基于混合模型的虚拟装配关键技术研究

针对虚拟装配中采用多边形网格模型引起的组件定位困难和碰撞检测精度低等问题,提出一种采用精确几何模型及其对应的多边形网格模型的混合模型作为底层数据,支持精确装配的虚拟装配系统构造方法,并基于Parasolid和Vir-tools平台进行了实现。基于混合模型的碰撞检测能根据计算精度和时间要求自适应求解,在速度快的同时,满足高精度碰撞检测要求;基于混合模型的组件装配,采用离散采样点定义装配路径,通过装配几何约束交互式定义限制组件的运动范围,通过自由度规约、装配约束求解实现了零部件精确定位,通过四元数插值实现装配路径中零部件位姿的平滑过渡,能满足高精度的装配要求。该方法已经在开发的多个系统中得到验证和应用。

Research on key technologies in virtual assembly based on accurate and polygonal mesh model

To solve the problems of low precision in collision detection and difficulties in components’ orientation,which are aroused by adopting polygonal mesh models in virtual assembly,a method of using both Parasolid and mesh model as virtual assembly base data is proposed and a virtual assembly prototype system based on Parasolid and Virtools platform is carried out.To simulate the assembly process more accurately,an assembly path record method is proposed,which using sampling points to define assembly path,defining geometry constraint interactivly,getting component accurate position and component degree of freedom by assembly constraint solving,making assembly path smoothness by quaternion spherical linear interpolation.A rapid collision detection algorithm based on Parasolid and mesh model is also achieved,which excludes disjoint geometry objects by hierarchical bounding box firstly,then interference is calculated by parasolid or certain level of detail mesh model based on real time requirement and precision.This method applied to several virtual assembly system.