WEST LAFAYETTE — A new underwater robot developed by Purdue University researchers could change the way autonomous vehicles operate beneath the surface by allowing a single robot to adapt its movement to the needs of a mission.
The patent-pending technology, developed by Yu She, an assistant professor in Purdue’s Edwardson School of Industrial Engineering, combines three different methods of underwater movement into one compact platform.
Photo by Purdue University
The robot can operate as a drifter, glider or thruster-powered vehicle, switching between the different approaches depending on conditions and mission requirements.
“It changes how it moves depending on what the mission needs: to conserve energy, travel farther, follow currents, actively reposition or escape from a constrained region,” She said.
The technology could have applications in ocean and lake monitoring, underwater infrastructure inspections, search-and-rescue operations, environmental sensing, current mapping and exploration beneath ice shelves.
Three robots in one
Traditional underwater robots typically rely on one primary method of movement. Each approach has its own advantages, but also limitations.
A drifting vehicle can conserve energy and travel with ocean currents, but it cannot easily change direction or return to a specific location. Gliders can travel long distances using relatively little energy but may have difficulty maneuvering in confined areas. Thruster-powered vehicles offer greater control but can consume significant amounts of energy.
Purdue’s new platform combines all three.
“Our technology integrates all three locomotion modes into a single compact underwater platform,” She said. “The robot chooses the appropriate mode depending on the mission requirement or environmental condition rather than being locked into one.”
That adaptability could make underwater missions more efficient and reduce the need to send multiple specialized vehicles for different tasks.
How the robot moves
The robot uses a combination of buoyancy regulation, internal mass shifting, foldable wings, and propulsion to change how it travels through the water.
In drifter mode, the robot adjusts its buoyancy and allows surrounding currents to carry it. This approach can be useful when conserving energy or tracking the movement of water is the primary goal.
In glider mode, the robot changes its buoyancy while shifting an internal mass to control its pitch. It then deploys hydrodynamic wings, converting its vertical movement into forward motion.
When more precise movement is required, the robot can activate a thruster and steering system to maneuver through the water, maintain its position, or move away from confined areas.
The result is essentially three types of underwater vehicles combined into one platform.
Addressing challenges in underwater exploration
She said the inability to change movement strategies can create significant challenges for underwater missions.
A robot that relies exclusively on drifting may be unable to reach a desired location or recover if currents carry it off course. A glider may have difficulty navigating tight or complicated environments, while a thruster-powered vehicle can quickly use up its available power.
Those limitations can lead to shorter missions, higher operating costs, reduced data collection, and an increased risk of a robot becoming trapped or lost.
For scientific research, the limitations can also mean less environmental data is collected, particularly during missions in remote or difficult-to-reach areas.
The new Purdue technology is designed to give researchers more flexibility by allowing the same vehicle to adjust its movement strategy throughout a single deployment.
Early testing shows promise
Researchers have already conducted underwater pool testing to demonstrate the robot’s basic capabilities.
The proof-of-concept tests demonstrated:
- Operation of the robot’s foldable wings underwater.
- Buoyancy-controlled ascent and descent.
- Thruster-assisted movement.
- Glider-mode travel using buoyancy changes, pitch control, and wing deployment.
“The tests confirmed that the main subsystems can operate together in water and that the robot can demonstrate the intended trimodal locomotion behaviors,” She said.
Currently, switching between the different movement modes is performed manually. Future versions could incorporate autonomous mode selection, allowing the robot to determine on its own whether drifting, gliding, or powered propulsion is the best option.
What’s next?
Researchers plan to conduct more extensive testing to measure the robot’s energy consumption, endurance, maneuverability, gliding efficiency and ability to transition between movement modes.
The team also plans to develop more advanced control systems that would allow the robot to make decisions based on its mission objectives and real-time environmental conditions.
“We also will develop more advanced closed-loop control and autonomous mode-selection algorithms so the robot can decide when to drift, glide or use propulsion based on mission goals and environmental feedback,” She said.
The technology was disclosed to the Purdue Innovates Office of Technology Commercialization, which has filed for patent protection. The research has received partial support from the National Science Foundation.
If further testing is successful, the adaptable underwater platform could offer researchers and other users a more versatile option for long-duration underwater missions — potentially allowing one robot to perform tasks that would otherwise require several specialized vehicles.
