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Engineers have developed a hopping robot that integrates rigid and soft materials for use in harsh and unpredictable environments such as disaster situations.
The robot, developed at Harvard University, is one of the first times rigid and soft components have been integrated in a 3D printed autonomous robot.
The robot is comprised of two main parts: a soft plunger-like body with three pneumatic legs, and a rigid core of the key components, including a battery and air compressor. It's movement is powered by combining butane and oxygen for combustion, while the primarily soft body absorbs impacts.
The body, which is produced in one continuous 3D print job, has nine different material layers, from a highly flexible and rubber-like layer to fully rigid and thermoplastic-like protective shell.
The different layers reduce stress where the rigid electronic components join the body to increase the robot's resiliency. The robot also has no sliding parts or traditional joints, improving reliability and making it more suitable for use in harsh environments.
To initiate movement, the robot inflates its pneumatic legs to tilt its body in the direction it wants to go. The butane and oxygen are then mixed and ignited, catapulting the robot into the air. The robot can reach up to six times its body height in vertical leaps and half its body width in lateral jumps.
The hopping motion could be an effective way to move quickly and easily around obstacles. The soft body would also allow it to survive large falls and other unexpected situations, said the research team.
Nicholas Bartlett, a researcher on the project, said: "The wonderful thing about soft robots is that they lend themselves nicely to abuse. The robot's stiffness gradient allows it to withstand the impact of dozens of landings and to survive the combustion event required for jumping. Consequently, the robot not only shows improved overall robustness but can locomote much more quickly than traditional soft robots."
Traditional methods of fabrication for “soft robots” have been costly and slow because they use custom moulds and multi-step assembly. The use of multi-material 3D printers enables engineers to prototype faster, and increase complexity more cheaply.
Robert Wood, Professor of engineering and applied sciences at the Harvard John A. Paulson School of Engineering and Applied Sciences said: "Soft robotics is a relativity nascent subfield and 3D printing is adding to the repertoire of things we can do in a really practical way,"
“The vision for the field of soft robotics is to create robots that are entirely soft. But for practical reasons, our soft robots typically have some rigid components, things like batteries and control electronics. This robot is a demonstration of a method to integrate the rigid components with the body of the soft robot through a gradient of material properties, eliminating an abrupt hard-to-soft transition that is often a failure point."