Light-Powered Aerial Soft Robot for Autonomous Cargo Transport

Researchers at North Carolina State University have developed a light-powered soft robot that can transport objects through the air along predefined tracks, similar to aerial trams. The robot can carry loads up to 12 times its weight and can climb slopes at angles of up to 80 ^°. 

We have previously created soft robots that can move quickly through the water and across solid ground, but wanted to explore a design that can carry objects through the air across open space. The simplest way to do this is to follow established an established track, similar to the aerial trams you see in the mountains, and we have now demonstrated that this is possible.

Jie Yin, Study Corresponding Author and Study Associate Professor, Mechanical and Aerospace Engineering, North Carolina State University

The soft robots are made of liquid crystal elastomers that resemble ribbons. These elastomers are twisted and then joined at the ends to form a loop, resembling a bracelet.

The "soft ring robot" is suspended from a track and can be made from materials such as wire, cable, and thread. The ring hangs parallel to the track at an angle because it is looped around it twice or thrice.

When exposed to infrared light positioned perpendicular to the track, the section of the ribbon that absorbs the most light contracts.

This generates a rolling motion: the light-exposed part of the ribbon contracts, pulling the "cooler" section into the light.

As the heated section cools, it transfers heat to the next section, repeating the cycle. The soft ring also propels itself along the track as it twists and rolls.

As the ribbon turns, it is like turning a screw, allowing the soft robot to move along the track even when carrying cargo up steep angles.

Jie Yin, Study Corresponding Author and Study Associate Professor, Mechanical and Aerospace Engineering, North Carolina State University

The researchers demonstrated that the soft ring robot could navigate tracks as thin as a human hair, or as thick as a drinking straw. The soft ring robot was also able to overcome obstacles on the track, such as knots or bulges. In addition to carrying loads more than twelve times its weight, the researchers showed that the robot could move up or down a slope.

We also showed that it can follow complex routes; it does not have to be a straight line. We have demonstrated that it can follow curved lines, circles, three-dimensional spirals, and so on, in a controlled way. We think the adaptability of the robot when it comes to navigating complex patterns in predictable ways holds promise for its utility in practical applications.

Fangjie Qi, Study First Author and Ph.D. Student, North Carolina State University 

Yin said, “We are now thinking about specific applications for this technology, as well as adapting the soft robots to respond to inputs other than infrared light. For example, developing a soft ring robot that operates in sunlight or in response to other external energy sources.”

Additional authors include NC State Ph.D. students Caizhi Zhou, Haitao Qing, and Haoze Sun.

The study was funded by the National Science Foundation.

Aerial tram-like autonomous soft ring robot. Video Credit: North Carolina State University

Journal Reference:

‌Qi, F., et al. (2025) Aerial Track‐Guided Autonomous Soft Ring Robot. Advanced Science. doi.org/10.1002/advs.202503288.