## 2 The Problem Statement
The launches of the device took place in the area of Lake Sapernoe in the Leningrad Region (Figure 8). This lake is characterized by clean, transparent water, which allows you to assess the movement of the glider visually. Moreover, there are practically no disturbing currents in it (the excitement is not more than 0.5 points), which makes it possible to best evaluate the results of the glider control system. The first experiment was conducted to study the glider's driving characteristics when the wings were located in the central part of the glider's body. During the tests, values were obtained for the number of immersion/ascent cycles, energy expended and hydrodynamic characteristics, reflecting the dynamics of the apparatus in transient modes (roll and trim angles of the glider) (Figure 9). Figure 8: Location of the experiment. Figure 7: An example of (**a**) a turning radius \(\hat{R}=25\) m. (**b**) Glider’s double turning circle maneuver. The results of the experiment show that the device was able to successfully pass the specified trajectory. It is possible to note the high values of the angles of immersion and ascent of the device (about 38 degrees on immersion and 35 degrees on ascent). This feature can be explained by the fact that the device went to shallow water, and the control system simply did not have time to work out the target values, although the graph (Figure 9a) reflects the moments when the control system successfully brought the device to the specified planning angles (22 degrees). During the mission, the glider performed 38 dive/ascent cycles within 1 h.  
The second experiment was conducted as part of the initiative work carried out by Oceanos JSC and St. Petersburg State Marine Technical University (SMTU) in 2020 in order to form a primary data array to ensure predictive modeling together with the St. Petersburg University of the State Fire Service of the EMERCOM of Russia, a series of full-scale trials of the upgraded SHADOW underwater glider [33, 34, 45, 46, 47]. In this experiment, the wings were shifted to aft. In one of the given missions, the vehicle was tasked to pass borders of three given areas with a subsequent return to the starting point of the mission. RedWave long-base hydroacoustic navigation onboard system and buoys, located in the operating area of the sea trials, helped to obtain the vehicle's position data. The results are presented in the Figure 10. Photos of the full-scale experiment are in the Figure 11.  
Figure 9: The underwater glider motion trajectory during the first experiment. (**a**) Angle data; (**b,c**) IMU data; (**d**) Depth data  
As a result, it can be seen that the vehicle has passed the specified areas with a slight deviation from the target trajectory. The maximum diving depth was 10 m, the mission time was 1.5 h, the distance traveled during the experiment was 2 km. As can be seen from the results of the full-scale experiment, the device completed a mission lasting 1 h and 50 min with a total distance of 1.5 km, completing 150 cycles of diving ascent with a maximum depth of 10-15 m. It can be seen that the device passed the specified target trajectory (highlighted in black in the figure), with minor deviations. Separately, you should pay attention to the moment of turning the glider on the third section, when the device exits the specified region. The developed configuration of the glider made it possible to make a U-turn within 20 m and reach the specified trajectory of movement.