EELWORM: a bioinspired multimodal amphibious soft robot

Exploration robots are challenged by a continuous adaptation to the terrain induced by ever changing environments. These adaptations can be subtle (e.g. when moving from a smooth to a rough terrain), however drastic changes in environment require robots to address different locomotion modes (e.g. crawling vs swimming). While each locomotion mode can be driven by a dedicated set of actuators, nature shows that multimodal locomotion is also possible by activating the same set of actuators in different sequences (e.g. swimming snakes). In this paper, we present EELWORM, a 40 cm long soft-bodied robot consisting out of an arrangement of five inflatable bending and elongating actuator modules that can be addressed individually. EELWORM is capable of both crawling and swimming by varying the actuation sequences within the same embodiment. We show multimodal locomotion at speeds of 2 body lengths per minute (crawling) and 3 body lengths per minute (swimming).