Research On 3D Surface Scanning Inspection Method Of Rotating Workpiece Based On Structured Light

Pipes,shafts,holes and other rotating workpieces are widely used in aerospace,petroleum metallurgy,military equipment and other fields.Strict surface feature accuracy and shape errors need to be guaranteed for specific types of rotating workpiece.The existing detection methods are limited by the cumbersome aspects of workpiece clamping,debugging and calibration,which makes the detection efficiency low.It is difficult to meet the needs of more convenient and faster measurement of rotating workpiece.For the purpose of solving the above problems,a structure light-based method for threedimensional surface scanning and inspection of rotating workpieces was proposed in this thesis,and a set of rotating scan inspection device was developed.The main work of the thesis is as follows:Firstly,a vision measurement system scheme under linear structured light illumination was designed,and a set of rotating scan inspection device was built based on this scheme.The rotary scanning technology was realized by the device which was consisted of probe,three-dimensional translation device and turntable,and surface scanning of rotating workpieces can be carried out by the device to obtain its complete three-dimensional surface point cloud data.Secondly,combined with the characteristics of rotary workpiece,the surface scanning detection model of rotary workpiece was established based on the column coordinate system,and the model calibration method under the homography transformation was designed,which not only guaranteed the calibration accuracy but also greatly simplified the calibration process.Thirdly,the point cloud alignment method based on central axis was studied deeply.The influence of the position and pose of the workpiece on the measurement results was analyzed and the point cloud alignment method was designed.The position and pose parameters of the workpiece were obtained by establishing a three-dimensional geometric model of the central axis of the rotating workpiece and fitting the central axis of the rotating workpiece by particle swarm optimization algorithm.The feasibility of the point cloud alignment method was verified by simulation experiments.Lastly,the diameter and shape errors of a glossy ring gauge with a nominal diameter of 73.9901mm were measured,and the measurement error of the diameter of the ring gauge is:7.1μm,the measurement of the standard deviation is:2.5 μm,the measurement error of roundness is:0.7 μm,the relative error of roundness error:14.58%.Cylindricity measurement value is:16.8 μm,measurement error is:0.5 μm;The measurement experiments were conducted on the rotating workpiece with three-dimensional geometric features,and the error of its threedimensional geometric features was measured to be within 20μm.The experimental results show that a structure light-based method for three-dimensional surface scanning and inspection of rotating workpieces which proposed in this thesis has high measurement accuracy and the characteristics of low calibration complexity and operation complexity,and can be applied to the measurement of the diameter,shape errors and surface geometric features of the rotating workpiece.It has certain theoretical significance to meet the requirements of high detection efficiency of the rotating workpiece.