Linear Aerodynamic Model Identification of a Flapping Wing MAV Based on Flight Test Data

Abstract

This paper presents an approach to the system identification of the Delfly II Flapping Wing Micro Air Vehicle (FWMAV) using flight test data. It aims at providing simple FWMAV aerodynamic models that can be used in simulations as well as in nonlinear flight control systems. The undertaken methodology builds on normal aircraft system identification methods and extends these with techniques that are specific to FWMAV model identification. The entire aircraft model identification cycle is discussed covering the set-up and automatic execution of the flight test experiments, the aircraft states, the aerodynamic forces and moments' reconstruction, the aerodynamic model structure selection, the parameter estimation and finally, the model validation. In particular, a motion capturing facility was used to record the flapper's position in time and from there compute the states and aerodynamic forces and moments that acted on it, assuming flapaveraged dynamics and linear aerodynamic model structures. It is shown that the approach leads to aerodynamic models that can predict the aerodynamic forces with high accuracy. Despite less accurate, the predictions of the aerodynamic moments still follow the general trend of the measured moments. Dynamic simulations based on the identified aerodynamic models show flight trajectories that closely match the ground truth spanning a number of flapping cycles. Finally, the dimensional aerodynamic forces and moments' coefficients of two of the identified aerodynamic models are presented.

Rigid-Body Kinematics Versus Flapping Kinematics of a Flapping Wing Micro Air Vehicle

“…10. The states in Table 4 that were reconstructed from the position and attitude of the ornithopter can be found in [21].…”

“…Thus, to prevent p, q, r from feeding wrong information into the force and moments equations, new attitude angles were devised. This methodology is explained in [21].…”

Tethered vs. free flight force determination of the DelFly II Flapping Wing Micro Air Vehicle

“…The procedure started with a series of flight tests at specified trim conditions [32], [33]. Afterwards, Flight Path Reconstruction techniques were applied that, together with a set of assumptions (Section II-B3), led to the proposed dynamics model and consequent calculation of the acting forces and moments.…”

“…More recently, Caetano et al [31], [32] reconstructed the forces and moments that acted on a tailed ornithopter (the DelFly II) in a series of more than 200 flight tests that covered the FWMAV's full flight envelope. The tests were performed in a motion cueing flight chamber in which several identification maneuvers were performed with a flying DelFly II.…”

Onboard/Offboard Sensor Fusion for High-Fidelity Flapping-Wing Robot Flight Data

“…Hence, when flight data is obtainable, an attractive modelling option, in alternative to often complex and computationally expensive theoretical or numerical models, is system identification. Previous system identification efforts [19,20,21,22,23,24,25] showed that a data-driven approach can yield realistic but simple models, as well as new insight, for a novel and complex type of vehicle, that is not known in great depth. However relatively limited work has been done in this field so far, largely due to the difficulty of obtaining suitable data.…”