基于CAD模型的测量规划与可视化

发布时间：2018-05-29 22:07

本文选题：面形再设计 + 测量规划系统　；参考：《大连理工大学》2012年硕士论文

【摘要】：面形再设计类零件制造过程中设计、加工、测量互为上下游,具有环节多、要求高、信息量大、关系复杂等特点。几何量测量作为面形再设计的基础和最终零件检验评价的依据,在整个制造过程中至关重要,现有的测量方法难以满足面形再设计零件制造过程中的测量要求。零件CAD模型包含了零件几何信息,按照CAD模型进行测量规划,能极大提高测量精度和效率,研究面向面形再设计零件加工过程的CAD制导测量技术对多源约束面形再设计类零件制造理论和技术的发展具有重要意义。本论文提出了基于IGES表面模型的测量规划系统开发方法,完成了测量规划系统的总体设计,研究了曲面的采样策略、测量规划和可视化显示方法。论文详细分析了面形再设计零件制造过程中的测量要求,确定采用IGES作为测量规划系统的开发基础,根据IGES特点和测量的任务要求分析了检测规划系统的开发工作,设计了软件的功能模块、制订了软件的开发方法和层次结构。针对一般曲面测量要求,提出均匀采样和按照曲率变化进行中点二次采样相结合的采样方法,并基于该方法为IGES中常见的三类曲面分别设计了采样规则。为剔除被裁剪区域的采样点,提出将曲面及其边界映射到归一化的二维参数空间,在参数空间对被裁剪点进行剔除的方法。为解决典型特征面的测量和评价问题,设计了典型特征面的识别以及被分割旋转面的重构方法,研究了典型特征面的Hamersley采样。研究的采样策略为实现零件表面信息的精确高效测量提供了保障。针对测量方向和速度影响测量精度和效率的问题,设计了沿曲面法线进行测量的测量方法,研究了各类曲面法线的计算方法,并对定位点、测量行程、测量顺序等进行了规划。为识别零件各面的拓扑结构以合理安排测量路径规划和避障,研究了边界匹配流程和方法。为零件整体测量规划奠定了基础。为提高系统灵活性和适用范围,采用基于OpenGL的测量对象和过程可视化技术,研究了将旋转面和列表柱面转化为NURBS曲面表达的方法,并设计了转化算法。模拟结果表明,设计的转化算法和显示方法能很好的实现CAD模型及规划路径的显示。综上所述,本论文研究的测量方法和技术,能满足面形再设计类零件制造过程中的测量要求,为进一步研究面形再设计类零件加工理论和技术提供了理论参考和实践保障,具有一定的参考价值。
[Abstract]:The design, processing and measurement of surface redesigned parts are upstream and downstream, with many links, high requirements, large amount of information and complex relationships. As the basis of surface redesign and the basis of final part inspection and evaluation, geometric measurement is of great importance in the whole manufacturing process, and the existing measurement methods are difficult to meet the measurement requirements in the manufacturing process of surface redesigned parts. The part CAD model contains the geometric information of the part. According to the CAD model, the measurement precision and efficiency can be greatly improved. It is of great significance to study the CAD guidance and measurement technology for the machining process of surface redesigned parts, which is of great significance to the development of the manufacturing theory and technology of multi-source constrained surface redesigned parts. In this paper, a method of developing measurement planning system based on IGES surface model is proposed, and the overall design of measurement planning system is completed. The sampling strategy, measurement planning and visual display method of surface are studied. In this paper, the measurement requirements in the manufacturing process of the surface redesigned parts are analyzed in detail, and the IGES is adopted as the development basis of the measurement planning system. According to the characteristics of the IGES and the requirements of the measurement task, the development work of the inspection planning system is analyzed. The function module of the software is designed, and the development method and hierarchy of the software are worked out. According to the requirements of general surface measurement, a sampling method based on uniform sampling and mid-point quadratic sampling according to curvature change is proposed. Based on this method, the sampling rules are designed for three kinds of surfaces that are common in IGES. In order to eliminate the sample points of the clipped region, a method is proposed to remove the clipped points in the parametric space by mapping the surface and its boundary to a normalized two-dimensional parametric space. In order to solve the problem of measuring and evaluating the typical feature surface, the recognition of the typical feature surface and the reconstruction method of the segmented rotating surface are designed, and the Hamersley sampling of the typical characteristic surface is studied. The studied sampling strategy provides a guarantee for the accurate and efficient measurement of the surface information of parts. Aiming at the problem that the direction and speed of the measurement affect the accuracy and efficiency of the measurement, the measurement method along the normal line of the curved surface is designed, the calculation method of the normal line of the various surfaces is studied, and the positioning point, the measuring stroke and the measuring sequence are planned. In order to identify the topological structure of each surface of the part and arrange the measuring path planning and obstacle avoidance, the boundary matching flow and method are studied. It lays a foundation for the whole measuring plan of parts. In order to improve the flexibility and applicability of the system, the method of transforming the rotating surface and the list cylinder surface into the representation of the NURBS surface is studied by using the OpenGL based measurement object and process visualization technology, and the transformation algorithm is designed. The simulation results show that the proposed transformation algorithm and display method can well display the CAD model and the planning path. To sum up, the measurement methods and techniques studied in this paper can meet the measurement requirements in the manufacturing process of surface redesigned parts, and provide a theoretical reference and practical guarantee for further research on the theory and technology of surface redesign parts. It has certain reference value.
【学位授予单位】：大连理工大学
【学位级别】：硕士
【学位授予年份】：2012
【分类号】：TH122

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