Why can't robots outrun animals?

Robotics engineers have worked for decades and invested many millions of research dollars in attempts to create a robot that can walk or run as well as an animal. And yet, it remains the case that many animals are capable of feats that would be impossible for robots that exist today.

"A wildebeest can migrate for thousands of kilometres over rough terrain, a mountain goat can climb up a literal cliff, finding footholds that don't even seem to be there, and cockroaches can lose a leg and not slow down," says Dr. Max Donelan, Professor in Simon Fraser University's Department of Biomedical Physiology and Kinesiology. "We have no robots capable of anything like this endurance, agility and robustness."

To understand why, and quantify how, robots lag behind animals, an interdisciplinary team of scientists and engineers from leading research universities completed a detailed study of various aspects of running robots, comparing them with their equivalents in animals, for a paper published in Science Robotics. The paper finds that, by the metrics engineers use, biological components performed surprisingly poorly compared to fabricated parts. Where animals excel, though, is in their integration and control of those components.

Alongside Donelan, the team comprised Drs. Sam Burden, Associate Professor in the Department of Electrical & Computer Engineering at the University of Washington; Tom Libby, Senior Research Engineer, SRI International; Kaushik Jayaram, Assistant Professor in the Paul M Rady Department of Mechanical Engineering at the University of Colorado Boulder; and Simon Sponberg, Dunn Family Associate Professor of Physics and Biological Sciences at the Georgia Institute of Technology.

The researchers each studied one of five different "subsystems" that combine to create a running robot -- Power, Frame, Actuation, Sensing, and Control -- and compared them with their biological equivalents. Previously, it was commonly accepted that animals' outperformance of robots must be due to the superiority of biological components.

"The way things turned out is that, with only minor exceptions, the engineering subsystems outperform the biological equivalents -- and sometimes radically outperformed them," says Libby. "But also what's very, very clear is that, if you compare animals to robots at the whole system level, in terms of movement, animals are amazing. And robots have yet to catch up."

More optimistically for the field of robotics, the researchers noted that, if you compare the relatively short time that robotics has had to develop its technology with the countless generations of animals that have evolved over many millions of years, the progress has actually been remarkably quick.

"It will move faster, because evolution is undirected," says Burden. "Whereas we can very much correct how we design robots and learn something in one robot and download it into every other robot, biology doesn't have that option. So there are ways that we can move much more quickly when we engineer robots than we can through evolution -- but evolution has a massive head start."

More than simply an engineering challenge, effective running robots offer countless potential uses. Whether solving 'last mile' delivery challenges in a world designed for humans that is often difficult to navigate for wheeled robots, carrying out searches in dangerous environments or handling hazardous materials, there are many potential applications for the technology.

Read more at Science Daily

Engineers design soft and flexible 'skeletons' for muscle-powered robots

Our muscles are nature's perfect actuators -- devices that turn energy into motion. For their size, muscle fibers are more powerful and precise than most synthetic actuators. They can even heal from damage and grow stronger with exercise.

For these reasons, engineers are exploring ways to power robots with natural muscles. They've demonstrated a handful of "biohybrid" robots that use muscle-based actuators to power artificial skeletons that walk, swim, pump, and grip. But for every bot, there's a very different build, and no general blueprint for how to get the most out of muscles for any given robot design.

Now, MIT engineers have developed a spring-like device that could be used as a basic skeleton-like module for almost any muscle-bound bot. The new spring, or "flexure," is designed to get the most work out of any attached muscle tissues. Like a leg press that's fit with just the right amount of weight, the device maximizes the amount of movement that a muscle can naturally produce.

The researchers found that when they fit a ring of muscle tissue onto the device, much like a rubber band stretched around two posts, the muscle pulled on the spring, reliably and repeatedly, and stretched it five times more, compared with other previous device designs.

The team sees the flexure design as a new building block that can be combined with other flexures to build any configuration of artificial skeletons. Engineers can then fit the skeletons with muscle tissues to power their movements.

"These flexures are like a skeleton that people can now use to turn muscle actuation into multiple degrees of freedom of motion in a very predictable way," says Ritu Raman, the Brit and Alex d'Arbeloff Career Development Professor in Engineering Design at MIT. "We are giving roboticists a new set of rules to make powerful and precise muscle-powered robots that do interesting things."

Raman and her colleagues report the details of the new flexure design in a paper appearing in the journal Advanced Intelligent Systems. The study's MIT co-authors include Naomi Lynch '12, SM '23; undergraduate Tara Sheehan; graduate students Nicolas Castro, Laura Rosado, and Brandon Rios; and professor of mechanical engineering Martin Culpepper.

Muscle pull

When left alone in a petri dish in favorable conditions, muscle tissue will contract on its own but in directions that are not entirely predictable or of much use.

"If muscle is not attached to anything, it will move a lot, but with huge variability, where it's just flailing around in liquid," Raman says.

To get a muscle to work like a mechanical actuator, engineers typically attach a band of muscle tissue between two small, flexible posts. As the muscle band naturally contracts, it can bend the posts and pull them together, producing some movement that would ideally power part of a robotic skeleton. But in these designs, muscles have produced limited movement, mainly because the tissues are so variable in how they contact the posts. Depending on where the muscles are placed on the posts, and how much of the muscle surface is touching the post, the muscles may succeed in pulling the posts together but at other times may wobble around in uncontrollable ways.

Raman's group looked to design a skeleton that focuses and maximizes a muscle's contractions regardless of exactly where and how it is placed on a skeleton, to generate the most movement in a predictable, reliable way.

"The question is: How do we design a skeleton that most efficiently uses the force the muscle is generating?" Raman says.

The researchers first considered the multiple directions that a muscle can naturally move. They reasoned that if a muscle is to pull two posts together along a specific direction, the posts should be connected to a spring that only allows them to move in that direction when pulled.

"We need a device that is very soft and flexible in one direction, and very stiff in all other directions, so that when a muscle contracts, all that force gets efficiently converted into motion in one direction," Raman says.

Soft flex

As it turns out, Raman found many such devices in Professor Martin Culpepper's lab. Culpepper's group at MIT specializes in the design and fabrication of machine elements such as miniature actuators, bearings, and other mechanisms, that can be built into machines and systems to enable ultraprecise movement, measurement, and control, for a wide variety of applications. Among the group's precision machined elements are flexures -- spring-like devices, often made from parallel beams, that can flex and stretch with nanometer precision.

"Depending on how thin and far apart the beams are, you can change how stiff the spring appears to be," Raman says.

She and Culpepper teamed up to design a flexure specifically tailored with a configuration and stiffness to enable muscle tissue to naturally contract and maximally stretch the spring. The team designed the device's configuration and dimensions based on numerous calculations they carried out to relate a muscle's natural forces with a flexure's stiffness and degree of movement.

The flexure they ultimately designed is 1/100 the stiffness of muscle tissue itself. The device resembles a miniature, accordion-like structure, the corners of which are pinned to an underlying base by a small post, which sits near a neighboring post that is fit directly onto the base. Raman then wrapped a band of muscle around the two corner posts (the team molded the bands from live muscle fibers that they grew from mouse cells), and measured how close the posts were pulled together as the muscle band contracted.

The team found that the flexure's configuration enabled the muscle band to contract mostly along the direction between the two posts. This focused contraction allowed the muscle to pull the posts much closer together -- five times closer -- compared with previous muscle actuator designs.

"The flexure is a skeleton that we designed to be very soft and flexible in one direction, and very stiff in all other directions," Raman says. "When the muscle contracts, all the force is converted into movement in that direction. It's a huge magnification."

The team found they could use the device to precisely measure muscle performance and endurance. When they varied the frequency of muscle contractions (for instance, stimulating the bands to contract once versus four times per second), they observed that the muscles "grew tired" at higher frequencies, and didn't generate as much pull.

"Looking at how quickly our muscles get tired, and how we can exercise them to have high-endurance responses -- this is what we can uncover with this platform," Raman says.

The researchers are now adapting and combining flexures to build precise, articulated, and reliable robots, powered by natural muscles.

Read more at Science Daily

Mini-robots modeled on insects may be smallest, lightest, fastest ever developed

Two insect-like robots, a mini-bug and a water strider, developed at Washington State University, are the smallest, lightest and fastest fully functional micro-robots ever known to be created.

Such miniature robots could someday be used for work in areas such as artificial pollination, search and rescue, environmental monitoring, micro-fabrication or robotic-assisted surgery.

Reporting on their work in the proceedings of the IEEE Robotics and Automation Society's International Conference on Intelligent Robots and Systems, the mini-bug weighs in at eight milligrams while the water strider weighs 55 milligrams.

Both can move at about six millimeters a second.

"That is fast compared to other micro-robots at this scale although it still lags behind their biological relatives," said Conor Trygstad, a PhD student in the School of Mechanical and Materials Engineering and lead author on the work.

An ant typically weighs up to five milligrams and can move at almost a meter per second.

The key to the tiny robots is their tiny actuators that make the robots move.

Trygstad used a new fabrication technique to miniaturize the actuator down to less than a milligram, the smallest ever known to have been made.

"The actuators are the smallest and fastest ever developed for micro-robotics," said Néstor O. Pérez-Arancibia, Flaherty Associate Professor in Engineering at WSU's School of Mechanical and Materials Engineering who led the project.

The actuator uses a material called a shape memory alloy that is able to change shapes when it's heated.

It is called 'shape memory' because it remembers and then returns to its original shape.

Unlike a typical motor that would move a robot, these alloys don't have any moving parts or spinning components.

"They're very mechanically sound," said Trygstad. "The development of the very lightweight actuator opens up new realms in micro-robotics."

Shape memory alloys are not generally used for large-scale robotic movement because they are too slow.

In the case of the WSU robots, however, the actuators are made of two tiny shape memory alloy wires that are 1/1000 of an inch in diameter.

With a small amount of current, the wires can be heated up and cooled easily, allowing the robots to flap their fins or move their feet at up to 40 times per second.

In preliminary tests, the actuator was also able to lift more than 150 times its own weight.

Compared to other technologies used to make robots move, the SMA technology also requires only a very small amount of electricity or heat to make them move.

"The SMA system requires a lot less sophisticated systems to power them," said Trygstad.

Trygstad, an avid fly fisherman, has long observed water striders and would like to further study their movements.

While the WSU water strider robot does a flat flapping motion to move itself, the natural insect does a more efficient rowing motion with its legs, which is one of the reasons that the real thing can move much faster.

Read more at Science Daily

Printed robots with bones, ligaments, and tendons

3D printing is advancing rapidly, and the range of materials that can be used has expanded considerably. While the technology was previously limited to fast-curing plastics, it has now been made suitable for slow-curing plastics as well. These have decisive advantages as they have enhanced elastic properties and are more durable and robust.

The use of such polymers is made possible by a new technology developed by researchers at ETH Zurich and a US start-up. As a result, researchers can now 3D print complex, more durable robots from a variety of high-quality materials in one go. This new technology also makes it easy to combine soft, elastic, and rigid materials. The researchers can also use it to create delicate structures and parts with cavities as desired.

Materials that return to their original state

Using the new technology, researchers at ETH Zurich have succeeded for the first time in printing a robotic hand with bones, ligaments and tendons made of different polymers in one go. "We wouldn't have been able to make this hand with the fast-curing polyacrylates we've been using in 3D printing so far," explains Thomas Buchner, a doctoral student in the group of ETH Zurich robotics professor Robert Katzschmann and first author of the study. "We're now using slow-curing thiolene polymers. These have very good elastic properties and return to their original state much faster after bending than polyacrylates." This makes thiolene polymers ideal for producing the elastic ligaments of the robotic hand.

In addition, the stiffness of thiolenes can be fine-tuned very well to meet the requirements of soft robots. "Robots made of soft materials, such as the hand we developed, have advantages over conventional robots made of metal. Because they're soft, there is less risk of injury when they work with humans, and they are better suited to handling fragile goods," Katzschmann explains.

Scanning instead of scraping

3D printers typically produce objects layer by layer: nozzles deposit a given material in viscous form at each point; a UV lamp then cures each layer immediately. Previous methods involved a device that scraped off surface irregularities after each curing step. This works only with fast-curing polyacrylates. Slow-curing polymers such as thiolenes and epoxies would gum up the scraper.

To accommodate the use of slow-curing polymers, the researchers developed 3D printing further by adding a 3D laser scanner that immediately checks each printed layer for any surface irregularities. "A feedback mechanism compensates for these irregularities when printing the next layer by calculating any necessary adjustments to the amount of material to be printed in real time and with pinpoint accuracy," explains Wojciech Matusik, a professor at the Massachusetts Institute of Technology (MIT) in the US and co-author of the study. This means that instead of smoothing out uneven layers, the new technology simply takes the unevenness into account when printing the next layer.

Inkbit, an MIT spin-off, was responsible for developing the new printing technology. The ETH Zurich researchers developed several robotic applications and helped optimise the printing technology for use with slow-curing polymers. The researchers from Switzerland and the US have now jointly published the technology and their sample applications in the journal Nature.

Read more at Science Daily

'Brainless' robot can navigate complex obstacles

Researchers who created a soft robot that could navigate simple mazes without human or computer direction have now built on that work, creating a "brainless" soft robot that can navigate more complex and dynamic environments.

"In our earlier work, we demonstrated that our soft robot was able to twist and turn its way through a very simple obstacle course," says Jie Yin, co-corresponding author of a paper on the work and an associate professor of mechanical and aerospace engineering at North Carolina State University. "However, it was unable to turn unless it encountered an obstacle. In practical terms this meant that the robot could sometimes get stuck, bouncing back and forth between parallel obstacles.

"We've developed a new soft robot that is capable of turning on its own, allowing it to make its way through twisty mazes, even negotiating its way around moving obstacles. And it's all done using physical intelligence, rather than being guided by a computer."

Physical intelligence refers to dynamic objects -- like soft robots -- whose behavior is governed by their structural design and the materials they are made of, rather than being directed by a computer or human intervention.

As with the earlier version, the new soft robots are made of ribbon-like liquid crystal elastomers. When the robots are placed 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; the warmer the surface, the faster the robot rolls.

However, while the previous version of the soft robot had a symmetrical design, the new robot has two distinct halves. One half of the robot is shaped like a twisted ribbon that extends in a straight line, while the other half is shaped like a more tightly twisted ribbon that also twists around itself like a spiral staircase.

This asymmetrical design means that one end of the robot exerts more force on the ground than the other end. Think of a plastic cup that has a mouth wider than its base. If you roll it across the table, it doesn't roll in a straight line -- it makes an arc as it travels across the table. That's due to its asymmetrical shape.

"The concept behind our new robot is fairly simple: because of its asymmetrical design, it turns without having to come into contact with an object," says Yao Zhao, first author of the paper and a postdoctoral researcher at NC State. "So, while it still changes directions when it does come into contact with an object -- allowing it to navigate mazes -- it cannot get stuck between parallel objects. Instead, its ability to move in arcs allows it to essentially wiggle its way free."

The researchers demonstrated the ability of the asymmetrical soft robot design to navigate more complex mazes -- including mazes with moving walls -- and fit through spaces narrower than its body size. The researchers tested the new robot design on both a metal surface and in sand.

"This work is another step forward in helping us develop innovative approaches to soft robot design -- particularly for applications where soft robots would be able to harvest heat energy from their environment," Yin says.

Read more at Science Daily

Robot 'chef' learns to recreate recipes from watching food videos

Researchers have trained a robotic 'chef' to watch and learn from cooking videos, and recreate the dish itself.

The researchers, from the University of Cambridge, programmed their robotic chef with a 'cookbook' of eight simple salad recipes. After watching a video of a human demonstrating one of the recipes, the robot was able to identify which recipe was being prepared and make it.

In addition, the videos helped the robot incrementally add to its cookbook. At the end of the experiment, the robot came up with a ninth recipe on its own. Their results, reported in the journal IEEE Access, demonstrate how video content can be a valuable and rich source of data for automated food production, and could enable easier and cheaper deployment of robot chefs.

Robotic chefs have been featured in science fiction for decades, but in reality, cooking is a challenging problem for a robot. Several commercial companies have built prototype robot chefs, although none of these are currently commercially available, and they lag well behind their human counterparts in terms of skill.

Human cooks can learn new recipes through observation, whether that's watching another person cook or watching a video on YouTube, but programming a robot to make a range of dishes is costly and time-consuming.

"We wanted to see whether we could train a robot chef to learn in the same incremental way that humans can -- by identifying the ingredients and how they go together in the dish," said Grzegorz Sochacki from Cambridge's Department of Engineering, the paper's first author.

Sochacki, a PhD candidate in Professor Fumiya Iida's Bio-Inspired Robotics Laboratory, and his colleagues devised eight simple salad recipes and filmed themselves making them. They then used a publicly available neural network to train their robot chef. The neural network had already been programmed to identify a range of different objects, including the fruits and vegetables used in the eight salad recipes (broccoli, carrot, apple, banana and orange).

Using computer vision techniques, the robot analysed each frame of video and was able to identify the different objects and features, such as a knife and the ingredients, as well as the human demonstrator's arms, hands and face. Both the recipes and the videos were converted to vectors and the robot performed mathematical operations on the vectors to determine the similarity between a demonstration and a vector.

By correctly identifying the ingredients and the actions of the human chef, the robot could determine which of the recipes was being prepared. The robot could infer that if the human demonstrator was holding a knife in one hand and a carrot in the other, the carrot would then get chopped up.

Of the 16 videos it watched, the robot recognised the correct recipe 93% of the time, even though it only detected 83% of the human chef's actions. The robot was also able to detect that slight variations in a recipe, such as making a double portion or normal human error, were variations and not a new recipe. The robot also correctly recognised the demonstration of a new, ninth salad, added it to its cookbook and made it.

"It's amazing how much nuance the robot was able to detect," said Sochacki. "These recipes aren't complex -- they're essentially chopped fruits and vegetables, but it was really effective at recognising, for example, that two chopped apples and two chopped carrots is the same recipe as three chopped apples and three chopped carrots."

The videos used to train the robot chef are not like the food videos made by some social media influencers, which are full of fast cuts and visual effects, and quickly move back and forth between the person preparing the food and the dish they're preparing. For example, the robot would struggle to identify a carrot if the human demonstrator had their hand wrapped around it -- for the robot to identify the carrot, the human demonstrator had to hold up the carrot so that the robot could see the whole vegetable.

"Our robot isn't interested in the sorts of food videos that go viral on social media -- they're simply too hard to follow," said Sochacki. "But as these robot chefs get better and faster at identifying ingredients in food videos, they might be able to use sites like YouTube to learn a whole range of recipes."

Read more at Science Daily

Robot provides unprecedented views below Antarctic ice shelf

High in a narrow, seawater-filled crevasse in the base of Antarctica's largest ice shelf, cameras on the remotely operated Icefin underwater vehicle relayed a sudden change in scenery.

Walls of smooth, cloudy meteoric ice suddenly turned green and rougher in texture, transitioning to salty marine ice.

Nearly 1,900 feet above, near where the surface of the Ross Ice Shelf meets Kamb Ice Stream, a U.S.-New Zealand research team recognized the shift as evidence of "ice pumping" -- a process never before directly observed in an ice shelf crevasse, important to its stability.

"We were looking at ice that had just melted less than 100 feet below, flowed up into the crevasse and then refrozen," said Justin Lawrence, visiting scholar at the Cornell Center for Astrophysics and Planetary Science. "And then it just got weirder as we went higher up."

The Icefin robot's unprecedented look inside a crevasse, and observations revealing more than a century of geological processes beneath the ice shelf, are detailed in "Crevasse Refreezing and Signatures of Retreat Observed at Kamb Ice Stream Grounding Zone," published March 2 in Nature Geoscience.

The paper reports results from a 2019 field campaign to Kamb Ice Stream supported by Antarctica New Zealand and other New Zealand research agencies, led by Christina Hulbe, professor at the University of Otago, and colleagues. Through support from NASA's Astrobiology Program, a research team led by Britney Schmidt, associate professor of astronomy and earth and atmospheric sciences at Cornell University, was able to join the expedition and deploy Icefin. Schmidt's Planetary Habitability and Technology Lab has been developing Icefin for nearly a decade, beginning at the Georgia Institute of Technology.

Combined with recently published investigations of the fast-changing Thwaites Glacier -- explored the same season by a second Icefin vehicle -- the research is expected to improve models of sea-level rise by providing the first high-resolution views of ice, ocean and sea floor interactions at contrasting glacier systems on the West Antarctic Ice Sheet.

Thwaites, which is exposed to warm ocean currents, is one of the continent's most unstable glaciers. Kamb Ice Stream, where the ocean is very cold, has been stagnant since the late 1800s. Kamb currently offsets some of the ice loss from western Antarctica, but if it reactivates could increase the region's contribution to sea-level rise by 12%.

"Antarctica is a complex system and it's important to understand both ends of the spectrum -- systems already undergoing rapid change as well as those quieter systems where future change poses a risk," Schmidt said. "Observing Kamb and Thwaites together helps us learn more."

NASA funded Icefin's development and the Kamb exploration to extend ocean exploration beyond Earth. Marine ice like that found in the crevasse may be an analog for conditions on Jupiter's icy moon Europa, the target of NASA's Europa Clipper orbital mission slated for launch in 2024. Later lander missions might one day search directly for microbial life in the ice.

Icefin carries a full complement of oceanographic instruments on a modular frame more than 12 feet long and less than 10 inches in diameter. It was lowered on a tether through a borehole the New Zealand team drilled through the ice shelf with hot water.

During three dives spanning more than three miles near the grounding zone where Kamb transitions to the floating Ross shelf, Icefin mapped five crevasses -- ascending one -- and the sea floor, while recording water conditions including temperature, pressure and salinity.

The team observed diverse ice features that provide valuable information about water mixing and melt rates. They included golf ball-like dimples, ripples, vertical runnels and the "weirder" formations near the top of the crevasse: globs of ice and finger-like protrusions resembling brinicles.

Ice pumping observed in the crevasse likely contributes to the relative stability of the Ross Ice Shelf -- the world's largest by area, the size of France -- compared to Thwaites Glacier, the researchers said.

"It's a way these big ice shelves can protect and heal themselves," said Peter Washam, a polar oceanographer on the Icefin science team and the paper's second author. "A lot of the melting that happens deep near the grounding line, that water then refreezes and accretes onto the bottom of the ice as marine ice."

On the sea floor, Icefin mapped parallel sets of ridges that the researchers believe are impressions left behind by ice shelf crevasses -- and a record of 150 years of activity since the Kamb stream stagnated. As its grounding line retreated, the ice shelf thinned, causing the crevasses to lift away. The ice's slow movement over time shifted the crevasses seaward of the ridges.

"We can look at those sea floor features and directly connect them to what we saw on the ice base," said Lawrence, the paper's lead author, now a program manager and planetary scientist at Honeybee Robotics. "We can, in a way, rewind the process."

Read more at Science Daily

Flying snakes help scientists design new robots

Robots have been designed to move in ways that mimic animal movements, such as walking and swimming. Scientists are now considering how to design robots that mimic the gliding motion exhibited by flying snakes.

In Physics of Fluids, by AIP Publishing, researchers from the University of Virginia and Virginia Tech explored the lift production mechanism of flying snakes, which undulate side-to-side as they move from the tops of trees to the ground to escape predators or to move around quickly and efficiently. The undulation allows snakes to glide for long distances, as much as 25 meters from a 15-meter tower.

To understand how the undulations provide lift, the investigators developed a computational model derived from data obtained through high-speed video of flying snakes. A key component of this model is the cross-sectional shape of the snake's body, which resembles an elongated frisbee or flying disc.

The cross-sectional shape is essential for understanding how the snake can glide so far. In a frisbee, the spinning disc creates increased air pressure below the disc and suction on its top, lifting the disc into the air. To help create the same type of pressure differential across its body, the snake undulates side to side, producing a low-pressure region above its back and a high-pressure region beneath its belly. This lifts the snake and allows it to glide through the air.

"The snake's horizontal undulation creates a series of major vortex structures, including leading edge vortices, LEV, and trailing edge vortices, TEV," said author Haibo Dong of the University of Virginia. "The formation and development of the LEV on the dorsal, or back, surface of the snake body plays an important role in producing lift."

The LEVs form near the head and move back along the body. The investigators found that the LEVs hold for longer intervals at the curves in the snake's body before being shed. These curves form during the undulation and are key to understanding the lift mechanism.

The group considered several features, such as the angle of attack that the snake forms with the oncoming airflow and the frequency of its undulations, to determine which were important in producing glide. In their natural setting, flying snakes typically undulate at a frequency between 1-2 times per second. Surprisingly, the researchers found that more rapid undulation decreases aerodynamic performance.

"The general trend we see is that a frequency increase leads to an instability in the vortex structure, causing some vortex tubes to spin. The spinning vortex tubes tend to detach from the surface, leading to a decrease in lift," said Dong.

Read more at Science Daily

A 'nano-robot' built entirely from DNA to explore cell processes

Constructing a tiny robot from DNA and using it to study cell processes invisible to the naked eye... You would be forgiven for thinking it is science fiction, but it is in fact the subject of serious research by scientists from Inserm, CNRS and Université de Montpellier at the Structural Biology Center in Montpellier[1]. This highly innovative "nano-robot" should enable closer study of the mechanical forces applied at microscopic levels, which are crucial for many biological and pathological processes. It is described in a new study published in Nature Communications.

Our cells are subject to mechanical forces exerted on a microscopic scale, triggering biological signals essential to many cell processes involved in the normal functioning of our body or in the development of diseases.

For example, the feeling of touch is partly conditional on the application of mechanical forces on specific cell receptors (the discovery of which was this year rewarded by the Nobel Prize in Physiology or Medicine). In addition to touch, these receptors that are sensitive to mechanical forces (known as mechanoreceptors) enable the regulation of other key biological processes such as blood vessel constriction, pain perception, breathing or even the detection of sound waves in the ear, etc.

The dysfunction of this cellular mechanosensitivity is involved in many diseases -- for example, cancer: cancer cells migrate within the body by sounding and constantly adapting to the mechanical properties of their microenvironment. Such adaptation is only possible because specific forces are detected by mechanoreceptors that transmit the information to the cell cytoskeleton.

At present, our knowledge of these molecular mechanisms involved in cell mechanosensitivity is still very limited. Several technologies are already available to apply controlled forces and study these mechanisms, but they have a number of limitations. In particular, they are very costly and do not allow us to study several cell receptors at a time, which makes their use very time-consuming if we want to collect a lot of data.

DNA origami structures

In order to propose an alternative, the research team led by Inserm researcher Gaëtan Bellot at the Structural Biology Center (Inserm/CNRS/Université de Montpellier) decided to use the DNA origami method. This enables the self-assembly of 3D nanostructures in a pre-defined form using the DNA molecule as construction material. Over the last ten years, the technique has allowed major advances in the field of nanotechnology.

This enabled the researchers to design a "nano-robot" composed of three DNA origami structures. Of nanometric size, it is therefore compatible with the size of a human cell. It makes it possible for the first time to apply and control a force with a resolution of 1 piconewton, namely one trillionth of a Newton -- with 1 Newton corresponding to the force of a finger clicking on a pen. This is the first time that a human-made, self-assembled DNA-based object can apply force with this accuracy.

The team began by coupling the robot with a molecule that recognizes a mechanoreceptor. This made it possible to direct the robot to some of our cells and specifically apply forces to targeted mechanoreceptors localized on the surface of the cells in order to activate them.

Such a tool is very valuable for basic research, as it could be used to better understand the molecular mechanisms involved in cell mechanosensitivity and discover new cell receptors sensitive to mechanical forces. Thanks to the robot, the scientists will also be able to study more precisely at what moment, when applying force, key signaling pathways for many biological and pathological processes are activated at cell level.

"The design of a robot enabling the in vitro and in vivo application of piconewton forces meets a growing demand in the scientific community and represents a major technological advance. However, the biocompatibility of the robot can be considered both an advantage for in vivo applications but may also represent a weakness with sensitivity to enzymes that can degrade DNA. So our next step will be to study how we can modify the surface of the robot so that it is less sensitive to the action of enzymes. We will also try to find other modes of activation of our robot using, for example, a magnetic field," emphasizes Bellot.

Read more at Science Daily

Robotic lightning bugs take flight

Fireflies that light up dusky backyards on warm summer evenings use their luminescence for communication -- to attract a mate, ward off predators, or lure prey.

These glimmering bugs also sparked the inspiration of scientists at MIT. Taking a cue from nature, they built electroluminescent soft artificial muscles for flying, insect-scale robots. The tiny artificial muscles that control the robots' wings emit colored light during flight.

This electroluminescence could enable the robots to communicate with each other. If sent on a search-and-rescue mission into a collapsed building, for instance, a robot that finds survivors could use lights to signal others and call for help.

The ability to emit light also brings these microscale robots, which weigh barely more than a paper clip, one step closer to flying on their own outside the lab. These robots are so lightweight that they can't carry sensors, so researchers must track them using bulky infrared cameras that don't work well outdoors. Now, they've shown that they can track the robots precisely using the light they emit and just three smartphone cameras.

"If you think of large-scale robots, they can communicate using a lot of different tools -- Bluetooth, wireless, all those sorts of things. But for a tiny, power-constrained robot, we are forced to think about new modes of communication. This is a major step toward flying these robots in outdoor environments where we don't have a well-tuned, state-of-the-art motion tracking system," says Kevin Chen, who is the D. Reid Weedon, Jr. Assistant Professor in the Department of Electrical Engineering and Computer Science (EECS), the head of the Soft and Micro Robotics Laboratory in the Research Laboratory of Electronics (RLE), and the senior author of the paper.

He and his collaborators accomplished this by embedding miniscule electroluminescent particles into the artificial muscles. The process adds just 2.5 percent more weight without impacting the flight performance of the robot.

Joining Chen on the paper are EECS graduate students Suhan Kim, the lead author, and Yi-Hsuan Hsiao; Yu Fan Chen SM '14, PhD '17; and Jie Mao, an associate professor at Ningxia University. The research was published this month in IEEE Robotics and Automation Letters.

A light-up actuator

These researchers previously demonstrated a new fabrication technique to build soft actuators, or artificial muscles, that flap the wings of the robot. These durable actuators are made by alternating ultrathin layers of elastomer and carbon nanotube electrode in a stack and then rolling it into a squishy cylinder. When a voltage is applied to that cylinder, the electrodes squeeze the elastomer, and the mechanical strain flaps the wing.

To fabricate a glowing actuator, the team incorporated electroluminescent zinc sulphate particles into the elastomer but had to overcome several challenges along the way.

First, the researchers had to create an electrode that would not block light. They built it using highly transparent carbon nanotubes, which are only a few nanometers thick and enable light to pass through.

However, the zinc particles only light up in the presence of a very strong and high-frequency electric field. This electric field excites the electrons in the zinc particles, which then emit subatomic particles of light known as photons. The researchers use high voltage to create a strong electric field in the soft actuator, and then drive the robot at a high frequency, which enables the particles to light up brightly.

"Traditionally, electroluminescent materials are very energetically costly, but in a sense, we get that electroluminescence for free because we just use the electric field at the frequency we need for flying. We don't need new actuation, new wires, or anything. It only takes about 3 percent more energy to shine out light," Kevin Chen says.

As they prototyped the actuator, they found that adding zinc particles reduced its quality, causing it to break down more easily. To get around this, Kim mixed zinc particles into the top elastomer layer only. He made that layer a few micrometers thicker to accommodate for any reduction in output power.

While this made the actuator 2.5 percent heavier, it emitted light without impacting flight performance.

"We put a lot of care into maintaining the quality of the elastomer layers between the electrodes. Adding these particles was almost like adding dust to our elastomer layer. It took many different approaches and a lot of testing, but we came up with a way to ensure the quality of the actuator," Kim says.

Adjusting the chemical combination of the zinc particles changes the light color. The researchers made green, orange, and blue particles for the actuators they built; each actuator shines one solid color.

They also tweaked the fabrication process so the actuators could emit multicolored and patterned light. The researchers placed a tiny mask over the top layer, added zinc particles, then cured the actuator. They repeated this process three times with different masks and colored particles to create a light pattern that spelled M-I-T.

Following the fireflies

Once they had finetuned the fabrication process, they tested the mechanical properties of the actuators and used a luminescence meter to measure the intensity of the light.

From there, they ran flight tests using a specially designed motion-tracking system. Each electroluminescent actuator served as an active marker that could be tracked using iPhone cameras. The cameras detect each light color, and a computer program they developed tracks the position and attitude of the robots to within 2 millimeters of state-of-the-art infrared motion capture systems.

"We are very proud of how good the tracking result is, compared to the state-of-the-art. We were using cheap hardware, compared to the tens of thousands of dollars these large motion-tracking systems cost, and the tracking results were very close," Kevin Chen says.

Read more at Science Daily

Scientists craft living human skin for robots

From action heroes to villainous assassins, biohybrid robots made of both living and artificial materials have been at the center of many sci-fi fantasies, inspiring today's robotic innovations. It's still a long way until human-like robots walk among us in our daily lives, but scientists from Japan are bringing us one step closer by crafting living human skin on robots. The method developed, presented June 9 in the journal Matter, not only gave a robotic finger skin-like texture, but also water-repellent and self-healing functions.

"The finger looks slightly 'sweaty' straight out of the culture medium," says first author Shoji Takeuchi, a professor at the University of Tokyo, Japan. "Since the finger is driven by an electric motor, it is also interesting to hear the clicking sounds of the motor in harmony with a finger that looks just like a real one."

Looking "real" like a human is one of the top priorities for humanoid robots that are often tasked to interact with humans in healthcare and service industries. A human-like appearance can improve communication efficiency and evoke likability. While current silicone skin made for robots can mimic human appearance, it falls short when it comes to delicate textures like wrinkles and lacks skin-specific functions. Attempts at fabricating living skin sheets to cover robots have also had limited success, since it's challenging to conform them to dynamic objects with uneven surfaces.

"With that method, you have to have the hands of a skilled artisan who can cut and tailor the skin sheets," says Takeuchi. "To efficiently cover surfaces with skin cells, we established a tissue molding method to directly mold skin tissue around the robot, which resulted in a seamless skin coverage on a robotic finger."

To craft the skin, the team first submerged the robotic finger in a cylinder filled with a solution of collagen and human dermal fibroblasts, the two main components that make up the skin's connective tissues. Takeuchi says the study's success lies within the natural shrinking tendency of this collagen and fibroblast mixture, which shrank and tightly conformed to the finger. Like paint primers, this layer provided a uniform foundation for the next coat of cells -- human epidermal keratinocytes -- to stick to. These cells make up 90% of the outermost layer of skin, giving the robot a skin-like texture and moisture-retaining barrier properties.

The crafted skin had enough strength and elasticity to bear the dynamic movements as the robotic finger curled and stretched. The outermost layer was thick enough to be lifted with tweezers and repelled water, which provides various advantages in performing specific tasks like handling electrostatically charged tiny polystyrene foam, a material often used in packaging. When wounded, the crafted skin could even self-heal like humans' with the help of a collagen bandage, which gradually morphed into the skin and withstood repeated joint movements.

"We are surprised by how well the skin tissue conforms to the robot's surface," says Takeuchi. "But this work is just the first step toward creating robots covered with living skin." The developed skin is much weaker than natural skin and can't survive long without constant nutrient supply and waste removal. Next, Takeuchi and his team plan to address those issues and incorporate more sophisticated functional structures within the skin, such as sensory neurons, hair follicles, nails, and sweat glands.

Read more at Science Daily

Scientists develop insect-sized flying robots with flapping wings

A new drive system for flapping wing autonomous robots has been developed by a University of Bristol team, using a new method of electromechanical zipping that does away with the need for conventional motors and gears.

This new advance, published today in the journal Science Robotics, could pave the way for smaller, lighter and more effective micro flying robots for environmental monitoring, search and rescue, and deployment in hazardous environments.

Until now, typical micro flying robots have used motors, gears and other complex transmission systems to achieve the up-and-down motion of the wings. This has added complexity, weight and undesired dynamic effects.

Taking inspiration from bees and other flying insects, researchers from Bristol's Faculty of Engineering, led by Professor of Robotics Jonathan Rossiter, have successfully demonstrated a direct-drive artificial muscle system, called the Liquid-amplified Zipping Actuator (LAZA), that achieves wing motion using no rotating parts or gears.

The LAZA system greatly simplifies the flapping mechanism, enabling future miniaturization of flapping robots down to the size of insects.

In the paper, the team show how a pair of LAZA-powered flapping wings can provide more power compared with insect muscle of the same weight, enough to fly a robot across a room at 18 body lengths per second.

They also demonstrated how the LAZA can deliver consistent flapping over more than one million cycles, important for making flapping robots that can undertake long-haul flights.

The team expect the LAZA to be adopted as a fundamental building block for a range of autonomous insect-like flying robots.

Dr Tim Helps, lead author and developer of the LAZA system said "With the LAZA, we apply electrostatic forces directly on the wing, rather than through a complex, inefficient transmission system. This leads to better performance, simpler design, and will unlock a new class of low-cost, lightweight flapping micro-air vehicles for future applications, like autonomous inspection of off-shore wind turbines."

Read more at Science Daily

Unease beyond the uncanny valley: How people react to the same faces

Increasingly, movies featuring humanoid robots, like Terminator or Ex Machina, are showing the titular "robot" akin to humans not only in intelligence but also appearance. What if Terminator-esque robots became the norm, making it difficult for us to tell them apart from actual human beings?

This is the premise of a new study published in PLOS ONE, which evaluated how human beings respond to images of people with the same face. It is not too far-fetched to imagine a future where human-like androids are mass-produced and are indistinguishable from flesh-and-blood human beings. Robotics and artificial intelligence are advancing at an unprecedented rate, with very closely human-like robots and CG characters, such as Geminoid, Saya, and Sophia already having been produced. Developers are optimistic they will one day create robots that surpass the uncanny valley -- a well-known phenomenon where humanoids elicit unpleasant and negative emotions in viewers when their appearance becomes similar to that of humans.

In such a future, how would we react?

A team of researchers from Kyushu University, Ritsumeikan University, and Kansai University, collaboratively conducted a series of six experiments involving different batches of hundreds of people to try and find that answer.

The first experiment involved rating the subjective eeriness, emotional valence, and realism of a photoshopped photograph of six human subjects with the exact same face (clone image), six people with different faces (non-clone image), and one person (single image). The second experiment comprised rating another set of clone images and non-clone images, while the third experiment consisted of rating clone and non-clone images of dogs. The fourth experiment had two parts: rating clone images of two sets of twins and then rating clone faces of twins, triplets, quadruplets, and quintuplets. The fifth experiment involved clone images of Japanese animation and cartoon characters. And the sixth and final experiment involved evaluating the subjective eeriness and realism of a different set of clone and non-clone images while also answering the Disgust Scale Revised to analyze disgust sensitivity.

The results were striking. Participants from the first study rated individuals with clone faces as eerier and more improbable than those with different faces and a single person's face.

The researchers termed this negative emotional response as the clone devaluation effect.

"The clone devaluation effect was stronger when the number of clone faces increased from two to four," says lead author Dr. Fumiya Yonemitsu from Graduate School of Human-Environment Studies at Kyushu University, who is also a Research Fellow of Japan Society for the Promotion of Science. "This effect did not occur when each clone face was indistinguishable, like animal faces in experiment three involving dogs."

According to him, "We also noticed that the duplication of identity, that is the personality and mind unique to a person, rather than their facial features, has an important role in this effect. Clone faces with the duplication of identity were eerier, as the fourth experiment showed. The clone devaluation effect became weaker when clone faces existed in the lower reality of the context, such as in the fifth experiment. Furthermore, the eeriness of clone faces stemming from improbability could be positively predicted by disgust, in particular animal-reminder disgust, as noticed in the sixth experiment. Taken together, these results suggest that clone faces induce eeriness and that the clone devaluation effect is related to realism and disgust reaction."

These results show that human faces provide important information for identifying individuals because human beings have a one-to-one correspondence between face and identity. Clone faces violate this principle, which may make humans misjudge the identity of people with clone faces as being the same.

So, what does this mean for a future in which humanoids are inevitable? According to the researchers, we need to think critically about introducing new technology in robotics or human cloning because of the potential for unpleasant psychological reactions other than the uncanny valley phenomenon.

Read more at Science Daily

New law of physics helps humans and robots grasp the friction of touch

Although robotic devices are used in everything from assembly lines to medicine, engineers have a hard time accounting for the friction that occurs when those robots grip objects -- particularly in wet environments. Researchers have now discovered a new law of physics that accounts for this type of friction, which should advance a wide range of robotic technologies.

"Our work here opens the door to creating more reliable and functional haptic and robotic devices in applications such as telesurgery and manufacturing," says Lilian Hsiao, an assistant professor of chemical and biomolecular engineering at North Carolina State University and corresponding author of a paper on the work.

At issue is something called elastohydrodynamic lubrication (EHL) friction, which is the friction that occurs when two solid surfaces come into contact with a thin layer of fluid between them. This would include the friction that occurs when you rub your fingertips together, with the fluid being the thin layer of naturally occurring oil on your skin. But it could also apply to a robotic claw lifting an object that has been coated with oil, or to a surgical device that is being used inside the human body.

One reason friction is important is because it helps us hold things without dropping them.

"Understanding friction is intuitive for humans -- even when we're handling soapy dishes," Hsiao says. "But it is extremely difficult to account for EHL friction when developing materials that controls grasping capabilities in robots."

To develop materials that help control EHL friction, engineers would need a framework that can be applied uniformly to a wide variety of patterns, materials and dynamic operating conditions. And that is exactly what the researchers have discovered.

"This law can be used to account for EHL friction, and can be applied to many different soft systems -- as long as the surfaces of the objects are patterned," Hsiao says.

In this context, surface patterns could be anything from the slightly raised surfaces on the tips of our fingers to grooves in the surface of a robotic tool.

The new physical principle, developed jointly by Hsiao and her graduate student Yunhu Peng, makes use of four equations to account for all of the physical forces at play in understanding EHL friction. In the paper, the research team demonstrated the law in three systems: human fingers; a bio-inspired robotic fingertip; and a tool called a tribo-rheometer, which is used to measure frictional forces. Peng is first author of the paper.

Read more at Science Daily

To climb like a gecko, robots need toes

Robots with toes? Experiments suggest that climbing robots could benefit from having flexible, hairy toes, like those of geckos, that can adjust quickly to accommodate shifting weight and slippery surfaces.

Biologists from the University of California, Berkeley, and Nanjing University of Aeronautics and Astronautics observed geckos running horizontally along walls to learn how they use their five toes to compensate for different types of surfaces without slowing down.

"The research helped answer a fundamental question: Why have many toes?" said Robert Full, UC Berkeley professor of integrative biology.

As his previous research showed, geckos' toes can stick to the smoothest surfaces through the use of intermolecular forces, and uncurl and peel in milliseconds. Their toes have up to 15,000 hairs per foot, and each hair has "an awful case of split ends, with as many as a thousand nano-sized tips that allow close surface contact," he said.

These discoveries have spawned research on new types of adhesives that use intermolecular forces, or van der Waals forces, to stick almost anywhere, even underwater.

One puzzle, he said, is that gecko toes only stick in one direction. They grab when pulled in one direction, but release when peeled in the opposite direction. Yet, geckos move agilely in any orientation.

To determine how geckos have learned to deal with shifting forces as they move on different surfaces, Yi Song, a UC Berkeley visiting student from Nanjing, China, ran geckos sideways along a vertical wall while making high-speed video recordings to show the orientation of their toes. The sideways movement allowed him to distinguish downward gravity from forward running forces to best test the idea of toe compensation.

Using a technique called frustrated total internal reflection, Song, also measured the area of contact of each toe. The technique made the toes light up when they touched a surface.

To the researcher's surprise, geckos ran sideways just as fast as they climbed upward, easily and quickly realigning their toes against gravity. The toes of the front and hind top feet during sideways wall-running shifted upward and acted just like toes of the front feet during climbing.

To further explore the value of adjustable toes, researchers added slippery patches and strips, as well as irregular surfaces. To deal with these hazards, geckos took advantage of having multiple, soft toes. The redundancy allowed toes that still had contact with the surface to reorient and distribute the load, while the softness let them conform to rough surfaces.

"Toes allowed agile locomotion by distributing control among multiple, compliant, redundant structures that mitigate the risks of moving on challenging terrain," Full said. "Distributed control shows how biological adhesion can be deployed more effectively and offers design ideas for new robot feet, novel grippers and unique manipulators."

From Science Daily

Inspired by cheetahs, researchers build fastest soft robots yet

Inspired by the biomechanics of cheetahs, researchers have developed a new type of soft robot that is capable of moving more quickly on solid surfaces or in the water than previous generations of soft robots. The new soft robotics are also capable of grabbing objects delicately -- or with sufficient strength to lift heavy objects.

"Cheetahs are the fastest creatures on land, and they derive their speed and power from the flexing of their spines," says Jie Yin, an assistant professor of mechanical and aerospace engineering at North Carolina State University and corresponding author of a paper on the new soft robots.

"We were inspired by the cheetah to create a type of soft robot that has a spring-powered, 'bistable' spine, meaning that the robot has two stable states," Yin says. "We can switch between these stable states rapidly by pumping air into channels that line the soft, silicone robot. Switching between the two states releases a significant amount of energy, allowing the robot to quickly exert force against the ground. This enables the robot to gallop across the surface, meaning that its feet leave the ground.

"Previous soft robots were crawlers, remaining in contact with the ground at all times. This limits their speed."

The fastest soft robots until now could move at speeds of up to 0.8 body lengths per second on flat, solid surfaces. The new class of soft robots, which are called "Leveraging Elastic instabilities for Amplified Performance" (LEAP), are able to reach speeds of up to 2.7 body lengths per second -- more than three times faster -- at a low actuation frequency of about 3Hz. These new robots are also capable of running up steep inclines, which can be challenging or impossible for soft robots that exert less force against the ground.

These "galloping" LEAP robots are approximately 7 centimeters long and weigh about 45 grams.

The researchers also demonstrated that the LEAP design could improve swimming speeds for soft robots. Attaching a fin, rather than feet, a LEAP robot was able to swim at a speed of 0.78 body lengths per second, as compared to 0.7 body lengths per second for the previous fastest swimming soft robot.

"We also demonstrated the use of several soft robots working together, like pincers, to grab objects," Yin says. "By tuning the force exerted by the robots, we were able to lift objects as delicate as an egg, as well as objects weighing 10 kilograms or more."

The researchers note that this work serves as a proof of concept, and are optimistic that they can modify the design to make LEAP robots that are even faster and more powerful.

"Potential applications include search and rescue technologies, where speed is essential, and industrial manufacturing robotics," Yin says. "For example, imagine production line robotics that are faster, but still capable of handling fragile objects.

Read more at Science Daily

Microrobots clean up radioactive waste

According to some experts, nuclear power holds great promise for meeting the world's growing energy demands without generating greenhouse gases. But scientists need to find a way to remove radioactive isotopes, both from wastewater generated by nuclear power plants and from the environment in case of a spill. Now, researchers reporting in ACS Nano have developed tiny, self-propelled robots that remove radioactive uranium from simulated wastewater.

The accidental release of radioactive waste, such as what occurred in the Chernobyl and Fukushima nuclear plant disasters, poses large threats to the environment, humans and wildlife. Scientists have developed materials to capture, separate, remove and recover radioactive uranium from water, but the materials have limitations. One of the most promising recent approaches is the use of metal-organic frameworks (MOFs) -- compounds that can trap specific substances, including radioactive uranium, within their porous structures. Martin Pumera and colleagues wanted to add a micromotor to a rod-shaped MOF called ZIF-8 to see if it could quickly clean up radioactive waste.

To make their self-propelled microrobots, the researchers designed ZIF-8 rods with diameters about 1/15 that of a human hair. The researchers added iron atoms and iron oxide nanoparticles to stabilize the structures and make them magnetic, respectively. Catalytic platinum nanoparticles placed at one end of each rod converted hydrogen peroxide "fuel" in the water into oxygen bubbles, which propelled the microrobots at a speed of about 60 times their own length per second. In simulated radioactive wastewater, the microrobots removed 96% of the uranium in an hour. The team collected the uranium-loaded rods with a magnet and stripped off the uranium, allowing the tiny robots to be recycled. The self-propelled microrobots could someday help in the management and remediation of radioactive waste, the researchers say.

From Science Daily

Hummingbird robot uses AI to soon go where drones can't

Hummingbird.

What can fly like a bird and hover like an insect?

Your friendly neighborhood hummingbirds. If drones had this combo, they would be able to maneuver better through collapsed buildings and other cluttered spaces to find trapped victims.

Purdue University researchers have engineered flying robots that behave like hummingbirds, trained by machine learning algorithms based on various techniques the bird uses naturally every day.

This means that after learning from a simulation, the robot "knows" how to move around on its own like a hummingbird would, such as discerning when to perform an escape maneuver.

Artificial intelligence, combined with flexible flapping wings, also allows the robot to teach itself new tricks. Even though the robot can't see yet, for example, it senses by touching surfaces. Each touch alters an electrical current, which the researchers realized they could track.

"The robot can essentially create a map without seeing its surroundings. This could be helpful in a situation when the robot might be searching for victims in a dark place -- and it means one less sensor to add when we do give the robot the ability to see," said Xinyan Deng, an associate professor of mechanical engineering at Purdue.

The researchers will present their work on May 20 at the 2019 IEEE International Conference on Robotics and Automation in Montreal. A YouTube video is available at https://youtu.be/jhl892dHqfA.

Drones can't be made infinitely smaller, due to the way conventional aerodynamics work. They wouldn't be able to generate enough lift to support their weight.

But hummingbirds don't use conventional aerodynamics -- and their wings are resilient. "The physics is simply different; the aerodynamics is inherently unsteady, with high angles of attack and high lift. This makes it possible for smaller, flying animals to exist, and also possible for us to scale down flapping wing robots," Deng said.

Researchers have been trying for years to decode hummingbird flight so that robots can fly where larger aircraft can't. In 2011, the company AeroVironment, commissioned by DARPA, an agency within the U.S. Department of Defense, built a robotic hummingbird that was heavier than a real one but not as fast, with helicopter-like flight controls and limited maneuverability. It required a human to be behind a remote control at all times.

Deng's group and her collaborators studied hummingbirds themselves for multiple summers in Montana. They documented key hummingbird maneuvers, such as making a rapid 180-degree turn, and translated them to computer algorithms that the robot could learn from when hooked up to a simulation.

Further study on the physics of insects and hummingbirds allowed Purdue researchers to build robots smaller than hummingbirds -- and even as small as insects -- without compromising the way they fly. The smaller the size, the greater the wing flapping frequency, and the more efficiently they fly, Deng says.

The robots have 3D-printed bodies, wings made of carbon fiber and laser-cut membranes. The researchers have built one hummingbird robot weighing 12 grams -- the weight of the average adult Magnificent Hummingbird -- and another insect-sized robot weighing 1 gram. The hummingbird robot can lift more than its own weight, up to 27 grams.

Designing their robots with higher lift gives the researchers more wiggle room to eventually add a battery and sensing technology, such as a camera or GPS. Currently, the robot needs to be tethered to an energy source while it flies -- but that won't be for much longer, the researchers say.

The robots could fly silently just as a real hummingbird does, making them more ideal for covert operations. And they stay steady through turbulence, which the researchers demonstrated by testing the dynamically scaled wings in an oil tank.

The robot requires only two motors and can control each wing independently of the other, which is how flying animals perform highly agile maneuvers in nature.

"An actual hummingbird has multiple groups of muscles to do power and steering strokes, but a robot should be as light as possible, so that you have maximum performance on minimal weight," Deng said.

Robotic hummingbirds wouldn't only help with search-and-rescue missions, but also allow biologists to more reliably study hummingbirds in their natural environment through the senses of a realistic robot.

"We learned from biology to build the robot, and now biological discoveries can happen with extra help from robots," Deng said.

Simulations of the technology are available open-source at https://github.com/purdue-biorobotics/flappy.

Early stages of the work, including the Montana hummingbird experiments in collaboration with Bret Tobalske's group at the University of Montana, were financially supported by the National Science Foundation.

Read more at Science Daily

First-in-world robot-assisted spinal surgery

Noah Pernikoff is back to his life in New York City after becoming the first patient in the world to undergo a complex three-part, robotic-assisted surgery. The robotic arms made it possible for the multidisciplinary team at Penn to successfully remove a rare tumor from Noah's neck, where the skull meets the spine. The ground breaking surgery was completed by a multi-surgeon team, led by Dr. Neil Malhotra, at the Hospital of the University of Pennsylvania in August 2017 over a span of two days and more than 20 hours.

Chordoma is a rare type of cancer that occurs in the bones of the skull base and spine. A chordoma tumor usually grows slowly and is often asymptomatic for years. In the case of 27-year-old Noah Pernikoff, a 2016 car accident revealed his surprising diagnosis.

Among his injuries from the accident, Noah -- who was working in New York City for a commercial contracting firm -- tore his rotator cuff and had several herniated discs. More important, however, was his post-accident nagging neck pain, which lead to an x-ray that revealed a concerning lesion in his neck, on his cervical spine. The lesion was clearly unrelated to the accident, and far more concerning than the minor injuries he had endured. After making a recovery from the accident, Pernikoff's father, a physician, encouraged his son to see a neurosurgeon for evaluation of the injury. The neurosurgeon Pernikoff saw ultimately recommended a biopsy of the spot, which resulted in a diagnosis of chordoma.

"I'm lucky because they caught mine early. For a lot of people, if it's not found and treated early, it's lethal," Pernikoff said. "The doctor said if I hadn't discovered it through the car accident it probably would have kept growing until it came to a point on my spinal cord where it caused paralysis or death. I feel very lucky in that regard." Unfortunately, the neurosurgeon explained to Pernikoff, while surgery is known to be the best option for chordoma, Pernikoff's would be too difficult to resect and he would have to try the second option, radiation with proton therapy.

Chordoma is extremely rare; it affects only one in 1 million people each year. Pernikoff's specific type of chordoma, located on his C2 vertebrae, is even rarer, making treatment a challenge. Pernikoff's neurosurgeon immediately referred him to Penn, where a multidisciplinary team reviewed his case, and his options, and began crafting a treatment plan -- not through radiation, but a complex surgery that had never been performed before.

Neil Malhotra, MD, an assistant professor of Neurosurgery and Orthopaedic Surgery and the vice chair of operations in the department of Neurosurgery, gathered a multidisciplinary team of physicians to treat Pernikoff's chordoma. Malhotra planned to remove the tumor through a rare and complex spinal surgery approach. Bert W. O'Malley Jr., MD, a professor and chairman of the department of Otorhinolaryngology: Head and Neck Surgery, planned to aid Malhotra's approach and improve Pernikoff's recovery by using a trans-oral robotic (TORS) approach for the second part of the surgery. TORS is the world's first group of minimally invasive robotic surgery techniques, invented at Penn, to remove benign and malignant tumors of the mouth and throat.

"This would be a first ever use of a robot in this manner -- a rare approach to an already rare and complex case," Malhotra said. "Our team needed to reconstruct the removed area of Pernikoff's spine using bone and rods, and that was only the beginning."

The stakes were high. Because of the placement of the tumor, Malhotra said removal could compromise the structural integrity of Pernikoff's spine, causing permanent paralysis. There was also a risk of complications such as bone and tissue breakdown, loss of sense of smell, fine motor skill issues, and complete paralysis. And, he said, "if we couldn't remove the entire tumor, it would likely grow back, perhaps more aggressive than before."

The surgery was performed in three parts. First, the neurosurgeons went through the back of Pernikoff's neck and cut the spine around the tumor to prepare for the second stage, removing the tumor through his mouth. The key to this stage would be to make ultrasonic bone cuts -- removing a piece of bone -- around the tumor without touching it, and without injuring the spinal cord that lay between the neurosurgeon and the tumor/spinal column. With stage one success, O'Malley and a team of three head and neck surgeons used the surgical robot to clear a path so Malhotra could remove the tumor, and part of the spinal column, in its entirety through the mouth. Finally, the team reconstructed Pernikoff's spinal column, which was now missing an important bone in his neck, using some of Pernikoffs' own bone from his hip and rods to finalize stabilization of the newly built portion of his spine.

Read more at Science Daily

Why a robot can't yet outjump a flea

The award for the fastest punch goes to mantis shrimp, which use their hammer-like appendages to smash open snail shells for food.

When it comes to things that are ultrafast and lightweight, robots can't hold a candle to the fastest-jumping insects and other small-but-powerful creatures.

New research could help explain why nature still beats robots, and describes how machines might take the lead.

Take the smashing mantis shrimp, a small crustacean not much bigger than a thumb. Its hammer-like mouthparts can repeatedly deliver 69-mile-per-hour wallops more than 100 times faster than the blink of an eye to break open hard snail shells.

Or the unassuming trap-jaw ant: In a zero-to-60 matchup, even the fastest dragster would have little chance against its snapping mandibles, which reach speeds of more than 140 miles per hour in less than a millisecond to nab their prey.

One of the fastest accelerations known on Earth is the hydra's sting. These soft-bodied aquatic creatures defend themselves with help from capsules along their tentacles that act like pressurized balloons. When triggered, they fire a barrage of microscopic poison spears that briefly accelerate 100 times faster than a bullet.

In a study to appear April 27 in the journal Science, researchers describe a new mathematical model that could help explain how these and other tiny organisms generate their powerful strikes, chomps, jumps and punches. The model could also suggest ways to design small, nature-inspired robots that come closer to their biological counterparts in terms of power or speed.

The secret to these organisms' explosive movements isn't powerful muscles, but rather spring-loaded parts they can cock and release like an archer's bow, said Sheila Patek, associate professor of biology at Duke University.

Tough yet flexible tendons, cuticles and other elastic structures stretch and release like slingshots, powering their jumps and snaps.

A short-legged insect called the froghopper, for example, has a bow-like structure called the pleural arch that acts like a spring. Latch-like protrusions on their legs control its release, allowing them to leap more than 100 times their body length despite their short legs. A person with that much power could jump nearly two football fields.

However, it's not clear how these mechanisms work together to enhance power, said Mark Ilton, a postdoctoral fellow at the University of Massachusetts Amherst.

While traditional mathematical models of performance take into account the inherent physical tradeoffs of muscle -- which can contract forcefully, or quickly, but not both -- they fail to factor in the tradeoffs inherent to springs and latch-like mechanisms as well. In other words, nothing can be faster, stronger, and more powerful at the same time.

"Until now these other components have been mostly black-boxed," Patek said.

The researchers developed a mathematical model of fast motion at small scales that incorporates constraints on springs and latches.

"Part of our goal was to try to develop a model that is equally generalizable to biological or engineered systems," said Manny Azizi, an assistant professor of ecology and evolutionary biology at the University of California, Irvine who studies jumping frogs.

First, they compiled data on the size and top speeds and accelerations for 104 species of elite plant and animal athletes. They compared the data to similar measurements for miniature robots inspired by ultrafast movements such as unfurling chameleon tongues, snapping Venus fly traps and hopping insects.

By incorporating the performance tradeoffs of biological and synthetic springs and latches, the researchers hope to better understand how variables such as spring mass, stiffness, material composition and latch geometry work together with muscles or motors to influence power.

The model allows researchers to input a set of spring, latch and muscle or motor parameters and get back details about an individual's theoretical maximum speed, acceleration, and other aspects of performance at a given weight.

The model has major implications for engineers. It suggests that robots can't yet outjump a flea in part because such quick, repeatable movements require components to be exquisitely fine-tuned to each other.

But the model gives researchers a tool to design small, fast-moving robots with more precisely matched components that work better together to enhance performance, said Sarah Bergbreiter, an associate professor of mechanical engineering at the University of Maryland who makes jumping robots the size of an ant.

"If you have a particular size robot that you want to design, for example, it would allow you to better explore what kind of spring you want, what kind of motor you want, what kind of latch you need to get the best performance at that size scale, and understand the consequences of those design choices," Bergbreiter said.

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