S2worm: A Fast-Moving Untethered Insect-Scale Robot With 2-DoF Transmission Mechanism

Designing terrestrial insect-scale robot with high maneuverability and autonomy is becoming an essential challenge in the field of robotics research. Previous work has indicated that compact transmission and integrated control devices can improve the application potential. In this work, an untethered insect-scale inchworm robot is designed and fabricated by using screw theory and smart composite microstructure method, and is named S
²
worm. The robot weighs 4.34 g and spans 4.1 cm in length. The robot is equipped with custom designed onboard control system and high voltage boost converter to provide the driving signal for the piezoelectric bending actuator. Attributing to the novel transmission mechanism with two degrees of freedom designed based on screw theory, the S
²
worm can be fabricated through the smart composite microstructure method easily and shows high mobility such as high crawling speed (27.4 cm/s, 6.7 body length/s) and small turning radius (1.7 cm, 0.4 body length/s). The S
²
worm holds the following advantages: small size, untethered, high mobility and low energy consumption. The robot is promising for application in planetary exploration, earthquake search and constructing insect-scale multi-robot system.