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| Image Credit: Courtesy of North Carolina State University |
Scientific Frontline: Extended "At a Glance" Summary: Feather Star-Inspired Underwater Robot
The Core Concept: An aquatic soft robot modeled after marine invertebrates known as feather stars that navigates seamlessly in three dimensions using only two pneumatic actuators.
Key Distinction/Mechanism: While traditional aquatic robots typically require at least six actuators for full mobility, this design leverages "mechanical intelligence." It utilizes the structural dynamics of elastic, monostable wings to achieve vertical ascension, horizontal propulsion, and rotational steering with minimal input.
Origin/History: Developed by engineers from North Carolina State University and the University of Virginia, with the foundational research published in the journal Science Advances in October 2026.
Major Frameworks/Components:
- Mechanical intelligence: Relying on the physical structure rather than complex computer inputs to govern movement.
- Actuation system: A central disk containing just two pneumatic actuators.
- Monostable wings: Four elastic appendages that snap downward when activated and return to their original position when deactivated.
- Tri-modal locomotion: "Jellyfish mode" for vertical movement, "fish mode" for horizontal travel, and "rotor mode" for axis rotation.
Branch of Science: Mechanical Engineering, Robotics, Biomimetics, Fluid Dynamics, and Marine Engineering.
Future Application: The platform holds potential for deep-sea exploration, underwater camera navigation, and the cooperative lifting or manipulation of submerged objects in remote marine environments.
Why It Matters: The invention proves that intelligent structural design can drastically reduce the mechanical complexity and energy requirements of aquatic robots, paving the way for more efficient and highly adaptable underwater exploration technologies.
Video of the feather star robot
Researchers have created an aquatic soft robot inspired by marine invertebrates called feather stars. The feather star robot is able to move through the water in all three dimensions, powered by only two actuators.
“One exciting aspect of this work is that it demonstrates how we can create robotic devices with an incredible range of motion using a minimum number of actuators, by taking advantage of intelligent design techniques,” says Jie Yin, corresponding author of a paper on the work and a professor of mechanical and aerospace engineering at North Carolina State University. Actuators are the parts of a machine that provide force or torque.
The feather star robot’s design draws on a concept called mechanical intelligence. This refers to dynamic objects—like robots—whose behavior is governed largely by their structure and how they interact with their environment, reducing the amount of input necessary from computers or human users.
“In this case, we created an aquatic soft robot that can move in three dimensions—up and down, forward and backward, and rotating on its axis,” Yin says. “Normally, you would need at least six actuators to accomplish this. But due to its structural design, we accomplish this range of motion with only two actuators in the feather star robot. This is an example of using mechanical intelligence to create a more efficient design.”
“We had previously created an aquatic robot inspired by a manta ray, and that design was capable of moving quickly through the water—but it did not have three-dimensional maneuverability,” says Haitao Qing, first author of the paper and a postdoctoral researcher at UC Berkeley who began work on this project while a PhD student at NC State. “Our goal with this work was to design a robot that had greater maneuverability without relying on unduly complicated mechanisms.”
“We were inspired by feather stars because they are able to move in any direction or hover in place by coordinating the movement of their limbs,” says Yin.
The feather star robot has four “wings” protruding from a central disk that contains two actuators. The wings are elastic and monostable, meaning the wings can be bent but will snap back to their original position. When both actuators are activated, all four wings snap down—and when the actuators are turned off, the wings snap back up. By rapidly activating and deactivating both actuators, the robot flaps its wings quickly and rises in the water column. When the actuators are turned off, the wings stop flapping, and the robot descends in the water column. And by flapping its wings slowly, the robot is able to hover in place. The researchers call this “jellyfish mode.”
To move forward or backward, the researchers only activate one actuator. This makes one wing flutter, like a tailfin, pushing the robot in the opposite direction. The researchers call this “fish mode.”
And by alternating rapidly between the two actuators, the researchers can make the robot rotate on its axis, allowing them to steer the robot in any direction. The researchers call this “rotor mode.”
“By combining these three modes, we can maneuver the robot in all three dimensions,” says Yin.
The researchers demonstrated the potential utility of the robots by showing how they can be used to explore underwater spaces with a camera, or can lift objects underwater, either alone or by working in concert with other robots.
“This design offers a versatile platform for integrating with other technologies for use in various underwater applications,” says Qing. “Future directions for this work include developing a fully wireless version. Also, we are mechanical engineers, and we’ve created a novel design for aquatic robotics. We would welcome collaborating with experts in other fields to explore potential applications for this design.”
Funding: This work was done with support from the National Science Foundation under grants 2126072 and 2329674, and the Office of Naval Research under MURI grant N00014-22-1-2616.
Disclosure: Qing and Yin are coinventors on a pending patent invention disclosure filed by North Carolina State University that is related to this work.
Published in journal: Science Advances
Title: Minimal-actuation feather star–inspired soft swimmers for multimodal 3D maneuverability
Authors: Haitao Qing, Yuanhang Zhu, Jiacheng Guo, Caizhi Zhou, Haoze Sun, Haibo Dong, Daniel Quinn, and Jie Yin
Source/Credit: North Carolina State University | Matt Shipman
Edited by: Scientific Frontline
Reference Number: eng100726_01