On Wed, 29 Oct 2014 11:12:37 -0700, gyansorova wrote:
> I suppose we could talk Kalman filters, but no, something more
> practical.
>
> When we sent to the moon and came back, we must have aligned the gyros
> on the moon. What reference did we use and how accurate is that?
If you know the rate that you're rotating in the inertial frame to well
within the accuracy of your gyros, you can adjust the bias until the gyros
read what they should. We know how fast the moon rotates in the inertial
frame, so there's your answer.
Alternately, if your gyros are gimbaled, you can align their axis of
rotation along your axis of rotation and null them.
Given that Kalman filters were pretty much developed FOR the space
program, I wouldn't be much surprised if some variation of it wasn't used
in flight -- if the gyros and accelerometers are accurate enough, you
could align the craft with the occasional astronomical sighting, or
possibly radar ranging of various handy objects like the moon, the earth,
or a report of the position of your craft as seen by earth-based radar.
--
Tim Wescott
Wescott Design Services
http://www.wescottdesign.com
Reply by ●October 29, 20142014-10-29
I suppose we could talk Kalman filters, but no, something more practical.
When we sent to the moon and came back, we must have aligned the gyros on the moon. What reference did we use and how accurate is that?
Hardy