Aerobatics on Three-Dimensional Paths for Agile Fixed-Wing Unmanned Aerial Vehicles

This work presents a nonlinear path-following strategy designed to enable an agile fixed-wing UAV to follow three-dimensional geometric paths while simultaneously performing different aerobatic maneuvers about its thrust axis. While agile fixed-wings and similar platforms are designed expressly for aerobatic flight, these maneuvers are seldom used in autonomous operation due to their complexity. The proposed system expands the autonomous capabilities the platform by allowing an independent roll command to be prescribed while still ensuring the UAV follows the intended path. This controller is built around a geometric attitude control system, a roll-decoupling velocity control, and a guidance law that steers the UAV onto the intended path through velocity commands. To verify the properties of the proposed control system, experimental outdoor flight tests are conducted. Results show the versatility of the control system, since arbitrary roll maneuvers can be achieved without additional aerodynamic characterization.