Design of a Compliant Flapping-Wing Mechanism With Flapping–Twist–Swing Motion

This article presents a method for analyzing and optimizing a compliant flapping-wing mechanism (CFWM) with the flapping–twist–swing motion for a flapping-wing aerial vehicle (FWAV). Originating from a spatial five-bar rigid linkage to mimic the flapping-wing motion, the CFWM is proposed by replacing two revolute joints with two-segment combined flexible beams and redesigning the spherical joint based on topology structure decomposition. The goal of this work is to minimize the path deviation between the original rigid linkage and the CFWM and the strain energy stored in the CFWM to reduce the needed input power. To this end, first, kinematic and strain energy models of a CFWM are derived utilizing elliptic integral solutions. Next, the optimization of the CFWM is carried out by minimizing the path deviation and strain energy subject to material failures and geometrical constraints, leading to the development of an FWAV. Experimental tests on the output path of the CFWM and the lift/thrust of the FWAV are implemented. The results demonstrate the effectiveness of the derived models in predicting the deflections of the CFWM and the feasibility of applying CFWMs to FWAVs.