无寄生运动3-DOF 2T1R并联机构拓扑设计与分析

Topology Design and Analysis of 3-DOF 2T1R Parallel Mechanism with No Parasitic Motion

摘要:

为充分研究少自由度并联机构所具备优势，拓宽其应用领域，设计并研究一种含冗余支链且无寄生运动三自由度两平移一转动（2T1R）并联机构，完成运动学和动力学分析。基于方位特征集（POC）的拓扑机构学理论方法，设计了一种含冗余支链且无寄生运动的两平移一转动并联机构，并进行拓扑分析，结果表明：该机构还具有部分运动解耦特性；根据基于拓扑特征运动学的建模方法，求得机构位置正反符号解；又基于位置反解分析了机构奇异性，基于位置正解给出了工作空间；基于虚功原理的序单开链法对机构进行动力学建模，求得了该机构移动副处的驱动力以及两个子运动链(SKC)连接处的支反力；概念设计了该机构的一种应用场景。

关键词:并联机构;方位特征;运动学;奇异性;序单开链;动力学

Abstract:

The topology design, kinematics and dynamics analysis of parallel mechanism with redundant branches but no parasitic motion were studied, and finally a conceptual application scenario was put forward based on the advantages of the mechanism itself. Firstly, a parallel robot with redundant branches but no parasitic motion was designed by using the type synthesis theory based on position and direction characteristics. The robot can realize translation in two directions and rotation in one direction. After topological analysis of the mechanism, it was found that the output motion of the mechanism met the expected design requirements, and it had partial motion decoupling characteristics, so it was easy to control the output of the moving platform through the driving pair. Secondly, the forward kinematics and inverse kinematics of the mechanism were obtained by using the kinematics modeling method based on topological characteristics. The singularity of the mechanism was analyzed by inverse solution, and the workspace was determined by positive position solution. In addition, the ordered single open chain method based on virtual work principle was used to model the dynamics of the mechanism. By solving the model, the driving force of driving joints on the static platform and the binding force at the joints connected by two sub-kinematic chains (SKC) were obtained. The simulation values of these two forces were obtained in the simulation software and compared. The results showed that the error between the simulation values and the theoretical values was small, so it was considered that the dynamic model established by the ordered single open chain method was correct. Finally, combined with the existing improvement of the moving target in shooting training, the conceptual design of parallel mechanism for military training application scenarios was given.

Key words:parallel mechanism;position and orientation characteristics;kinematics;singularity;ordered single open chain;dynamics