Complex Constraint Oriented Reconstruction And Optimization Of Autobody Class A Surface

The automatic surface reconstruction based on point cloud data in engineering is the key technology of body design,modification design and component structure design.Reverse design shortens the development cycle of new products and improves the efficiency of model design significantly.In the body development process,it is important to reconstruct Class A surface through the cloud points.Class A surface is a kind of surface in the body model with high requirements or special requirements for surface quality.But in the body reverse reconstruction process,the automation of the reconstruction function is not the majority method.Designers still have to build model manually and adjust the model.The main reason for this phenomenon is that the quality of Class A surface is an aesthetics category which is of ambiguous definition.Although the Class A surface defines the factor which must be satisfied,but we cannot know which surface is Class A surface.Therefore,in the process of constructing Class A surface,the full participation of engineering designers is necessary.On the other hand,the current commercial reverse engineering software is more inclined to provide a simple,efficient and unified solution.But the autobody surface reconstruction is complex,it is difficult to show through a simple form.At the same time,the general reverse software just can provide non-parametric model,which limits the engineers to modify and adjust.Therefore,the current commercial solutions cannot adapt to this complex engineering situation.In view of the above problems,this paper attempts to solve the practical problems by using optimization solution in reverse engineering.The traditional reverse problem will be transformed into the optimization problem by introducing the constraint evaluation.At the same time,engineers can control the optimization of the target and design constraints to ensure the quality of surface reconstruction.In this paper,we take advantage of computer which can calculate quickly to replace manual edit based on complex constraints and evaluation.In addition,this paper summarizes the modeling methods,classifies and forms the templates,designs different iterative methods for the manual modeling of different templates.This study is based on the Siemens NX platform,which is widely used in the automotive industry,and introduces Knowledge Fusion.This paper introduces the construction method and optimization process of the template through two typical surfaces of the vehicle body.According to the different surface template,we give the automation modeling methods,engineering objectives and optimization of the library.The final example shows that the mathematical model constructed by this study can produce the result of basically satisfying the requirements,which greatly reduces the designer’s modification and iteration times.Relative to the traditional reverse process,this method increased efficiency of the reverse.At the same time,this paper will apply to other field based on the optimization of the parametric model and achieve a satisfactory result.