Cooperative search and localization of ground moving targets by a group of UAVs considering fuel constraint

A cooperative task allocation and search algorithm is proposed to find and localize a group of ground based moving targets using a group of Unmanned Air Vehicles (UAVs), working in a decentralized manner. It is assumed that targets have RF emissions. By using an algorithm including Global Search (GS), Approach Target (AT), Locate Target (LT) and Target Reacquisition (TR) modes, UAVs cooperatively search the entire parts of a desired area, approach to the detected targets, locate the targets, and search again to find the targets that stop transmitting their RF emissions during the localization process, respectively. In GS mode, UAVs utilize a cost function to select the best zone for search. In LT mode, each UAV performs a circular motion around the target and uses extended Kalman filter to estimate the target position. Furthermore, a fuel tanker is considered to provide fuel for UAVs during the flight. Therefore, two more operating modes as Approach to Fuel Tanker (AFT) and Fueling (FUE) are added to the operating modes. Before switching to the AFT mode, UAVs take turn using a fueling decision function. In AFT mode, the future position of the fuel tanker is predicted by UAVs to reduce the approach time.