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."

Comments

Re:Cats landing on their feet

[Rob Carr]

Cats reposition themselves to land on their feet because they can sense the change in velocity (dv/dt = acceleration). My professor stated this only works for small height values (less than 20 ft), otherwise, the acceleration due to gravity might result in an unpleasant aftermath.

Actually, it's the short falls that tend to kill cats. Cats (like skydivers) can assume a position that reduces the terminal velocity and presents the greatest surface area for impact, reducing the force per unit of surface area. It takes a while to rotate and get into the position, so if the fall is too short, the cat will land in an awkward position and is far more likely to die.

This is not to say that the cats that fell from a great height were uninjured - just that they were more likely to have non-fatal injuries.

I wonder...

[Unnngh!]

...if the robot can survive terminal velocity falls like cats. Cats falling from very high heights (i.e. skyscrapers) tend to survive the fall better than those falling from lower elevations.

Re:Like a...?

[Rei]

There are serious applications for this. Namely, being able to orient yourself in space without using propellant is a very valuable ability.

The real surprise is that this is nothing radical; I really don't get why it deserves a press release. Probes have been using momentum wheels, for example, to do the same thing for decades. What is the big advantage of this over, say, a small set of momentum wheels? All I can really say about it is that it's more complex, and seems more likely to wear and have part failures.

Story Musgrave

[Ferante]

In grad school one of my physics professors wrote a paper on orienting onself in zero g with no net angular momentum. One student was just convinced it was impossible. Soon thereafter we were visted by Story Musgrave (one of astronauts who fixed Hubble) and the professor told him of the paper. Story immediately sat down on a swivel chair and demonstrated the motion necessary to turn in zero g without grabbing on to anything. It's interesting how a concept that caused some interesting debates among the students suddenly became obvious when it was directly demonstrated.