Path planning and control for multiple point surveillance by an unmanned aircraft in wind

In this paper, we explore the surveillance of multiple waypoints by a constant velocity aircraft in the presence of wind. It is assumed that the aircraft has a maximum turning rate and that the wind is equal to a known constant plus small possibly time varying components. The proposed strategy consists of separate path planning and control algorithms. The path planning is done by calculating the shortest time path through all of the waypoints in the presence of a known constant wind. During this step, the allowed turning rate is assumed to be less than the actual maximum turning rate of the vehicle. This algorithm produces a ground path that can be tracked by the control algorithm. The control algorithm breaks the desired trajectory into smaller sections which can each be approximated by a polynomial. A spatial sliding surface controller is then used to track each polynomial in the presence of the unknown wind disturbances