Locating, trajectory planning and control of an underwater propeller cleaning manipulator

After a long time of navigation, marine fouling occurs on a ship's hull and propeller, leading to higher frictional resistance of the hull and lower effectual output of the propeller, and it also damages the hull and propeller. Currently, there are extensive studies on robots for underwater cleaning of ship hulls with large areas and relatively regular surfaces. However, robots for underwater cleaning of propellers with complicated spatial surfaces are still in demand. Motivated by this need, a solution for cleaning the propeller by the underwater manipulator is proposed in this study. Coarse registration and iterative closest point fine registration were adopted to improve the propeller's locating accuracy. Non-dominated sorting genetic algorithm-II was applied to optimize the trajectory of the B-spline joint to obtain an optimized trajectory that meets the specific requirements of the underwater manipulator. Finally, sliding mode control was adopted for high trajectory tracking. The integrated task of locating, trajectory planning, and control was simulated. The simulation results demonstrate the effectiveness of the above methods and the feasibility of the proposed scheme. This study serves as a guideline for further research in the analysis and system design of the underwater manipulator for cleaning propellers.