New soft robots can navigate complex environments like mazes without input from humans or computer software, new research shows.

“These soft robots demonstrate a concept called ‘physical intelligence,’ meaning that structural design and smart materials are what allow the soft robot to navigate various situations, as opposed to computational intelligence,” says Jie Yin, an associate professor of mechanical and aerospace engineering at North Carolina State University and corresponding author of a paper in the Proceedings of the National Academy of Sciences.

The soft robots are made of liquid crystal elastomers in the shape of a twisted ribbon, resembling translucent rotini. When you place the ribbon on a surface that is at least 55 degrees Celsius (131 degrees Fahrenheit), which is hotter than the ambient air, the portion of the ribbon touching the surface contracts, while the portion of the ribbon exposed to the air does not.

This induces a rolling motion in the ribbon. And the warmer the surface, the faster it rolls.

“This has been done before with smooth-sided rods, but that shape has a drawback—when it encounters an object, it simply spins in place,” says Yin. “The soft robot we’ve made in a twisted ribbon shape is capable of negotiating these obstacles with no human or computer intervention whatsoever.”

The ribbon robot does this in two ways. First, if one end of the ribbon encounters an object, the ribbon rotates slightly to get around the obstacle. Second, if the central part of the robot encounters an object, it “snaps.”

The snap is a rapid release of stored deformation energy that causes the ribbon to jump slightly and reorient itself before landing. The ribbon may need to snap more than once before finding an orientation that allows is to negotiate the obstacle, but ultimately it always finds a clear path forward.

“In this sense, it’s much like the robotic vacuums that many people use in their homes,” Yin says. “Except the soft robot we’ve created draws energy from its environment and operates without any computer programming.”

“The two actions, rotating and snapping, that allow the robot to negotiate obstacles operate on a gradient,” says Yao Zhao, a postdoctoral researcher and the paper’s first author.

“The most powerful snap occurs if an object touches the center of the ribbon. But the ribbon will still snap if an object touches the ribbon away from the center, it’s just less powerful. And the further you are from the center, the less pronounced the snap, until you reach the last fifth of the ribbon’s length, which does not produce a snap at all.”

The researchers conducted multiple experiments demonstrating that the ribbon-like soft robot is capable of navigating a variety of maze-like environments. The researchers also demonstrated that the soft robots would work well in desert environments, showing they were capable of climbing and descending slopes of loose sand.

“This is interesting, and fun to look at, but more importantly it provides new insights into how we can design soft robots that are capable of harvesting heat energy from natural environments and autonomously negotiating complex, unstructured settings such as roads and harsh deserts.” Yin says.

Additional coauthors are from Penn and NC State. The National Science Foundation supported the work.

Source: NC State

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‘Balloon art’ soft robot doesn’t need to plug in

A pneumatic, shape-changing soft robot can navigate its environment without requiring a tether to a stationary power source, report researchers.

It’s like balloon art on steroids.

It’s also a major step in the effort to bring soft robots to human environments, where their characteristics are uniquely suited for interaction with and around people.

“…the robot is actually a collective of individual robotic rollers, which work together to move the robot and change its shape.”

“The main challenge that we’re trying to address is to make a human-scale soft robot,” says mechanical engineering professor Elliot Hawkes of the University of California, Santa Barbara. The work appears in the journal Science Robotics.

Most soft robots to date tend to be small, and often tether to the wall for power or compressed air, he explains. But what if they could create a soft robot large enough and strong enough to perform human-scale interactions and independent enough to navigate diverse, unstructured environments, such as disaster zones?

Enter the isoperimetric soft robot, a roughly four-foot-tall pneumatic robot that can move by deforming its soft, air-filled fabric tubes—while keeping its perimeter constant.

“The idea is that you can change the shape of the soft robot by using simple motors that drive along the tubes, instead of using the slow, inefficient pumps that are normally used,” says Hawkes, who conducted research for this paper while at Stanford University.

“The casual description of this robot that I give to people is Baymax from the movie Big Hero 6 mixed with Transformers. In other words, a soft, human-safe robot mixed with robots that can dramatically change their shape,” says Nathan Usevitch, a graduate student in mechanical engineering at Stanford.

Three kinds of robotics in one

The isoperimetric robot is actually a combination of concepts from three distinct robotic areas—soft robotics, truss robots, and collective robots—that together create new capabilities. The soft fabric tubes allow the robot to traverse irregular surfaces and deform as needed, and are light while being strong. The motors also can connect to each other via three-degree-of-freedom universal joints to create truss-like structures that can support weight and allow locomotion in three dimensions. And the motor “nodes” that allow the tubes to bend are themselves small, simple collective robots that together roll along the fabric tube and pinch to form joints of varying angles.

Perhaps the most notable thing about the robot is that it doesn’t require inflation and deflation to move, doing away with the need for a connection to an external, stationary source of air or an unwieldy, bulky onboard pump. The motors are powered by small batteries.

“We were looking at ways to make it untethered, and we realized that we didn’t need to pump air in and out; what we really needed to do was to move the air around,” Hawkes says. This was, in fact, one of the group’s major design challenges.

“It turns out that when you have air, even at relatively low pressure, there are huge forces that it applies,” he says, so much of the engineering actually went into creating the nodes that roll along the tube and pinch to create joints. The advantage here, Hawkes adds, is that the robot’s operation is quicker and more seamless than it would be if it had to inflate and deflate in the process.

“What’s exciting to me is that the robot is actually a collective of individual robotic rollers, which work together to move the robot and change its shape,” says Mac Schwager, assistant professor of aeronautics and astronautics and Stanford and coauthor of the paper. “This helps make it an adaptable and robust system.”

What could this sort of soft robot do?

The researchers envision many uses for this type of robot. In a collapsed building scenario, for instance, it could crawl flat into tight spaces and reconfigure into a three-dimensional truss to create space and support weight. For planetary exploration, it packs light and can navigate uncertain terrain. It can pick up and even manipulate loads, and its soft nature allows it to work alongside humans. Its simple, modular construction allows students and other robot-builders to create a variety of their own robots in different shapes for diverse purposes.

Taken together, the robot’s size, freedom of movement, strength, and utility in real-world scenarios represent the type of focus that Hawkes and his group think will be beneficial. Soft robot research is new and exciting, Hawkes says, and it’s taking off.

“But as a field, we need to think critically about what contributions each research project offers, what problems it solves, or how it advances the field,” he says, “as opposed to just making another cool gizmo.”

Other contributors to the work are from Stanford.

Source: UC Santa Barbara, Stanford

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New material offers lots of perks to soft robots

Researchers have created a new metal-based material for use in soft robots.

“Origami robots” are state-of-the-art soft, flexible robots that could find use in drug delivery in human bodies, search and rescue missions in disaster environments, and humanoid robotic arms.

Because these robots need to be flexible, they are often made from soft materials such as paper, plastic, and rubber. To be functional, sensors and electrical components are often added on top, but these add bulk to the devices.

Combining metals such as platinum with burned paper (ash), the new material has enhanced capabilities while maintaining the foldability and lightweight features of traditional paper and plastic. In fact, the new material is half as light as paper, which also makes it more power efficient.

Prosthetics and soft robots

These characteristics make the new material a strong candidate for making flexible and light prosthetic limbs which can be as much as 60% lighter than their conventional counterparts. Such prosthetics can provide real-time strain sensing to give feedback on how much they are flexing, giving users finer control and immediate information—all without the need for external sensors which would otherwise add unwanted weight to the prosthetic.

This lightweight metallic backbone is at least three times lighter than conventional materials used in the fabrication of origami robots. It is also more power-efficient, enabling origami robots to work faster using 30% less energy. The new material is also fire-resistant, making it suitable for use in robots that work in harsh environments. The new material can withstand burning at about 800 C (1,472 F) for up to 5 minutes.

In addition, the conductive material has geothermal heating capabilities on-demand—sending a voltage through the material causes it to heat up, which helps to prevent icing damage when a robot works in a cold environment. These properties could help create light, flexible search-and-rescue robots that can enter hazardous areas while providing real-time feedback and communication.

How they made the new material

Researchers create the metal-based material through a new process called “graphene oxide-enabled templating synthesis.” They first soak cellulose paper in a graphene oxide solution, before dipping it into a solution made of metallic ions such as platinum. The material then burns in an inert gas, argon, at 800 C (1,472 F) and then at 500 C (932 F) in air.

The final product is a thin layer of metal—90 micrometers (μm), or 0.09mm—made up of 70% platinum and 30% amorphous carbon (ash) that is flexible enough to bend, fold, and stretch. Other metals such as gold and silver can also be used.

The work appears in the journal Science Robotics.

Team leader Chen Po-Yen used a cellulose template cut out in the shape of a phoenix for his research. “We are inspired by the mythical creature. Just like the phoenix, it can be burnt to ash and reborn to become more powerful than before,” says Chen, assistant professor at NUS Chemical and Biomolecular Engineering.

Conductive backbones

The team’s material can function as mechanically stable, soft, and conductive backbones that equip robots with strain sensing and communication capabilities without the need for external electronics.

Being conductive means the material acts as its own wireless antenna, allowing it to communicate with a remote operator or other robots without the need for external communication modules. This expands the scope of origami robots, such as working in high-risk environments (e.g. chemical spills and fire disaster) as remote-control untethered robots, or functioning as artificial muscles or humanoid robotic arms.

“We experimented with different electrically conductive materials to finally derive a unique combination that achieves optimal strain sensing and wireless communication capabilities,” says Yang Haitao, doctoral student at NUS Chemical and Biomolecular Engineering and the first author of the study. “Our invention therefore expands the library of unconventional materials for the fabrication of advanced robots.”

Chen and his team are now looking to add more functions to the metallic backbone. One promising direction is to incorporate electrochemically active materials to fabricate energy storage devices such that the material itself is its own battery, allowing for the creation of self-powered robots. The team is also experimenting with other metals such as copper, which will lower the cost of the material’s production.

Source: National University of Singapore

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