【作者】 贾桂红；

【导师】 韩庆瑶；

【作者基本信息】 华北电力大学（河北） ， 机械电子工程， 2005， 硕士

【摘要】 本文针对复杂轮廓曲线造型及数控加工的需求,首先采用NURBS 方法对由型值点定义的自由曲线进行描述,该方法基于NURBS 曲线的反算算法。并基于二分法和最小二乘法提出了用直线和圆弧分别逼近曲线的算法,前者原理简单,易于实现;后者拟合段数少,而且逼近精度较高。在直线和圆弧逼近的基础上,又继续研究了用两者对NURBS 曲线进行混和逼近的算法,该算法根据曲线曲率的大小而选用不同的逼近方式,即满足了精度的要求,又减少CAD 系统与CNC 系统的数据传送,提高了加工效率和质量。更多还原

【Abstract】 To meet the requirements of modeling and NC machining of complex-contour curve, at first, the thesis discusses how to acquire the control vertex from data points. It bases on the reverse-calculation of NURBS, then two approaching algorithms with lines and circular arcs are presented, the former is based on dichotomy and its principle is so simple that can be programmed easily, the latter uses least square circular arc to fit the curve and its approaching precision is high though the number of circular arcs is smaller. Another approaching algorithm with line or curve is proposed on the basis of the former methods. The curve’s curvature decides which approaching method to choose. The algorithm reduces the information transferred from the CAD system to the CNC system and improves the efficiency and quality of machining.更多还原