Experimental study on accurate heading control of an underwater robot, yShark

Recently, fast and accurate motion of an underwater robot becomes a key issue because overall efficiency and quality of missions such as underwater structure inspection, underwater mapping, and underwater surveillance highly depend on the low-level control performance. In particular, accurate heading control performance has great influence on horizontal motion quality. However, thruster nonlinearity with dead-zone and difference among horizontal thrusters make the problem difficult because an underwater robot is mostly in a transient state during fine motion control, In this paper, an accurate heading control scheme is proposed to improve control performance using a simple null motion control based PD controller. The proposed scheme was verified by experimental pool tests with an underwater robot, yShark which has been developed by Korea Institute of Ocean Science and Technology (KIOST).