ON MARCH 17, 2008, A COPY of a promotional video for a robot named “BigDog” was posted on YouTube. The clip went viral, becoming the most-watched clip on YouTube that day, with more than 2.5 million views. It currently ranks as the 11th most-viewed video of all time in YouTube’s science and technology category, with more than 11.1 million views.
The video shows a waist-high robot with four thin black legs carefully maneuvering over a pile of rocks, taking running leaps over obstacles, and ascending snowy hills with short, quick strides. In one scene, when a man attempts to kick the robot over, it skips back from the blow and then rights itself. When the robot slips on an ice patch, its legs bend to shift its weight and recover its balance.
BigDog’s appeal is perhaps its contrast to even the most modern robots, which appear built to remind us that the long-promised robotic revolution is still generations away, exhibiting the clunky, mechanical movements employed by sci-fi cyborgs of the 1950s. BigDog seems alive, almost athletic—traits it owes to the goal of its creator, Boston Dynamics: to create a machine that didn’t move like a machine, but like an animal.
TURNING TO ANIMAL STRUCTURES for inspiration just makes sense, says robotics engineer Mike Grygorcewicz, BMET ’08. “They have spent millions of years progressing, so they make for a good model.” Good, but hard to replicate. “You don’t just build something like BigDog the first time around,” says Grygorcewicz. “There is a lot of trial and error.” First as a co-op student, and now as a robotics engineer, Grygorcewicz has been working with BigDog since the middle of the last decade. He was there for the celebrations when it walked 10 feet, and years later to witness it make a 13-mile trek. The project was funded by the US Defense Department’s Defense Advanced Research Projects Agency (DARPA), which saw BigDog’s potential to serve as a kind of mechanical pack mule for troops navigating the rough terrain of places like Afghanistan. It has carried up to 340 pounds and reached a top speed of 6 mph without a payload; it can be operated remotely or use a light sensor to follow a human leader.
The design process was a slow evolution, beginning with a single leg, then adding a second, and finally expanding to four legs that could maintain balance. The version shown on the YouTube video is BigDog 3.5, the culmination of four ground-up redesigns that involved streamlining the robot and tweaking elements like leg shape. “As we learned more about what worked and what didn’t, the platform evolved,” says robotics engineer Andy String, BELM ’07.
The hardest part about building BigDog—or any walking robot, for that matter—is that there’s no reference point. “If you’re building a car, you can just look at the last car you built,” says senior robotics engineer John Giarratana, BELM ’02. “But for the seven years I’ve been here, everything that we’ve done has been completely uncharted territory.” Even to those who work closely on the project, the results can be surprising. String spent months helping to build the reflex electronics on BigDog but was still amazed when he watched the robot’s graceful ice-slip recovery. “Trying to get BigDog to react the way you would expect an animal to react was very difficult. And when it did accomplish that reaction, you just got this feeling like, ‘I can’t believe it’s doing that. I can’t believe it’s reacting in that way to that stimulus.’ ” Further evidence of the robot’s polish came later that day, when—upon returning to the parking lot where the video was shot—String took a spill on the very same ice patch BigDog had just successfully navigated.
“Nobody else is doing this kind of work,” says robotics engineer Christian Weagle, BEET ’05. “There have been some legged robots that have been built in educational institutions, but nobody has ever tried to build durable, fieldable robots of this quality before,” he says. “It’s one thing to build a robot that can perform for a couple of weeks for a grad student’s thesis. It is a whole other thing to build a robot that has to work in the real world and can perform in combat conditions where people’s lives depend on it.”
BIGDOG’S CELEBRITY HAS NOT BEEN LIMITED to the Internet. The Discovery Channel has made a visit to the company’s Waltham, Mass., headquarters, and the robot has been mentioned everywhere from CNN to The New York Times. Giarratana still regularly opens up magazines to find stories on BigDog, and even random conversations at the gym reveal a public awareness of his work. “I knew I was a part of something crazy when the video came out, and within a week, it was on The Colbert Report.” These days, BigDog is just one of several projects on the engineers’ plate. There is also LS3, a much larger version of BigDog set to debut sometime next year. A two-legged robot named PETMAN that seeks to recreate human gait and movement is also in the works, developed to help the government test chemical protection suits.
There are other projects, too— projects the engineers have spent countless hours working on that they can’t reveal the slightest bit of detail about. It would be, they all say, really amazing if they could talk about it, but they can’t. Given the celebrity status of their previous work, though, we’ll all know as soon as they can. —DAN MORRELL