Bigdog becomes Alphadog -- walking robots step closer to the real world


Earlier I wrote about the transportation potential of walking robots-of-burden like BigDog. While these robots are not for the long haul, a whole range of options are opened up by a wheeled vehicle that can get to where the road ends, and then lower legs to walk along rough terrain, up stairs and up hills.

Boston Dynamics has gone even further with their latest model, AlphaDog

The AlphaDog's legs are hydraulic, and so adding legs like this to a car which has a motor and compressor is not so far fetched. In this design they could easily fold up into the sides of a single person wheeled vehicle. In the video, the robot is shown carrying 400lbs of weights, and a range of 20km is claimed. You might not quite want to ride it yet, but that's coming.

Let's look at some of the consequences for transportation and cities:

  • Houses need not be on streets to have full access by small vehicles and cargo delivery robots. They can be on the side of hills and up stairs. Neighbourhoods can be built with just small lightly paved or graded paths so that the robot's legs don't disturb the terrain.
  • The robots may well, in a controlled environment, be able to place their feet with good precision. As such the path for a walking robot might look like just a series of stone pads dotting the grass -- the way some paths for people look. In reality they would be more sturdy, but that's what they could look like.
  • In developing countries which do not have infrastructure, they may never have to put in that much infrastructure. Combined with flying robots, delivery of goods can become possible to any location, and at high speed.
  • The world's tourist destinations may become swamped with people who can ride a walking robot to remote locations where before the daunting hike kept the crowds down. There will be efforts to ban walking chairs, but the elderly and disabled will be able to fight such bans as discriminatory.
  • Indeed, for the disabled and aged, the walking chair robot might well open up lots of the world that is now closed. The main issue would be power and noise. The motors that power BigDog are very noisy. AlphaDog in the video is using external power.
  • Robotic cargo delivery (deliverbots) need no longer be limited to places you can roll up to. That can include places inside buildings, even up stairs.


Pure walking robots will always be less efficient than wheeled vehicles. I think a leg/wheel hybrid would be the ultimate all-terrain vehicle. Picture a regular SUV or Hummer type vehicle that rolls along on wheels most of the time, but when it gets stuck or encounters troublesome terrain like mud or the pile of rocks in the video, 4 or 6 legs unfold from the sides/corners of the vehicle, it walks across the obstacle, then sets back down on its wheels and drives away. Perhaps full walking isn't needed; the legs could be "power assist" to jack the vehicle across the tough spots.

Another possibility for increasing efficiency would be to put wheels on the ends of the legs. Ooh, a rollerblading robot!

But indeed it might make sense that the legs would allow a wheeled vehicle to slowly move itself over very rough terrain, never getting stuck. Particularly a robot not in a hurry. The wheels (especially if independently driven) could apply forward motion if they touch things, though doing that in a way that doesn't tumble the robot over might take some work.

The design of AlphaDog seems ripe though to have the legs come up and rest on wheels, or also to insert a chair in it, possibly reclined so the legs don't dangle too far down -- because when the robot slips its body can get close to the ground. Of course if the robot is going to tip over, you can't readily carry people. But I know that Boston Dynamics helps to sell this as a transport for wounded soldiers so they hope for a tip-free robot. Their inspiration is the mountain goat, which can do pretty amazing things on 4 small hooves.

As it happens, I'm in Greece now, and hilltop towns with pedestrian-only "streets" (narrow, and with stairs in many places) are common on the islands. They evolved as anti-piracy measures, being easy to defend and hard to raid. The solution, then as now, for bringing heavy materials into the inner houses, is donkeys,

That said, given the maintenance and performance of donkeys, a cheap Alpha Dog could take over the market, just as cars took over from horses everywhere else.

We've all seen these non-car "streets" but today people shy away from building anything like that. What I am speculating is that walking robots (for cargo or people) might change how people think about this, and as a result open up all sorts of new real estate to new uses (and at lower prices.) For good and ill.

I was thinking about how you said it could be a "roller blading robot". I thought of an idea that isn't quite that. If this were to be put in the car, for sticky situations like the listed above, what if instead of having the legs folded under or around the car, the wheels where parts of the legs. I'm not trying to go transformer on you guys, but looking at the AlphaDog and its legs and hooves, when I look at it, I can picture wheels on the inside side of the bottom half of the legs, so that when a car is stuck or such, it rolls up onto its "legs" instead of having them fold out.

Wishful thinking? Maybe.

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