Kinematics analysis and design of 4PC-2R parallel mechanism

4PC-2R并联机构设计及运动分析

¹ School of Mechanical and Electrical Engineering, Shaanxi University of Science and Technology, Xi′an 710021, China
² Ulster College, Shaanxi University of Science and Technology, Xi′an 710021, China

Received: 18 June 2024

Abstract

With the rapid development of new energy vehicle industry, the energy supply efficiency of a heavy electric truck becomes a key factor that restricts its wide application. This paper proposes a new 3T1R parallel mechanism with movement as its motion input, which can be used in the fast power exchange of the heavy electric truck. The 2-PCR parallel mechanism is modeled with the SolidWorks software. Its degrees of freedom are examined with the helix theory and validated with the modified G-K formula. The kinematics is solved primarily with the closed-loop vector method. The Matlab is employed to graphically determine the mechanism′s working space. The results indicate the mechanism possesses 4 degrees of freedom, 3 translations across the X, Y and Z axes and 1 rotational degree of freedom around the Z axis. The movement in the Y and Z directions is independent, and the freedom of rotation around the Z axis interferes with the movement in the X direction. The output point can not only move in the X direction but also drive its rotational angle when it moves in the X direction. Based on this mechanism, the 4PC-2R parallel mechanism is proposed for further optimization. The comparison of the two mechanisms shows that the 4PC-2R parallel mechanism is smoother. Finally, the mechanism′s parameters are refined with the genetic algorithm so as to expand the working space of the 4PC-2R mechanism. The practical application of the 4PC-2R parallel mechanism demonstrates that it has a streamlined structure, an expansive operational range and fluid motion characteristics, thus being safer and more effective for a heavy electric truck′s power exchange.

摘要

针对电动重卡的换电作业过程, 设计了一种以移动副作为输入的新型3T1R并联机构。利用SolidWorks软件完成了2-PCR并联机构的三维建模。基于螺旋理论对机构的自由度进行了深入分析, 并通过G-K公式对其分析结果进行了验证, 确保了理论分析的准确性; 采用闭环矢量法对其进行运动学求解; 针对2-PCR机构X方向移动和绕Z轴转动相互干涉这一不足, 对机构进行优化得到4PC-2R并联机构。对4PC-2R并联机构进行了相应的自由度分析和运动学求解, 通过2个机构的对比, 可知4PC-2R并联机构运动更平稳。运用遗传算法优化机构参数, 进一步扩大了4PC-2R机构的工作空间, 该机构用于电动重卡的换电装置上, 可以有效提高电动重卡的换电效率和安全性。