[PSUBS-MAILIST] Ping 360 Scanning Sonar

Fri Sep 27 04:40:12 EDT 2019

Hi Ian,
I was going to describe a similar set up to your tethered buoy idea,
but left my message brief.
The tricky part would be the direction finding sonar.
I had thought of a tethered buoy with a device underneath that 
determined the angle of the tether. Lots of variables though, like a bow
in the tether if you turned back on your path. At a depth of 250ft your
position could go out by quite a bit, & current could effect it.
With the motorised buoy idea you would have 2 small RC boat motors
giving tractor steering & an array of 4 or 5 sonars. There would be 1 sonar
pointing down & the others pointing outward on a slight angle. The buoy
would move toward the strongest signal, continually attempting to keep the
buoy directly above the submarine. The buoy would have GPS, & send it's
position periodically via an acoustic signal to the sub. The sub in turn would
send speed & directional information to the buoy so that it could predict
It's required speed & direction.
I REALLY like my idea of hacking a standard boat chart plotter & feeding the
GPS signal from the Buoy in to it. That way every thing is plotted, you can put way 
points in & easily go back to any points of interest. Possibly synchronise readings
from an electronic depth gauge with the chart plotter.
You will have fun going about it bit by bit the way you described. That's probably
a wise approach. If you are diving in the sea the tidal currents will add another
level of complexity.
As a diver I have had a lot of trouble at times finding a cray hole I thought
was easy to find again; so have no illusions as to how difficult it is navigating
under water.
Alan

> On 27/09/2019, at 7:19 PM, irox via Personal_Submersibles <personal_submersibles at psubs.org> wrote:
> 
> 
> Hi Alan,
> 
> you're right, it's probably a lot of work to get to that stage.  Also a
> lot of components and complexity to keep dry and reliable, I feel that
> that might be half (or more) of the challenge.
> 
> I would start with a smaller part first, like a compass using a fiber optic
> gyro and a 3D flux gate compass.  Then get some experience dealing with the
> issues of reliability of more complex/sensitive electronics in a sub-interior
> environment. Once I think I've got some electronic-environmental solutions,
> I'll look at getting a simple sonar setup. And just keep building from there.
> 
> For your powered buoy, will it be able to relay position data back to the sub?
> 
> I had an idea for using a tethered buoy to do positioning.  The buoy would be
> tethered with an ROV cable which was strong enough to be the sole tether and
> could do (relative) high speed digital comms between sub and buoy.  The buoy
> would have a GPS receiver and an acoustic pinger on board.  On board the sub,
> a direction finding passive sonar (3 or more transducers) and a digital depth
> gauge.
> 
> To get the sub's position, send a command to the buoy to return a GPS reading
> and send a ping at the same time, simultaneously take the sub's depth reading.
> Once you have the depth of the sub (digital depth gauge), the direction
> of the buoy (direction finding sonar), and the distance from the sub to the buoy
> (time from the ping sent to ping received), it's a bit of trigonometry but you
> can determine the position of the sub relative to the buoy. This sub-buoy position
> delta would be used as an offset to the returned GPS coordinates, giving the
> actual position of the sub.
> 
> 
> Cheers,
>  Ian.
> 
> 
> 
> -----Original Message-----
>> From: Alan via Personal_Submersibles <personal_submersibles at psubs.org>
>> Sent: Sep 26, 2019 10:50 PM
>> To: Personal Submersibles General Discussion <personal_submersibles at psubs.org>
>> Subject: Re: [PSUBS-MAILIST] Ping 360 Scanning Sonar
>> 
>> Hi Ian,
>> that sounds like a lot of work. Good project though.
>> I am still looking at options for getting a GPS signal in to a standard chart
>> plotter. Best prospect so far is a motorised buoy with GPS & sonar array
>> to track & follow the sub. I may be tempted to pursue it as I have access
>> to a sonar expert.
>> Cheers Alan
>> 
>>> On 27/09/2019, at 4:16 PM, irox via Personal_Submersibles <personal_submersibles at psubs.org> wrote:
>>> 
>>> 
>>> Hi Alan,
>>> 
>>> one of your fwd's from Blue Robotics had links to it, it looks really neat.
>>> Probably the most exciting part is the open source aspect, since we can
>>> potentially customize the software to our needs.
>>> 
>>> One project I'm interested in advancing is combining FiberOptic Gyros, Mems
>>> accelerometers, 3D flux gate compass, and sonar, as part of a underwater
>>> navigation, mapping and positioning system.
>>> 
>>> Essentially, the IMS sensors are used to understand short term movements of
>>> the sub (drift won't be a worry short term), which helps with accurately
>>> determining the positioning of the sub relative to the sonar targets.
>>> Then do characterization analysis on the sonar data to determine which
>>> objects are static (not moving) and objects not persistent (moving or unreliable
>>> to image with sonar).  This allows us to generate a persistent sonar
>>> image/map (remembering all the things that were observed previously), and use
>>> the previously identified static objects/characteristics to accurately determine the
>>> sub's current position/location via sonar and IMS data.
>>> 
>>> I did build part of a proto-type for this a few years ago, but other things
>>> came up.  I think this would be great thing to add to Gamma. :)
>>> 
>>> Cheers,
>>> Ian.
>>> 
>>> 
>>> -----Original Message-----
>>>> From: Alan via Personal_Submersibles <personal_submersibles at psubs.org>
>>>> Sent: Sep 24, 2019 12:42 AM
>>>> To: personal_submersibles at psubs.org
>>>> Subject: [PSUBS-MAILIST] Ping 360 Scanning Sonar
>>>> 
>>>> Hi all,
>>>> thought this video on the Blue Robotics "Ping 360" scanning sonar was good,
>>>> https://m.youtube.com/watch?v=yXYo2c0TSJY
>>>> I am not sure whether it was on their site last time we discussed it.
>>>> It is rated to 300 meters.
>>>> Alan
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>> 
>> 
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