Two Approaches to Robotic Skin Materials

Researchers at two leading robotics research labs have come up with different approaches to skin materials for robots.

Researchers at two leading robotics research labs have come up with different approaches to skin materials for robots. Both of these technologies from MIT's Computer Science and Artificial Intelligence Laboratory (CSAIL) and Georgia Tech's Healthcare Robotics Lab may be usable in medical or orthopedic and prosthetic applications.


CSAIL researchers have developed a programmable viscoelastic material (PVM), plus a method of fabrication, that could be used as shock-absorbing skins to help make robots safer, tougher, and nimbler. For anyone who's seen BattleBots in action, that need is a no-brainer: robots are often more fragile than they look, and usually don't have much in the way of padding for protection. This can lead to some spectacular (and sometimes messy) wipeouts.


BattleBots, robots

Members of these two BattleBot teams presented their designs at the Design & Manufacturing Minneapolis show last September. They also gave tips about designing both rugged robots and medical devices, which have some challenges in common. (Source: Naomi Price/UBM)

The new material contrasts with regular viscoelastics that have both solid and liquid qualities but are time-consuming to customize using existing fabrication methods, team leader Daniela Rus, who is CSAIL's director, told Design News . The team's new method includes 3D printing standard materials with a non-curing liquid, using a multimaterial printer to carefully control material characteristics. The researchers used an Objet multimaterial printer because that's what they happened to have in the lab. "But this process is not specific to those machines: any of the drop-on-demand 3D printers could be used," she said. This form of inkjet printer is commonly used in micro- and bio-fabrication for rapid prototyping.

PVM is based on a previous project called " printed hydraulics ," said Robert MacCurdy, a postdoc in CSAIL's Distributed Robotics Lab, and lead author in its recent paper describing PVM . In October, the team presented this paper at the IEEE/RSJ International Conference on Intelligent Robots and Systems in Korea. It was co-authored by Rus and two other postdocs: Jeffrey Lipton and Shuguang Li.

"The key enabling idea behind both of these efforts, from a fabrication perspective, is the discovery that it's possible to print with both solidifying and non-solidifying materials simultaneously," said MacCurdy. "This capability makes it possible, in the case of printed hydraulics, to design very complex hydraulically-actuated assemblies and fabricate them automatically, that is, assembly-free fabrication."

The PVM technique lets users program every single part of a 3D-printed object to the exact levels of stiffness and elasticity they need, depending on the task they need it to perform. This gives design engineers much more control in realizing specific mechanical properties, and it's also a more streamlined manufacturing process.

Traditionally, if you want a piece of viscoelastic material, also known as rubber, you have to know ahead of time what the material's composition will be and mix together or mold the rubber into the desired shape. That piece has the same mechanical properties throughout the entire material. "You might need to make several parts separately and join them together," said MacCurdy. "This approach allows software to


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