Development of a Soft Leg-Wheel Hybrid Module Inspired by Bacterial Flagella

The softness and flexibility of soft robots give them strong adaptability, enabling them to move and perform tasks in narrow and irregular environments. But in flatter environments, their mobility has a large gap with wheeled robots. This paper addresses the issue of low mobility of soft robots in flat environments, and proposes a new type of leg-wheel hybrid mechanism inspired by bacterial flagella. The structure uses a tendon-driven continuum structure as the soft body part, just like the flagellar filaments of bacteria; the wheel motion is realized by driving the soft body part for continuous turn-over, just like the rotational motion of bacterial flagellar filaments driven by its base motor. In this paper, the design and kinematic analysis of the structure are presented in detail. To verify the feasibility of the structure, a prototype is implemented. The experiments are conducted on the motion and load capacity of the structure in both wheel mode and leg mode. The experimental results show the viability of the structure.