Research On Positioning For Electric Vehicle Charging Socket By Laser Scanning

With the development and popularization of electric vehicle high-power DC charging technology,the size and weight of the charging plug have increased significantly compared with the AC charging plug.The current charging method of electric vehicles is manual operation,labor intensity and low operating efficiency.And there is a danger of fire and electric leakage due to damage to the line,rain or snow.The use of robots for charging of electric vehicles is an ideal automatic charging solution for electric vehicles.With the development of automatic parking technology,there is an urgent need for automatic charging systems.The positioning of the charging socket is a pivotal link in the automatic charging system.Based on the analysis of the existing positioning technology,this paper studies the positioning of the charging socket of electric vehicle by using laser.The aim is to design a positioning system which can accurately locate the charging socket of electric vehicle and provide stable position information for the automatic charging.Based on the analysis of the ranging principle used in laser scanning technology,the line laser laser triangulation method is used to scan the shape of the charging socket.A measurement system coordinate system is established,and a positioning method based on the circular feature of the charging socket is proposed.The improved double threshold method is used to extract the features in the image,and finally the three-dimensional coordinates and angle of the center of the charging socket are obtained.The overall scheme of the positioning system is designed.The laser and the camera are installed at the end of the robot.The laser is emitted in the horizontal direction,and the scanning of the charging socket is realized by the movement of the robot.The positioning process is divided into two parts: rough positioning and precise positioning,The workflow of each link of the positioning process is determined.The suitable camera and laser are selected according to the performance indicators that the positioning system needs to achieve.The system control program and hardware driver are designed.The charging socket positioning algorithm was verified by experiments.The calibration of the positioning system were completed,which enabled the precise positioning of the points on the laser strip in the workspace.The reliability of the laser extraction algorithm was verified under different illumination conditions.Positioning experiments were carried out on the center position and deflection angle of the chargingsocket respectively.In the precise positioning range,the position measurement accuracy can reach ±1mm and ±1°,meeting the requirement of the automatic charging system for the position and orientation of the charging port.