Method of Visual Formation Control for Large Group of AUV in Environment with Obstacles

The paper proposes a modification of the method for formation control of the group of autonomous uninhabited underwater vehicles (AUVs) in the unknown environment containing obstacles for large group of AUV. AUVs move in the “leader-follower” mode in the given formation. The AUV-leader has information about the mission, moves to the target and defines the motion trajectory to safely avoid the detected obstacles. AUV-followers follow the leader, in accordance with the place given to them in the formation. For this movement, information about the current position of the AUV-leader is used. In the basic proposed method, the followers receive this information via hydroacoustic communication channels. Obstacles and the distance to them are determined via onboard rangefinders. The low bandwidth of hydroacoustic channels and large delays in data transmission do not provide safe and accurate movement of group members when they are close to an obstacle or to another AUV. To solve this problem, using onboard video cameras of AUV-followers and technical vision to determine the position of the leader, on which a special light beacons are installed, is proposed. This approach makes possible eliminating delays in the receiving of information by the followers and ensure the safe movement of the AUV group when using high-precision control systems. The main difficulty of using visual information in underwater environment is the limited visibility distance. To consider this limitation, some AUV-followers can act as leaders for other followers. This will allow to form groups from a large number of AUV. At the same time, a control system with a predictive model is used to ensure high accuracy of controlling the movement of the AUV inside the formation when bypassing obstacles. The effectiveness of the proposed method is confirmed by the results of mathematical simulation.