# ENDURUNS: An Integrated and Flexible Approach for Seabed Survey Through Autonomous Mobile Vehicles
## 3 System Functionalities
### Unmanned Surface Vehicle  
The USV is designed to act as a mothership for the AUV hybrid vehicle but also as a means of facilitating communication between the ENDURUNS remote control centre and the AUV when it is operating at depth. The USV also feeds the information to the AUV in order to confirm its exact position in the territory of the mission with the aim of providing high quality data geo-referencing.  
The USV was designed to be compact and lightweight, it is 7 m long and 2 m width, manufactured using glass-fibre reinforced composites with the resin infusion method. It is a 100% electric unit, with the power pack consisting of a rechargeable Li-ion battery, flexible marinised photovoltaic panels manufactured of monocrystalline Si and a hydrogen fuel cell. The overall USV schema is represented in Figure 3.  
The Li-ion battery are used to power both the electric thrusters, which are responsible for providing mobility of the USV, and the rest of the electronic components installed on board. The photovoltaic panels are responsible for recharging the battery pack, while the fuel cell switches on only if the panels can not work properly, e.g., during the night, with bad weather conditions.  
In the present configuration, the USV is not equipped with scientific instruments, but it is designed for receiving and processing onboard the scientific data acquired by the hybrid AUV. The processed information is then transferred via stellate to the RMCC. The RMCC is also connected to the autopilot of the USV, providing the necessary information to navigate to/from the target survey area. Safe navigation is guaranteed by the anti-collision system, consisting of AIS, GPS, lidar and radar systems. The Table 5 summarizes the most relevant components installed onboard of the USV.  
Figure 2: The modular hybrid AUV overview. The length are reported in mm; the letters from (**a–f**) represent the propulsion module, the navigation module, the primary energy module, the secondary energy module, the payload module and the nose module, respectively.  
\begin{table}
\begin{tabular}{l l l} \hline \hline
**Component** & **Model** & **Description** \\ \hline Thrusters Engines & BlueRobotics T200 & the USV is equipped with two thrusters, 390 W each \\ \hline Autopilot Unit & SPECTRE AP PCB & remote control autopilot for USV \\ \hline Radar & UMRR Type 42 & 3D object tracking in ultra high definition for traffic radar \\ \hline GPS Receiver & UBLOX & NEO-M8N \\  & (USB Dongle) & it compute the absolute USV position \\ \hline GPS Antenna & AQHA5.0A.301111 & active multi-band Global Navigation Satellite System (GNSS) \\ \hline CPU Power source & NeoNSy Rugged Intel 6 th & compact fanless rugged embedded computer \\ \hline Satellite Modem \& antenna & Thales VSSELINK & global satellite coverage for maritime communications, with uninterrupted coverage from pole to pole \\ \hline Wi-Fi modem \& antenna & WL-WN570 HN2 & Long-Range high performance links \\ \hline Acoustic system USBL & EVOLOGICS USBL & AUV/USV underwater acoustic communication with additional functionality of acoustic transponder \\ \hline \hline \end{tabular}
\end{table}
Table 5: The main USV navigation components and sensors.  
Figure 3: Lateral, top and diagonal views of the ENDURUNS Unmanned Surface Vehicle (USV).