【摘要】 本文根据作者应用B样条方法进行计算机辅助汽车车身覆盖件几何设计的初步实践,介绍了重节点非均匀B样条曲线与曲面的算法、性质和应用实例;并对CAGD中应用B样条方法的其它几个问题,诸如非均匀B样条曲线的光顺、具有四条以上边界的曲面造型、曲面拼接与追加造型,任意斜截面的外形计算等,进行了一些探讨。本文所介绍的用重节点非均匀B样条方法设计的数控绘图程序,把前置与后置有机地结合起来,自动生成绘图指令信息与控带,不需用户书写源程序,在更大程度上体现了自动编程的优越性。本文所用的方法和所设计的程序具有一定的通用性,可应用于其它具有复杂外形的产品的几何设计。更多还原

【Abstract】 Based on our initial practice of applying B-spline method to computer aided geometric design of automobile bodies,this paper presents the algorithm, properties and applying examples of the nonuniform B-spline curves and surfaces combined with a multi-knot method. Besides, some problems about the application going and fitting the surface with more than four boundaries, piecing one surface of B-spline method to CAGD,such as smoothing the nonuni- form B-spline curve, designing and fitting the surface with more than four boundaries, piecing one surface to another (including additional geometric modelling) and computing the contours of arbitrary sections.An NC (Numerical control) drawing program, designed with the aid of the B-spline multi-knot method, is also introdused.Using the information of multiknots,the program can generate automatically NC instructions or NC paper tapes. without the need of user’s writing source program and therefore it shows to a larger degree the advantages of automatical programming.The methods and the programs introdused in this paper have certain generality and may be applied to geometric design of products having complex contours.更多还原