基于运动约束的拖挂式自行车机构自由度数分析

Degree of Freedom Analysis of Ttowed Bicycle Mechanism Based on Mmotion Constraint

为解决现有两轮自行车机构负载能力不足的问题,通过u形块挂接一组以上挂接车架和车轮的新型自行车机构,研发提出一种以自行车为牵引车,为了解这种具有约束区域无限制的机构是否需要无限控制量的问题,对系统进行了自由度分析。采用广义数学归纳法和传统G-K法相结合,对挂接k+1节的自行车机构进行自由度计算;对于计算中的运动约束数量,采用相对运动原理寻找系统的运动约束方程。计算结果表明,多节拖挂式自行车机构自由度与挂接车节数的数量无关,始终为3。虚拟样机仿真和物理样机实验结果均表明,运动约束关系曲线的计算值与测量值基本一致,验证了运动约束分析与机构自由度计算的准确性。

In order to solve the problem of insufficient load capacity of the existing two wheeled bicycle mechanism,a new bicycle mechanism with more than one group of frame and wheels connected by U-shaped block is developed and proposed.In order to understand whether this kind of mechanism with unlimited constraint area needs unlimited control amount,the degree of freedom of the system is analyzed.In this paper,the generalized mathematical induction method and the traditional G-K method are combined to calculate the degree of freedom of the bicycle mechanism with K+1 section.For the number of motion constraints in the calculation,the relative motion principle is used to find the motion constraint equation of the system.The calculation results show that the degree of freedom of the multi section Trailer bicycle mechanism has nothing to do with the number of articulated vehicle sections,which is always 3.The results of virtual prototype simulation and physical prototype experiment show that the calculated value of motion constraint relationship curve is basically consistent with the measured value,which verifies the accuracy of motion constraint analysis and mechanism degree of freedom calculation.