基于约束的虚拟装配技术研究

为了实现基于约束的虚拟装配操作，给出了虚拟环境中装配约束的统一表达方法，以及约束与自由度的等价关系和运动自由度的归约等，提出了一套虚拟装配中的约束处理算法。首先，利用装配关系自动识别算法，判断两个零件几何约束元素之间的位姿关系是否在给定的误差范围内；其次，使用定位求解算法，使主动体零件在满足已经确认约束的基础上，以最小的位姿调整量满足新约束；最后，提出了基于广义坐标系的运动导航算法，根据装配零件满足的约束对其运动进行引导。这些算法已经应用于集成虚拟装配环境的系统中，实践证明它们能很好地支持集成虚拟装配环境的约束处理，实现了虚拟装配过程与实际装配过程的高度统一。

Research on constraint-based virtual assembly technologies

In order to realize constraint-based virtual assembly operation,unified representations of assembly constraint,equivalent relationship between constraint and Degree of Freedom(DOF),and movement DOF reduction in virtual environment were proposed;and several algorithms on constraint treatment were put forward.Firstly,automatic recognition algorithm was applied to judge whether position and orientation relation between two geometrical elements of constraint were within tolerant errors extent.Secondly,to meet new constraint,position and orientation of active part was modified with minimum adjustment based on satisfying already affirmed constraints according to positioning solution algorithm.Finally,movement navigation algorithm based on generalized coordinate system was put forward,and part movement was guided according to assembly constraints.These algorithms have been applied to Integrated Virtual Assembly Environment(IVAE)system.Applications have indicated that the proposed algorithms could provide better support for constraint treatments in IVAE and has realized closer combination of virtual and real assembly process.