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Comment by Cuuugi | Hacker News Reader

So does a car. Whats your point?

It's a pity this was downvoted because that's exactly the sort of thing against which new tech should be tested.

So, to really answer the 'what's your point' question I think the point is that bipedal could be more energy efficient than wheels and that feet can go where wheels can not.

> I think the point is that bipedal could be more energy efficient than wheels and that feet can go where wheels can not.

The second one, absolutely. As for the former, I don't think you can get any more efficient than a wheel on a flat track - certainly biped movement is a lot less efficient since you need to work against gravity.

The perceived efficiency of bipedal movement comes mostly from the ludicrous efficiency of biological actors when converting chemical into kinetic energy – a cyclist (or even runner) can go a day on the chemical energy that would get a motorcycle to the next petrol station [0].

Also consider that even the fastest bipedal runners tend to go much slower than any motorised vehicle, and even quadruped animals rarely reach into what is considered standard with cars.

[0] The guideline daily amounts for a human are roughly 10 MJ, from personal experience, cycling a bit during the day only increases that marginally (e.g. 10-20%). It seems reasonable to claim 1 MJ per 100 km cycled, whereas one kg of gasoline (~1L) is at ~42 MJ. Given the usual 1-10L/100 km, 1 MJ appear to correspond to a few kilometres.

Here is a trivial proof of the former: take an elite biped marathon runner on foot vs an older marginally in shape biped like myself on a bicycle, and on my bicycle I can beat the elite runner quite easily.

Another way to model it is I can quite easily maintain 10 MPH without much if any sweating on a bike trail, but on a calm hike with the kids on the same trail I struggle to achieve 3 MPH average.

I think the fact that cars don't use bipedal locomotion to achieve fast velocities is the point.

I am not aware of any bipedal cars, and I think that's the point here. A machine that moves like human, yet for the first time ever can actually do it faster than we can.

It doesn't move like a human. It has digitigrade legs and a forward-backwards horizontal balance thing. It runs, I guess, like a raptor.

It's not a big shock that things built for speed can run faster than humans can. Horses can also run faster than humans. So can cheetahs. Ostriches, if you want something bipedal.

Exactly. It also can't move in any of the other ways a human can, it certainly won't be climbing obstacles.

It's not as if humans are the pinnacle of power efficiency. We're versatile, but inefficient. So if you're going to compare a machine to human movement, it should be on the basis of versatility. A car is way more efficient than a human at moving on a flat track.

A human uses less energy going a mile on foot than a car does. So for one definition of efficient, the human wins. They should still win even if they are carrying a modest load.

I guess I would have used effective where you said efficient.

(If you add in the energy used by modern agriculture to produce the food the human ate, the car probably wins: http://ideas.4brad.com/holy-cow-walking-consumes-more-gasoli...)

http://www.youtube.com/watch?v=aIwCwwrDnGI The wheel of cheese rolls effortlessly down the hill with no power source, while the bipeds all end up turning into makeshift wheels trying to catch up to it.

How much of that comes from bipedal motion, vs the way that humans break down their food?

How much energy does a human use when he carries a car for a mile?

I'm curious how I could have better phrased my comment so as to not invite responses like this. I guess I realize that 'efficient' vs 'effective' is a quibble, but I was trying to respond to the ambiguous usage of 'efficiency', not trying to give the final answer on the comparison.

Sorry, I realized you were trying to be circumspect, I just was instantly visited with a vision of a guy trudging around a track with a car on his back.

Cars aren't bipedal so no, a car doesn't "run" faster than a human.

Cars can't jump over obstacles, climb stairs, or traverse rubble.

Hrm, seems like an opportunity :)

Paving, for the win!

I was originally thinking along the lines of hillclimbing jeeps. But imagine a treaded vehicle that could automatically level and pave a road. There are these things https://www.youtube.com/watch?v=jkVBg_-OviI and these things https://www.youtube.com/watch?v=3ZMPoHahaj8 but they all look like they're running on ground that has already been cleared and leveled. It would be really interesting to see something that could dig through ground and rock like a tunnel digging machine and compresses the material into tile blocks to use as pavers.

One key difference is friction. With wheels there is continuous contact with the substrate, which means continuous friction and thus energy loss. Since this robot has an aerial phase, this should be considered an advancement towards the energy efficiency of most land animals who only* lose energy due to friction when in contact with a substrate.

Edit: *not factoring wind resistance, which is present regardless of mode of locomotion.

Simple really, robots will do most physical jobs better than us and society needs to adapt to that. They will also be used in tasks we find disgusting like military conflict. Seeing how little real outrage drones deaths are causing; mostly because of deft political handling of the press; do you think employing robots against "other people" really is going to be much different?

The best outcome is that the onset of robots doing much of the work is that it frees enough of the world from economic strife to end the need for warfare.

> frees enough of the world from economic strife to end the need for warfare.

While this sounds good, I'm not sure this would happen for two reasons:

- we'd have to completely change the system of work / salaries / resource allocation - the way we're going right now we'll end up with smaller number of companies providing services / resources to huge society that is much larger than needed to support those companies

- I don't believe people have a need for warefare... they may actually be more interested in it, assuming their other daily needs are satisfied in an easier way

Why do you think automating much more work would make life better for people in general?

The world has economic strife not in the least because of greed, and violence not in the least because of the lust for power. I am afraid more efficiency might not necessarily reduce those, it might even enhance them.

Biologicals still have an edge - the power-plant issue. Until batteries get a LOT better, or fuel cells get cheaper, a person that lives off of peanut butter and lemonade is a real advantage.

Especially since a very active human will only require the energy equivalent of a liter or two of gas per day.

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