A PVC pipe ROV

Waterproof Housing, Frames, and Buoyancy Methods.
RonGinger
Posts: 6
Joined: Feb 1st, 2015, 8:32 pm

Re: A PVC pipe ROV

Post by RonGinger »

I considered using the OpenRov electronics but the more I studied it the more complicated it looks. I have settled on using two Arduinos connected by RS485 serial communication. I have the basic program written now, working on details. It looks like I will have to use a Megga on the top end for pins- I want to add a simple LCD display and need inputs for two joysticks.

I have purchased a fishing camera and also a simple security camera- this was only $19 on Amazon. My grandson made a pan-tilt mechanism on our 3D printer. I have stripped down the security camera to its single board. I dont think I will use the waterproof fishing camera just use the monitor and box.

The cat5 has 4 twisted pairs, I will use one for the video signal, one for the RS485 pair and one pair as ground. I have thought about using the last pair as a separate RS485 link and have an uplink and a downlink pair, but I dont think that is necessary.

Initially I will have very minimal uplink info, just a battery voltage and a bilge water alarm. I want to add things like pressure and many even an IMU like OpenROV has done. But first i will be happy with just simple controlled movement and a video feed.
hobbydude
Posts: 24
Joined: Nov 18th, 2013, 8:28 pm

Re: A PVC pipe ROV

Post by hobbydude »

Great work so far. I would like to know how well those watertight connectors go for your thuster wires. Would be good to weigh up the ROV with equivilant to your gear plus a bit and lower to 30m for water leak testing. Tie of a second rope to assist with retrieve.
perfo
Posts: 151
Joined: Jan 27th, 2015, 12:05 am

Re: A PVC pipe ROV

Post by perfo »

I too am going a very similar route to you and using standard foul pipe (150mm) it is pretty sturdy and I'm not expecting any problems due to plastic fatigue. I do have a concern for my screw on end caps though so time will tell on that. I plan on filling my ROV with a slight positive pressure with dry nitrogen. That should keep any condensation to a minimum and I have a pressure sensor in the hull to tell me if I have a leak...

I'd be pleased to find out how you get on with those end caps....
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TigerShark
Posts: 108
Joined: Jan 7th, 2014, 2:43 pm
Location: Washington State

Re: A PVC pipe ROV

Post by TigerShark »

These plugs that expand with a wing nut work pretty well to seal pipes:
https://sites.google.com/site/mbbackus/robotics/nxtsub
I think you might have issues with a thread in closure. Mine leaked pretty badly. You need something that actually seals better with pressure, threads prevent that unless it is very tight and has an o-ring at the bottom.
perfo
Posts: 151
Joined: Jan 27th, 2015, 12:05 am

Re: A PVC pipe ROV

Post by perfo »

I do intend to put a rubber gasket at the end, so finger crossed they will do the trick...
RonGinger
Posts: 6
Joined: Feb 1st, 2015, 8:32 pm

Re: A PVC pipe ROV

Post by RonGinger »

I should have updated this a while ago. My results have not been very good. I have had a LOT of trouble with the arduinos and uploading new code to them to test. I have discovered that code that sends serial data fouls up the bootloader process. I bought a separate loader module from Sparkfun and have some better success, but it is still very slow and painful and with many failures. I do not understand how arduino has become so successful with all the troubles I have had loading. From reading many forums I am not alone.

I did get some code that reads my joysticks, sends it via rs-485 to the ROV and then drives the correct servo motors.

I tried a float test with disastrous results, due to a dumb mistake on my part. When I made the main hull I drilled a circle of holes around the end to hold on the end and press against the O-ring seal. I set the hole depth by measuring the thickness of the PVC sheet I had to make the end. But the clear plexi I used for the camera end was a bit thinner and the screws bottomed before applying pressure to the plexi. Simple solution, I ordered a box of SS washers to add under the screws, but when it came time to do the final assembly I forgot the washers. When we tried the float test the hull rapidly filled with sea water. I was so determined to see the thrusters run that I tried them for a few seconds.

In the end I thoroughly doused the interior and electronics with sea water. That stuff is a terror on electronics. It ruined my Lipo drive battery and the 5v logic battery along with some other wiring.

I put it all aside for a few weeks, then decided to try again. I have water tested the hull with fresh water and no electronics, and renewed all the wiring and electronics. I had all the controls working on the bench, but when I inserted it into the hull I guess some wires came loose because I cannot get it to work now.

I have decided to throw in the towel. I have placed my camera and video monitor on craigslist and would be happy to sell the blue robotics t100 thrusters, with or without the hull. I have many other projects I want to work on and this one has taken all the time I want to put into it.
Bindo
Posts: 112
Joined: Apr 7th, 2015, 4:42 pm

Re: A PVC pipe ROV

Post by Bindo »

Not so good! Don't give up!

On the ardunio, the serial pins need to be disconnected from your rs485 converters before it'll accept a new program!
perfo
Posts: 151
Joined: Jan 27th, 2015, 12:05 am

Re: A PVC pipe ROV

Post by perfo »

The more failures you have the more expert you'll be when you get it :)
I feel your pain as I'm an "expert" in a lot of projects. Just put all the stuff in a box and put it to one side. If in six months you've still lost all interest then get rid of em,,,but just think how far you've come and where you'd have to start, if you did it all again.

If you can get hold of a some distilled water (or make it) then you can test the crafts with relative safety. As the water doesn't conduct you can fill the ROV up with the stuff and all it needs is a good drying out to recover it..
I played with arduino but ended up going the raspberry pi route instead.. The RPI isn't as good as the arduino for real time i/o stuff but makes up for it in other ways and no silly boot problems...

Stick with it Fella....
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KR2_Diving
Posts: 391
Joined: Aug 30th, 2012, 11:43 am
Location: Currently: NW Suburbs of Chicago. Originally: NE Wisconsin

Re: A PVC pipe ROV

Post by KR2_Diving »

Hey Ron,
DON'T GIVE UP!!

There is no set rule in how long it takes to "complete' an ROV, and as I am sure many people on the forum can confirm, projects like this are often never fully "complete'! There is always something that can be tweaked or updated!

Personally, I have been at it for a few YEARS now, and I have never even gotten wet yet! I tinker here and there... try new things... and sometimes even learn something along the way!

Worst case... set it aside for a few months like Perfo has suggested... but don't give up! You can do it! And when you do... we will all be here to cheer you on!

Keep diving my friend! Keep Diving!

Ryan
"KR2_Diving"
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