Self-Folding "Rollbot" Paves Way for Totally Free Robots

Today, most software robots rely on external power and control, whether they are connected to external systems or equipped with rigid components. Researchers at the Harvard School of Engineering and Applied Sciences John A. Paulson and Caltech have developed software-based robotic systems inspired by origami, able to move and change in response to external stimuli, opening the way to completely independent software. robots.

The research is published in Robotic science.

"The ability to integrate active materials into 3D printed objects makes it possible to design and manufacture all-new classes of flexible robotic materials," said Jennifer A. Lewis, Hansjorg Wyss's inspiring engineering professor. Biologist at SEAS and co-lead author of the study.

Researchers have turned to origami to create versatile, versatile robots. With sequential folds, origami can encode multiple shapes and features into one structure. Using materials known as liquid crystal elastomers that change shape when they are exposed to heat, the research team has printed in 3D two types of flexible hinges that bend at different temperatures and can therefore be programmed to be folded in a specific order.

"Thanks to our three-dimensional printing method of active hinges, we have total programmability with regard to the temperature response, the amount of torque that the hinges can exert, their bending angle and the orientation of the hinges. Our manufacturing method facilitates the integration of these active components with other materials, "Arda Kotikian, graduate student at SEAS and at the Graduate School of Arts and Sciences and co-premier of the School of Arts and Sciences. ; article.

"The use of hinges facilitates the programming of robotic functions and the control of robot transformation Instead of deforming the entire body of a flexible robot in a way that is difficult to predict, you only need to program a few small areas of your structure. will respond to temperature changes, "said Connor McMahan, Caltech's graduate student and co-lead author of the article.

To illustrate this method, Kotikian, McMahan and the team built several software devices, including an unattached software robot, nicknamed the "Rollbot". The Rollbot begins as a flat sheet about 8 centimeters long and 4 centimeters wide. When it is placed on a hot surface, at about 200 ° C, a set of hinges bends and the robot curves into a pentagonal wheel.

Another set of hinges is integrated on all five sides of the wheel. A hinge bends when in contact with the hot surface, causing the wheel to turn to the next side where the next hinge bends. Leaving the hot surface, the hinges unfold and are ready for the next cycle.

"Many software robots require connection to external power and control systems or are limited by the force they can exert.These active hinges are useful because they allow software robots to operate in environments where fasteners are impassable and lifting objects many times heavier than hinges, "McMahan said.

Another device, when placed in a warm environment, can bend to form a compact folded shape resembling a paper clip and unfold when it is cooled.

"These unattached structures can be passively controlled," said Kotikian. "In other words, all we have to do is expose the structures to specific temperature environments and they will react according to the way we have programmed the hinges."

Although this research only addresses temperature responses, liquid crystal elastomers can also be programmed to respond to light, pH, humidity, and other external stimuli.

"This work shows how the combination of reactive polymers in an architectural composite can lead to self-activated materials in response to different stimuli, and in the future, such materials can be programmed to perform increasingly complex tasks. , blurring the boundaries between materials and robots, "said Chiara Daraio, professor of mechanical engineering and applied physics at Caltech and co-lead author of the study.