Influence of Wing Kinematics on Lateral Dynamic Stability of Bioinspired Flapping Wing Micro Air Vehicle involving Multibody Dynamics

Abstract

Tailless bioinspired flapping wings micro air vehicle (FWMAV) dependent systems have gained much importance in current years because of their exceptional traits such as agility, superior maneuverability, and compactness particularly in confined spaces. However, these traits have imposed various challenges in their design and development involving aerodynamics, structure, multibody dynamics, wings flexibility, fluid-structure interaction, control, and insect-scale hardware. Previous studies have mostly dealt with longitudinal stability and have ignored multibody dynamics effects. The current study compares the effect of measured hawkmoth and simplified sinusoidal (more practical for control implementation) wing kinematics on lateral motion stability characteristics of a hawkmoth-like multibody FWMAV in both hovering and forward flight. A multibody dynamics (MBD) simulation environment is employed that incorporates the time dependent inertia effects of all the system parts and flapping wings. The multibody dynamics environment is attached to a modified quasi-steady (QS) aerodynamic model for analyzing the hovering and forward flight lateral dynamics characteristics. A gradient-dependent trim searching algorithm that involves system dynamics-aerodynamics coupling is implemented to get precise trim conditions at various flight speeds by solving fully coupled nonlinear six degrees of freedom (6-DOF) equations of motion. For obtaining stability derivatives at each flight speed, trim conditions are searched numerically to obtain accurate trim flight trajectories using the gradient of control effectiveness matrices. Lateral dynamics characteristics of the FWMAV in hovering along with forward flight are analyzed using eigenmode analysis for both the measured hawkmoth and simplified sinusoidal wing kinematics. For measured hawkmoth wing kinematics, there exists a stable fast subsidence mode, a stable slow subsidence mode, and a stable oscillatory mode. However, for simplified sinusoidal wing kinematics, there exists a stable fast subsidence mode, an unstable slow divergence mode, and a stable oscillatory mode having speed dependent varying characteristics. This study is crucial for tailless FWMAV's stability and control investigators and developers to analyze the influence of more practical simplified sinusoidal wing kinematics on a multibody FWMAV for designing efficient flight controllers in both hovering and forward flight.