Designing Optimal Trajectory in presence of Terrain and Threat for Unmanned Aerial Vehicles

In this paper an optimal control-based approach is proposed for designing three-dimensional trajectory for unmanned aerial vehicles (UAV’s). In this approach, by defining a cost function, based on the flight time and the avoiding terrain and threat objectives, the safe trajectory is planned so that UAV avoids obstacles and threatened zone, as an optimal procedure. Besides, digital elevation map (DEM) is interpolated by using spline surfaces. This leads to reduction of digital data and further smoothing the trajectory. The algorithm is presented in terms of constant speed and energy assumptions. For constant speed situation, the heading and flight path angle rate constraints is satisfied implicitly. In contrast with constant speed assumption, constant energy assumption beside the mentioned constraints leads to satisfying speed and altitude limitations. Finally, this approach is recommended for trajectory planning of autonomous vehicles in presence of threatened zones.