Real-Time Insitu Strategies for Enhancing UAV Endurance by Utilizing Wind Energy

This paper presents real-time practical strategies for enhancing the endurance of Unmanned Aerial Vehicle (UAV) flights by utilizing wind energy. Consistent with actual flight, no regional knowledge of the wind field is assumed. Rather, the technique relies solely on making “optimal” decisions at each successive time instant, given the instantaneous values of estimated local wind speeds. Based on these estimates, optimal airspeed and/or heading angle corrections are determined to minimize the instantaneous power requirement for steady level flight. UAV dynamics are described in terms of a dynamic point-mass model, and vehicle motion is constrained via boundary controls to a three-dimensional region around a specified target point. Models of closed-loop trajectory tracking are developed using the method of dynamic inversion for both airspeed vector tracking and boundary trajectory tracking. A nominal reference trajectory is assumed in which the UAV flies a fixed radius, constant altitude orbit with an airspeed that would maximize the endurance in zero wind. Simulations conducted for varying wind patterns compare the average power consumption of the proposed strategy with that of the reference trajectory. Obtained results indicate a potential saving in power consumption and in endurance of the UAV by simply using the appropriate wind component instantaneously during the flight regime.