Research On Cooperative Control Of Welding Robot Workstation

With the continuous development of welding automation,the tasks to be accomplished by the welding robot are becoming more and more complex.A single welding robot has been difficult to meet the needs of today's complex welding tasks.The coordinated operation of the welding robot and the positioner can make up the shortage of the single welding robot and increase the work space.Therefore,the problem of coordinating the welding robot and the positioner has become the development trend in the welding field.In this paper,a welding robot workstation consisting of a single welding robot and a positioner is taken as a research object,and some key technologies of its coordinated motion control are studied.The contents are as follows:Firstly,the application requirements of welding robot workstations were analyzed,the selection of important equipment was made,and the welding robots,positioners and peripherals were introduced in detail.A welding robot system consisting of a two-DOF positioner and a six-DOF welding robot is constructed.The safety protection system and the control system of the robot workstation are designed.The overall scheme of the robot workstation is completed.Secondly,the forward kinematics and inverse kinematics of the welding robot are analyzed by D-H method and matrix transformation.The optimal inverse solution selection principle is given for the inverse solution problem.The positive kinematics and inverse kinematics are also carried out for the positioner,and the downhand welding position is also given.The inverse solution method of positioner under the condition of pose constraint is applied,and the correctness of the forward and inverse solution of robot is verified by simulation.Third,the trajectory planning in the motion of the welding robot is studied,including the trajectory planning of the circular arc,the straight line and the point to point motion of the Cartesian space,the three polynomial interpolation and the five polynomial interpolation in the joint space.In order to improve the end-movement stability of the welding robot,and according to the trajectory control characteristics of the welding robot,an acceleration and deceleration control algorithm is given and implemented.The simulation results show that the curve trajectory is smooth and the feasibility of the algorithm is verifiedFinally,the cooperative control algorithm of the welding robot workstation is studied.The least squares method is used to calibrate the position relationship between robot andpositioner.A collaborative control algorithm for robot workstation based on kinematic chain coupling and decoupling is proposed,taking two common complex space weld line workpiece as object.and set up the simulation system of welding robot collaborative work.Through simulation,it is verified that each joint of the robot system operate within a reasonable range,and the trajectory of the welding torch is ideal,welding distance to meet actual requirements.The coordinated movement of the robot workstations was realized and the correctness of the algorithm was verified.Finally,according to the on-site welding test,it is shown that the welding robot and the positioner work well together,and the weld seam is smooth and well formed.