走出多个“8”字形轨迹的无碳小车机构设计

Structural design of carbon-free cars for realizing multiple 8-shaped paths

为了实现无碳小车完成1~N个8字形路径并通过预设障碍桩,文中提出一种通用的无碳小车结构设计方法,只需更换不同的凸轮零件即可完成不同类型8字形路径。考虑到前轮摆角和车速为影响小车运动轨迹的两大主要因素,首先以两相切正圆形为理想的8字形轨迹,推导一定车速下的脉冲式前轮摆角规律;对该脉冲式规律进行合理修正后,获得切实可行的前轮摆角规律,并以此求解出所需的凸轮从动件运动规律,从而通过解析法获得凸轮轮廓,完成凸轮零件设计。通过对单8字、双8字和三8字为例的3种路径的求解和仿真,结果表明该结构能完成预定的8字形路径,并通过指定间距的障碍桩。文中研究为每年的全国大学生工程训练综合能力竞赛提供指导,也可对其他特殊功能的车辆设计给予参考。

In order to enable the carbon-free cars to realize 1-N 8-shaped paths and pass the preset obstacle pile,this article presents a general design of carbon-free cars,which is available for different types of 8-shaped paths by changing the cam parts. Since the swing angle of the front wheel and the vehicle speed serve as the two main factors which affect the car trajectory,firstly,the trajectory with the two-phase tangent circle is set as the ideal 8-shaped orbit,and then the pulse-style swing angle law of the front wheel at a certain speed is derived. Based on the reasonable correction of the law,a practical swing angle of the front wheel is obtained,and then the motion law of the cam follower is identified. After that,the cam profile is obtained based on a series of analysis,and finally the design of the cam parts is ensured. Through the demonstration of solving the single 8-shaped,double 8-shaped and three 8-shaped paths,the proposed structure is successful to realize the predetermined 8-shaped path and pass the obstacle pile with a specified space. The study provides guidance for engineering-training comprehensive ability competitions of national college students every year,and gives reference for the design of other vehicles with special functions.