Swashplateless-elevon Actuation for a Dual-rotor Tail-sitter VTOL UAV

Abstract

<p>In this paper, we propose a swashplateless-elevon actuation (SEA) approach for dual-rotor tail-sitter vertical takeoff and landing (VTOL) unmanned aerial vehicles (UAVs). Different from the conventional elevon actuation (CEA) approach where both pitch and yaw are controlled by elevons, the SEA adopts a swashplateless mechanism to generate an extra moment to control the pitch and uses the elevons to control the yaw only without adding additional actuators. This decoupled control can effectively alleviate the saturation of elevons' deflection required by large pitch and yaw control actions, and improve the disturbance rejection performance in presence of large external disturbances. Furthermore, the SEA can overcome the actuation degradation of CEA when it is in close proximity to the ground, hence enabling a smoother and more stable take-off process. We validate and compare the performances of the SEA and CEA in various real-world flight conditions including take-off, disturbance rejection, and position step response, showing that the SEA is more robust than the CEA. Furthermore, we also verified the SEA in transition process and fixed-wing mode flight of the VTOL UAV, indicating that the SEA can perform accurate pitch control in presence of high-speed incoming airflow and maintain a stable attitude during the fixed-wing mode flight.<br></p>