Research On Synchronous Measurement Method Of 3D Topography Based On EtherCAT Motion Control Platform

High-precision 3D topography measurement technology plays an important role in modern industrial production,especially in precision detection fields and scientific research such as aerospace,medical equipment,automobiles,ships and so on,which use highprecision mechanical parts largely.Through high-precision 3D topography measurement,the workpiece can be found in time whether it meets the qualified standards in production,and it can also guide the processing of workpiece,so as to improve the processing quality of the part.Aiming at the problem that the traditional 3D topography measurement has low efficiency and low accuracy,which is hard to meet the requirement of stable detection while moving with 3D topography high precision for modern enterprises and market,a synchronous measurement method of 3D topography based on EtherCAT motion control platform is proposed in this thesis.Firstly,the requirements of 3D topography synchronous measurement are analyzed based on the conventional measurement process.On this basis,the overall scheme is designed including 3D topography synchronous measurement based on EtherCAT and point cloud processing system.And then the hardware structure of the synchronous measurement device and the software design of the measurement system are completed,including PDO data design,synchronous sampling process design and communication protocol design.After measuring the 3D topography point cloud data,in order to make the measurement data more intuitive and the roughness,appearance defects,assembly tolerances and so on of the part model easier to analyze,the point cloud data is 3D reconstructed.In view of the poor surface reconstruction effect of Poisson 3D reconstruction algorithm,an improved point cloud reconstruction algorithm is proposed to improve the effect of 3D topography reconstruction.Outlier points are removed by statistical filtering to realize filtering processing of point cloud data.Aiming at the problem that the normal direction of point cloud is uncertain in traditional algorithm,normal redirection is carried out.Then the greedy projection triangulation algorithm is used to triangulate the point cloud data quickly.Finally,the holes in the surface model are detected and repaired to ensure the quality of the surface.Finally,the function and performance of the measurement system are verified through measurement experiment.The optical displacement sensor,servo equipment,and so on are used to build an experimental platform.The synchronization measurement function is verified through synchronization test.The obtained point cloud data is used for 3D reconstruction test,including filter processing,visualization processing,surface reconstruction and hole repair.Finally,the measurement accuracy of the system is verified.The experimental result show that the performance of the synchronous measurement system and the point cloud processing system is reliable,and the measurement accuracy can reach the micron level to achieve the expected functional requirements.