Development And Application Of Vision System Of Robot For Grinding And Polishing Straight Pipe Weld Based On Vision Guidance

At present,the grinding and polishing of welds mainly depends on the way that workers observe the appearance of welds through eyes and judge grinding and polishing parameters through experience.This way of relying on human eye recognition and artificial grinding and polishing will not only cause great harm to the workers' bodies,but also the surface quality of the weld after grinding and polishing is difficult to be guaranteed.In recent years,the rapid development of robot automatic grinding and polishing technology and robot vision measurement technology provides a new technical solution for weld grinding and polishing.In this paper,the key technologies of the robot based on visual guidance are studied.In the actual process of weld grinding and polishing,due to the irregular changes of weld height and width,it is necessary to adjust the robot position and posture in real time,so that the grinding and polishing wheel can change in the direction of weld height and width in real time to ensure the weld surface quality after grinding and polishing.Therefore,this paper first determines the overall scheme and process of the robot based on the visual guidance,and develops the robot based on the robot mechanical body,which integrates the visual system and the grinding and polishing system.This robot mainly guides the robot to grind and polish the weld seam with the correct position and posture through the on-line measurement of the vision system.The structure and principle of the grinding and polishing system and the vision system are designed and introduced respectively from the system level.According to the actual processing requirements,the hardware of each system of the robot platform based on visual guidance is designed and developed.Through the above design and integration of the grinding and polishing system,robot body and the hardware and software in the vision system,the experimental platform of weld grinding and polishing robot based on the vision guidance is finally developed.Then the theoretical basis and mathematical description of the vision system modeling of the robot are analyzed.The mathematical model of stereo vision system based on monocular laser is constructed.Through this model,the transformation relationship model among camera coordinate system,image coordinate system and world coordinate system is obtained,and the mathematical model of vision system of weld polishing robot is established;the theoretical basis of line structured light calibration is analyzed,and the plane equation of line structured light is obtained by using the plane chessboard as the calibration target on the MATLAB experimental platform;The different forms and methods of hand eye calibration are analyzed and compared.The hand eye calibration between vision system and robot is completed by using ceramic standard ball.At last,in order to realize the information interaction between vision system and robot,the software of vision system is developed.In order to verify the feasibility of the intelligent welding robot experimental platform developed in this paper,the robot welding operation experiment was carried out.By comparing the real-time grinding and polishing of vision system guided robot with traditional teaching grinding and polishing,the advantages of vision system guided robot in robot grinding and polishing are verified.The repeated measurement accuracy experiment of the vision system is carried out for the point on a certain section of the weld.The results show that the vision system adopted in this paper has high stability.In this paper,the starting point of weld grinding and polishing is shifted in width direction,and the ability of vision system to guide robot grinding and polishing in this case is studied.