Can DC Motors Directly Drive Flapping Wings at High Frequency and Large Wing Strokes?

This paper proposes and experimentally validates a method for driving flapping wings at large wing strokes and high frequencies with a DC motor, based on direct, elastic transmission. The DC motor undergoes reciprocating, rather than rotary, motion avoiding the use of nonlinear transmissions such as slider-crank mechanisms. This is key to compact, easy to fabricate, power efficient, and controllable flapping mechanisms. First, an appropriate motor based on maximum power transfer arguments is selected. Then, a flapping mechanism is prototyped and its experimental performance is compared with simulations, which take into account the full dynamics of the system. Despite inherent nonlinearities due to the aerodynamic damping, the linearity of the direct, elastic transmission allows one to fully exploit resonance. This benefit is best captured by the dynamic efficiency, close to 90% at larger wing strokes in both experimental data and simulations. We finally show a compact flapping mechanism implementation with independent flapping motion control for the two wings, which could be used for future autonomous micro-aerial vehicles.