Engineers have developed a snake-like robot with the ability to grow in length and slither into the most inaccessible places.

The new robot is called RoBoa.

RoBoa was created in the Autonomous Systems Lab at ETH Zurich. It moves flexibly and efficiently through narrow spaces such as pipes or sewers and combs through debris in the wake of catastrophes.

Its soft and pneumatic design make the snake-like robot safe for use by people and in dangerous environments where there is a danger of explosion and sparks must be avoided.

RoBoa can currently extend up to a length of 100 meters (about 328 feet).

The robot is also equipped with a speaker and microphone to allow direct communication with victims in the case of emergency.

RoBoa was originally developed as part of a student focus project. Thanks to a Pioneer Fellowship, it is now close to market launch and could have a major impact on inspection and search and rescue operations.

The cofounders of RoBoa will be presenting insights into their research work at the ETH booth at ETH Industry Day @ Open-i.

Source: ETH Zurich

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A new robot can sever its own limbs to escape tricky situations.

Self-amputation may seem like a drastic move, but it’s a survival tactic that’s proved particularly handy for numerous creatures.

Roboticists have drawn inspiration from lizards, crabs, and other animals who shed parts of themselves without looking back, all for the purpose of moving forward.

Outside the lab, a robot could face many potential perils: A falling tree limb, perhaps, or getting stuck under a rock on a search-and-rescue mission. In most cases, that would be it for the robot.

But the Yale University lab of Rebecca Kramer-Bottiglio has developed a technology that allows a robot to selectively disconnect its limbs and free itself from such potential pitfalls.

Conversely, it allows separate robots to join together to take on tasks that they couldn’t do on their own.

Critical to the technology is a material that the roboticists invented in the lab that they call a bicontinuous thermoplastic elastomer. The thermoplastic they use is a rubbery solid at room temperature that melts into a liquid at about 284 °F. It’s infused in a foam-like structure made from silicone that holds the thermoplastic in place when it’s melted into a liquid.

How it works: Two silicone bodies each have a layer of bicontinuous thermoplastic elastomer on their exposed surfaces. The foams are heated so that the thermoplastic melts into liquid. The silicone matrix holds the molten material like a sponge, preventing it from flowing out. Upon contact of the two parts, the molten material combines into a continuous liquid mass. The material then cools and solidifies to connect the two parts. And to disconnect, the joint is heated so that the material melts and weakens, allowing the two parts to separate easily.

“So if the robot is doing its normal operations and walking around the wild, but then something happens to one of its legs—a big rock falls on it, for example—normally the whole robot would be stuck if it were cast in whole,” says Bilige Yang, a PhD student and the lead author of the work.

“But because we have the ability to melt away and weaken this joint where the material is, the rest of the robot will be able to walk away without its amputated leg.”

It’s a similar tactic used by lizards; if an attacker grabs its tail, the lizard automatically releases the limb and scurries to safety. And a crab will shed an injured appendage that’s slowing it down. But the Kramer-Bottiglio lab also points to the world of ants as a source of inspiration. For instance, many ants can link up to form a bridge to cross a gap on the forest floor or form into the shape of a ball to float on water.

Yang points to two small robotic devices on a counter in the lab, and a gap too wide for either of them to safely cross alone.

“If each individual robot tried to cross the gap, it would just fall through,” he says. “But if you have a few of them together, they can make it across. You can imagine this in different types of search-and-rescue missions where the robot will be able to navigate these types of scenarios much better.”

Up next, the research team will apply this technology to many other soft robots they’ve developed in the laboratory.

“Our material not only aids in robot survival—it enables dynamic shape-change,” Kramer-Bottiglio says. “Robotic modules can self-reconfigure into different morphologies to perform tasks that demand specific shapes and behaviors.”

A paper on the robot appears in Advanced Materials.

Source: Yale

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Researchers have developed artificial muscles for robot motion.

Their solution offers several advantages over previous technologies: it can be used wherever robots need to be soft rather than rigid or where they need more sensitivity when interacting with their environment.

Many roboticists dream of building robots that are not just a combination of metal or other hard materials and motors but also softer and more adaptable. Soft robots could interact with their environment in a completely different way; for example, they could cushion impacts the way human limbs do, or grasp an object delicately.

This would also offer benefits regarding energy consumption: robot motion today usually requires a lot of energy to maintain a position, whereas soft systems could store energy well, too. So, what could be more obvious than to take the human muscle as a model and attempt to recreate it?

Biological inspiration

The functioning of artificial muscles is based on biology. Like their natural counterparts, artificial muscles contract in response to an electrical impulse. However, the artificial muscles consist not of cells and fibers but of a pouch filled with a liquid (usually oil), the shell of which is partially covered in electrodes.

When these electrodes receive an electrical voltage, they draw together and push the liquid into the rest of the pouch, which flexes and is thus capable of lifting a weight. A single pouch is analogous to a short bundle of muscle fibers; several of these can be connected to form a complete propulsion element, which is also referred to as an actuator or simply as an artificial muscle.

The idea of developing artificial muscles is not new, but until now, there has been a major obstacle to realizing it: electrostatic actuators worked only with extremely high voltages of around 6,000 to 10,000 volts. This requirement had several ramifications: for instance, the muscles had to be connected to large, heavy voltage amplifiers; they did not work in water; and they weren’t entirely safe for humans.

Robert Katzschmann, a robotics professor at ETH Zurich, together with Stephan-Daniel Gravert, Elia Varini, and other colleagues have now developed a new solution.

The HALVE of it

Gravert, who works as a scientific assistant in Katzschmann’s lab, has designed a shell for the pouch. The researchers call the new artificial muscles HALVE actuators, where HALVE stands for “hydraulically amplified low-voltage electrostatic”.

“In other actuators, the electrodes are on the outside of the shell. In ours, the shell consists of different layers,” says Gravert.

“We took a high-permittivity ferroelectric material, i.e., one that can store relatively large amounts of electrical energy, and combined it with a layer of electrodes. Next, we coated it with a polymer shell that has excellent mechanical properties and makes the pouch more stable,” Gravert explains.

This meant the researchers could reduce the required voltage, because the much higher permittivity of the ferroelectric material allows large forces despite low voltage. Not only did Gravert and Varini develop the shell for the HALVE actuators together, but they also built the actuators themselves in the lab to use in two robots.

One of these robotic examples is an 11-centimeter-tall gripper (about 4.3 inches tall) with two fingers. Each finger is moved by three series-connected pouches of the HALVE actuator. A small battery-operated power supply provides the robot with 900 volts. Together, the battery and power supply weigh just 15 grams (about 0.5 ounces). The entire gripper, including the power and control electronics, weighs 45 grams (about 1.58 ounces). The gripper can grip a smooth plastic object firmly enough to support its own weight when the object is lifted into the air with a cord.

“This example excellently demonstrates how small, light and efficient the HALVE actuators are. It also means that we’ve taken a huge step closer to our goal of creating integrated muscle-operated systems,” Katzschmann says with satisfaction.

Diving into the future

The second object is a fish-like swimmer, almost 30 centimeters long (about 11.8 inches), that can move smoothly through the water. It consists of a “head” containing the electronics and a flexible “body” to which the HALVE actuators are attached. These actuators move alternately in a rhythm that produces the swimming motion. The autonomous fish can go from a standstill to a speed of three centimeters per second in 14 seconds—and that’s in normal tap water.

This second example is important because it demonstrates another new feature of the HALVE actuators: as the electrodes no longer sit unprotected outside the shell, the artificial muscles are now waterproof and can also be used in conductive liquids.

“The fish illustrates a general advantage of these actuators—the electrodes are protected from the environment and, conversely, the environment is protected from the electrodes. So, you can operate these electrostatic actuators in water or touch them, for example,” Katzschmann explains.

And the layered structure of the pouches has another advantage: the new actuators are much more robust than other artificial muscles.

Ideally, the pouches should be able to achieve a great deal of motion and do it quickly. However, even the smallest production error, such as a speck of dust between the electrodes, can lead to an electrical breakdown—a kind of mini lightning strike.

“When this happened in earlier models, the electrode would burn, creating a hole in the shell. This allowed the liquid to escape and rendered the actuator useless,” Gravert says. This problem is solved in the HALVE actuators because a single hole essentially closes itself due to the protective plastic outer layer. As a result, the pouch usually remains fully functional even after an electrical breakdown.

The two researchers are clearly delighted to have taken the development of artificial muscles a decisive step forward, but they are also realistic.

As Katzschmann says, “Now we have to ready this technology for larger-scale production, and we can’t do that here in the ETH lab. Without giving too much away, I can say that we’re already registering interest from companies that would like to work with us.”

For example, artificial muscles could one day be used in novel robots, prostheses, or wearables; in other words, in technologies that are worn on the human body.

The research appears in Science Advances.

Source: ETH Zurich

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