Autonomous UAV Control for Low-Altitude Flight in an Urban Gust Environment

With rapid advances in the unmanned aerial vehicle (UAV) field and their growing popularity in a wide range of civilian and commercial applications, UAV operation in urban areas is inevitable. For small size UAVs conducting low-level flight in an urban landscape, wind disturbances pose a significant challenge. Ensuring safety while flying in proximity to buildings and other obstacles requires a thorough understanding of the nature of these disturbances and the expected performance of an autopilot in their presence. This study focuses on the position control of a quadrotor UAV in an urban wind environment. A literature review provides an in-depth survey of the state of the art in quadrotor flight control. Urban wind conditions are modelled around a single building through a Computational Fluid Dynamics (CFD) analysis using Large Eddy Simulation (LES). Modelled transient wind flow velocities are applied to create a realistic simulation environment for a custom built quadrotor prototype named TARA. Four different control techniques are selected and implemented for the autonomous position control of TARA. A precise simulation methodology is employed to ensure consistent flight testing under diverse representative wind conditions. The results are evaluated under a carefully crafted set of criteria and selected performance metrics. Based on the analysis, a hybrid control scheme is proposed, with simulation and experimental data confirming its improved ability in dealing with realistic urban wind disturbances with an average position hold within a single body length.