[PSUBS-MAILIST] Underwater GPS for divers

[Sean T. Stevenson via Personal_Submersibles]

"11 independent sensors"

I'm going to assume that these are the 9 typical axis measurements in an IMU (3 orthogonal accelerometers, 3 orthogonal rate gyros, and three orthogonal magnetometers), plus the gps (useless except on the surface) and a depth sensor used to fix position / velocity in the Z direction? There's not specific discussion of error in the article, but I'd be really surprised if the position uncertainty didn't continually accumulate in the absence of a DVL or some other means of limiting the integration error in the horizontal plane. I played around with an IMU many years ago - neat device, except it did periodically need external correction to zero the accumulated integration error. GPS will do this at the surface, and a depth sensor will do it for one axis at depth. Deadband can help, but then you have a minimum speed of movement at which the device will work. Call me skeptical, but I'd like to see the tech specs.

Sean



On March 6, 2016 11:58:09 AM MST, "Al Secor via Personal_Submersibles" <personal_submersibles at psubs.org> wrote:
>Interesting navigation device using a combination of GPS and inertial
>guidance could be  useful for psubs....
>
>http://scubadiverlife.com/2016/03/05/project-ariadna-will-offer-gps-for-divers/
>
>Al Secor
>_______________________________________________
>Personal_Submersibles mailing list
>Personal_Submersibles at psubs.org
>http://www.psubs.org/mailman/listinfo.cgi/personal_submersibles
-------------- next part --------------
An HTML attachment was scrubbed...
URL: <http://www.whoweb.com/pipermail/personal_submersibles/attachments/20160307/65247c6a/attachment.html>