Synchronized actuation strategy and study of clap-and-fling phenomenon in hummingbird inspired robot

This study presents the design and development of a hummingbird-inspired robot, engineered to mimic the flight dynamics of a real flapping bird through synchronized flapping. While prior flapping-wing robotic studies have primarily focused on mechanical design or open-loop actuation, limited attention has been given to closed-loop synchronization of independently actuated wings and its direct impact on lift generation. The robot uses two independently actuated motors that are controlled by two Proportional–Integral ( PI ) and one Proportional ( P ) control system to regulate the frequency and phase difference of the wings, respectively. Precise synchronization of the wings is crucial for optimal lift generation, with this system achieving an average lift of 57.2 g at a nominal flapping frequency of 8 Hz. Magnetic encoders are integrated with each wing to monitor and adjust wing frequency and phase in real time. Experimental results demonstrate that synchronized wing movements significantly enhance lift generation, while asynchrony reduces lift. The temporal variation of the measured lift force shows a distinguishable peak toward the end of the forward stroke. It is hypothesized that the clap-and-fling phenomenon results in this increase in lift force. Furthermore, a reduced-order model is proposed to rationalize the variation of lift force with flapping frequency. The key contribution of this work is the experimental validation of closed-loop wing synchronization and its quantified effect on lift generation in a bioinspired flapping-wing robot. This work underscores the potential of bioinspired robotics, precise control systems, and innovative mechanisms to achieve efficient lift generation in flapping-wing systems.