Fundamentals of soft robot locomotion

Abstract

Soft robotics and its related technologies enable robot abilities in several robotics domains including, but not exclusively related to, manipulation, manufacturing, human-robot interaction and locomotion. Although field applications have emerged for soft manipulation and human-robot interaction, mobile soft robots appear to remain in the research stage, involving the somehow conflictual goals of having a deformable body and exerting forces on the environment to achieve locomotion. This paper aims to provide a reference guide for researchers approaching mobile soft robotics, to describe the underlying principles of soft robot locomotion with its pros and cons, and to envisage applications and further developments for mobile soft robotics.

Keywords: animal locomotion; bioinspiration; biomimetics; robot locomotion; soft robotics.

Figure 1.

Examples of soft robots designed for different locomotion modalities: peristaltic crawling (a) (adapted from [5], credits to M.P. Nemitz, Wormbot); walking (b); walking and crawling (c); jumping (d) (credits to C. Stefanini, cricket robot); morphing wing flight (e), (adapted from [6], credits to M. Di Luca, morphing wing drone); jet propulsion swimming (f); undulation swimming (g); vibration-based (h) and morphing wheels (i). (Online version in colour.)

Figure 2.

Mean (highlighted in the figure), minimum and maximum speeds, expressed as body length per second (BL s⁻¹), of the types of soft robots presented in this paper. The speed of jumping robots is computed as the maximum achievable range (i.e. resulting from 45° jumps) divided by the sum of jumping and charging times.