Ardupilot goes into the water Part 1

Hello everybody,
this is my first blogpost on this site.
In the following i will describe my experience, my ups and downs while
developing an ArduPilot based depth surveying system for lakes.
I know, this site is primarily for flying platforms. Please leave a comment, if you think that this is not the right place. Maybye, some of my findings are also interesting for flying platforms.

The Beginning:

If you are a scuba diver, depth is one of your major concerns.

If you are one an unknown divespot, depth is the major concern.

Two years ago, those were my thoughts, when we went diving in a mountain lake on the North Italian side of the Alps, where nobody had been diving before us.
How deep will it go ?
What will be the structure of the ground ?
What about the slope ?

On this lake, the story started.

The native people only had speculations and stories about the lake, but nobody could tell us what we really wanted to know.

Discussion with the native people, with every beer, the depth went deeper.

So the idea was born to survey the depth of this lake prior to submerge our bodies into the unknown.

The equipment consisted mainly of a Depth sounder with GPS (aka Fishfinder), a Body-Board, a GMR walkie-talkie and me, swimming with all that stuff criscross around the lake.

The „Ground-crew“ stood on the lakefront with the second GMR, writing down my „depth-and-waypoint-readings“ .

In the evening, all the waypoint data was collected and put manually into the laptop, running an old Version of the FUGAWI software. The depth profiles were manually drawn on a few sheets of paper.

The result was not very spectacular, the profile of the lake had mainly the shape of a bathtube, filled to one third with mud.

Here i am mounting the Sonar to the Body-Board.

surveying the hard (and cold) way...

But, what lasted, more than the result of that action, was the idea of automating that process.

To be continued...

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  • I read you entire series and loved it!! Great work.
    Few of us are planning to make a similar project excluding the sonar as its way too expensive. I had a few questions regarding a few components
    1)Which ardupilot board have you used ?
    2)You mentioned using arduino where was it used and for what purpose?

    Please pardon me if the questions are very basic but this is my first project with an autonomous vehicle.
  • Hi Harald,

    Very nice post! with my colleagues we are developing an Autonomous Submarine Vehicle (AUV) and we are very motivated doing it.

    The main issue is the communication between the user and the AUV since it doesn't have an umbilical cable (i.e in a ROV). The navigation system was also complex to arrange because there is not GPS signal underwater. This was solved using dead reckoning navigation and a built-in Kalman filter in order to integrate and filter the IMU data and hence to obtain the actual vehicle position.

    As you see, it is a challenging project and in fact this is my first comment in the diy drones community. I'm looking forward to continue learning and developing this exciting project, to share it to the community. Now we are in prototype tests and making efforts to develop the AUV, to use it for biological, oceanographic and marine research.

    Thank you for sharing your work, I hope someday to share ours :)



  • It is good to know that such a depth sounder is out there.

    I am looking for a depth sounder that can measure to 9 feet and cost $20. I want to be able to detect when the bottom is coming up to beach me.

  • Peter,

    depending on what depth you want to measure, there are a lot of options...
    A realy small one is the Garmin Intelliducer.

    I already have used it, but you have to make a data fusion between GPS and the sonar data.
    I have made this with an Arduino Mega, the OpenLog from Sparkfun and an EM406 GPS and it worked fine.

  • I have been looking for a depth sounding sensor to add to my APM controlled sail boat.  Do you know of any small depth sounding sensor?

  • Herald, I bought the book that outlines and detailes your section on roboat. My question is regarding the Arduino Skript(Code) to get the heading from two waypoint. The Function to calculate the course between two waypoints shows to multiply by the number "69.1" How and where did you get that number? If you could let me know I'd appreciate it.

     You can email me as well to vann_solo at yahoo dot com


    Harry vS

  • I'm also interested to know if ArduPilot may be adapted to marine use. Keep us posted on your progress!
  • You can combine this with DrDepth: . It generates depth maps form GPS+Sonar data.
  • Arrghh, need part 2. This is not fair :-)
  • I'd like to join the native people for a beer.
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