Gallery: Robots Evolve More Natural Ways of Walking
01evolving-walking-robot
Robots that look like oversized hockey pucks, dune buggies or refrigerators may be practical for cleaning floors, exploring Mars or dispensing beer, but it's the walking robots that capture our imagination. The trick is making them use their legs to walk efficiently, not like stiff-legged metal monsters out of a 1950s B movie. A new computer simulation by a Vermont researcher shows how robots might learn to walk better by starting on their bellies, the same way animals evolved. For the simulation, Josh Bongard created [virtual robots that could change their shapes over time](http://www.physorg.com/news/2011-01-robust-robots-babies-video.html). The robots started with snakelike bodies. His simulation applied different movement algorithms to the robots' segmented spines. If the algorithms were successful at moving the robots closer to a target, they'd be used in the next iteration. If not, they'd be thrown away. <script src="http://admin.brightcove.com/js/BrightcoveExperiences.js" type="text/javascript"></script><object class="BrightcoveExperience" id="myExperience760251532001"><param name="bgcolor" value="#FFFFFF"></param><param name="width" value="660"></param><param name="height" value="423"></param><param name="playerID" value="3698508001"></param><param name="publisherID" value="1564549380"></param><param name="isVid" value="true"></param><param name="dynamicStreaming" value="true"></param><param name="@videoPlayer" value="760251532001"></param></object><script type="text/javascript"> runMobileCompatibilityScript('myExperience760251532001', 'anId'); </script><script type="text/javascript">brightcove.createExperiences();</script> In each iteration, successful algorithms would be tested alongside slightly modified versions. After many iterations, the robots had evolved effective movement patterns and were able to slither rapidly towards the goal. Then Bongard added legs. As the legs slowly grew, the simulation evolved from slithering to walking. What's more, it learned how to walk much more quickly than simulations that had legs from the very start. "You can think of the changing bodies of these robots as training wheels," says Bongard, who teaches an evolutionary robotics course at University of Vermont, where he is an assistant professor. The slowly-growing legs allowed the algorithms, or "controllers" in robotics parlance, to deal with one problem at a time: first wiggling, then balance. The result is a much more natural gait, too. "The walking controllers are a little different than what we've seen before," says Bongard. "The quadruped uses its spine a lot more, to sort of throw its legs forward. That's much more natural, the way that four-legged animals like dogs walk." It's difficult to make robots change their bodies or grow legs in the physical world, but Bongard built a proof of concept using Lego Mindstorms. This robot (shown above) has a simple jointed spine and four legs. At first, an added brace keeps the legs splayed out to the sides, like a lizard's, then gradually pulls them together, eventually allowing the robot to stand up on its legs. The prototype shows that a similar evolutionary process could be used to develop effective walking gaits in real robots, Bongard says. *Photo credit: Josh Bongard*
02boston-dynamics-bigdog
Whether they have two, four or many legs, robots that walk have more in common with animals like us than their wheeled and non-mobile cousins. That might make it easier for us to imagine them being part of our lives. It is also why legged robots are often so darn cute — or, sometimes, creepy. But it's not just cuteness or coolness that interests roboticists fascinated by the mechanics of legged locomotion. "Legged machines can move over much more rugged terrain than wheeled machines can," says Bongard. That's one of the reasons that the Pentagon has given millions to Boston Dynamics to develop BigDog, a [four-legged robot pack mule](http://stag-komodo.wired.com/dangerroom/2010/04/video-militarys-robotic-pack-mule-battles-the-mud/) that can carry upwards of 300 pounds while picking its way through mud, snow, ice and piles of cinder blocks. BigDog's four legs are, to some people, disturbingly lifelike. They're remarkably effective at moving the robot from place to place, and they're even able to keep BigDog on its feet after receiving a hefty shove from the side. (They inspired an unforgettable [BigDog parody video](http://gizmodo.com/372272/video-of-bigdog-beta-quadruped-robot-is-so-stupid-its-hilarious).) Bongard's simulated robots showed a similar robustness. After evolving from slithering to walking, the robots were subjected to virtual "winds" that tried to push them off course. The robots that started by slithering were better able to resist the new forces than robots that had started up on all fours. *Photo credit: Boston Dynamics* [#iframe: http://www.youtube.com/embed/cNZPRsrwumQ](640x390)||||||
03cornell-ranger
The ability to cover rough terrain is not the only reason to make legged robots: Walking, it turns out, is very efficient for covering long distances. Vertical legs (as opposed to the horizontally splayed legs of, say, a lizard) can make use of a "passive swing," in which the leg acts as a pendulum while swinging forward to take another step. In robots, as in humans, that motion is done with almost no expenditure of energy: Your muscles are relaxed, and a robot's servos don't need to apply force. "It's hugely energy efficient," says Bongard. "That's one of the reasons for bipedalism. We can travel huge distances without expending much energy." One walking robot, the Cornell Ranger shown above, set a [robotic distance record last year](http://stag-komodo.wired.com/gadgetlab/2010/07/adorable-walking-robot-sets-distance-record/), walking 14.3 miles, or more than a half-marathon, before it ran out of juice. Ranger is technically bipedal, although it has four legs, because its legs work only in pairs. It may not have the most elegant gait, but Ranger can take 20,000 steps for each penny's worth of electricity it uses, the Cornell team claims. *Photo courtesy Cornell University* <script src="http://admin.brightcove.com/js/BrightcoveExperiences.js" type="text/javascript"></script><object class="BrightcoveExperience" id="myExperience275300033001"><param name="bgcolor" value="#FFFFFF"></param><param name="width" value="660"></param><param name="height" value="423"></param><param name="playerID" value="3698508001"></param><param name="publisherID" value="1564549380"></param><param name="isVid" value="true"></param><param name="dynamicStreaming" value="true"></param><param name="@videoPlayer" value="275300033001"></param></object><script type="text/javascript"> runMobileCompatibilityScript('myExperience275300033001', 'anId'); </script><script type="text/ja </p> "></script>
04tu-delft-flame
Until recently, robots that walk on legs have been more of a novelty than a practical area of research. That's because they're more difficult to design. Indeed, building a successful walking robot might require a completely different, and more biological, approach. One area that researchers have focused on since the 1990s is "passive dynamics," or unpowered movement. Work by aeronautical engineer Tad McGeer showed that lifelike two-legged machines could "walk" down ramps without the use of any motors at all. The [Technical University of Delft's Biorobotics Laboratory](http://www.3me.tudelft.nl/live/pagina.jsp?id=c4fa06f1-b767-4a67-a19e-ea3356400f06〈=en) has expanded on this work with robots that are either unpowered or use unpowered movements as part of their gait. Just as the human leg swings forward under its own momentum, these robots walk more efficiently and naturally by incorporating momentum into their gaits. The constantly changing dynamics of this kind of walking are a challenge for robot designers, who have responded by incorporating more biologically inspired ways of controlling their devices, often by using evolutionary systems to hone the algorithms that coordinate the robot's sensors and servos. TU Delft's "Flame" robot, shown above, uses "series elastic actuation" in its hips, knees and ankles. That means that there is a spring between each motor and its associated joint, instead of having the motors connected directly to the joints. "This absorbs shocks from the foot hitting the floor each step," explains Martijn Wisse, who helped develop the robot, "and it allows for cheap force/torque control. The latter is key to generate natural motions; without force/torque control, the joints would make jerky 'robotic' motions because it would forcefully follow a prescribed trajectory, regardless of the amount of force that such a (potentially very unnatural) trajectory would require." *Photo courtesy Martijn Wisse/Technical University of Delft*
05arduspider
Not every walking robot has to have two or four legs. Six-legged robot insects can be an effective and relatively simple way for DIY enthusiasts to get involved in legged robotics. That's because six-legged robots are stable (they always have at least four legs available for support) and their legs can move in pairs, so you only need three servos to control six legs. Maker [Jose Julio built this six-legged bot](http://www.diydrones.com/profiles/blogs/arduspider-sara-my-daughters) for his daughter using an Arduino control board, three servos and an IR sensor. The ArduSpider, as he calls it, can work in manual mode (you control each of the servos individually), assisted mode (you tell it which direction to move and it works out the proper leg movements) or wholly autonomous (it wanders around entertaining your children and terrifying the pets). *Photo: Jose Julio/DIY Drones* [#iframe: http://www.youtube.com/embed/xqUhlYrN_Po](640x390)||||||
06athlete
[Ryuma Niiyama's Athlete](http://www.isi.imi.i.u-tokyo.ac.jp/~niiyama/) is a bipedal robot that can run and jump, and manages to balance on its own pretty well too. Niiyama took a slightly different approach to constructing Athlete's legs compared to most robot legs. Instead of an articulated ankle, Athlete uses a reverse curved leaf spring not unlike the prosthetics used by runners like [Oscar Pistorius](http://stag-komodo.wired.com/wired/archive/15.03/blade.html) and [Aimee Mullins](http://www.ted.com/talks/aimee_mullins_prosthetic_aesthetics.html). The hardware appears to work well, and the robot can run for a few steps before its feet slip out from under it. Apparently Niiyama is still [working out the kinks in the software](http://stag-komodo.wired.com/gadgetlab/2010/12/robot-runs-on-human-like-legs/). *Photo credit: Ryuma Niiyama* [#iframe: http://www.youtube.com/embed/bXqUjiNw8fo](640x390)||||||
07dna-biped
Robots don't have to be big in order to walk. Nadrian Seeman at New York University built a [bipedal "robot" out of DNA](http://seemanlab4.chem.nyu.edu/Nanobot.html) in 2004 that used the properties of strands of DNA to "walk" back and forth between specific footholds, which are also made of DNA. Seeman envisioned using this technique in nanotech manufacturing, although practical applications are probably a long way off. Still, it's pretty amazing. *Image: Nadrian Seeman* via [BotJunkie](http://www.botjunkie.com/2010/01/20/autonomous-bipedal-robot-built-out-of-dna/)
08chumby-walker
Chumby is an easily modifiable, Linux-based computer that can be used for a wide variety of DIY projects. With the addition of a couple of legs by [EMG Robotics](http://www.robotsee.com/chumby.html), it can even become a simple walking device. Granted, the Chumby walks a bit like the Frankenstein monster, but as this is a demo meant to show off the flexibility and ease of construction, that's not surprising. via [Gadget Lab](http://stag-komodo.wired.com/gadgetlab/2010/10/chumby-one-gadget-turned-into-a-bipedal-robot/)
09pvc-biped
Ken McMullan wanted to build an [inexpensive bipedal robot](http://bipedblog.blogspot.com/). So he built a framework out of PVC sheeting, commonly used in ventilation ducts. Combined with several servos, an inexpensive CPU and a cheap power pack, he was able to build his two-legged robot for $120 in about 40 working hours. McMullan got as far as programming the robot to do squats and make some basic single-leg motions when he posted his last update in 2008. via [Let's Make Robots](http://letsmakerobots.com/node/571)
10low-cost-bipedal-robot
Building a bipedal robot involves a multitude of challenges, not least of which is giving the robot a sense of proprioception. That's the sense that we humans have of where our body parts are in space. With a robot, it means you can't just issue a command to a servo and move a leg to a defined position -- your robot needs to react to its dynamically changing position in space in order to move, balance and (ideally) react to external forces. This DIY robot project only cost about $150, but the fact that it took 200 hours to build gives some sense of how difficult robot walking can be. via [Let's Make Robots](http://letsmakerobots.com/node/2423)
11bipedal-robot-kit
Want to build a walking robot, but don't have time to machine your own parts, write your own software and program the logic board yourself? There are kits you can buy, like this $123 [bipedal robot kit](http://robokitsworld.com/index.php?main_page=product_info&products_id=223) from Robokitsworld.com, which also sells [hexapod robot kits](http://robokitsworld.com/index.php?main_page=product_info&cPath=64&products_id=230).
12biper-4
This pair of robot legs was part of a series built in the 1980s by Isao Shimoyama and Hirofumi Miura at the University of Tokyo, [according to the Computer History Museum](http://www.computerhistory.org/VirtualVisibleStorage/artifact_main.php?tax_id=04.05.04.00), in whose collection it appears. Unlike its predecessor, Biper-3, this robot had knee joints. Its large, flat feet were necessary to keep it from tipping over. *Photo credit: [Marshall Astor/Flickr.com](http://www.flickr.com/photos/lifeontheedge/351686699/)*
13asimo
Perhaps the most famous recent bipedal robot is Honda's Asimo. Billed as "the world's most advanced humanoid robot," Asimo has made numerous stage appearances over the past decade on behalf of Honda. Not actually a Honda product, Asimo is part of the car company's research into robotics and human mobility, with the aim of creating a robot that can act as a helpful companion to people who might need assistance. [Asimo celebrated its 10th anniversary](http://world.honda.com/news/2010/c101029ASIMO-10th-Anniversary/) last October. Behind the Asimo project lie years of research into robot locomotion, including the development of a walking system that's able to deal with stairs, uneven ground, and even being pushed without falling over. One other thing they got right: It's very cute. *[Photo credit: Honda / Flickr.com](http://www.flickr.com/photos/hondanews/3989943689/)*
