Sean Lynch wrote:
On Tue, Dec 17, 2002 at 01:26:37AM +0000, Ian Woollard wrote:
I was wondering whether it might be possible to make an accurate
gyroscope out of a ball bearing floating in an air bearing.
In principle you just start it spinning before launch, point 3 or 4
optical mice at it, and read off the rotation; it should be quite
accurate, fairly light, and reasonably cheap.
Comments?
Unless it's bumped.
Don't think that's a problem physically- you can ensure that the pressure
is high enough that the ball won't touch the sides and the electronics can
cancel any slight lateral movement easily enough.
I would imagine that reading the rotation of the bearing would be
significantly more complex than pointing optical mice at it. Optical
mice are designed to read textured surfaces, and a ball bearing would
need to be quite smooth to avoid being affected by movement of air.
Not sure, a few scratches or paint spots wouldn't disturb the air much, and
the spinning would help. Well, it could be an issue, but it's soluble. Alternatively,
inductive pickups would work, but it's probably messier.
I don't really see the problem with FOGs. They're not particularly
expensive when you get anywhere above the scale we're working at now,
I thought they weighed in at around $20 k; didn't Johns cost that? I think
that's fairly expensive. Are there cheaper ones? I was wondering about how
to do guidance for an orbital capable vehicle I'm thinking about. Probably
need under a degree accuracy over 5 minutes.
and for our current scale, decent solid state gyros should work fine
($50-$150 range).
I believe they have a drift around 1 degree/second, great if you have GPS
to compare against, but GPS capable of orbital velocity cost $10k or so?
