Re: HP, weight and visability

[Jon@huv.com (Jon Hylands)]

On Fri, 10 Apr 1998 20:10:01 -0400 (EDT), Jonathan Wallace <jon@whoweb.com>
wrote:

> I was reading about sub navigation on the HUV web page and had
> a thought.  For short depth excursions, does it make sense to
> tag along a surface antenna with appropriate wiring to the sub
> so that GPS signals can be transmitted to the sub interior?

I think it would complicate things somewhat. You have to worry about
snagging it on stuff, or dragging it into a boat (what if it got caught in
a propeller and started reeling your sub in?).

I think a much simpler solution is to do dead reckoning while submerged,
and readjust when you surface. Or perhaps have an antenna on the end of an
eight foot cable, so you don't have to completely surface.

For a sub that stays more or less level side-to-side, and only pitches a
small amount (say less than 45 degrees) up or down, I would say that a dead
reckoning system would be very easy. You can buy an electronic compass
module that handles direction, pitch, and roll, or you can just rig
together some sensors for yourself for pitch and roll and use a simple
compass like the Vector 2XG.

Once you know where you are in three dimensions (approximately), you can
use depth charts on the computer to animate a three-dimensional terrain map
of the bottom with respect to where you are. You can also use a depth sonar
to corroborate information from the chart.

I'll be using most of that type of technology for my AUV (Micro Seeker),
and I for one will be very interested to see how well it works in practice.

Later,
Jon

--------------------------------------------------------------
   Jon Hylands      Jon@huv.com      http://www.huv.com/jon

  Project: Micro Seeker (Micro Autonomous Underwater Vehicle)
           http://www.huv.com