自行车系统是一个具有非完整约束的复杂系统，可以根据最小作用量原理通过欧拉-拉格朗日方程求解，利用差分

代替微分及一系列修正截断误差的方法计算近似值. 利用MATLAB，只要给定任意质点系的拉格朗日函数以及约束系数，即

可求出系统的近似解，并通过这个方法为分析自行车的运动与稳定性提供一种新的思路.

A bicycle system is a complicated one with non-complete constraints，which can be solved by the

Euler-Lagrange equation according to least action principle. The approximate calculation is solved by using the

difference instead of the differential and methods to correct the truncation error. Using MATLAB，as long as Lagrangian function of any system with finite degrees of freedom and the constraints are provided，the approximate solution

can be found. And this simple method can be applied to the approximate calculation of the bicycle system to

analyze the motion and stability of the bicycle.