Newsgroups: comp.robotics
Subject: Re: WANTED: Electronic compasses and gyros.
From: greg.jackson@mecheng.fullfeed.com (Greg Jackson)
Path: brunix!news.Brown.EDU!noc.near.net!howland.reston.ans.net!vixen.cso.uiuc.edu!uwm.edu!daffy!uwvax!gorgon!fullfeed!mecheng!greg.jackson
Distribution: world
Message-ID: <af.2062.33.0NAF5F03@mecheng.fullfeed.com>
References: <DULIMART.93Oct25205508@pacific.cps.msu.edu>
Date: Tue, 26 Oct 93 18:53:00 +0000
Organization: MechEng / ASME
Lines: 24

-> (Ananth Krishnan) writes:
-> >>I'm looking for sources of electronic compasses and gyros.
->
-> There is a company called KVH in Rhode Island. I don't have the
-> address right now.  But I can give it to you later.  Please remind me
-> so.

I think the KVH guys make a fluxgate compass.  It will do a decent job
of measuring the earth's field if held horizontal, not near steel, and
not moved around much.

There are also people that make laser ring gyros which use
interferometer techniques and relativistic principles to check out
acceleration.  Those devices work wherever relativity applies (most
places I can think of) and are pretty accurate.  I think they are core
devices for aircraft navagation.  The light goes around a circle (hence
the term "laser ring") in both directions.  When the ring accelerates
forward, the light on one side of the ring is phase shifted from the
light that is currently on the other side of the ring.  The phase shift
is measured from shifts in the interference pattern as the two light
paths collide. While the shift is pretty small for non-relativistic
speeds, the light wavelength is smaller still and the system provides
good sensitivity to acceleration.  A double integral of acceleration
will yield position but watch out for integrator drift.
