Scientists innovate underwater exploration with manta ray-inspired robot

HANGZHOU -- In a laboratory at Westlake University in East China's Zhejiang province, a group of young researchers is pushing ahead the underwater exploration frontiers with an unlikely muse: the manta ray.

On the night of March 4, their creation, the Sea Guru II, which measures 3 meters in length and width and stands 1.5 meters tall, successfully completed a landmark 2,000-meter deep-sea trial in the South China Sea. Within just two hours, it executed complex movements and operations near the seafloor.

"By mimicking the manta ray's fluid silhouette, we've solved buoyancy and stability issues that plague humanoid underwater robots," said Fan Dixia, 35, the project's principal investigator. "The design also exhibits gentler profiles, lower noise emissions, and reduced water disturbance."

The latest model builds upon its predecessor, Sea Guru I, which in 2023 successfully operated at depths of 2,000 meters, according to the team.

Following the initial accomplishment, the team faced a pivotal choice that would shape the course of their research. "We could chase greater depths, or prioritize enhancing operational capability," said 34-year-old Li Weikun, the submersible's chief designer.

The team opted for the latter, and this decision led to multiple key innovations. While the first-generation model had modular fins that extended like wings, Sea Guru II incorporated fully flexible undulating fins with wave-like movements that closely mimic fish locomotion.

"This redesign not only streamlines the submersible's profile to meet hydrodynamic demands, but also boosts the propulsive efficiency and directional control," said Fan.

The vehicle also features sophisticated internal systems for adaptive altitude, depth and orientation control, enabling real-time monitoring and autonomous navigation adjustments in complex underwater environments.

The highlight of the update is Sea Guru II's "belly pod," which carries tools ranging from robotic arms to miniature drone submarines, or "baby fish."

"These 'baby fish' can reach spaces too tight for the main vehicle," said Fan. In the March sea trial, these underwater drones carried out exploration missions in the hydrothermal vent zone.

Additionally, the submersible's "fishtail" can automatically extend, retract and adjust its angle as needed to capture a broader underwater view.

The manta ray-inspired design greatly enhanced the stability, efficiency and flexibility of humanoid robots underwater. Unlike traditional propeller-driven submersibles, fish-shaped ones minimize disturbance to the deep sea. "This bionic design reduces interference with the marine environment," said Fan.

Sea Guru II's enhanced capabilities, including rapid underwater turns, autonomous obstacle navigation and collaborative missions with miniaturized drones, make it suitable for ecological surveys, seabed mining, and infrastructure repair, according to the team.

This development aligns with broader national plans outlined in this year's government work report, which called for "a major push to develop the marine economy."

Data from the Ministry of Natural Resources shows China's marine economy reached a significant milestone in 2024, with its gross ocean product exceeding 10 trillion yuan (approximately $1.4 trillion) for the first time.

The team is looking toward more ambitious horizons. "Our goal is to advance foundational innovations, making them more precise, agile, and reliable, to establish a robust technical framework for humanity's next leap into deeper oceans," Fan said.