the branch chains that meet the requirements of branch chains configuration criteria and F&C (degree of freedom & constraint) line graph are assembled. In this paper, two types of 2 rotational and 1 translational (2R1T) redundant actuated parallel mechanisms and one type of 2 translational and 1 rotational (2T1R) redundant actuated parallel mechanisms with few branches and closed-loop units were taken as examples, and 238, 92 and 15 new configurations were synthesized. All the mechanisms contain closed-loop units, and the mechanisms and the actuators both have good symmetry. Therefore, all the mechanisms have excellent comprehensive performance, in which the two rotational DOFs of the moving platform of 2R1T redundant actuated parallel mechanism can be independently controlled. The instantaneous analysis shows that all mechanisms are not instantaneous, which proves the feasibility and practicability of the method.

【 授权许可】

CC BY