Design and Experimental Verification of a Roll Control Strategy for Large Wingspan Flapping-Wing Aerial Vehicle

Most flapping-wing aircraft wings use a single degree of freedom to generate lift and thrust by flapping up and down, while relying on the tail control surfaces to manage attitude. However, these aircraft have certain limitations, such as poor accuracy in attitude control and inadequate roll control capabilities. This paper presents a design for an active torsional mechanism at the wing's trailing edge, which enables differential variations in the pitch angle of the left and right wings during flapping. This simple mechanical form significantly enhances the aircraft's roll control capacity. The experimental verification of this mechanism was conducted in a wind tunnel using the RoboEagle flapping-wing aerial vehicle that we developed. The study investigated the effects of the control strategy on lift, thrust, and roll moment during flapping flight. Additionally, the impact of roll control on roll moment was examined under various wind speeds, flapping frequencies, angles of attack, and wing flexibility. Furthermore, several rolling maneuver flight tests were performed to evaluate the agility of RoboEagle, utilizing both the elevon control strategy and the new roll control strategy. The results demonstrated that the new roll control strategy effectively enhances the roll control capability, thereby improving the attitude control capabilities of the flapping-wing aircraft in complex wind field environments. This conclusion is supported by a comparison of the control time, maximum roll angle, average roll angular velocity, and other relevant parameters between the two control strategies under identical roll control input.