An optimal trajectory control strategy for underwater welding robot

Abstract

The underwater welding robots are replacing humans in several harsh working environments however further strategies are required to achieve better control of robotic motion in order to extend their utility. This paper presents a smooth trajectory control strategy to improve the welding quality and efficiency using an underwater welding robot to perform the arc welding process. First, a mathematical model of the underwater welding robot is established using the D-H parameter method. Second kinematics equations for the movement of the robot are deduced. To improve the accuracy of the trajectory, the tool coordinate system is calibrated using the six-point method. Finally, linear interpolation with parabolic transition is combined with a six-dimensional space vector to develop a Cartesian space trajectory planning for the robot, which can ensure a smooth welding process. The results show that by using the above control strategy for underwater welding experiments, a smooth welding seam is achieved, which improves the weld quality and shortens the time taken to complete the weld.