Research On Kinematics Analysis And Weld Trajectory Planning Of Welding Robot

At present,welding robots are widely used,but in the process of use,most welding robots adopt teaching programming,which undoubtedly increases the programming workload and preparation time.In this paper,the welding seam trajectory is extracted by visual image,and the trajectory curve is generated by interpolation and fitting to obtain the parameter control robot motion.This article mainly carries on the research from the following several aspects:(1)Motion Analysis of Welding Robot.Taking ER10-C60 robot as an object,the kinematics model of the robot is established by using D-H method.The positive and reverse motion relationship of joints is analyzed,and the motion form of welding robot is discussed.Based on the relationship between the joint angle and the terminal coordinates,the expressions of the joint solutions are obtained,and the authenticity of the inverse kinematics solutions is analyzed.The necessary preparations are made for the welding seam trajectory generation and the robot motion control.(2)Visual image extraction of weld seam.Starting from the correlation of robot coordinate system,image coordinate system and world coordinate system,a welding seam image shooting device is designed.The camera calibration method is used to reduce the radial distortion and tangential distortion error of the image and to improve the precision of weld track extraction.The robot hand-eye calibration method is used to improve the terminal response speed of the robot and to create conditions for improving the precision of the welding torch trajectory.(3)A visual information extraction device for binocular vision is designed.According to the requirements of the weld image processing,a visual filming device,a dynamic driving device and a fixed auxiliary device are designed in three parts,which meet the extraction conditions of the line welds,such as the linear welds and the arc welds.(4)Welding image processing.By using the methods of grayscale,binarization,segmentation and corrosion expansion,the welding seam image is processed,the edge contour of the weld is extracted,and the robot control system is introduced to solve the problems of automatic extraction of weld contour and information import.(5)Trajectory planning.According to the seam contour extracted from visual image,a simple or complex trajectory is fitted with linear and arc curves in the joint space coordinate system,the Cartesian space coordinate system,the space and plane cycloid coordinate system.The weld trajectory is obtained by interpolation calculation,which is convenient for robot joint motion planning.By analyzing the motion process of the welding robot,the kinematic relationship of each joint is obtained,and the motion accuracy is more effectively controlled.The relationship between the image coordinate and the robot coordinate and the terminal actuator is connected from the camera and the robot hand-eye calibration,and then a visual camera is designed to capture the weld seam image.The clear weld image profile is obtained by various image processing methods,and then transformed into coordinates and transmitted into the robot system for recognition.Different weld trajectory planning methods are proposed to meet the needs of welding work.