# A Review of Autonomous Tugboat Operations for Efficient and Safe Ship Berthing
## 2 Current Developments of Unmanned/Autonomous Towing Technology
### Projects Related to Autonomous Towing
Subsequently, there has been an ongoing effort to develop the world's first remotely controlled unmanned commercial tugboat that can operate over a wide range in collaboration with the Abu Dhabi Port Authority (ADP) of the United Arab Emirates (UAE) [17]. The development of such an autonomous tugboat is expected to provide significant benefits, such as improved safety, efficiency, and cost-effectiveness of towing operations in the region. Finally, the IntelliTug project is a large-scale collaboration between PSA(Port of Singapore Authority) Marine, Wartsila, Lloyd's Register, and TCOMS (Technology Center for Offshore and Marine Singapore) aimed at developing an autonomous navigation system for tugboats. The project uses PSA Polaris, a tugboat equipped with a range of sensors including short-range, high-resolution radar and a dynamic positioning (DP) system, as shown in Figure 7. The combination of these sensors enables the construction of a smart navigation system that can determine the optimal route for the tugboat and avoid various obstacles, including moving ships [9]. This enables the possibility of constructing an optimal route while avoiding various obstacles, including those presented by moving ships. In addition, the Virtual Anchoring function demonstrated in Figure 8 is an innovative feature that aims to enable the autonomous performance of daily tasks by the smart tugboat. This technology has the potential to relieve the captain from the burden of executing manual standby maneuvers, thereby allowing them and the crew to concentrate on other critical tasks. The use of such intelligent systems can greatly enhance operational efficiency and safety while reducing workload and crew fatigue [9]. Figure 6: Autonomous tugboat designed by [PERSON] [16]. Figure 7: Sensor suite of IntelliTug project [9]. Table 1 displays a comparison of the advanced tugboat projects mentioned above. Typically, these projects focus on the development of remote control and smart tugboats, with a target automation level of around 2 to 3. To date, there have been no projects that have attempted to berth using fully autonomous or remotely controlled tugboats. Achieving the fully autonomous tugboat stage requires the development of technologies that can handle complex situations, such as allocation of the control forces and compensation for environmental disturbance and interaction effects among tugboats [8]. Furthermore, it is essential to develop technologies that can operate and control a group of tugboats, so-called swarm control. \begin{table}
\begin{tabular}{c c c c c} \hline \hline
**Reference** & **Project** & **Content** &
\begin{tabular}{c} **Participating** \\ **Company** \\ \end{tabular} & **Autonomous Level** \\ \hline
[10] & \begin{tabular}{c} \\ \end{tabular} & \
\begin{tabular}{c} The world’s first \\ successful remote \\ operation of the \\ tugboat \\ \end{tabular} &
\begin{tabular}{c} Maersk Line, Rolls \\ Royce \\ \end{tabular} & Level 2 \\
[12] & \begin{tabular}{c} \\ \end{tabular} & \
\begin{tabular}{c} [10] Announced the \\ joint development of \\ RECOTUG (2021) \\ developed from the \\ project and capable of \\ fully remote control. \\ \end{tabular} &
\begin{tabular}{c} Maersk Line, Svitzer, \\ Kongsberg, ABS: \\ American Bureau of \\ Shipping \\ \end{tabular} & Aim for Level 3 \\ \hline
[13] & \begin{tabular}{c} ABB/KEPPEL (2021) \\ \end{tabular} & \
\begin{tabular}{c} First successful remote \\ control of a tugboat in \\ South Asia at the port \\ of Singapore \\ \end{tabular} &
\begin{tabular}{c} Keppel Marine, ABB \\ \end{tabular} & Level 2 \\
[9] & \begin{tabular}{c} InteliTug (2019) \\ \end{tabular} & \
\begin{tabular}{c} Trials are underway at \\ the Port of Singapore, \\ aiming to realize smart \\ tugs autonomously \\ performing a variety of \\ routine tasks. \\ \end{tabular} &
\begin{tabular}{c} PSA Marine, Wartsila, \\ Lloyd’s Register, \\ TCOMS (Technology \\ Center for Offshore \& \\ Marine Singapore) \\ \end{tabular} \\ \hline \hline \end{tabular}
\end{table}