Metal Phone Shell Three-dimensional Measurement System Based On Fringe Projection

Structured light three-dimensional(3D)measurement has the advantages of non-contact,high precision,low cost,it has been widely used in industrial manufacturing,cultural and education,health care and so on.Phone shell shape and sizes are very complex,and its machining accuracy will affect the yield of subsequent mobile phone assembling.Therefore,measuring all kinds of critical sizes is necessary.Traditional methods of phone shell precision measurement are using caliper and industrial measurement microscope and other measurement tools,which have low efficiency and large artificial errors.And traditional methods can only detect two-dimension plane sizes,mature three-dimensional measurement equipment is less.In addition,many sizes are need to measure,cooperation measurement with multi-station and multi-equipment will be costly and complex.To solving above difficulties,this dissertation put forward a metal phone shell key dimensions auto measurement system with double-node three-dimensional sensing method based on Phase Measuring Profilometry to get three-dimensional data efficiently and developing software module for detecting key dimensions from model,can simplify process and reduce cost.The main works includes:Firstly,a metal phone shell measurement system based on fringe projection is proposed.The system is composed of double-node three-dimensional sensor,assistant motion device,and pose transformation unit.Three-dimensional sensor of each node includes two industrial cameras and a projection device.Two three-dimensional sensor nodes measure front and side phone shell respectively.Assistant motion device drives phone shell to every measurement location for obtaining all of the measured data.Combined with the calibration results of two-node sensors,the point cloud from sensors will be stitching automatically;And point cloud coordinates in all of the location are normalized with circle mark points.Point cloud optimization method is researched for realizing point cloud filter,key dimensions extraction,etc.Secondly,metal phone shell three-dimension measurement system software is built.Software include two-node sensors synchronous projection and acquisition module,assistance motion device moving control and communication module,three-dimensional model reconstruction module,point cloud data processing module and size extraction module.The system achieves the function of phone shell point cloud data acquisition and key size automatic extraction within one minute.Thirdly,the accuracy of three-dimensional reconstruction and dimension extraction of the system are analyzed.Phone shell measurement result is analyzed by contrasting phone shell sample measurement result with machining sizes.Subsequently,the analysis is given by measuring standard plane.Meanwhile,the accuracy of the system is evaluated by measuring and analyzing boss column height under 100 times.For those measuring results that exceed the accurate range,reasons causing error will be thinking about.