Uav Formation Safety Transformation Strategy for Aerial Refueling

Aerial refueling technology utilizes tankers to refuel other aircraft in the air. Before sequential aerial refueling, multiple UAVs (including the tanker and receivers) are expected to perform a formation transformation. In this process, multiple receivers start from the observation area on the left side of the tanker and move to the pre-docking position to prepare for docking. During the transformation, the tanker and receivers maintain a close formation, characterized by small inter-aircraft distances and low safety margins. To ensure inter-aircraft safety during formation transformation, this work first defines the safety envelopes of the tanker and receivers according to their fuselage shapes. Based on these envelopes, a safe flight area for the UAVs is generated. Within this area, relative flight paths for formation transformation are planned using the Rapidly-exploring Random Tree (RRT) algorithm. These planned paths serve as desired positions within the formation, and an appointed-time prescribed performance control (APPC) method is designed to ensure flight safety throughout the transformation. Finally, simulations are conducted to demonstrate the effectiveness of the proposed scheme.