# Method for Detecting Abnormal Activity in a Group of Mobile Robots
## 1 Introduction  
Today, the popularity of mobile robotic systems is growing. The areas of their application vary from everyday use to the military industry. Mobile robots can be divided into the following four groups: autonomous land vehicles, unmanned aerial vehicles (UAVs), autonomous marine vehicles, and autonomous underwater vehicles (APA) [1]. At the same time, these devices operate quite unstably, and frequent failures are observed. Devices easily fail and can be destroyed. Environmental conditions strongly affect the behavior of the mobile robots. UAVs are especially affected by the environment. Mobile robots are generally controlled by an operator with the use of a wireless channel. Mobile robots are often located outside the controlled area; they have limited computing power and a small-capacity battery [2]. There are a large number of attacks aimed at taking control of the mobile robot, and denial of system operation. Such attacks could be implemented at the data link and physical layer by an external attacker [3]. These attacks can cause significant damage to the network. Their goals are the destruction of the system, disruption of the network, and penetration into the mobile robotic system (MRS). If the attacker's task is to penetrate the MRS, get access to all devices, change the logic of the system operation, and receive confidential information, then the intruder could implement internal active attacks on the MRS. In order to develop an effective system for detecting and blocking network attacks, it is necessary to understand which components of the system are most exposed to network attacks, as well as which indicators the attack affects. There are several ways to control the MRS: remote control, independent control, overall control, and group control. At the same time, group management systems can be fully distributed or hierarchical, where the group leader stands out. Different technologies are used to organize each type of control system. Wireless communication channels and communication protocols are used to organize the management process of the MRS. In particular, communication protocols are used to transmit control commands, exchange collected data, etc. Table 1 represents management types of mobile robotic systems and features of the wireless network implemented to organize the management process. When identifying anomalous behavior in the groups of mobile robots, it is necessary to clearly understand what technologies and algorithms are used in their development and implementation on the real objects. This is necessary because the structure, algorithms, and methods of functioning mobile systems differ significantly from standard computer networks. At the same time, the groups of mobile robots are divided into the following types of mobile networks, depending on the functions they perform and the type of mobile robot used:  
* VANET (vehicular network ad hoc network) is the wireless network with (unmanned) vehicle subscribers that implement fully decentralized control in the absence of base stations or reference nodes. Topology rapidly changes with a random connection of nodes. * MANET (mobile ad hoc network) is a wireless decentralized network [4] with random mobile devices that is implemented in the absence of base stations or reference nodes. The MANET topology is dynamic, and the connection of nodes is random. * FANET (flying ad hoc network), by analogy with the mobile peer-to-peer network MANET and vehicle peer-to-peer network VANET, is a special type of peer-to-peer self-organizing network based on unmanned aerial vehicles (UAVs) [5].