Performance of Low-Cost Air-Data Sensors for Airspeed and Angle of Attack Measurements in a Flapping-Wing Robot

Abstract

Air-data measurements are one of the essential observations for system identification of flapping-wing unmanned aerial vehicles (UAVs). The effects of intensive high-amplitude oscillations of ornithopters on air-data measurements were studied in detail. The movements of an average-sized ornithopter were simulated through a two-degree-of-freedom (2-DOF) mechanism in a wind tunnel, and measurements of an air-data system (pitot and air vane) attached to the mechanism were studied. pitot tests were conducted at different airspeeds and angles of attack (AoAs) using three pitot tubes. The same experimental conditions were created for air-vane measurements. Results revealed that within certain limits, the average measured airspeed was close to the true airspeed values. Two filters were proposed and used for real-time airspeed estimation. Based on the measurements, the oscillation amplitude of the air vane was almost twice that of the real AoA oscillations. However, the mean values of air-vane measurements and real AoAs coincided over one flapping period. For real-time estimation of AoA, which varies very fast with flapping, an estimator based on the least-squares method was implemented.