Electro-driven fibrous soft actuators towards flapping-wing control for insect-scale robots

Flapping-wing control is critical to the development of flapping-wing micro aerial vehicles (FMAVs). Existing electro-driven soft actuators for such applications face challenges in balancing the requirements for low driving voltage and high actuation performance (actuation strain, strain rate, and power density). In this study, electro-driven fibrous soft actuators of liquid crystal elastomer (LCE) have been designed and created, which achieve excellent comprehensive performance: low voltage actuation (<6.4 V), a large actuation strain (a maximum actuation strain of 43%), fast actuation strain rate (up to 1417% s^-1), and high power density (up to 1631 W kg^-1), and wide frequency bandwidth (50 Hz). Furthermore, electro-driven fibrous actuators have mimicked the actuation function of dragonfly direct flight muscles. The flapping frequency, amplitude, and angle of a single wing were precisely controlled by electrical parameters. Moreover, through programmable drive of two LCE fibrous actuators, the flapping phase difference characteristics of the forewings and hindwings of dragonflies under different flight modes were imitated. This work highlights the significant potential of electro-driven LCE fibers as high-performing artificial muscles for the development of biomimetic FMAVs.