From: hal@finney.org
Date: Thu Aug 12 1999 - 20:21:51 MDT
Ken Meyering, <ken@define.com>, writes:
> I have a very simple task which a muscle actuator might improve:
>
> Spinning a superball around inside a lucite (acrylic) globe.
>
> Again, for those interested in a very simple yet rewarding project:
>
> HOME DEPOT - Lighting Department
> PART # P012WA (12" White)
> 5 1/4" Neckless
> Price: $17.90
>
> And TARGET (Toy Department)
> Wham-O Superball
> Price: $1.79
You can get those hand-held exercise balls that are somewhat similar.
There is a large wheel inside whose axis is mounted in a groove on the
interior of the ball. Once you get it spinning, by torqueing the ball
you make the wheel's axis spin against one side of the groove so that the
wheel's direction of orientation rotates. This then causes gyroscopic
precession that keeps the wheel's axis pressed against that side.
By rotating your wrist at just the right rate you feed energy into the
spinning wheel and it gets going really, really fast, thousands of RPMs.
With practice you can hold your hand almost still, making tiny little
circles, and be holding this screaming banshee of a wheel which is
spinning frantically. It's pretty impressive. These things are actually
kind of dangerous and you can get a nasty burn/scrape if you touch the
exposed wheel when it is at maximum RPM.
> Imagine what you could do with hand-cranked power generation?
> Soybeans in, electricity out. Now that's a workforce!
As far as power output, the human body isn't that great. Go to the
gym and try an exercise bike or an upper body ergometer. These things
usually have a power rating in watts. It's tough to maintain any useful
amount of power for long. Maybe if you could accumulate your power
output from all day long, siphoning off a few milliwatts from each step,
it might add up to something. I saw the other day that someone patented
the idea of getting power from pressing keys on your laptop, to extend
its battery life.
Hal
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