Research On The Technology Of CAD Reverse Modeling Based On Multi-sensor Measurement

With the rapid development of manufacturing and computer science, more and more attention has been paid to the studies on the reverse engineering, which now is a research focus. Reverse engineering technique is in such a background request to produce and develop together. Reverse engineering is relative to the positive for the project. On the basis of the physical product, sample or prototype, three-dimensional digital models are generated. And then on the basis of the digital model of production, processing or secondary development is conducted to achieve innovation. Due to the physical sample can be copied in a very short period of time, which can shorten the product development cycle, improve productivity, product quality and market competitiveness, increase economic efficiency of enterprises.Reverse engineering includes data measurement, data preprocessing and surface reconstruction, data measurement is usually divided into contact measurement and non-contact measurement, along with science and technology development, a simple measurement technology cannot meet the actual demand, so there appears multi-sensor combinations measurements. Existing reverse modeling method is mainly for the same density, with similar precision measurement data. In order to meet the new requirements of modern digital systems for reverse engineering model reconstruction method proposed remedy existing modeling and reverse engineering of software deficiencies, this paper studies the technology based on multi-sensor data measurement.Firstly,introduced two main methods of measurement in reverse engineering: contact and non-contact measurement according to the principle of analyzing the advantages and disadvantages of two methods of measuring. CAD model reconstruction of the basic theories were reviewed, detailed introduced the commonly used three modeling methods:based on the curve of model reconstruction; Based on the polygon mesh model reconstruction; Based on the characteristics of the model reconstruction.Combined with the advantages and disadvantages of two kinds of data measurement methods, in view of the free surface, first with a non-contact measurement method for free-form surface of the initial CAD model, then using three coordinate measuring machine measurement point of a small amount of high precision, based on energy optimization method is used to complete the initial model of point constraint deformation, or the cross section of a surface measured with three coordinate measuring machine, complete the initial model of line constraint deformation, two kinds of measuring data of data fusion. Specific examples was given to verify the feasibility and effectiveness of data fusion.In view of the sample which have scanning blind area such as a deep hole, alignment method is presented based on the characteristics of data. With the laser scanning the surface of the sample, three coordinate measuring machine to obtain the optical scanning blind area, using data alignment method based on the characteristics of the two groups of measuring data of alignment, finally achieve the model reconstruction based on multi-sensor measurement data.