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Sorry that I haven't responded sooner as we have had a power
outage for most of the day on the facility where I reside. Not familiar with the Microstrain 3DM-GX1. It appears that
it is a 3-degree of freedom unit and for proper navigation 6-degrees of freedom
are required…3 gyros (with low drift) and 3 accelerometers. You can review the
IMU 6-DOF v2 unit at www.sparkfun.com that I briefly glanced
over. They do not provide drift information and this is critical for
determining the accuracy of your dead-reckoning. If the drift of this unit isn’t
bad, it still has to be integrated into a nav package and the mathematics aren’t
inconsequential…major matrix manipulation. I believe that there are sonar units that will provide SOG
information but haven’t looked into the matter for some time. Respectfully, Jay K. Jeffries Andros Is., -----Original Message----- Jay - how do the specifications of the $300 sensor you were looking at compare to the Microstrain 3DM-GX1? Also, can an off-the-shelf sonar be
used to provide speed-over-ground? -Sean |