So I finally got a chance to take the ROV out for a test. I knew that there was a buoyancy issue as it floats to high in the water. So I took along a bag of small pebbles and some zip lock bags.
It turned out that I need an extra 700g of weight to get the ROV almost neutrally buoyant in the water. So I’m adding a bracket to hold some square plates that gives me 100g a plate.
The video isn’t all that great but it shows that the system works. Notice the bags on top with blue tape on.
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I have reprinted the brackets for the battery to accommodate two M8 bolts to hold my ballast weights. The ROV has now an extra 800g of ballast and now I only need some good weather to do a second test.
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Some of you might remember my ROV project https://www.robotshop.com/letsmakerobots/node/19254 that I made for my kids and me. It failed miserably as I never got the USB webcam to work over the 15m CAT5 cable and the whole project went on a shelf (it was destined for the bin, but I couldn’t bring my self to throwing it away).
As this is a complete rebuild I’m starting a new page instead of updating the old project. I hope that’s ok.
I felt that my initial design of having 40mm PP plastic tubing to hold the electronics and motors, and the battery below as power source and ballast where sound so I kept this design.
The webcam where replaced by a CMOS/CCD car rear view camera. That had the added effect that I no longer had to bring my PC along to view the video stream. So I bought a cheap 7” LCD TFT monitor and found myself a great case to mount it in.
There are plenty of room inside for my Arduino, power regulator and LiPo battery
And on the lid I have a spool for the cable
The drive system is still the same and uses my custom made stuffing-box / motor mount. They are still driven by the serial motor driver from Pololu http://www.pololu.com/catalog/product/1110 The motor drivers work great and I had no problem stacking two of them together inside the 40mm pipe.
I’ve also gotten a 3D printer sins my first attempt and could print out all sorts of stuff for this project.
One of my biggest problems with the ROV was how to get at waterproof connection to the CAT5 cable. I dident want to permanently mount the cable to the ROV so I got myself some waterproof connector and packed Sugru http://sugru.com/ around the cable and penetration. It made a solid but yet slightly flexible bond.
The pipe fittings them self are not glued together but there is a rubber gasket inside the fitting that makes it waterproof. On top of that I added some self vulcanizing tape on the joints to aid the waterproofing. On that several layers of paint.
Some more pictures of the ROV
I got it reassembled after painting today, but it has been raining all weekend so I’ll put up a video sometime next week (hopefully).https://www.youtube.com/watch?v=hHEg8KjKNwE