Representation of Dynamic Positioning on Hovering Type Autonomous Underwater Vehicle in Precise Welding Operations

This paper proposes dynamic positioning (DP) on a hovering autonomous underwater vehicle (HAUV) to perform accurate underwater processes such as welding operations. High maneuverability, high controllability, and hovering of the robot were the prerequisites of this operation, which increase its accuracy and velocity and reduce costs and human health risks. Other types of thrusters were used in this robot to reduce the number of thrusters and controller''s complexity. Controlling every 6 degrees of freedom to perform this type of operation was done. Furthermore, such a delicate operation required controlling the translational and rotational movements together. There was also a need to control the velocities to travel in a prescribed distance at a reasonable time. The possibility of dynamic positioning for welding and maintaining position at a point was defined for the robot. Then the robot''s performance under a defective state-servo motor failure, thruster malfunction-and the subsequent effects on the performance during the predetermined missions were investigated. Simulation results demonstrated that the HAUV has the capability to perform dynamic positioning operations. In this article, one of the prevalent classic control methods called PID controller was employed for controlling the movements of the robot.