Re: [PSUBS-MAILIST] Auto pilots

["Sean T. Stevenson" <cast55@telus.net>]

On the subject of obtaining heading information, one solution I have used in an
industrial project where magnetometer based sensors could not be used due to
strong magnetic / electric field influences was to employ two GPS sensors,
separated by some distance.  While the absolute GPS error varies in time, the
instantaneous error at two locations in close proximity to one another will be
almost identical - thus, an accurate heading may be obtained as the vector
between the two sensor positions.  This obviously is only applicable to surface
machinery / vessels.

As for autopilot for subs, I have been playing with a 3DM-GX1 sensor from
Microstrain.  These retail for about $1500 apiece (I'm using it at work - used
on another project).  All solid state, magnetometer based heading sensing, but
possibly useful for a (relatively) low cost inertial navigation solution?  It
would just need to be mounted in a non-ferrous enclosure and positioned as far
as possible from large ferrous bodies or other magnetic influences.

-Sean







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