Moving through water costs far more energy than walking on land, because drag rises steeply with speed, and that cost limits how long and how far a diver can work. A team led from the School of Advanced Manufacturing and Robotics at Peking University built what the university describes as the first portable underwater exoskeleton system for assisting divers' knee movement, targeting the flutter kick that propels most diving.
The device is a bilateral, cable-driven knee exoskeleton. Motion sensors detect the kick cycle and force-based control delivers assistive torque to the knees in real time, so the machine contributes during the propulsive phase rather than resisting the diver's own movement. Cable drive keeps the actuators away from the joint itself, which matters for a device that must be worn and must survive immersion.
Testing involved six experienced divers, compared against their own unassisted diving. Wearing the exoskeleton reduced air consumption by 22.7 per cent, quadriceps activation by 20.9 per cent and calf activation by 20.6 per cent. The divers adapted readily, showing natural movement patterns and improved energy economy rather than fighting the assistance, which is often the failure mode for wearable robotics. The study was published in IEEE Transactions on Robotics.
Reducing oxygen consumption translates fairly directly into extended dive times and improved safety margins, since air supply is usually the binding constraint on a working dive. Marine research, underwater construction and diver training are the applications the authors identify. The sample of six is small, as is typical for exoskeleton studies, so the effect sizes should be read as promising rather than settled.