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Like A Cat, New Robot Lands On Its Feet
eckenheimer writes "Students at the Physics Department at Drury University have developed a robot that uses motions and contortions of its body
to orient itself in zero gravity. According to the project site, 'If you've ever seen a cat land on its feet after falling while upside down then you've seen the idea behind our project.' The effort is a proposal for the NASA Reduced Gravity Student Flight Opportunities Program."
I see no completed robot, no performance data or even a simulation of how it will perform in the real world. Just a REAAALLY bad web site (No page navigation? Come on!) and some digital photos of these kids and their drawings. The dates in the pages and some photos are from fall of 2003. If these were college seniors (as it says in the "meet the team" section) at the time they have already graduated by now, and abandoned these pages.
How is this newsworthy?
But their project is about " a robot that uses motions and contortions of its body to orient itself in zero gravity" but they describe it using a situation caused by gravity "If you've ever seen a cat land on its feet after falling while upside down then you've seen the idea behind our project."
Statistics show that there are more feline fatalities between floors 3-10 then[sic] there are after 10.
I bet statistics also show that there are more buildings with top floors between 3-10 than there are buildings > 10. But what do I know?
Why would a robot (or human for that matter) designed for zero g require feet? Go back to the drawing board... replace those feet with a couple more arms.
"No one brings a clearly dead cat to the vet."
If the fall is high enough, the odds of living decrease and therefore no cats are brought to the vet unless they miraculously survived. The study self-selects for those cases. Ergo...bad stats. Grrr...the bane of my social sci existence.
do the math you twit. Perpetual motion is still impossible because toast doesnt care what side it lands on when it's already got fur all over it.
-- 'The' Lord and Master Bitman On High, Master Of All
I'm no scientist, all I know is that my cat fell from my apartment on the 17th floor and was really fucking dead after that. Where she landed there was no big mess, no blood coming out of her mouth, really pretty clean so I guess her landing was perfect. But at that height it didn't matter.
Obviously my one cat "study" isn't the scientific method, but if your average living mammal falls from 17 floors up, they will mostly fucking die and skyscrapers are even higher. I've smacked mice and rats off roofs about 50 feet high with a baseball bat and they survived and limped away, but I don't know about cats falling from skyscrapers.
Then your statistics class was flawed.
I'll grant that people are less likely to bring a dead cat to the vet. But that simply won't explain the data.
Trauma produces a spectrum of results, from "uninjured" to "dead." The curve is basically bell shaped, but as the forces involved increase the curve will skew toward "dead."
Let's divide the result of the cat impact up into 6 groups:
We can assume that most dead cats and most uninjured cats are not brought to the vet. Still, the shape of the curve we see (i.e. brought into the vet) tells us about the shape of the curve we can't see. For short falls, there are many more of "eventually fatal" cases and far fewer (in proportion) of the others we see. In contrast, for the falls from a greater height, cats were far less likely to die if they made it to the vet at all. This implies that either a) greater falls give cats a chance to impliment a survival strategy or b) greater falls are less likely to kill the cat if the cat does not die instantly. "B" would be truly bizarre.
What we would expect to see based on the physics backs up the study as well. Cats have been repeatedly observed to go into a "drag" mode if given enough distance to fall. Terminal velocity for the "drag" mode would be far less than the terminal velocity of the non-drag mode. Cats entering "drag mode" have been observed to slow down - just as a parachutist going from "tumble" to "drag" mode slows down. This means that the cats slow down - if they don't get the chance to slow down, then they will be going faster than if they have enough time to fall. The "drag" position also allows the cat the most surface area to impact on. The force per unit of surface area is far less, whereas a cat that lands on it's feet has a far, far greater force per unit of surface area - something that's more likely to produce massive trauma damage.
And there's the final clue. Above a certain height, there's no significant change in the type and severity of trauma seen. Once the cat hits terminal velocity, additional altitude doesn't change outcome.
This sig seemed like a good idea at the time....
I'd have to disagree...
I remember experimenting with my cat growing up to see how short a height it could recover in over a sofa cushion.
I remember being pretty amazed at how short a distance it could twist around in. I think it was definitely under a foot in height that it could land on its feet in. Anything less it could still manage to land on its side ad least.
I don't think that a fall of about 8 inches could be considered life threating for a cat.
First, there is no bell curve in this study. They reported "Three of the cats were dead upon arrival and 8 more died in the next twenty-four hours, leaving 104 living cats or about 90%". All we know is that 104 of the 115 cats survived. There is no data as to the amount of trauma they incurred, so dividing them into 6 groups is pointless.
Secondly, we don't know how many cats are falling from places in the first place. The data could be supported if 10000 cats are falling and 104 survived. Doesn't sound good to me.
Alternate theories abound and are not disproven either. If there was an intervening circumstances (trees, awnings, boxes, flags, etc), that would allow a small % to decrease speed some. Or maybe some cats are less prone to die. Maybe between 5-10% are very light weight cats. There is no data given to a margin of error, so 5-10% could be completely realistic when no population size is known.
If your cat fell from a 5 story building and had a 10% chance of living and you brought the barely living cat in, we now have a cat in the study, but the cat has a much better than 10% chance of living because the cat already wasn't splattered.
Keep doing that for higher and higher heights. A 5% chance of living and then bring the living cat in. The cat initially had a 1 in 20 chance, but now that it's at the clinic it's already lived, so the odds are a heck of a lot better than that. Everytime a cat survives from a higher and higher fall, the odds in the clinic keep getting better and better because the surviving cats are part of a smaller and smaller group of "cats that survive falls".
I like that the rebuttal has no scientific value but is still rated +5 Insightful. Nothing about thermodynamics, just the supposed emotions of toasted bread.
You rejected a perfectly valid and testable hypothesis without citing any expermiental results. Who's post had no scientific value?
I like that the rebuttal has no scientific value but is still rated +5 Insightful. Nothing about thermodynamics, just the supposed emotions of toasted bread.
A joke theory cannot be rebutted by a scientific response. A joke theory can only be refuted by a better joke.
-a