Simplified Wake Vortex Encounter Modeling and Inner Loop Controller Analysis for Small UAS

Abstract

Wake vortices generated by manned aircraft pose a significant hazard to the safe operation of UAS at and near airports. To analyze this hazard, a simplified methodology for modeling and simulating small UAS wake vortex encounters is proposed. The wake vortex is approximated as a spatially linear wind field, which allows for seamless integration with standard flight dynamics models. This simplified approach is suitable for evaluation and categorization of the hazard presented by wake vortex encounters, as it can be rapidly developed and applied to a variety of UAS and wake encounter scenarios. As unmanned aircraft typically operate with some level of automatic control, roll and pitch hold controllers are designed to assess the impact of automatic control on the severity of the wake encounter. Simulation results showed that controllers designed for maximum disturbance rejection leads to noticeable attenuation of the UAS response to prolonged wake vortex encounters.