A compliant thorax design for robustness and elastic energy exchange in flapping-wing robots

Flapping wing insects benefit from a compliant thorax that provides elastic energy exchange and resiliency to wing collisions. In this paper, we present a flapping wing robot that uses an underactuated compliant transmission inspired by the insect thorax. We developed a novel fabrication method that combines carbon fiber (CF) laminate and soft robotics fabrication techniques for transmission construction. The transmission design is optimized to achieve desired wingstroke requirements and to allow for independent motion of each wing. We validate these design choices in bench-top tests measuring transmission compliance and kinematics. We integrate the transmission with laminate wings and two types of actuation, demonstrating elastic energy exchange and limited lift-off capabilities Lastly, we tested collision mitigation through flapping wing experiments that obstructed the motion of a wing. These experiments demonstrate that an underactuated compliant, transmission can provide resilience and robustness to flapping wing robots.