Arc Welding Additive Manufacturing Motion System Modeling And Trajectory Tracking Control Algorithm Design

Arc welding additive manufacturing technology has the characteristics of high efficiency,strong flexibility and good workpiece performance,etc.,and has been widely used in the manufacturing research of multi-structure irregular large metal components.Arc welding additive manufacturing cannot be separated from moving mechanism.Currently,there are a variety of mechanical equipment used for arc welding additive manufacturing technology.Among them,the moving mechanism combined with industrial robot and positor provides more freedom of movement,which is suitable for flexible intelligent manufacturing and can improve production efficiency and reduce production cost.In theie paper,the kinematics and dynamics modeling of the arc welding additive manufacturing motion mechanism composed of the industrial six-axis robot(Kuka KR 60-3)and the H-shaped biaxial displacement mechanism produced by Shandong Aotai Electric Co.,Ltd are studied.At the same time,combined with the characteristics of arc welding additive manufacturing process,the path planning and design of the moving mechanism were carried out to ensure that the robot end effector would follow an arc trajectory relative to the end worktable of the positioner under the condition that the welding torch was always vertical.Finally,the inverse dynamics control method and robust control algorithm are adopted to design the tracking control algorithm for the motion system of arc welding additive manufacturing.The specific research contents are as follows:(1)Modeling part: firstly,D-H method was used to calibrate the coordinate system of the moving system of arc welding additive manufacturing,and the positive and negative solutions of the pose were obtained;Then,the first order kinematics equation and the second order kinematics equation of the kinematic mechanism were obtained by Jacobian matrix,and the velocity and acceleration were analyzed.Finally,Lagrange method was used to establish the dynamic equations of the robot and the locator respectively,and the position,velocity and acceleration of the six joints of the robot and two joints of the locator were simulated.(2)Path planning: Firstly,the trapezoidal velocity planning and the modified trapezoidal velocity planning in the specified time are introduced.By comparing the advantages and disadvantages of the two methods,the modified trapezoidal velocity planning method is selected as the follow-up planning method.Secondly,based on the arc welding additive manufacturing process,the arc trajectory of the robot end-effector on the end workbench of the positioner was planned.Finally,the trajectories of joint space and operation space were obtained by Matlab simulation.(3)The part of trajectory tracking control algorithm: two control schemes are designed to realize the cooperative movement of the positioner and the robot.Firstly,a control scheme based on PD linear compensation and dynamic nonlinear compensation is designed according to the inverse dynamic control scheme of the robot.Then,the control scheme based on PD linear compensation and dynamic nonlinear compensation is further improved.Based on the original control law,a stability module for uncertain error disturbance is added into the robust control method,so as to form a more excellent control system with large range asymptotic stability.Finally,the joint space Angle process data,angular velocity process data and angular acceleration process data of the joint motion system in motion planning were used to carry out Simulink simulation,and the simulation data of the two control schemes were compared and analyzed.