在对HUST-CAID（哈尔滨理工大学计算机辅助工业造型设计）系统进行研究的基础上，首先引入了自由曲面特征。然后结合HUST—CAID系统定义了自由曲面特征的分类和参数化，同时系统为用户提供了一组适当的参数，使用户能够直观的设计任意曲面，而不必参与曲面的底层设计。当用户修改参数时，系统就会自动提供相应的反馈。为了求解出与约束一致的图形，还给出了一种新颖的原型驱动约束求解算法，并在HUST—CAID系统中进行了仿真实验，结果显示，此算法能够有效地简化约束求解和特征造型的过程。

The freeform feature modeling was introduced in HUST-CAID.Classification and parameters were defined combining with the HUST-CAID system(computer aided industry design system developed by Harbin university of science and technology);users could intuitively design any curved surface using a set of suitable parameters provided by the system without concerning the lower layer design.If users want to modify the parameters,the system will correspondingly provide feedback automatically.In order to obtain the right graphics agree with the constraint,it is provided a new novel prototype-driven constraint solving algorithm.The simulation result in HUST-CAID shows that this novel algorithm simplified constraint solving and feature modeling greatly.