System Design and Sea-Trial Validation of a Long-Duration Autonomous Unmanned Surface Vessel for Cultural Heritage Surveys
This paper presents the system design and sea-trial validation of a long-duration autonomous unmanned surface vessel developed for cultural heritage survey missions in coastal and shallow-water environments. The proposed USV adopts a 48 VDC-based power distribution architecture supplying propulsion, navigation, control, communication, and exploration subsystems. To enhance operational reliability and fault tolerance, dual independent battery banks and a differential twin-thruster propulsion system are employed, enabling continued maneuverability under partial system failure conditions. For seabed exploration, the USV integrates a multibeam echo sounder (MBES) and a side-scan sonar (SSS) within a mode-based exploration framework that supports wide-area bathymetric mapping, high-resolution seabed imaging, and integrated survey missions. Autonomous navigation is achieved through GNSS-AHRS sensor fusion, providing real-time position and attitude estimation, while seamless switching between autonomous and remote-control modes ensures safe and flexible operation. A compact catamaran-type prototype with a maximum speed of 4 knots was developed and validated through real sea trials. Experimental results demonstrate stable autonomous trajectory tracking and reliable mode switching during more than 4 hours of continuous operation. Battery state of charge (SoC) measurements indicate sufficient energy margins, corresponding to an estimated operational endurance exceeding 6 hours. These results demonstrate that the proposed system provides a reliable system-level USV platform integrating autonomous navigation, fault-tolerant power architecture, and multi-sensor exploration capabilities validated through real sea trials.