Shanghai Jiao Tong University researchers have developed a soft amphibious robot that transitions between crawling on land, moving underwater, and swimming—without any structural reconfiguration—while operating in temperatures from -20°C to 70°C.
A Multimodal Amphibious Robot Driven By Soft Electrohydraulic Flippers, published in Cyborg and Bionic Systems, the breakthrough demonstrates the first amphibious soft robot based on electrohydraulic actuators capable of multimodal locomotion transitions. The robot achieves swimming speeds up to 5.9 cm/s, making it one of the most agile soft amphibious systems developed to date.
Electrohydraulic Actuation: Converting Voltage to Thrust
At the heart of the design are three soft electrohydraulic flippers arranged in radial symmetry. Each flipper consists of a sealed pouch filled with silicone oil, covered with carbon electrodes that convert electrical signals into hydraulic pressure and mechanical movement. This elegant energy conversion chain—from electrical to hydraulic to mechanical—delivers high efficiency with minimal noise, addressing a long-standing challenge in soft robotics actuation.
Three Locomotion Modes, One Compact Platform
The robot's versatility stems from its three distinct locomotion modes. On land, it crawls at 2.9 cm/s using asymmetric friction at the flipper tips. Underwater crawling reaches 3.2 cm/s by leveraging fluid interaction forces. In swimming mode, synchronized flipper oscillations generate vortex rings that enhance thrust, pushing performance to 5.9 cm/s—verified through fluid dynamics simulations.
Seamless Environmental Transitions Without Reconfiguration
What sets this robot apart is its seamless environmental transition capability. The system smoothly shifts from terrestrial crawling to underwater crawling to surface swimming without requiring any mechanical reconfiguration—a rare achievement in amphibious robotics. This adaptability is complemented by exceptional temperature resilience: the robot maintains near-room-temperature performance in 61.3°C hot water and continues operating at 2.7 cm/s in 2.1°C cold water.
From Lab to Real-World Deployment
The research team—led by Professor Wenming Zhang from Shanghai Jiao Tong University, with collaborators from Tongji University and Northwestern Polytechnical University—has opened new possibilities for soft robotics deployment in unpredictable environments. Potential applications span search-and-rescue operations, environmental monitoring, and infrastructure inspection where both terrestrial and aquatic access are required.
The work demonstrates that electrohydraulic actuation technology, combined with thoughtful mechanical design, can bridge the gap between experimental soft robotics and real-world deployment in complex, multi-environment missions.
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