Multimodal Soft Amphibious Robots Using Simple Plastic-Sheet-Reinforced Thin Pneumatic Actuators

A large challenge in the field of soft amphibious robotics is achieving high maneuverability and multi-terrain adaptability through multi-modal locomotion in hybrid terrestrial-aquatic environments. To address this issue, drawing inspiration from fruit-fly larvae and Spanish dancer sea slugs, a novel tethered soft amphibious robot with multi-modal locomotion is proposed in this paper, performing forward, backward, turning, and self-overturn motions both on land and in water. It leverages plastic sheet-reinforced thin pneumatic actuators, which are constructed from thermoplastic membranes and embedded with a non-stretchable plastic sheet, enabling bi-directional bending with large angles. The robot achieves a forward jumping velocity of 1.77BL/s and a forward swimming velocity of 0.69BL/s, both faster than previously reported soft amphibious robots; connecting two actuator units in parallel, it achieves agile turning with a velocity of 111.8 $^\circ$ /s. Our proposed robot demonstrates exceptional multi-terrain adaptability, facile terrestrial-aquatic transition capabilities, and underwater buoyancy adjustment ability. Especially when accidentally overturned, it can recover itself without external assistance, a capability rarely achieved by other soft robots.