March 2, 2024

New Soft Robots Display Multiple Behaviors Simultaneously: Rolling, Spinning, and Orbiting

Soft robots, known as twisted ringbots, have been developed by researchers that exhibit three distinct behaviors simultaneously: rolling forward, spinning like a record, and following an orbit around a central point. These robots, which function without the need for human or computer control, hold great potential in the development of soft robotic devices for mapping and navigating unknown environments.

The twisted ringbots are constructed using twisted ribbon-like liquid crystal elastomers, resembling a bracelet loop. When placed on a surface with a temperature of at least 55°C (131°F) higher than the ambient air, the part of the ribbon in contact with the surface contracts, causing the robot to roll. The warmer the surface, the faster the rolling motion.

The ribbon rolls on its horizontal axis, contributing to the ring’s forward momentum. Furthermore, the twisted ringbots spin along their central axis, akin to a record on a turntable. As the robots move forward, they follow an orbital path around a central point, essentially moving in a large circle. However, if the twisted ringbots encounter a boundary, such as the wall of a box, they will navigate along the boundary.

Jie Yin, the corresponding author of the study and an associate professor of mechanical and aerospace engineering at North Carolina State University, explains that this behavior holds significant potential for mapping unknown environments.

The physical intelligence of the twisted ringbots determines their behavior, relying on their structural design and materials, rather than being guided by human or computer intervention.

The researchers can manipulate the behavior of the twisted ringbot by adjusting its geometry. For instance, twisting the ribbon in one direction or the other determines the direction of spin. The width of the ribbon and the number of twists can also affect the speed of the robot.

In proof-of-concept testing, the researchers demonstrated that the twisted ringbot could follow the contours of various confined spaces. Regardless of the starting position within these spaces, the robot was able to navigate to a boundary and map the contours by following the boundary lines. It can also identify any gaps or damage in the boundary.

By introducing two twisted ringbots that rotate in different directions into more complex spaces, the researchers were able to map the boundaries. Each robot follows a different path along the boundary, and comparing their paths allows the contours of the space to be captured.

Yin explains that in theory, any complex space can be mapped by introducing enough twisted ringbots, each contributing part of the picture. Furthermore, considering the cost-effectiveness of producing these robots, this approach becomes a viable solution.

Soft robotics is still an emerging field, and Yin believes that finding new methods to control the movement of soft robots in an engineered and repeatable manner is crucial for advancing the field. This research expands our understanding of the possibilities within this exciting field.

The study was co-authored by postdoctoral researchers Yanbin Li and Yao Zhao, recent Ph.D. graduate Yaoye Hong, and Ph.D. student Haitao Qing, all from NC State.

1. Source: Coherent Market Insights, Public sources, Desk research
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