## 3 Problem Research
### MASS Problem  
MASS was formulated in 2018 by the International Maritime Organization (IMO) and includes four successive levels, where MASS 1 is the base level of ship autonomy, with level 4 understood as fully unmanned ships sailing according to their control system. Figure 3 quotes MASS definitions generally written by the IMO [6; 20].  
\begin{table}
\begin{tabular}{c l l l} \hline \hline
**Symbol** & **Name of the Signal** & **Range** & **Unit** \\ \hline ng & Main propeller rotational speed & (\(-\)200; +480) & [rpm] \\ \(\delta\) & Rudder deflection angle & (\(-\)35; +35) & [deg] \\ sstd & Relative thrust of the bow tunnel thruster & (\(-\)1, +1) & [-] \\ sstr & Relative thrust of the stern tunnel thruster & (\(-\)1, +1) & [-] \\ ssod & Relative thrust of the bow rotary thruster & (0, +1) & [-] \\ \(\alpha_{d}\) & Bow rotary thruster deflection angle & (\(-\)120, +120) & [deg] \\ ssor & Relative thrust of the stern rotary thruster & (0, +1) & [-] \\ \(\alpha_{r}\) & Stern rotary thruster deflection angle & (\(-\)120, +120) & [deg] \\ \hline \hline \end{tabular}
\end{table}
Table 1: Input signals of the propulsion and control devices of the “Blue Lady” ship [PERSON] adapted with permission from Ref. [26].  
Figure 2: The model ship “Blue Lady”, lenght—13.75 [m], width—2.38 [m].  
The authors of this paper believe the above definitions should be considered together with the problems presented below, in Figure 4, by scientists working with issues of autonomous (unmanned) control.  
Scientists are dealing with the problems of autonomous (unmanned) ship control [27]. According to the authors, the issues in Figure 4 are four areas that are related to MASS. The concept of MASS problems addresses issues in automation, computer science, electronics, energy, navigation, and maritime law. Therefore, these issues are very extensive. The proposal to divide MASS makes it possible to define scientific work on autonomous control.  
1. **PILOT-CAPTAIN, communication technology**. For example, the performance of research in a port in Poland requires consideration of the maritime law in the port. It is currently impossible to perform research without the permission of the port of authority. The main rule is related to the presence of a captain and a minimum number of crew on the vessel.  
Figure 4: General division of MASS issues.  
Figure 3: IMO regulations for the four levels of MASS [20].  
**Legal rules in ports and on the high seas.** Quite an elaborate issue turns out to be the work on maritime law (for example, during a collision, who will bear the responsibility: machine or man, captain or the quay?).
* **Security and navigation.** Safety principle nowadays is probably the most and best described scientific issue. Many interesting algorithms related to optimization are proposed [18; 29; 30; 28], anthill algorithms [31; 32].
* **Ship control technology.** Ship control is so complicated that it is necessary to consider risks not only by computer simulations, but based on real models, which is also realized by scientists from University in Trontheim [33; 34], Volda University Colege [35], School of Marine Engineering [36; 37], and Gdynia Maritime University [38; 39; 40; 41; 42; 43; 44; 45; 46].