New underwater robot could make ocean missions more reliable

Purdue University’s College of Engineering has developed a patent-pending underwater robot designed to change its movement strategy while deployed. Led by Yu She, an assistant professor in the Edwardson School of Industrial Engineering, the work combines three forms of locomotion in one compact platform: passive drifting, buoyancy-driven gliding, and thruster-powered travel. The robot can select the mode suited to a mission’s needs or environmental conditions, such as conserving energy, covering longer distances, tracking water currents, actively repositioning, or leaving a constrained area. The technology could support ocean and lake monitoring, current and flow mapping, underwater-structure inspection, exploration below ice shelves, environmental sensing, search-and-rescue work, and distributed underwater data collection.

The design addresses tradeoffs associated with vehicles limited to a single way of moving. A drifter can follow currents but may be unable to reach a target or recover from an undesirable route. A glider can offer endurance but may have difficulty in confined or complex spaces. A thruster-driven vehicle can maneuver directly but can consume power quickly, shortening a mission. Such constraints can raise operating costs, reduce mission duration and data coverage, increase the chance of a robot being lost or trapped, and require operators to use several specialized platforms. The integrated architecture coordinates buoyancy regulation, internal mass shifting, foldable wings, propulsion, and steering. In drifter mode, the robot adjusts buoyancy and moves with surrounding flow; in glider mode, it changes buoyancy, shifts internal mass to control pitch, and deploys wings that convert vertical motion into forward travel.

Proof-of-concept pool testing demonstrated operation of the foldable-wing mechanism underwater, buoyancy-regulated descents and ascents, thruster-assisted translation, and glider motion using coordinated buoyancy adjustment, pitch control, and wing deployment. According to She, the tests showed that the main subsystems can work together in water and produce the intended three-mode behavior. Switching between modes is currently manual. Future work will investigate autonomous switching so the robot can choose whether to drift, glide, or use propulsion based on mission goals and environmental feedback. Researchers also plan more rigorous characterization of energy consumption, endurance, maneuverability, gliding efficiency, transition performance, control accuracy, and robustness in more realistic underwater environments. Purdue Innovates’ Office of Technology Commercialization has applied for patent protection for the intellectual property.