Research On Combination Measurement Technology Based On 3D Model

The assemblely measurement is a key step in its manufacture process.The current measuring equipment is laser tracker,which is suitable for measuring anti-aircraft missile geometry measurement based on a small number of measuring points.But for the situation of a large number of measuring points of the special surface,multi-holes and other measurement occasions,it has the issues of low measuring efficieccy,low measuring accuracy and so on.This paper combines the measuring characteristics of laser tracker and 3D laser scanner,focuses on the study of the combination measurement technology based on 3D model and achieves the key technology of calibrating 3D laser scanner's cumulative error,preprocessing the point cloud data,evaluating the measurement uncertainty and so on.The theoretical research and simulation results show that the technology is feasible.It can significantly improve the measurement efficiency under the premise of ensuring measuring efficiency.The main research contents of this paper are as follows:1.This paper analyzes the bottleneck technology and puts forward the overall plan of combination measurement by using laser tracker and 3D laser scanner.Based on the block measurement method,it achieves the measuring field's unify and measurement scheme's establishing.The coordinates unify algorithm based on PSO is also proposed.2.This paper studies the preprocessing technique of large-scale point cloud data,including point cloud filtering and simplifying.There are two methods proposed to filter point cloud data.One is based on the distance from point to nearby points and another is based on the number of nearby points.It puts forward the estimation algorithm of point cloud curvature based on octree data structure.The data redundancy is removed on the basis of estimation curvature.3.This paper constructes the uncertainty evaluation platform of the combination measurement based on SA(Spatial Analyzer).The platform software evaluates the simulation uncertainty of the combination measurement based on the Monte Carlo algorithm.By analyzing the source and impact of cumulative error,the cumulative error of 3D laser scanner is calibrated by using laser tracker to.Besides,it evaluates the uncertainty value and sensitive direction.4.With one size anti-aircraft missile as study object,this paper simulates the anti-aircraft missile's specific measuring elements and evaluates the measurement result uncertainty.Furthermore,it proves the feasibility of using laser tracker and 3D laser scanner to complete anti-aircraft missile's assemblely measurement.