Research On Weld Tracking System Of Gantry Welding Robot

Aiming at a large number of large-scale structural welds in shipyards,this paper develops a 5-DOF welding robot based on a rotating arc sensor based on a gantry platform.This robot has a large working range and is particularly suitable for welding large welding parts.The welding robot uses a rotating arc sensor to detect and track the weld.The rotating arc sensor is a real-time weld tracking sensor.Compared with an external weld sensor such as a vision sensor,it has no pre-adjustment,and is not affected by arc and splashes.,good real-time and other advantages.Therefore,the development of a rotating arc sensor based gantry welding robot used in shipbuilding and other industries is of great significance in improving the level of automated welding in China's shipbuilding industry.This paper mainly focuses on the construction of robot hardware system,the tracking of fillet welds at high inclination angles,and the related technologies of robot planning,planning and motion control.The robot hardware system is mainly composed of a gantry moving platform,a torch oscillating mechanism,a rotating arc torch,and a robot control system.This article designed the torch oscillating mechanism and torch connecting plate and other institutions.The robot control system uses an embedded control system based on PC104 bus,which has functions such as motion control,signal acquisition and processing.Designed and optimized related hardware circuits,reduced flying lines between circuits,and improved the system's anti-interference and stability.The basic principle of the rotating arc sensor is studied.Based on the predecessors,the signal filter is designed.The least squares method is used to fit the filtered current signal into a straight line.The slope of this line represents the deviation of the weld.A geometric model of the height of the rotating arc torch was established.Through the study of this model,the welding currents of the first and second half cycles in a welding torch rotation cycle were respectively fitted by the least squares method,and the welding torch was in the presence of the inclination angle.The method of identifying weld deviations,ie the average of the slopes of the two straight lines,represents the deviation.In addition,the fuzzy controller is designed in this paper.The fuzzy controller is used to control the robot tracking weld.Finally,lattice-shaped fillet welds in a lattice-shaped cabin were studied and classified into straight fillet welds and 90-degree fold fillet welds.The kinematics equation of the welding robot was established,the position and attitude of the welding torch were described,the workpiece coordinate system of the weldment and the origin of the welding torch were set,the welding robot's 90° polyline fillet weld trajectory planning was completed,and the rotating arc was used.The sensor recognizes the rightangle points and divides the welding of the 90°-fold line fillet weld of the robot into two straight-line fillet welds,which ensures welding to the weld at the corner points.Through experiments,the welding of fillet welds at 90° is completed,which verifies the feasibility of welding robots in grid-shaped cabins.