- The Washington Times - Friday, March 10, 2006

Big Dog, a robotic mule from Boston Dynamics, astonishes the way a horse would walking through your living room and out the back door.

The headless beast can negotiate strange or rough terrain. The Boston company is developing it for DARPA, the Defense Advanced Research Projects Agency.

Now, when you think of robots, you probably think of an awkward, clunky contrivance that slowly lurches around and looks foolish. I do, anyway.

Not Big Dog. It walks with rapid natural-looking steps that resemble those of a real horse (although it does appear to have one set of legs on backward).

The company calls it the Most Advanced Quadruped Robot On Earth, and I believe them.

Boston Dynamics says that so far Big Dog trots at about three-and-a-half miles an hour, will climb a slope of 35 degrees, and carry 120 pounds.

In case anyone doubts it, there is a lengthy video clip on the company’s Web site showing the beast doing most of these things. (Of course it’s possible that they have two guys inside it with their legs stuck out, but I’m trusting them.) To help with navigation, it has a stereo video system and a laser gyroscope.

The Army is interested in Big Dog because a horse can handle terrain that a wheeled vehicle can’t. But making a robot that actually does anything useful is a bear of a problem.

The thing needs sensors to know its orientation with respect to the ground, more sensors to know how much each of its joints is bent and the applied force, more sensors to detect the pressure of the ground and software to make sure everything works with everything else.

This is hard enough on flat ground when nothing surprising happens. But Big Dog goes across broken rock as if it had grown up there.

It is powered by a two-cycle gasoline engine that runs the hydraulic actuators that work the legs. The idea is simple, but I’m glad I didn’t have to do the programming.

A major trick with robots is making them respond rapidly enough to the unexpected. I’ve seen experimental dancing robots that swayed nicely to music and lifted their feet up and down.


But if they had tripped over something, or someone had shoved them, they would have gone down. Nice research projects, but not real practical.

A couple of times in the film clip, when Big Dog is prancing around — and “prancing” is the right word — one of its handlers puts his foot in its side and gives it a hard shove. It (he? she?) leans precipitously as if about to fall.

Then a leg shoots out to the side to prevent the collapse, and three seconds later Big Dog is upright and prancing again.

“Wow!” thought I. Robby the Real-Time Robot.

There was a time, not all that long ago, when the computation would have had to be done by a mainframe or minicomputer attached to the robot by a cable. But of course today you can put almost any amount of computing power in a cigar box.

I haven’t seen Big Dog in person. (Maybe I’ll get the editor to buy me one, for research.) In the video it doesn’t go over high obstacles such as big rocks.

Still, it is the most natural-looking robot I’ve seen and has amazing reflexes.

A skeptic might ask why the Pentagon needs to invent a mule when we already have perfectly good ones that eat grass.

Some places don’t have grass.

And it’s just really neat.

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