We develop a decentralized hybrid controller for fixed-wing UAVs assisting a manned helicopter in a United States Coast Guard search and rescue mission. The UAVs assist the manned helicopter by providing an expanded sensor footprint using onboard cameras. We consider two UAVs, one flying on either side of the helicopter, with constant velocity and maximum turn rate constraints. Tracking the helicopter around sharp corners will be difficult due to these constraints and the difference in path lengths for the two UAVs. To solve this problem, we propose a hybrid controller that allows the UAVs to swap positions in an attempt to improve the tracking and ground coverage performance of the formation. We discuss tracking control, the position swapping algorithm and collision avoidance. Simulation results demonstrate improved search efficiency and aircraft safety.
