Bio-inspired gust mitigation system for a flapping wing UAV: modeling and simulation

The growing use of drones today necessitates improved UAVs performance and capabilities. These requirements include flights in operational environments full of obstacles which present navigation and stability problems due to large-scale turbulence. To address this major concern, turbulence alleviation capabilities of natural counterparts have been studied in depth. Birds use inherent active and passive flow mechanism in their flapping wings and also deflection of covert feathers to stabilize themselves in turbulent airflows. This paper presents a novel bio-inspired gust mitigation system (GMS) for flapping wing UAVs mimicking covert feathers of birds. GMS senses the forces experienced from turbulent airflows and actuates to perform local airflow manipulations to alleviate them. GMS comprises of electromechanical feathers capable of deflecting out of the airfoil once they encounter turbulence. Modeling of single electromechanical feather assists in development of a complete GMS model that is further integrated in wing, modeled as flexible Euler-Bernoulli beam, and a complete dynamic model of flapping wing is obtained using bond graph modeling approach. We perform digital simulations and compute state-space equations to analyze model internal dynamics and responses. Comparison of the simulation results of wing without GMS and GMS-integrated wing, in response to vertical gust, confirms the efficacy of offered design. Furthermore, a good agreement between the present simulation results and experimental results from the literature validates the proposed model. As a result, the offered design successfully marks an initial step toward research into bio-inspired active gust mitigation systems for flapping wing UAVs.