Research On 3D Measurement System Of Car Body Based On Line Structured Light

This thesis aims at the actual demand of Hangzhou Wahaha Group Co.,Ltd intelligent loading system.The line structured light three dimensional measurement technology is applied to the body measurement of the intelligent loading system.Body measurement is an important part of intelligent loading.Through the measurement of the body,the vehicle type is obtained to determine the distribution of the pallet pallet cargo to realize the automatic loading and unloading of the goods.The purpose is to save the time of loading and unloading,and to reduce the labor cost and improve the efficiency of the enterprise logistics.This thesis studies the three-dimensional measurement of the body in the intelligent loading project.The main contents of this thesis include:1.Overall design of line structure light body measurement system.The measuring principle of the optical triangulation is analyzed,and then direct and oblique two optical measurement method is introduced.Then the two methods are compared,and the principle of direct optical trigonometry is chosen as the basic principle of the measurement system.Finally,the overall plan of the measurement system is made,including the composition of the hardware and software systems.2.An improved algorithm for the center extraction of light bars is proposed,and a specific process is designed.In the process of light strip image preprocessing,the mean filtering algorithm is improved.The skeleton deburring algorithm is introduced into the light strip thinning process,which effectively removes the burr interference.Extraction of light strip image center of simulated car.The experimental results show that the algorithm for extracting the center of light stripe is more applicable and can meet the requirements of measurement speed and measurement precision in industrial field.It lays the foundation for system calibration.3.Calibration of body measurement system.The mathematical model of the measurement system is set up,and the conversion relation between the various coordinate systems is deduced.A scanning model of measurement system is set up according to the scanning direction of line structured light sensor.In this thesis,a circular mark point target is designed to realize the automatic coding of the circular mark point.By combining the method of line fitting and target plane parameter calibration,the calibration method of laser plane parameters is improved to achieve simple and rapid calibration of light plane.4.An experimental platform for body measurement system is set up.Camera image acquisition interface is designed under Visual Studio2013 software platform to realize real-time acquisition and automatic preservation of large volume scanned images.The system calibration experiment and the simulation of the three dimensional measurement experiment of the car are carried out,and the results are analyzed.The experimental results show that the line structured light 3D measurement system built in this thesis can reconstruct the 3D surface of the simulated car.It meets the actual industrial measurement requirements.