Wired comms to ArduRover (for underwater use)?

Posted by bigkahuna on August 4, 2015 at 8:02pm

Has anyone used wired comms (not wireless) to their ArduRover project?  I'm looking at how I might use ArduRover for an underwater ROV and the first requirement will be that I communicate via a wire (preferably a single twisted pair).  The idea would be to use the Mission Planner to navigate the ROV on the water's surface to the desired location and then go into manual mode and dive underwater.

Another issue I'll also have to tackle will be how to modify the code for vertical thrust (to move the ROV up and down).

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Replies

  • Víctor Mayoral August 7, 2015 at 12:53pm

    @bigkahuna, I doubt it. The student has had several issues and this will probably push back the dates/outcome. Nevertheless, the student seems motivated and he's mentioned his will of continuing coding after the GSOC period ends.

    @Craig, there's no docs prepared yet. Code is not ready yet and needs to tested in hardware.

  • Víctor Mayoral August 7, 2015 at 12:33pm

    Hi everyone,

    There's an existing project that is porting the OpenROV code to APM supported by the Google Summer of Code: BeaglePilot 2.0. The code is being maintained at https://github.com/BeaglePilot2/ardupilot.

    Also see APM Submarine

    Regards,

    BeaglePilot2/meta
    Contribute to BeaglePilot2/meta development by creating an account on GitHub.
    • Developer
      Craig Elder > Víctor Mayoral August 7, 2015 at 12:46pm

      Victor, do you have some documentation on this work?

      https://github.com/BeaglePilot2/ardupilot/tree/master/APMsubmarine

      BeaglePilot2/ardupilot
      APM Plane, APM Copter, APM Rover source. Contribute to BeaglePilot2/ardupilot development by creating an account on GitHub.
    • bigkahuna > Víctor Mayoral August 7, 2015 at 12:42pm

      Wow!  Looks awesome Victor.  How far a long is the project?  The schedule shows a completion sometime this month, is that likely to happen?

  • Ben August 5, 2015 at 6:52am

    You know on subs, we used a towed array to for coms. It's basically an antenna with a float on it. I've been thinking about doing a submersible rover, and it's the cheapest thing I could think of. Bassically you can have 15 feet or what ever your max depth is on a clock spring reel. So as you go down the spool spring would fight the float to extend line. When it comes back up, it will wind on it's own, and it will give you a good visual indicator on the top of the water. 


    one last thought, a cheap tape measure guts might just work in that application. 

    • bigkahuna > Ben August 5, 2015 at 8:09am

      @Ben - That's actually been done.  But in my particular application the risk of snagging the wire would outweigh the benefit I think.  One advantage of having a tether is that if you get lost (and in poor visibility and no sonar that happens) you can always pull on the tether to retrieve the ROV.

    • bigkahuna August 5, 2015 at 6:54pm

      Normal Cat5e patch cord (stranded) is too weak IMO.  "Tactical" grade Cat5e is considerably tougher, and yes, stiffer.  Low cost, off the shelf, tether cable is pretty hard to find.  You either have to buy excess stock from a manufacturer or make some compromises.

    • David Skipper > bigkahuna August 6, 2015 at 5:36am

      http://www.vdctrading.com/shop/van-damme-cable/data-lighting/tourca... 

      how about this ?

    • bigkahuna August 6, 2015 at 6:49am

      How tether thickness and weight effect the ROV really depends on how big and heavy the ROV is.  ROV tethers, in general, tend to be heavy and fairly stiff.  Most I've worked with have thick, PVC covers and tightly packed centers.  On my last build I used tether I bought from Outland Tech.  Very nice cable, but I would consider it pretty stiff.

      Standard CAT5e cable has an air void which is generally a bad idea for use underwater.  Direct burial CAT5e cable uses a gel to block water ingress but is generally solid core wire so not suitable for our purposes.  Tactical CAT5e (such as what Gebco offers:  http://www.gepco.com/products/proav_cable/network/4pr_cat5Eheavydut...) looks to be the best option.  Just be sure to get the stranded core version.

      Another way of getting around this, and offering the ultimate in thin tethers, is to consider using fiber optics.

  • This reply was deleted.
    • bigkahuna August 5, 2015 at 6:07am

      @Thomas - RS485 is exactly what I was thinking, too.  Would you mind sharing your setup?  Yes, I've considered using "HomePlugs" but haven't tried them yet.

      @Craig - Thanks for the heads up.  Started to scan through some of the code and have to say it's over my head.  Is anyone else working on modding the code for ROV use?

This reply was deleted.