  Fixed-wind unmanned aerial vehicles (UAVs) are essential for low cost aerial
surveillance and mapping applications in remote regions. One of the main
limitations of UAVs is limited fuel capacity and hence requires periodic
refueling to accomplish a mission. The usual mechanism of commanding the UAV to
return to a stationary base station for refueling can result in fuel wastage
and inefficient mission operation time. Alternatively, unmanned gound vehicle
(UGV) can be used as a mobile refueling unit where the UAV will rendezvous with
the UGV for refueling. In order to accurately perform this task in the presence
of wind disturbances, we need to determine an optimal trajectory in 3D taking
UAV and UGV dynamics and kinematics into account. In this paper, we propose an
optimal control formulation to generate a tunable UAV trajectory for rendezvous
on a moving UGV taking wind disturbances into account. By a suitable choice of
the value of an aggressiveness index in our problem setting, we are able to
control the UAV rendezvous behavior. Several numerical results are presented to
show the reliability and effectiveness of our approach.
