四面体式折展机械臂设计与分析

为解决现有部分机械臂收拢率低、末端姿态不可调节等问题,基于四面体单元提出一种折展机械臂机构。首先,阐述了一种单自由度四面体单元机构,该机构具有高刚度和较好的折展性,基于螺旋理论分析了四面体单元的自由度;其次,将多个四面体单元通过特定组合构造一种多自由度折展机械臂机构,以2个四面体单元组成的机构为例,基于几何方法求解各节点的位置、姿态和速度,并得出多个单元组合机构的运动规律;通过ADAMS仿真分析对运动理论分析结果进行验证,应用Workbench有限元仿真软件进行静力学和模态分析;最后,进行了折展实验。研究表明,基于四面体单元的折展机械臂具有多自由度、姿态可调及大收拢率的特点。

Design and Analysis of Tetrahedral Deployable Mechanical Arm

In order to meet the application requirements of deployable mechanism in agricultural machinery, aerospace and other fields, a deployable mechanism based on tetrahedral unit was proposed to solve the problems of low folding rate and unadjustable orientation of some existing mechanical arms. Firstly, a single degree of freedom (DOF) tetrahedral unit mechanism was introduced, which had good expansibility and high rigidity. Based on the screw theory, the DOF of tetrahedral unit was analyzed. Secondly, a multiple DOFs deployable mechanical arm mechanism was constructed by combining several tetrahedral units. Taking the deployable mechanical arm mechanism composed of two tetrahedral units as an example, the position, orientation and speed of each node were solved based on geometric method, and the motion law of the mechanism was obtained. Then, the theoretical analysis results were verified by ADAMS simulation analysis, and the theoretical values of the position and velocity of the end node were highly consistent with the simulation values. Furthermore, the statics and modal analysis were carried out by using Workbench simulation software to demonstrate the high rigidity and stability of the deployable mechanical arm mechanism. Finally, a prototype of machining and assembly principle was built and the deployable experiment was completed. The results showed that the deployable mechanical arm based on tetrahedral unit had the characteristics of multiple DOFs, adjustable orientation and large folding rate.