Design, Manufacturing, and Testing of Robo Raven

Most current bird-inspired flapping wing air vehicles (FWAVs) use a single actuator to flap both wings. This approach couples and synchronizes the motions of the wings while providing a variable flapping rate at a constant amplitude or angle. Independent wing control has the potential to provide a greater flight envelope. Driving the wings independently requires the use of at least two actuators with position and velocity control. Integration of two actuators in a flying platform significantly increases the weight and hence makes it challenging to achieve flight. We used our successful previous designs with synchronized wing flapping as a starting point for creating a new design. The added weight of an additional actuator required us to increase the wing size used in the previous designs to generate additional lift. For the design reported in this paper, we took inspiration from the Common Raven and developed requirements for wings of our platform based on this inspiration. Our design process began by selecting actuators that can drive the raven-sized wing independently to provide two degrees of freedom over the wings. We concurrently optimized wing design and flapping frequency to generate the highest possible lift and operate near the maximum power operating point for the selected motors. The design utilized 3D printed parts to minimize part count and weight while providing a strong fuselage. The platform reported in this paper, known as Robo Raven, was the first demonstration of a bird-inspired platform doing outdoor aerobatics using independently actuated and controlled wings. This platform successfully performed dives, flips, and buttonhook turns demonstrating the capability afforded by the new design.