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

Several formulations have been proposed to model the dynamics of ornithopters, with inconclusive results regarding the need for complex kinematic formulations. Furthermore, the impact of assumptions made in the collected results was never assessed by comparing simulations with real flight data. In this study, two dynamic models of a flapping wing micro aerial vehicle were derived and compared: 1) single rigid-body aircraft equations of motion and 2) virtual work principle derivation for multiple rigid-body flapping kinematics. The aerodynamic forces and moments were compared by feeding the states that were reconstructed from the position and attitude data of a 17 g free-flying flapping wing micro aerial vehicle into the dynamic equations of both formulations. To understand the applicability of rigid-body formulations to flapping wing micro aerial vehicles, six wing-to-body mass ratios and two wing configurations were studied using real flight data. The results show that rigid-body models are valid for the aerodynamic reconstruction of flapping wing micro aerial vehicles with four wings in an "X" configuration and two-winged flapping wing micro aerial vehicles with a total wing-to-body mass ratio below 24 and 5.6%, respectively, without considerable information loss.