## 3 Development of a Group Interaction System  
An important element in expanding the functionality of MRC groups' application is the development of adaptive systems for group interaction, which allow heterogeneous objects (heterogeneous groups) to organize their operation in unknown environments. It should  
Figure 11: Photos of the full-scale experiment. (**a**) The first experiment; (**b**) The second experiment  
Figure 10: Underwater glider motion trajectory during the second experiment to reach the borders of 3 given areas. (**a**) Three mission regions; (**b**) 3D mission trajectory graph; (**c**) Angle data; (**d**) Depth data. be noted that the wave glider is the connecting link of the group and allows correcting and analyzing the current group state. Since this vehicle has a larger onboard energy reserve due to the solar cells available, its onboard computer system makes additional calculations concerning the intra-group state in real time. That makes it possible to quickly adjust the path-planning system for each vehicle or the group as a whole. In particular, it is not uncommon to change the mission \"on the fly\". The reason for this may be the detection of obstacles, the inability to overcome a current in a sailing area or a significant deviation from the target parameters. In this case, it is important to develop such a group management system, including a group motion path-planning system, which would consider the characteristics of the group (homogeneous and heterogeneous groups) and allow the group to continue the mission despite the changed environmental parameters that have arisen. A detailed description of the mathematical model of the developed wave glider was presented by the authors in the articles [48; 49; 50; 51]. As discussed above, underwater gliders may be of hybrid design. Examples of such vehicles are certain versions of gliders presented in the articles [52; 53; 54; 55; 56]. Some of the hybrid glider models are shown in the Figure 12.  
Such modernization of the glider design is required in the following cases when the glider:  
* moves in horizontal plane;
* overcomes the strong current zones (overcomes the thermocline);
* needs functionality and maneuverability improvement in order to overcome obstacles as well. A communication system between vehicles is a basis of any group control system. Examples of the interaction of vehicles in various approaches to the implementation of group control systems are described in detail in the papers [57; 58; 59]. Thus, in a centralized system (which has an external supervisor), vehicles do not interact with each other, but only transmit the required information to a single device that  
Figure 12: Hybrid underwater glider models: (**a**) SLOCUM hybrid; (**b**) China HUG; (**c,d**) SHADOW hybrid version by SMTU and Oceanos JSC. processes the data received from all vehicles. This approach provides lower computational costs on each of the devices, ease of implementation and scaling, but also faces a risk when data do not reach the supervisor or the supervisor is out of order. In this case, the group ceases to function. In a decentralized approach, each vehicle communicates with another one. The approach is highly dependent on the communication channel between the vehicles; though it is quite difficult to implement the approach, it is more flexible and allows increasing the overall survivability of the group. Each developer decides on their own which approach to implement, considering the goals and objectives of the project. At the same time, in order to implement the control system and the MRC group path planning, taking into account the peculiarities of the communication systems (both hydroacoustic and radio communications), it is advisable to use a centralized control system, in which the supervisory device is a wave glider capable of providing constant monitoring and an analysis of the group state. The multilevel system for the MRC group path planning [60], developed earlier by the authors, is based on the approaches of using the hybrid planners.