Design of flexible hinges in electromagnetically driven artificial flapping-wing insects for improved lift force

This paper presents a design approach to determine the bending stiffness of the flexible hinge in electromagnetically driven artificial flapping-wing insects for improved lift force. The prototype insects are fabricated by laser cutting technique and have a wingspan of 3.6 cm and a total mass of 84 mg. To induce effective wing rotational movements for improved aerodynamic performances, the geometric parameters of the flexible hinge in the wing rotation mechanism are optimized based on lift force simulations and bending stiffness tests on the enlarged flexible hinges. With an applied AC current of 420 mA (AC voltage of 0.5 V), the prototype #4 with optimized flexible hinge can produce effective wing rotational movements with a maximum rotation angle of 50° and a flapping amplitude of ±50.6° at 65 Hz. Such wing movements can generate a measured average lift force of 384.5 µN to produce a total lift force to weight ratio of 0.47. With this magnitude of lift force, the prototype can slide on a tilted guide rail with an inclined angle of 7°. Such results validate the feasibility of the design approach of the flexible hinge in the artificial insects for improved lift force.