Multidirectional Planar Motion Transmission on a Single-Motor Actuated Robot via Microscopic Galumphing

Insect-scale mobile robots can execute diverse arrays of tasks in confined spaces. Although most self-contained crawling robots integrate multiple actuators to ensure high flexibility, the intricate actuators restrict their miniaturization. Conversely, robots with a single actuator lack the requisite agility and precision for planar movements. Herein, a novel eccentric rotation-dependent multidirectional transmission is presented using a tilted eccentric motor and a simplistic two-legged structural configuration for planar locomotion. The speed of the eccentric motor is modulated to enable alternating microscopic jumps to propel the system, creating a mode of motion analogous to galumphing of seals. Upon modeling the motion dynamics and conducting experiments, the effectiveness of direct motion transmission is substantiated through microscopic galumphing encompassing left/right crawling and straight-forward crawling. Finally, a 1.2 g untethered robot is developed, which demonstrates enhanced straight crawling and spot turning, traverses narrow tunnels, and achieves precise movements. Therefore, the proposed motion-transmission technique provides a comprehensive set of innovative solutions of underactuated agile robots.