Aerodynamic Force Control for Tilt-Wing eVTOL Using Airflow Vector Estimation

Abstract

Research and development are active in electric vertical takeoff and landing (eVTOL) aircraft. In particular, tilt-wing eVTOL aircraft receives much attention as one of the most efficient configurations; however, they are likely to be unstable during the transition from hover to cruise because the lift and thrust have limitations depending on the airflow and tilt angle. This study proposes a new aerodynamic force control method using airflow vector estimation. The airflow vector is estimated by combining motor current, rotational speed, and Pitot-tube measurements. Aerodynamic force control is achieved through the proper design of a feedback controller using disturbance observers (DOBs) to cope with propeller-wing interference caused by the propeller slipstream. This method takes advantage of the motor control performance and is unique in which it monitors the airflow vector and actively changes the tilt angle to quickly obtain the desired acceleration. The effectiveness of the method is verified via simulations and experiments in a wind tunnel.