| 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...
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