Design, Fabrication and Performances of a Biomimetic Robotic Earthworm

This paper presents the design and development of a microrobot which aims to replicate the locomotion principle of earthworms. By investigating the biological field, the authors developed artificial earthworms by mimicking the structures and locomotion principles of real ones. Prototypes with or without micro-legs (which affect the locomotion performance) have been developed. Each prototype has four modules which can be driven independently according to defined undulatory patterns with a typical frequency of 0.5 Hz. Each module is actuated by one or more SMA springs whose configuration has been designed in order to limit the wiring problems and optimizing working frequency. The robots are covered by shaped silicone material which can be used as a platform to insert tiny legs for obtaining differential friction conditions. Preliminary tests demonstrate that the maximum speed of earthworm prototypes can reach 0.22 mm/s without micro-legs and 2.5 mm/s with micro-legs, thus approximating the behavior of biological earthworms