为解决数控系统进行微小直线段平稳加工的问题,提出了一种拟合方法.综合了误差限制下的微小直线段长度、拐角、直线段相交点单调性等判定条件,将连续的微小直线段分割成若干区域.使用非线性最小二乘法将每一个区域内的点拟合成PH曲线,并通过模拟退火方法调整切矢量来控制拟合误差.根据区域的连接情况,将切矢量分为单向和双向两种调节方法.在模拟退火算法中,将微小直线段的斜率作为切矢量的初始值,利用细分直线的方法逐点计算弓高误差,并将此误差作为目标函数来快速进行切矢量的调整.结果表明,对微小直线段进行区域划分可以提高拟合效率.在控制弓高误差的情况下,此方法可以形成具有良好精度的光滑曲线,可以获得平稳的速度轨迹. In order to solve the problem of the smooth machining of the small linear section of CNC system, a fitting method is proposed, which combines the judgment conditions such as the length of tiny straight line, the monotonicity of corner and intersection of straight line, Which is divided into a number of regions.Using the nonlinear least squares method, the points in each region are fitted to the PH curve and the tangent vectors are adjusted by the simulated annealing method to control the fitting error.According to the connection of regions, In the simulated annealing algorithm, the slope of the tiny straight line segment is taken as the initial value of the tangent vector, and the bow height error is calculated point by point by the method of subdivision straight line, and the error is taken as an objective function The results show that the partitioning of the tiny straight line segments can improve the fitting efficiency.When controlling the high error of the bow, this method can form a smooth curve with good accuracy and get a steady velocity trajectory.