【作者】 鞠华；

【导师】 陈子辰； 王文；

【作者基本信息】 浙江大学 ， 机械制造及其自动化， 2003， 博士

【摘要】 在产品开发及制造过程中，计算机辅助技术已被应用得相当广泛。新型计算机辅助技术的发展使得CAD／CAM无缝制造技术得以实现。由于在许多情况下设计者和制造者面对的是实物样件，需要将实物模型转化为CAD模型。因而产品信息模型是实现无缝制造技术的关键。与这种以实物模型为依据生成数据信息模型相关的技术，已发展为CAD／CAM中的一个相对独立的范畴，即逆向工程(Reverse Engineering)。在机械领域中，逆向工程(Reverse Engineering)是在没有设计图纸或者设计图纸不完整以及没有CAD模型的情况下，按照现有零件的模型(产品原型或油泥模型)，利用各种数字化技术及CAD技术重新构造CAD模型而克隆或创造实物产品的过程。在与制造业密切相关的航空航天、汽车、造船及模具等工业领域，未来追求对产品功能和外形等方面的日益严格的要求，这使得自由曲面零件在现代工业中得到了越来越广泛的应用。其加工质量和生产周期对提高产品的性能和市场的响应速度起着关键作用。本文结合浙江省科技计划重点项目“多传感器集成的智能化柔性测量、加工一体化装备研制”和浙江省先进制造技术重点实验室建设项目“三坐标数控曲面测量系统”，以自由曲面为研究对象，以获取自由曲面精确数据信息模型为目标，在传统数控铣床上研制开发基于运动控制卡的开放式数控非接触式激光测量系统，同时对逆向工程中的关键技术——自由曲面非接触式测量规划、测点数据的处理、误差补偿等技术进行研究，以有效地实现自由曲面的零件设计与制造的集成，实现制造过程的集成化、智能化、低成本。 论文首先分析了逆向工程技术在先进制造技术领域发展的必然和它的概念，通过分析逆向工程的应用领域、国内外发展现状，归纳出逆向工程的特点和研究热点，进而提出本论文选题的依据，概述了本论文的主要研究内容和论文结构。在分析开放式数控系统的基础上，提出“PC+运动控制卡”的开放式数控非接触式激光测量系统的体系结构。分别分析IPC与两种运动控制卡，包括PMAC和GT-400-SV集成的工作原理。给出系统的总体框架构成和激光非接触测头的数据采集原理。对数控非接触式激光测量系统的软件构成进行分析，然后给出基于开发的激光测量系统进行逆向工程关键技术研究的总体研究框架。 在截面线法测量的基础上，对阶梯式跟踪法、直线式跟踪法和仿形式跟踪法进行分析比较。基于三次参数样条曲线的性质，在有界曲率的平面曲线的有界性的基础上，提出通过圆弧外延点位控制测头自动跟踪曲面，即后续测量点根据已测前三点求得的圆弧曲率沿切线方向或曲率外延来进行预测，并根据测点矢量来估测保证数字化几何信息的充分性。并通过给定理论B样条曲线，对该算法进行仿真，验证该算法的有效性。 对逆向工程技术的第二步数据点的处理进行研究。首先剔除粗大误差，然后浙弓工大理六节攀士学七忆论文对测点数据进行滤波处理，再对大规模数据点进行压缩。在分析各种数据压缩算法的基础上，针对激光非接触测量设备提出一种基于直线度和距离偏差相结合的自适应数据压缩算法，通过实例对算法进行分析与比较。 在分析激光三角测量的原理的基础上，建立激光测头的仿真模型，研究影响激光测量精度的影响因素。然后，设计实验，分别分析待测物体的表面特征，包括表面粗糙度、颜色、材料和表面倾角等对测量精度的影响。最后，对实验数据进行误差分析，首次提出误差表征法对测量数据进行补偿修正。 针对逆向工程中曲面部分破损、不完整，或者由在逆向工程过程中因测量方法和测量设备的局限而造成的阻塞和可及性问题使获取的数据信息不完整，提出了采用神经网络实现逆向工程中数据修补的方法。通过BP反向传播算法分析了神经网络在数据修补等几何造型方面的应用可能以及存在的问题。根据径向基网络学习速度快、避免了局部极小值的优点，建立了径向基神经网络模型，通过仿真实验分析径向基网络模型在数据拟合中应用的有效性。 基于开发的激光测量系统对前面各章理论进行实验研究。研究了表面轮廓边界的确定。并对从数据点到曲面重建再生成加工路径和从数据点直接生成数控加工路径通过实例进行了分析。 最后对本文的研究内容和主要工作进行了总结，并展望了下一步的研究方向。更多还原

【Abstract】 Computer aided technologies have been widely utilized in product development and manufacturing. The development of advanced computer aided technologies make it possible to realize the CAD/CAM integrated manufacturing. In many cases, designers and manufacturers only can obtained an original or physical model, and it is needed to change the physical model into CAD model. So the product information model is the key to complete the integration of design and manufacturing. In industrial application, the basic concept of producing a part based on an original or physical model without the use of engineering drawing is called "Reverse Engineering". Reverse engineering typically starts with measuring an existing object so that a surface or solid model can be deduced in order to exploit the advantages of CAD/CAM technologies. It is often necessary to produce a copy of a part, when no original drawings or documentation are available. In other cases we may want to re-engineer an existing part, when analysis and modifications are required to construct a new improved product. Especially in the aeronautical, automotive, shipbuilding, die and mould, and aerospace manufacturing industries that frequently encounter complex surfaces, since shorter lead time has become a competitive advantage. To satisfy the tremendous need for product shape design and functional modification, reverse engineering has played an important role in recent years. The dissertation is incorporated with the Provincial Key Science and Technology planning of Zhejiang-Research and developent on the integration instrument of intelligentization flexible measurement and machining based on multi-sensor, and the project for the Construction of Zhejiang Province Key Lab of Advanced Manufacturing Technology supported by Zhejiang province-Three coordinate NC(numerical control) surface measuring system, an open NC non-contact laser measurement system was developed aiming at obtaining the precise data information model of freeform surfaces. At the same time, the key technologies for reverse engineering such as non-contact measuring planning for freeform surfaces, measured data processing, error compensation etc. were researched to realize the integration of design and manufacturing for freeform surface parts.Firstly in the dissertation, the inevitable trend of reverse engineering being applied in the advanced manufacturing industry field and the definition of reverse engineering was analyzed. After identifying the purpose of reverse engineering, the main application area and the research situation of domestic and abroad, the characters and research hot spot were induced. Then, the main research aim of this dissertation was put forward and the research contents were summarized.The open numerical control system-"PC+motion control card" for non-contact laser measurement system was presented. The communication principle between I PC and two motion control card including PMAC and GT-400-SV card was analyzed respectively. The precision servo and mechanism are narrated, and the software structure is introduced. The overall framework of key technologies in reverse engineering based on the developed lasermeasuring system was given out.Based on the cross-section curves measuring, several adaptive digitizing approaches including ladder tracing, line tracing and profile tracing techniques are analyzed and compared. A plane curve which has a finite maximum curvature is bounded locally by two tangent circles, based on this, the arc length extrapolation is proposed. It is that the next measurement point can be predicted via arc length extrapolation and can be adaptive to sense the change of freeform surfaces. And the reliability of the digitizing geometry information can be verified according to the measured points vectors. Finally, the methodology was tested and verified by computer simulation.The pre-processing of measured points is the second necessary step in reverse engineering. After eliminating the crass error, filter methods used in signal processing are use更多还原