Insect-scale robots can squeeze into places their larger counterparts can’t, like deep into a collapsed building to search for survivors after an earthquake.However, as they move through the rubble, tiny crawling robots might encounter tall obstacles they can’t climb over or slanted surfaces they will slide down. While aerial robots could avoid these hazards, the amount of energy required for flight would severely limit how far the robot can travel into the wreckage before it needs to return to base and recharge.To get the best of both locomotion methods, MIT researchers developed a hopping robot that can leap over tall obstacles and jump across slanted or uneven surfaces, while using far less energy than an aerial robot.The hopping robot, which is smaller than a human thumb and weighs less than a paperclip, has a springy leg that propels it off the ground, and four flapping-wing modules that give it lift and control its orientation.<iframe width="640" height="360" src="https://www.youtube.com/embed/UlxQz8F59Hk?&amp;wmode=opaque&amp;rel=0&amp;enablejsapi=1&amp;origin=https://www.wevolver.com" frameborder="0" class="fr-draggable"> </iframe>The robot can jump about 20 centimeters into the air, or four times its height, at a lateral speed of about 30 centimeters per second, and has no trouble hopping across ice, wet surfaces, and uneven soil, or even onto a hovering drone. All the while, the hopping robot consumes about 60 percent less energy than its flying cousin.Due to its light weight and durability, and the energy efficiency of the hopping process, the robot could carry about 10 times more payload than a similar-sized aerial robot, opening the door to many new applications.“Being able to put batteries, circuits, and sensors on board has become much more feasible with a hopping robot than a flying one. Our hope is that one day this robot could go out of the lab and be useful in real-world scenarios,” says Yi-Hsuan (Nemo) Hsiao, an MIT graduate student and co-lead author of a paper on the hopping robot.Hsiao is joined on the paper by co-lead authors Songnan Bai, a research assistant professor at The University of Hong Kong; and Zhongtao Guan, an incoming MIT graduate student who completed this work as a visiting undergraduate; as well as Suhan Kim and Zhijian Ren of MIT; and senior authors Pakpong Chirarattananon, an associate professor of the City University of Hong Kong; and Kevin Chen, an associate professor in the MIT Department of Electrical Engineering and Computer Science and head of the Soft and Micro Robotics Laboratory within the Research Laboratory of Electronics. The research <a href="https://doi.org/10.1126/sciadv.adu4474" target="_blank">appears today in Science Advances</a>.<h2>Maximizing efficiency</h2>Jumping is common among insects, from fleas that leap onto new hosts to grasshoppers that bound around a meadow. While jumping is less common among insect-scale robots, which usually fly or crawl, hopping affords many advantages for energy efficiency.When a robot hops, it transforms potential energy, which comes from its height off the ground, into kinetic energy as it falls. This kinetic energy transforms back to potential energy when it hits the ground, then back to kinetic as it rises, and so on.To maximize efficiency of this process, the MIT robot is fitted with an elastic leg made from a compression spring, which is akin to the spring on a click-top pen. This spring converts the robot’s downward velocity to upward velocity when it strikes the ground.“If you have an ideal spring, your robot can just hop along without losing any energy. But since our spring is not quite ideal, we use the flapping modules to compensate for the small amount of energy it loses when it makes contact with the ground,” Hsiao explains.As the robot bounces back up into the air, the flapping wings provide lift, while ensuring the robot remains upright and has the correct orientation for its next jump. Its four flapping-wing mechanisms are powered by soft actuators, or artificial muscles, that are durable enough to endure repeated impacts with the ground without being damaged.<img src="https://s3-us-west-1.amazonaws.com/wevolver-project-images/froala%2F1744293625738-MIT-HoppingRobots-02-press.jpg" style="width:100%px" class="fr-fic fr-dib" />The hopping robot, which is smaller than a human thumb and weighs less than a paperclip, has a springy leg that propels it off the ground, and four flapping-wing modules that give it lift and control its orientation. Credit: Courtesy of the researchers“We have been using the same robot for this entire series of experiments, and we never needed to stop and fix it,” Hsiao adds.Key to the robot’s performance is a fast control mechanism that determines how the robot should be oriented for its next jump. Sensing is performed using an external motion-tracking system, and an observer algorithm computes the necessary control information using sensor measurements.As the robot hops, it follows a ballistic trajectory, arcing through the air. At the peak of that trajectory, it estimates its landing position. Then, based on its target landing point, the controller calculates the desired takeoff velocity for the next jump. While airborne, the robot flaps its wings to adjust its orientation so it strikes the ground with the correct angle and axis to move in the proper direction and at the right speed.<h2>Durability and flexibility</h2>The researchers put the hopping robot, and its control mechanism, to the test on a variety of surfaces, including grass, ice, wet glass, and uneven soil — it successfully traversed all surfaces. The robot could even hop on a surface that was dynamically tilting.“The robot doesn’t really care about the angle of the surface it is landing on. As long as it doesn’t slip when it strikes the ground, it will be fine,” Hsiao says.Since the controller can handle multiple terrains, the robot can easily transition from one surface to another without missing a beat.For instance, hopping across grass requires more thrust than hopping across glass, since blades of grass cause a damping effect that reduces its jump height. The controller can pump more energy to the robot’s wings during its aerial phase to compensate.Due to its small size and light weight, the robot has an even smaller moment of inertia, which makes it more agile than a larger robot and better able to withstand collisions.The researchers showcased its agility by demonstrating acrobatic flips. The featherweight robot could also hop onto an airborne drone without damaging either device, which could be useful in collaborative tasks.In addition, while the team demonstrated a hopping robot that carried twice its weight, the maximum payload may be much higher. Adding more weight doesn’t hurt the robot’s efficiency. Rather, the efficiency of the spring is the most significant factor that limits how much the robot can carry.Moving forward, the researchers plan to leverage its ability to carry heavy loads by installing batteries, sensors, and other circuits onto the robot, in the hopes of enabling it to hop autonomously outside the lab.“Multimodal robots (those combining multiple movement strategies) are generally challenging and particularly impressive at such a tiny scale. The versatility of this tiny multimodal robot — flipping, jumping on rough or moving terrain, and even another robot — makes it even more impressive,” says Justin Yim, assistant professor at the University of Illinois at Urbana-Champagne, who was not involved with this work. “Continuous hopping shown in this research enables agile and efficient locomotion in environments with many large obstacles.”This research is funded, in part, by the U.S. National Science Foundation and the MIT MISTI program. Chirarattananon was supported by the Research Grants Council of the Hong Kong Special Administrative Region of China. Hsiao is supported by a MathWorks Fellowship, and Kim is supported by a Zakhartchenko Fellowship.

MIT researchers developed a hopping robot that can leap over tall obstacles and jump across slanted or uneven surfaces, while using far less energy than an aerial robot. Credit: Melanie Gonick, MIT

MIT engineers developed an insect-sized jumping robot that can traverse challenging terrains and carry heavy payloads.

Hopping gives this tiny robot a leg up

Diminutive device can leap 23 times its body length

A springtail-like jumping robot

RAVEN (Robotic Avian-inspired Vehicle for multiple ENvironments) © Alain Herzog CC BY SA

EPFL researchers have built a drone that can walk, hop, and jump into flight with the aid of birdlike legs, greatly expanding the range of potential environments accessible to unmanned aerial vehicles.

Bird-inspired drone can jump for take-off

Scientists from ITMO have come up with a three-step algorithm for the development of manipulators and walking or wearable robots. Compared to the usual methods, the new approach results in lighter, more efficient, affordable, and compact mechanisms. Walking robots that can move without having a full map of their surroundings are just one example of the designs produced by the new method. Another is the jumping robot made by the researchers to demonstrate their new algorithm.<h1 dir="ltr" id="isPasted">Why it’s hard to combine movement and energy efficiency in robots</h1>Industrial robots need to move with high speed and precision. These are achieved with powerful electric drives that are very demanding in terms of the energy they consume. This means that such robots often need to be connected to a power outlet, making them stationary.Mobile robots are a whole other matter, however. They have to be designed in a way that allows them to perform all their tasks with just the energy they can get from a battery. And it can’t be the case of just increasing the battery’s capacity either – here, “more powerful” also means “heavier.” If a robot wastes half the energy gained from a heavier battery just to carry this battery around, it’s not a very efficient robot. That’s why researchers engineer robotic systems in a way that will make use of the mechanism’s inherent dynamics, thus requiring less energy.<h1 dir="ltr">Overcoming the challenge</h1>In robotics, such mechanisms are designed with morphology in mind. This means that most of the dynamics needed for the robot’s movements are provided by its body (the spread of its weight, its elasticity, or mechanical links). The control systems for such robots don’t need to program their every move, instead focusing on supporting its existing dynamics.&nbsp;When designing such robots, engineers must follow a formalized process that takes into account not only control algorithms, but also the design of the robot’s mechanics. According to Ivan Borisov, an engineer at ITMO’s Research Center “Strong AI in Industry,” for a long time robotics specialists concentrated on developing new algorithms while still using the same hardware and principles as in industrial robots.&nbsp;However, the success of Cassie the robot <a href="https://www.researchgate.net/publication/331449776_Walk_this_way_To_be_useful_around_people_robots_need_to_learn_how_to_move_like_we_do" target="_blank">has shown</a> that in order to achieve high speed, robustness, and capacity to navigate unstructured environments, robots need to be designed differently. First and foremost, they need to be adaptive and energy efficient.<iframe width="640" height="360" src="https://www.youtube.com/embed/a_YGPbWJO5g?&amp;wmode=opaque&amp;enablejsapi=1&amp;origin=https://www.wevolver.com" frameborder="0" allowfullscreen="" class="fr-draggable" data-lf-form-tracking-inspected-kn9eq4roawkarlvp="true" data-lf-yt-playback-inspected-kn9eq4roawkarlvp="true" data-lf-vimeo-playback-inspected-kn9eq4roawkarlvp="true"></iframe><h1 dir="ltr" id="isPasted">The method from ITMO</h1>ITMO scientists used the principles of morphological design to suggest their own method of designing mechanisms for manipulator, locomotion, and wearable robots. The method is based on a three-step algorithm.First step: creating an open kinetic chain. Here, the algorithm determines which parts should make up the mechanism and the trajectories they need to follow in order to produce the desired movements.Second step: closing the chain of parts that make up the mechanism (the kinetic chain is closed when each link in the chain has over two connections). Here, the algorithm determines which links in the chain need to be connected to the core mechanism so that a drive can be transported to a different joint. At this point, the program may also decide to remove or add certain connections in order to lower inertia. This helps preserve energy and speed up the robot.&nbsp;Third step: placing electric drives with maximal efficiency. At this stage, physical and virtual elastic elements are also integrated into the mechanism. With these, the robot can adapt to the environment, cushion itself against rough and uneven surfaces, and conserve energy.By targeting performance and maximum functionality at every step, this approach produces more efficient devices.<img src="https://s3-us-west-1.amazonaws.com/wevolver-project-images/froala%2F1718581571013-1323200.jpg" style="width: 100%px;" class="fr-fic fr-dib">Ivan Borisov. Photo by Dmitry Grigoryev / ITMO.NEWS<blockquote id="isPasted">“Using our method, we can develop any leverage mechanism, such as a leg mechanism for a walking robot, a finger mechanism for a grasping device, or parts of an exoskeleton. What’s even more, we can make robots that are able to function in unstructured or unknown environments. For instance, a walking robot that will be able to map out their surroundings even in bad lighting or an anthropomorphic wrist that can grasp objects it can’t see,” explains Ivan Borisov.</blockquote>To demonstrate the algorithm’s capacity, the researchers developed a jumping robot that can move on uneven terrain. The robot moves thanks to self-sustained vibrations of its drive and springs; it can change the speed and direction of its movements. Thanks to the new method used in its design, the robot requires a drive four times less powerful than a similar robot designed with the classical approach.&nbsp;According to Ivan Borisov, the method squeezes the most out of each part of the algorithm, maximizing the drives’ efficiency and using elastic parts to restore some of the used energy.<img src="https://s3-us-west-1.amazonaws.com/wevolver-project-images/froala%2F1718581765992-ezgif-4-4d6d52b5a1.gif" style="width: 100%px;" class="fr-fic fr-dib">Flexible jumping robot. Video by Dmitry Grigoryev / ITMO.NEWS<h1 dir="ltr" id="isPasted">What’s next&nbsp;</h1>The new method will be presented at the prestigious IEEE International Conference on Robotics and Automation (SJR 1.92), where ITMO will be this year’s only Russian participant.Additionally, the researchers are developing software that will use the algorithm to generate designs of walking robots and trajectories of their electric drives. It will also test the suggested solutions in a simulated environment.A similar&nbsp;<a href="https://github.com/aimclub/rostok" target="_blank">program</a> for grasping devices has already been developed at ITMO. This one can design a robot based on the parameters of an object it needs to grasp. For instance, if you need a device for grasping apples, you need to simply indicate the fruit’s characteristics – then, the algorithm will generate the mechanism’s structure with optimal parameters.According to the researchers, as the method involves randomization, it can produce several solutions for the same problem, allowing the human operating it to choose the best one.&nbsp;Both algorithms are meant to assist designers in making mechatronic and robotic systems, including industrial, collaborative, or manipulator robots.

Flexible jumping robot. Photo by Dmitry Grigoryev / ITMO.NEWS

Scientists from ITMO have come up with a three-step algorithm for the development of manipulators and walking or wearable robots. Compared to the usual methods, the new approach results in lighter, more efficient, affordable, and compact mechanisms. 

Scientists Suggest New Method to Make More Adaptive and Autonomous Robots

A new study led by <a href="https://mechse.illinois.edu/" id="isPasted" target="_blank">mechanical science and engineering</a> professor <a href="https://mechse.illinois.edu/people/profile/tawfick" target="_blank">Sameh Tawfick</a> demonstrates a series of click beetle-sized robots small enough to fit into tight spaces, powerful enough to maneuver over obstacles and fast enough to match an insect&rsquo;s rapid escape time.&nbsp;The findings are published in the Proceedings of the National Academy of Sciences.Researchers at the University of Illinois Urbana-Champaign and Princeton University have studied click beetle anatomy, mechanics and evolution over the past decade.&nbsp;<a href="https://news.illinois.edu/view/6367/589930360" target="_blank">A 2020 study</a> found that snap buckling &ndash; the rapid release of elastic energy &ndash; of a coiled muscle within a click beetle&rsquo;s thorax is triggered to allow them to propel themselves in the air many times their body length, as a means of righting themselves if flipped onto their backs.&ldquo;One of the grand challenges of small-scale robotics is finding a design that is small, yet powerful enough to move around obstacles or quickly escape dangerous settings,&rdquo; Tawfick said.In the new study, Tawfick and his team used tiny <a href="https://www.science.org/doi/10.1126/science.aax7304" target="_blank">coiled actuators</a> &ndash; analogous to animal muscles &ndash; that pull on a beam-shaped mechanism, causing it to slowly buckle and store elastic energy until it is spontaneously released and amplified, propelling the robots upward.<iframe src="https://www.youtube.com/embed/3udLRU9_qog?&wmode=opaque&rel=0&enablejsapi=1&origin=https://www.wevolver.com" frameborder="0" allowfullscreen="" class="fr-draggable" data-lf-form-tracking-inspected-kn9eq4roawkarlvp="true" data-lf-yt-playback-inspected-kn9eq4roawkarlvp="true" data-lf-vimeo-playback-inspected-kn9eq4roawkarlvp="true" style="width: 765px; height: 509px;"></iframe>&ldquo;This process, called a dynamic buckling cascade, is simple compared to the anatomy of a click beetle,&rdquo; Tawfick said. &ldquo;However, simple is good in this case because it allows us to work and fabricate parts at this small scale.&rdquo;Guided by biological evolution and mathematical models, the team built and tested four device variations, landing on two configurations that can successfully jump without manual intervention.&ldquo;Moving forward, we do not have a set approach on the exact design of the next generation of these robots, but this study plants a seed in the evolution of this technology &ndash; a process similar to biologic evolution,&rdquo; Tawfick said.The team envisions these robots accessing tight spaces to help perform maintenance on large machines like turbines and jet engines, for example, by taking pictures to identify problems.&ldquo;We also imagine insect-scale robots being useful in modern agriculture,&rdquo; Tawfick said. &ldquo;Scientists and farmers currently use drones and rovers to monitor crops, but sometimes researchers need a sensor to touch a plant or to capture a photograph of a very small-scale feature. Insect-scale robots can do that.&rdquo;Researchers from the University of Birmingham, UK; Oxford University; and the University of Texas at Dallas also participated in this research.The Defense Advanced Research Projects Agency, the Toyota Research Institute North America, the National Science Foundation and The Royal Society supported this study.

Mechanical science and engineering professor Sameh Tawfick led a new study introducing click beetle-sized robots small enough to fit into tight spaces, powerful enough to maneuver over obstacles and fast enough to match an insect’s rapid escape time. Graphic by Michael Vincent

Researchers have made a significant leap forward in developing insect-sized jumping robots capable of performing tasks in the small spaces often found in mechanical, agricultural and search-and-rescue settings.  

Click beetle-inspired robots jump using elastic energy

MIT&rsquo;s new mini cheetah robot is springy and light on its feet, with a range of motion that rivals a champion gymnast. The four-legged powerpack can bend and swing its legs wide, enabling it to walk either right-side up or upside down. The robot can also trot over uneven terrain about twice as fast as an average person&rsquo;s walking speed.Weighing in at just 20 pounds &mdash; lighter than some Thanksgiving turkeys &mdash; the limber quadruped is no pushover: When kicked to the ground, the robot can quickly right itself with a swift, kung-fu-like swing of its elbows.Perhaps most impressive is its ability to perform a 360-degree backflip from a standing position. Researchers claim the mini cheetah is designed to be &ldquo;virtually indestructible,&rdquo; recovering with little damage, even if a backflip ends in a spill.<iframe src="https://www.youtube.com/embed/xNeZWP5Mx9s?&wmode=opaque" frameborder="0" allowfullscreen="" class="fr-draggable" style="width: 789px; height: 444px;"></iframe>MIT&#39;s new mini cheetah robot is the first four-legged robot to do a backflip. At only 20 pounds, the limber quadruped can bend and swing its legs wide, enabling it to walk either right side up or upside down. The robot can also trot over uneven terrain about twice as fast as an average person&#39;s walking speed. Video: Melanie Gonick/MIT In the event that a limb or motor does break, the mini cheetah is designed with modularity in mind: Each of the robot&rsquo;s legs is powered by three identical, low-cost electric motors that the researchers engineered using off-the-shelf parts. Each motor can easily be swapped out for a new one.&ldquo;You could put these parts together, almost like Legos,&rdquo; says lead developer Benjamin Katz, a technical associate in MIT&rsquo;s Department of Mechanical Engineering.The researchers will present the mini cheetah&rsquo;s design at the International Conference on Robotics and Automation, in May. They are currently building more of the four-legged machines, aiming for a set of 10, each of which they hope to loan out to other labs.&ldquo;A big part of why we built this robot is that it makes it so easy to experiment and just try crazy things, because the robot is super robust and doesn&rsquo;t break easily, and if it does break, it&rsquo;s easy and not very expensive to fix,&rdquo; says Katz, who worked on the robot in the lab of Sangbae Kim, associate professor of mechanical engineering.<img src="https://s3-us-west-1.amazonaws.com/wevolver-project-images/froala%2F1586529356052-MIT-Mini-Cheetah-02.jpg">Lead developer Benjamin Katz, left, and co-author Jared Di Carlo, were inspired by a class they took last year, taught by EECS Professor Russ Tedrake, and set about programming the mini cheetah to perform a backflip. Photo: Bryce VickmarkKim says loaning mini cheetahs out to other research groups gives engineers an opportunity to test out novel algorithms and maneuvers on a highly dynamic robot, that they might not otherwise have access to.&ldquo;Eventually, I&rsquo;m hoping we could have a robotic dog race through an obstacle course, where each team controls a mini cheetah with different algorithms, and we can see which strategy is more effective,&rdquo; Kim says. &ldquo;That&rsquo;s how you accelerate research.&rdquo;<h2>&ldquo;Dynamic stuff&rdquo;</h2>The mini cheetah is more than just a miniature version of its predecessor, Cheetah 3, a large, heavy, formidable robot, which often needs to be stabilized with tethers to protect its expensive, custom-designed parts.&ldquo;In Cheetah 3, everything is super integrated, so if you want to change something, you have to do a ton of redesign,&rdquo; Katz says. &ldquo;Whereas with the mini cheetah, if you wanted to add another arm, you could just add three or four more of these modular motors.&rdquo;Katz came up with the electric motor design by reconfiguring the parts to small, commercially available motors normally used in drones and remote-controlled airplanes.Each of the robot&rsquo;s 12 motors is about the size of a Mason jar lid, and consists of: a stator, or set of coils, that generates a rotating magnetic field; a small controller that conveys the amount of current the stator should produce; a rotor, lined with magnets, that rotates with the stator&rsquo;s field, producing torque to lift or rotate a limb; a gearbox that provides a 6:1 gear reduction, enabling the rotor to provide six times the torque that it normally would; and a position sensor that measures the angle and orientation of the motor and associated limb.Each leg is powered by three motors, to give it three degrees of freedom and a huge range of motion. The lightweight, high-torque, low-inertia design enables the robot to execute fast, dynamic maneuvers and make high-force impacts on the ground without breaking gearboxes or limbs.&ldquo;The rate at which it can change forces on the ground is really fast,&rdquo; Katz says. &ldquo;When it&rsquo;s running, its feet are only on the ground for something like 150 milliseconds at a time, during which a computer tells it to increase the force on the foot, then change it to balance, and then decrease that force really fast to lift up. So it can do really dynamic stuff, like jump in the air with every step, or run with two feet on the ground at a time. Most robots aren&rsquo;t capable of doing this, so move much slower.&rdquo;<img src="https://s3-us-west-1.amazonaws.com/wevolver-project-images/froala%2F1586529400132-MIT-Mini-Cheetah-03.jpg">Bejamin Katz came up with the mini cheetah&rsquo;s electric motor design by reconfiguring the parts to small, commercially available motors normally used in drones and remote-controlled airplanes. Photo: Bryce Vickmark<h2>Flipping out</h2>The engineers ran the mini cheetah through a number of maneuvers, first testing its running ability through the hallways of MIT&rsquo;s Pappalardo Lab and along the slightly uneven ground of Killian Court.In both environments, the quadruped bound along at about 5 miles per hour. The robot&rsquo;s joints are capable of spinning three times faster, with twice the amount of torque, and Katz estimates the robot could run about twice as fast with a little tuning.The team wrote another computer code to direct the robot to stretch and twist in various, yoga-like configurations, showcasting its range of motion and ability to rotate its limbs and joints while maintaining balance. They also programmed the robot to recover from an unexpected force, such as a kick to the side. When the researchers kicked the robot to the ground, it automatically shut down.&ldquo;It assumes something terrible has gone wrong, so it just turns off, and all the legs fly wherever they go,&rdquo; Katz says.When it receives a signal to restart, the robot first determines its orientation, then performs a preprogrammed crouch or elbow-swing maneuver to right itself on all fours.Katz and co-author Jared Di Carlo, an undergraduate in the Department of Electrical Engineering and Computer Science (EECS), wondered whether the robot could take on even higher-impact maneuvers. Inspired by a class they took last year, taught by EECS Professor Russ Tedrake, they set about programming the mini cheetah to perform a backflip.&ldquo;We thought it would be a good test of robot performance, because it takes a lot of power, torque, and there are huge impacts at the end of a flip,&rdquo; Katz says.The team wrote a &ldquo;giant, nonlinear, offline trajectory optimizations&rdquo; that incorporated the robot&rsquo;s dynamics and actuator capabilities, and specified a trajectory in which the robot would start out in a certain, right-side-up orientation, and end up flipped 360 degrees. The program they developed then solved all the torques that needed to be applied to each joint, from each individual motor, and at every time period between start and end, in order to carry out the backflip.&ldquo;The first time we tried it, it miraculously worked,&rdquo; Katz says.&ldquo;This is super exciting,&rdquo; Kim adds. &ldquo;Imagine Cheetah 3 doing a backflip &mdash; it would crash and probably destroy the treadmill. We could do this with the mini cheetah on a desktop.&rdquo;The team is building about 10 more mini cheetahs, each of which they plan to loan out to collaborating groups, and Kim intends to form a mini cheetah research consortium of engineers, who can invent, swap, and even compete with new ideas.Meanwhile, the MIT team is developing another, even higher-impact maneuver.&ldquo;We&rsquo;re working now on a landing controller, the idea being that I want to be able to pick up the robot and toss it, and just have it land on its feet,&rdquo; Katz says. &ldquo;Say you wanted to throw the robot into the window of a building and have it go explore inside the building. You could do that.&rdquo;

MIT’s new mini cheetah robot is springy, light on its feet, and weighs in at just 20 pounds.  Photo: Bryce Vickmark

Robot’s lightweight, high-power design is the perfect platform to share and play, developers say.

Mini cheetah is the first four-legged robot to do a backflip

EPFL scientists are developing a three-legged robot for search and rescue missions that can crawl, roll, jump, and – like a Swiss Army knife – fold away into compact form, all on less power than your standard LED light.

Meet Tribot, the three-legged origami robot designed and built by EPFL scientists. Tri- for three legs and -bot for robot, this super-light critter fits in the palm of your hand, is cheap to build, runs on less than one watt of power, and may one day be deployed in mass for search and rescue mission

Meet Tribot, the Swiss Army knife of robots for rescue missions

<div data-wow-delay=".09s">A frenetic, hopping rodent is giving University of Michigan engineers new ways to think about and design two-legged robots.Biologists and engineers from U-M, Harvard University and the University of California, San Diego used information theory to, for the first time, quantify the entropy in an animal’s gait in three dimensions. The team’s findings, published in Nature Communications on Sept. 5, could help engineers make biomimetic robots that are tailored to specific environments.“This work points at a new way of building a robot that may be useful in navigating desert environments or desert planets,” said <a href="https://me.engin.umich.edu/people/faculty/ramanarayan-vasudevan" rel="noopener noreferrer" target="_blank">Ram Vasudevan</a>, U-M assistant professor of mechanical engineering and a co-author of the paper. “We want to try and build robots that are capable of thriving in all sorts of environments.”He recalled a time when NASA’s wheeled Curiosity rover got stuck in the Martian desert.“It dug a deeper and deeper hole,” Vasudevan said. “What if they had taken a look at how these rodents travel through the desert? Evolution has found a suitable solution several times over. Until now, we haven’t appreciated how useful a system it is in this context.”<iframe src="https://www.youtube.com/embed/35MSBu7-mk0?&amp;wmode=opaque" allowfullscreen="" class="fr-draggable" style="width: 800px; height: 421px;" frameborder="0"></iframe>The researchers explain their approach to studying the jerboa and its future applications to robotics. Video: Evan Dougherty, Michigan Engineering Communications &amp; Marketing.<div data-wow-delay=".09s">For biologists seeking to understand the ecological structure of animal communities, the findings also show how sudden changes in direction, gait and speed help the jerboa—a bipedal desert rodent—elude hungry predators and gain a competitive edge over their quadrupedal neighbors. The researchers compared the behavior of jerboas to jirds, which have four legs and are in the gerbil family.<h4>Entropy is the answer</h4>The jerboa is native to North Africa and Central Asia. Although bipedalism has evolved multiple times in rodents—including kangaroo rats and Australian hopping mice—jerboas are the only group to use three different gaits when moving on their long hind legs: hopping, skipping and running. They can leap more than half a meter high, which is about ten times their hip height.Talia Moore, a postdoctoral research fellow in the U-M Department of Ecology and Evolutionary Biology, was tasked with characterizing the jerboa’s locomotion and comparing it to other bipedal animals.<img src="https://s3-us-west-1.amazonaws.com/wevolver-project-images/froala%2F1563294792374-jerboa-gif-5.gif" style="width: 766px;" class="fr-fic fr-dib">IMAGE: &nbsp;In order to study a jerboa’s gait, the researchers had the rodent run laps around a track with a strategically placed high-speed camera and force plate. Credit: Talia Moore&nbsp;“When we put the jerboa on a force platform, every step had a different signature,” Moore said. “I thought, ‘This is so weird. It’s like they’re completely unpredictable and I’m unable to characterize it based on the techniques we have.’”She consulted with Vasudevan. “I said, ‘Ram, I wish there was a way to measure unpredictability,’” Moore recalls. “He said, ‘There is.’”They borrowed a metric of randomness from information theory—entropy. Entropy is a measure of the uncertainty of an outcome. With it, they developed a model that calculates the probability that the animal will move in a specific way.Moore and her colleagues suspected that these herky-jerky movements help jerboas foil an aerial predator’s efforts to calculate an intercept course.<h4>Jerboas vs. jirds in the wild and the lab</h4>Since they wanted to see how these animals behave in their natural habitat, they traveled to northwestern China and designed a novel set of field experiments to study whether jirds and jerboas escape predators in different ways.Combining their observations and their new model, they found that the jerboas were much more unpredictable than the jirds. Their maneuvers included momentary bursts of acceleration, kangaroo-like hopping, erratic zigzagging and acrobatic leaps.To test whether the jerboa’s unpredictability truly corresponds to increased predator-evasion success, the researchers performed behavioral experiments that measured the animals’ tendency to seek shelter, which is called thigmotaxis.Small foraging animals face a conflict between their needs to venture out for food and to stay under cover—to avoid becoming food. Due to this conflict, the amount of time an animal spends in an open area varies with its ability to evade predators. As evasiveness increases, the behavioral affinity to shelter, and so-called “open-field anxiety,” decrease.During simulated predation trials, Moore and her colleagues observed that the bipedal jerboas explored the entire experimental enclosure, while jirds tended to remain near the walled periphery. She performed a second experiment in the lab with captive-bred animals that had never seen predators before. The results from both experiments suggest that bipedalism in rodents is associated with lower thigmotaxis and greater predator evasion in open settings.<h4>Why this matters for robotics</h4>Much of the research into robot locomotion involves smooth movement in low-variability environments. But these findings demonstrate some of the limits to that perspective.For biomimetic robots to interact with the world, we’ll need to engineer unpredictability in motion.<cite>Talia Moore</cite><div data-wow-delay=".09s">“The key insight here is it’s a big engineering challenge to engineer unpredictability this has shown that it’s a worthwhile pursuit,” Vasudevan said.Added Moore, “If we want to make more biomimetic robots that interact with the world around us, we’re going to need to think about how to engineer unpredictability in motion.”The paper is titled “Unpredictability of escape trajectory explains predator 2 evasion ability and microhabitat preference of desert rodents.” Co-authors in addition to Moore and Vasudevan are Kimberly L. Cooper of the University of California, San Diego, and Andrew A. Biewener of Harvard University. The study was funded in part by a Chapman Memorial Scholarship to Moore.</div> </div></div>

IMAGE:  The jerboa - a bipedal desert rodent native to North Africa and Central Asia. Credit: Christian Baker

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