Research On Method And System For 3-D Shape Measurement Of High Temperature Metal Parts

Measurement environment of high temperature metal parts is complex,so make the traditional contact measurement method failed,the non-contact measurement technology based on structured light is an important direction to solve above problem.There are three technology difficulties in this measurement technology,first is the interference of high temperature radiation on the structure light projection,which makes the brightness of the light emitted by the metal element itself is much stronger than that of the projected grating fringes,so results in the failure of the measurement.Second is the algorithm of obtaining the three-dimensional depth of the metal parts is complex.Third is the measurement process of a large number of point clouds requires a very high calculate rate.In order to solving the above problems,this paper establishes a set of 3D measurement system of high temperature metal parts based on structured light,the main research contents and results are as follows:(1)Research on the image characteristics and high temperature filtering technology of high temperature metal parts.In this paper,the high temperature image acquisition scheme based on the principle of spectrum selectivity is selected by experiments and theories.Two key technologies are involved in the project,namely,digital filter technology and physical filter technology.In this paper,the feasibility and reliability of the combination of these two technologies are verified by experiments,which can effectively suppress the impact of high temperature on image acquisition.At last,the program is implemented and hardware type is selected.(2)Design the three dimensional measurement system and do measurement experiments.The design of three dimensional measurement system includes the overall design,the hardware design and software design of binocular vision system.At the same time,in order to verify the reliability of the system,select typical metal parts to carry out three dimensional measurement experiments,get the disparity map of metal parts and 3D depth information,and analyze the accuracy of the third depth information.(3)Three dimensional measurement software system embodies the core idea of the measurement,and stereo matching is an important part of three dimensional measurement algorithm.The software system uses the gray coding method to encode and decode the structured light grating to realize the stereo matching.It is proved that this method has high precision.In addition,a stereo matching method based on REAF algorithm is studied in this paper.(4)A large number of point cloud computing requires for speed,so in this paper,we use the framework of CPU+GPU,the part of a large number of parallel computing such as gray encoding and decoding is processed in GPU,speed is verified to improve a lot.