Shape Memory Alloy‐Based Soft Amphibious Robot Capable of Seal‐Inspired Locomotion

Abstract Robots are often required to have multimodal and amphibious capabilities for dynamic environments. Although shape memory alloy (SMA) has been exploited in creating various types of deformation in soft actuators, no SMA‐based multimodal soft amphibious robot has been reported. This study describes a soft amphibious robot made of SMA‐based soft actuators that mimics the terrestrial and subaqueous motion of crawling seals. The soft amphibious robot named SEALicone exhibits two gaits, crawling terrestrial locomotion and oscillatory underwater propulsion. The robot consists of two types of SMA‐based soft actuators: the backbone actuator with wave‐like deformation and the support actuator with fusiform deformation. These actuators in the robot collectively deform allowing the robot to generate distinct locomotion styles that mimic those of the crawling seals. Straight advance and turning motions of the robot in both environments are evaluated, and the transitional motion between the two environments is also demonstrated. This study lays the important groundwork in designing multimodal soft robots that can operate across different environments.