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Running Hexapod Gets Fancy New Tunable Legs

You may not realize it, but you've got a lot of springiness going on in your legs. You may also not realize that you change that springiness depending on whether you're running or walking, what surface you're on, and whether or not you're carrying stuff. Our bodies (and most animals) are able to dynamically adapt our legs and gaits to make us more efficient under changing conditions. Dynamic adaptation is something that robots are notoriously bad at, but EduBot, a son or cousin or something of the venerable RHex, has been experiment with six new "tunable" legs that allow it to adjust its gait on the fly.

EduBot's legs are made out of carbon fiber, and by changing the location of a slider along the leg, the overall stiffness of each leg can be adjusted independently. Of course, once the stiffness of the legs changes, EduBot has to adapt its gait to match, which it does all by itself by analyzing its own speed, efficiency, and stability. A bunch of different experiments were performed to help the robot learn what leg stiffnesses and gaits produced the most desirable movement patterns on different surfaces and while carrying different loads, and generally the robot was able to figure out what worked best within 70 tries worth of experimentally fiddling with its own programming. I say "generally," because sometimes it took longer, and because watching the robot failing to use the correct gait is pretty funny:

Overall, these experiments have shown that EduBot runs fastest and most efficiently with stiffer legs, but that things can change on softer surfaces (say, grass, or a shaggy carpet) or with payloads, indicating that adaptive and dynamic leg compliance really would be a useful thing to have on a robot, despite the added complexity. Next up will be teaching the robot to adjust its legs on the fly, and it'll be interesting to see how this technology might benefit other robots (or even humans) with similar limbs.

EduBot's new legs were presented in an ICRA paper entitled "Experimental Investigations into the Role of Passive Variable Compliant Legs for Dynamic Robotic Locomotion," by Kevin C. Galloway, Jonathan E. Clark, Mark Yim, and Daniel E. Koditschek, from Harvard University, Florida A&M, and the University of Pennsylvania respectively.

[ EduBot ]

Brilliant Little Jumping Robot Only Needs One Motor

Jumping offers a way for very small robots to get over very large obstacles using a minimal amount of energy. It's tricky, though, because while the first jump might be pretty easy, subsequent jumps depend on the ability of the robot to right itself, aim, and go again. That's essentially three separate subsystems, but since you're only ever using one at a time, the risk is that your robot ends up being three times as bulky as is strictly necessary. And in small robots, efficiency is everything.

EPFL's locust-inspired jumping robot solves one of these problems with a weighted roll cage that helps the bot passively return to an upright position whenever it lands. A second motor then allows the robot to rotate within the cage to change its jumping direction. This works quite well, but it adds bulk plus another motor to the whole system.

Jianguo Zhao and a team from Michigan State University have created a jumping robot that somehow manages to do everything that it needs to do with just one single motor. It can change its orientation, right itself, and then jump (really freakin' high) with one motor and some clever mechanical engineering. Check it out:

The actual jumping mechanism was directly inspired by the legs of a frog, but it's really the rest of the robot that's so cool. Everything is driven by one tiny pager motor, and here's how it works:

  • To jump, the pager motor engages a gear which pulls the robot's body down towards its legs, slowly charging four torsional springs. The gearing and springs help keep the power requirements low without sacrificing jumping energy. When the springs are fully charged up, the gear trips a little lever, and the legs are released. Boing!

  • After re-entry, the robot inevitably finds itself lying prone. By driving the pager motor backwards, the same gear that charges the springs instead spins against the ground without engaging anything, allowing the body of the robot to rotate to a new position.

  • To get up, as the robot's body is pulled down towards its legs, little arms deploy outwards, driven by that same downward motion. These arms push the robot up into a standing position, and keep it there until liftoff.

I really love how simple and clever this all is. It's efficient, too: the robot is 8 centimeters tall and only weighs 20 grams, including the motor and a 50 mAh battery, but it can make approximately 285 jumps without needing to be recharged.

The designers think that it should be possible to make the robot jump even higher and farther, and of course at some point they're going to want to stick some sensors on there or something to move it from just being awesome to being awesome and useful at the same time.

This robot was presented at ICRA in a paper entitled "Development of a Controllable and Continuous Jumping Robot" by Jianguo Zhao, Ning Xi, Bingtuan Gao, Matt W. Mutka, and Li Xiao, all from Michigan State University.

[ MSU ]

Robotic Construction Machine Causes Explosion at Fukushima

fukushima remote control construction equipment
A teleoperated robotic excavator similar to the one above caused an oxygen cylinder to explode.

Editor's Note: John Boyd is an IEEE Spectrum contributor reporting from Kawasaki, Japan. This is part of IEEE Spectrum's ongoing coverage of Japan's earthquake and nuclear emergency.

A teleoperated robotic construction machine accidentally hit an oxygen cylinder at the Fukushima Dai-ichi nuclear plant this Tuesday, causing the cylinder to explode. The unmanned machine, a grapple-equipped excavator fitted with cameras to guide a remote operator, was clearing radioactive debris from the south side of the No. 4 reactor building when a loud explosion was heard around 2:30 p.m.

Despite the loudness of the blast, a Tokyo Electric Power Co. (TEPCO) official told IEEE Spectrum that, “It turned out to be nothing. There was no damage and there was nothing to repair. And the machine is being used again.” He added that the cylinder contained "compressed oxygen, so the noise was loud."

The machine, which the TEPCO official insists is "not a robot," was removing debris flung from the No. 3 reactor building after a hydrogen explosion occurred there on March 14, following the meltdown of the reactor’s fuel rods. Workers are trying to clear the plant of radioactive debris from at least two hydrogen explosions in order to facilitate the set-up of reactor cooling systems and also the transfer of pooled radioactive water from the reactor and turbine buildings to a central radioactive waste disposal facility and other temporary storage.

Because much of the rubble is highly radioactive, TEPCO is employing machines like the remote controlled excavator to remove the contaminated debris. But as this explosion shows, that doesn't mean there are no risks. In fact, an operator controlling a teleoperated robotic machine by relying on cameras rigged to the vehicle may have impaired visual access, making it difficult to spot dangerous objects like oxygen cylinders amid the piles of rubble.

Dr. Robin Murphy, director of the Center for Robot-Assisted Search and Rescue (CRASAR) at Texas A&M University, in College Station, and a world experts on rescue robotics, says that she sees "these kinds of accidents or operator errors all the time." The problem, she explains, is that roboticists are still trying to improve remote presence technologies to allow operators to effectively see and act remotely through a device such as a robot or sensor.

"Many manufacturers think that a certain camera position or multiple cameras will solve the problem of what is sometimes called situation awareness or sensemaking, but this neglects the whole host of subtle, but real, cognitive barriers that arise from working remotely and having perception mediated," she says. Remote operating a robotic system in a constrained environment -- say, an office or in space or underwater -- might actually be easier compared to a disaster-stricken area, which is not well understood and not engineered to make it easy for the robot. "Disasters continue to offer surprises and difficult to model situations."

Image: TEPCO

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German Robot Plays Pool, Throws Down Robot Pool Gauntlet

Well, it's inevitable now. RoboGames obviously needs to add a new event: robot pool. Willow Garage got their PR2 sinking balls as part of a week-long hackathon, and at ICRA, the Germans answered back with a similarly-sized dual arm robot able to pocket five balls in a row:

Thomas Nierhoff, a masters student at Technische Universität München (TUM), used a human-sized mobile robot with dual 7-DOF arms that's able to manipulate a pool cue similarly to how a human does. A camera above the table tracked the positions of the balls and helped the robot plan its shots, separating each into various difficulty thresholds to help the bot decide which it should take. It managed to nail most of the easier shots about 80% of the time, which isn't too shabby, and seems like it would probably make it competitive with the PR2.

It's a shame, then, that Germany is such a long way from California. But wait! It just so happens that there are several PR2s in Germany. And it also just so happens that one of them is right there at TUM, albeit in a different lab. Personally, I don't see how it would be possible not to set up a friendly little game, and if Rosie wants to get involved too, I'm all for that. Place your bets in the comments!

This robot was presented at ICRA in a paper entitled "Playing Pool with a Dual-Armed Robot" by Thomas Nierhoff, Omiros Kourakos, and Sandra Hirche, all with the Institute of Automatic Control Engineering at TUM.

[ TUM ]

Microdrones Film Confused African Wildlife

microdrones md4-1000 film african wildlife

It's a well known fact that animals from the Arctic to Africa have absolutely no idea what to think about robots. Taking full advantage of this phenomenon, Microdrones let one of their MD4-1000 quadrotors loose on safari in Kenya, and it set about capturing video like you've probably never seen before.

While I'm not one to spout propaganda about how robots are revolutionizing every aspect of our lives (okay, I totally am), this is an entirely new way of filming animals that's just beginning to be explored through trial and error. We're used to watching animals from afar through gigantic zoom lenses, but small flying robots offer the opportunity to get in the middle of things without causing too much of a ruckus, and this is just one of the first tentative stabs at a whole new world of footage that would do David Attenborough proud. And it's not just for animals, either: imagine flying one of these things into an erupting volcano.

It looks like these clips are part of a show that Microdrones is putting together for TBS Television Japan, but we'll make sure and let you know if it ever shows up online.

[ Microdrones ]

DARPA Concludes Nano Air Vehicle Program, We Wonder What's Next

The original concept, on left, and the final robot, on right

We've written a fair number of articles starting with the phrase "DARPA wants" followed by something that's nearly always entirely improbable and often borderline nutty. It's rare that DARPA actually gets exactly what it wants, but with their Nano Air Vehicle program, that seems to have happened.

As the above video shows, it was definitely not an easy process to make a life sized, fully controllable surveillance robot that's more or less indistinguishable for a hummingbird, but AeroVironment managed to pull it off. Of the technical goals and milestones that DARPA set out for the robot, it managed to meet all and exceed many:

  • Demonstrate precision hover flight within a virtual two-meter diameter sphere for one minute.

  • Demonstrate hover stability in a wind gust flight which required the aircraft to hover and tolerate a two-meter per second (five miles per hour) wind gust from the side, without drifting downwind more than one meter.

  • Demonstrate a continuous hover endurance of eight minutes with no external power source.

  • Fly and demonstrate controlled, transition flight from hover to 11 miles per hour fast forward flight and back to hover flight.

  • Demonstrate flying from outdoors to indoors, and back outdoors through a normal-size doorway.

  • Demonstrate flying indoors 'heads-down' where the pilot operates the aircraft only looking at the live video image stream from the aircraft, without looking at or hearing the aircraft directly.

  • Fly the aircraft in hover and fast forward flight with bird-shaped body and bird-shaped wings.

AeroVironment says that it would take a decade to make this robot ready for deployment, but DARPA doesn't just hand out piles of cash to make cool stuff for no reason. There's a future here, whether or not we hear about it immediately, so just make sure to give hummingbirds a second look from now on.

[ Nano Air Vehicle Program and AeroVironment ]

Juggling Robots Get Fancier

UPDATE: The Czech roboticists updated their video with labels and a slow motion sequence, making it easier to see how the robot juggles three, and then four, and finally five balls, and also how it drops one ball at the end.

Robots are especially good at juggling. This is not to say that juggling is a particularly easy problem to tackle, because it's not, but it's a fun excuse to design a robot to demonstrate precision control and high-speed object tracking. The robot in the video above, for example, was built by three masters students from the Department of Control Engineering at the Czech Technical University in Prague. It uses three linear motors, including one for each arm and a third for a central ball deployment system, along with two pivoting "hands" to catch and toss up to five balls at once. The feedback loop is closed using data from encoders built in the motors, and a high-speed camera helps to fine-tune the trajectories of the balls.

You don't actually need a high-speed vision system to juggle, though. We first met the "blind juggler" with it's fascinating passively adaptive single ball juggling capability back in 2009. Since then, it's gotten a fairly significant upgrade over the past year or so, which its designer, Philip Reist from ETH Zurich, presented last month at ICRA:

Remember, there's no sensing going on here. No cameras, no force sensors, no microphones, nothing at all. The robot is able to juggle without having any idea what the ball is doing, simply by virtue of the level of feedback control inherent in its design. It's really quite beautiful... You know, from a mechanical perspective. You can read about how this is possible here.

The Pendulum Juggler robot was presented in an ICRA paper unsurprisingly entitled "Design of the Pendulum Juggler," by Philipp Reist and Raffaello D’Andrea from the Institute for Dynamic Systems and Control, ETH Zurich, Switzerland.

[ Five Ball Juggler ] via [ Hack a Day ]

[ Blind Juggler ]

Gecko-Inspired Window Washing Robot is Powered Entirely by Water

gecko-inspired climbing cleaning robot

Batteries and motors are heavy and inefficient in that they expend a significant percentage of their power just moving their own mass. This is especially apparent in climbing robots, which spend most of their time hoisting themselves vertically upward. Researchers from Zhejiang University in China have developed a robot that's capable of sticking to smooth surfaces, climbing vertically, and washing windows, relying almost entirely on water pressure:

To function, the robot gets connected to a faucet with a loop (a really long loop, if necessary) of hose. As water flows through the hose, its pressure accomplishes several things. First, the water passes through fluidic vacuum generators, which use that same Bernoulli principle that those supersonic jet grippers take advantage of to turn the motion of a fluid into a vacuum. This allows the bot's feet to stick to any smooth surface.

Then, the water is routed through a solenoid valve to a piston that's attached to the "spine" of the robot. The inspiration for this design was the gecko, arguably the best wall-climber in existence, and the upshot of it is that the robot can climb relatively quickly (constrained only by the time it takes to establish a solid vacuum) and turn in either direction with just one single spinal actuator. And of course lastly, the water is squirted out at the end of the robot's arm to do the actual washing.

The robot does currently use a very small battery to power the wireless communication system and to trip the servo to control the direction of motion, but it's certainly possible that a small turbine could run all that stuff instead. The present design is able to lift twice its body weight in payload using just standard tap water pressure, and future versions might be able to conduct inspections, fight fires, paint, or even perform repairs.

This robot was presented in an ICRA paper entitled "A Gecko Inspired Fluid Driven Climbing Robot," by Jilin Liu, Zhangqian Tong, Jinyuan Fu, Donghai Wang, Qi Su, and Jun Zou of the Institute of Mechatronic Control Engineering at Zhejiang University, China.

This Is What PR2s Do for Fun

People have programmed PR2s to do all sorts of fun things, but most of these things are human-y fun, not robot fun. Georgia Tech has built what they're calling a "PR2 Playpen," which is designed to keep their PR2 busy (and entertained?) while teaching it valuable life skills at the same time.

Robots tend to have difficulty when it comes to interacting with unfamiliar objects. We've seen some clever ways to at least partially circumvent this, but to perform best, robots need to be taught how to pick things up and then practice with different algorithms to find what works. This is rather time consuming, and the PR2 Playpen is designed to help automate the task. A conveyor belt drops random objects one at a time into a workspace in front of a PR2, which studies them and attempts to pick them up. The robot can autonomously evaluate different controllers and strategies, while collecting data to improve its algorithms at the same time.

The other benefit to this system is that the robot can keep itself busy and productive without any human supervision. There's a limited amount of time that research labs can keep their PR2s hard at work, and I bet that even the busiest lab would have trouble actively using their robots more than 50 percent of the time, if that. With the PR2 Playpen, the robot can spend all night every night teaching itself to get better at grasping things, and thanks to ROS, all robots everywhere will be able to benefit from what it learns.

[ Georgia Tech Healthcare Robotics Lab ]

Little Amphibious Tumbling Robot Tackles Tough Terrain

As components get smaller, robots are getting smaller as well, but in general small robots have big problems with obstacles and rough terrain. We've seen a variety of examples of robots that have found ways around this problem (most notably robots that jump or fly), but this might be the most creative yet: it's a robot that tumbles.

By "tumble," I mean that this robot is designed to move by flipping itself end-over-end in a somersaulting motion. It's called Aquapod, and it was created by the University of Minnesota's Center for Distributed Robotics. Aquapod uses two carbon fiber arms connected to servo motors that can rotate continuously to, as the researchers put it, "induce a tumble."

The reason that it's called Aquapod, incidentally, is that it's also waterproof, with the ability to control its buoyancy, floating or sinking or even just chilling out somewhere in the water column. This enables it to operate quite happily on land as well as in water, where it can sink itself to the bottom of lakes and streams and tumble along the bottom.

Aquapod might not be the fastest robot ever, but it has no trouble tumbling over slippery surfaces, through sand, and towards skeptical ducks. The offset arms help to give it more degrees of freedom to escape from vegetation and other obstacles, trading a little bit of efficiency for increased robustness.

The general intent is for Aquapod to be used in water monitoring or aquatic sensor deployment, where bunches of them can team up to float down rivers, sinking and floating and deploying sensors and taking measurements as they go. It would even be possible to stick one underneath an iced-over lake to monitor fish populations during the winter, where the robot could move around by "inverse tumbling" on the underside of the ice while upside-down.

Next up will be to work in solar power along with autonomous control for long-duration research. Even without any of that stuff the robot is still a very promising platform, though, since it's estimated to cost only about $2,000 to build.

Aquapod was presented in an ICRA paper entitled "Aquapod: Prototype Design of an Amphibious Tumbling Robot," by Andrew Carlson and Nikos Papanikolopoulos from the Center for Distributed Robotics at the University of Minnesota.

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