The flight of unmanned aerial vehicles (UAVs) has numerous associated challenges. Small size is the major reason of their sensitivity towards turbulence restraining them from stable flight. Turbulence alleviation strategies of birds have been explored in recent past in detail to sort out this issue. Besides using primary and secondary feathers, birds also utilize covert feathers deflection to mitigate turbulence. Motivated from covert feathers of birds, this paper presents biologically inspired gust mitigation system (GMS) for a flapping wing UAV (FUAV). GMS consists of electromechanical (EM) covert feathers that sense the incoming gust and mitigate it through deflection of these feathers. A multibody model of gust-mitigating FUAV is developed appending models of the subsystems including rigid body, propulsion system, flapping mechanism, and GMS-installed wings using bond graph modeling approach. FUAV without GMS and FUAV with the proposed GMS integrated in it are simulated in the presence of vertical gust, and results’ comparison proves the efficacy of the proposed design. Furthermore, agreement between experimental results and present results validates the accuracy of the proposed design and developed model.

The Unmanned Aerial Vehicles (UAVs) generally execute their missions in atmospheric boundary layer and this region is highly turbulent which drastically degrades UAVs stability. Drawing inspiration from nature for the solution, it is revealed that natural birds utilize covert feathers to tackle gusts and turbulence. This paper presents design of an active biomimetic Gust Alleviation System (GAS) augmented with robust H_∞ controller for a flapping wing UAV (FUAV) replicating bird’s covert feathers. Reduced order model of the proposed design is computed using bond graph modelling method. Stability analysis is performed to study internal dynamics of the proposed design. A comparison is made between the proposed H_∞ controller-augmented GAS and Linear quadratic regulator (LQR) controller-based GAS in response to external gust disturbances. The H_∞ controller augmented GAS design demonstrate more robust behavior of the FUAV compared to LQR based design and successfully alleviates gusts up to 50%. Finally, consistency between the obtained results and literature data confirms the validity of offered H_∞ controller.