Weld Seam Tracking And Control Of Wheeled Mobile Welding Robot With Multi-Line Laser Sensor

Automated welding has gradually replaced manual welding with its advantages of good quality,high efficiency and low labor cost.Welding robot is a common form of automatic welding.Automatic tracking of the weld seam can be achieved by sensing the weld information and feeding it back to the robot through sensing technology.At present,the arm welding robot is widely used due to its high precision and mature technology,but its position is fixed,the volume is large,and the flexibility is insufficient.For the problem that arm robot cannot adapt to the welding work for large workpieces,small spaces and some non-structural environments,mobile robot combined with sensor is adopted to achieve a highly flexible and adaptable welding robot system.Firstly,the hardware and software system of the robot is built with the wheeled mobile welding robot and multi-line laser sensor as the core,including mobile robot mechanism,multi-line laser vision sensing system,control system and the welding equipments.Secondly,a hybrid gear train mechanism suitable for the wheeled robot is proposed.The four wheels can be driven and turned simultaneously by two forward motors and two steering motors,which reduces the complexity of control and improves the motion accuracy of the mechanism.Combining the speed analysis of the hybrid gear train with the principle of no side slip steering,the kinematics model of the robot is established under the conditions of no side slip steering.The motion simulation based on circular trajectory is carried out by virtual prototyping technology,which verified the correctness of the mechanism and its kinematics model.Then,for the typical welding trajectories such as oblique line,polyline and circular arc,the welding trajectory information acquisition method based on multi-line laser sensor is proposed.And a posture angle deviation calculation model of the robot during tracking is proposed for the arc-shaped welding trajectory.Combined with the kinematics model of the mobile robot,PID control method and fuzzy control method,the weld seam tracking controller for coordinated control of robot posture and slider is designed.Finally,the joint control simulation models based on typical welding trajectories are established,and the tracking control simulations of the welding trajectories such as oblique lines,polylines and circular arcs are carried out.The error of the weld seam tracking does not exceed ±0.2mm,and the tracking error in the stable section does not exceed ±0.01 mm.The results show that the proposed control method can improve the control precision and stability of the robot.On this basis,the related algorithms are designed,the control software is developed under Windows XP and VC++ 6.0 environment,and the weld seam tracking experiment of the oblique trajectory is carried out.The tracking deviation is less than ±0.3mm,which proves that the welding robot system can satisfy the requirements of actual welding.