Research On Trajectory Tracking Control Of Six-DOF Arc Welding Robots

Due to the characteristics of robot system with time-varying, strong coupling and nonlinear system, there is friction, load changes, the random disturbance factors as well in the actual operation of the control system, which requires the robot has good adaptability.Recently robot control problem has become the frontier of research in the field of robot control.In order to meet the requirement about motion stability of HP20 robot, decreasing the tracking error, achieving precise control of the robot system, further improve the quality of welding.Taking the HP20 robot as the study object, research aspects of the kinematics, dynamics and control, with modeling,simulation and analysis.The four contents mainly the main contents are as follows:(1) The forward kinematics problem is analyzed by the homogeneous transformation matrix and D-H method,the inverse kinematics problem is analyzed by the analytic method, and the dynamics problem is analyzed by the method of Lagrange energy balance. Finally,the mathematical model of kinematics and dynamics were deduced, providing the basis for the trajectory planning.(2) Based on kinematics and dynamics, interpolate and plan the robot path respectively in the joint space and Cartesian space. The former includes three polynomial method, five order polynomial method and parabolic transition interpolation method, and the latter consists of linear interpolation and circular interpolation method,making each joint running smoothly, satisfy the trajectory and meeting smooth requirements of Trajectory planning.(3) In order to observe and verify the above theory visually, using the MATLAB GUI platform by calling the function and establishing a graphics user interface by programming, the interface is mainly to achieve three simple functions with Robotics Toolbox:the first is to generate 3D structure diagram of the robot in the working space,observe operation condition real-time;the second is the inverse kinematics problem simulation; the third is to plan path by using two ways, generating simulation curves of position, velocity and angle acceleration,providing the basis for trajectory tracking control.(4) Based on the trajectory planning, discuss the application of adaptive control in the control system of the robot, through the MATLAB simulation analyzing, under this controller, robot can follow the desired trajectory with a smaller steady-state error.Through the calculation, analysis and experimental results show that the adaptive control algorithm in this paper can achieve precise control of the robot system, and has reached the purpose of further improving the quality of welding robot.