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BlueROV - well received


(JL Picard) #1

Hi all,

I’d like to share with you some progress, and very much hope that other people working on their BlueROV will do the same.

Bluerobotics, and Rusty in particular, have been kind enough to send me one of the first BlueROV. The parcel was perfectly packed and everything very well protected.

I’ve already assembled 90% of the kit (haven’t fixed the thrusters yet). Very easy thanks to the detailed step-by-step documentation. Still working (slowly…!) on the electronics and software. The BlueROV is a very elegant, solid and modular hardware kit. Much better than what I imagined during the Kickstarter campaign. You can tell that Bluerobotics team have put a lot of thoughts (and probably a lot of love :0) ) in its design.

I can’t speak much about the T100 (with BlueESC) yet… as I haven’t tested them in water. But it seems to be a solidly built product. And when applying a proper PWM signal, it turns, which is a good sign ;0) A couple of issues remain with driving the ESC through I2C; still working on it, with Rusty’s help. The latest documentation updates are important.

 

Shopping list (items that you’ll need to get while waiting for your kit, if you don’t have it already)

  • Epoxy
    • "Marine epoxy" is recommended by BlueRobotics. In the US, it seems a fairly common product (Locite Marine Epoxy).
    • Otherwise, Rusty told me that "standard" epoxy would do as well.
    • In Hong Kong, where I live, I could not find anything named "Marine epoxy". So, I browsed many hardware shops, checked many epoxy brands and products until I found one that said to be suitable for boat repairs. This one was pretty thick, and not very easy to apply (impossible to use a syringe like in the documentation) - not sure if it will do. If somebody has some advice...
  • Silicon sealant
    • The flanges that were shipped with my BlueROV are different from the new ones available on BR's store. They require the application of silicon sealant between the flange's flat edge and the end-cap (while the new ones are based on an O-Ring).
    • So if you receive the same flange as the one I have, get some sealant. I'd recommend white colour (not transparent), as it is easier to see that there are no air bubbles. If your flanges are with an o-ring, probably no need.
  • Hex keys
 

Electronics - components to control / power the ROV

  • Optional:
    • Rasp.io Duino (Arduino on RPi) - very convenient. Useful to reprogram the BlueESC. May be useful in the future, to control potential submarine actuators (servos, motors). Regardless of BlueROV, if you have a RPi and would like to try Arduino, go ahead with this board.
    • Environment sensors, inside the hull. I took this board, quite inexpensive (<USD10), embedding 3 sensors:
      • Temperature & humidity (ambient air) HTU21D
      • Barometric sensor (up to 1.1 bar only, but sensitive; enough to detect a hull breach?) BMP180
      • Light sensor (probably useless) BH1750FVI
  • Not decided yet:
    • Batteries
    • Internal battery charging system (BMS / PCM) (potentially charging during dive, for unlimited autonomy)
    • Tether
    • Temperature sensor (batteries)
Software
  • OS: Raspbian Jessie (for native Gstreamer libraries that Whezzy do not have - not checked yet though)
  • Main application: I'm going for Node.js (because asynchronous programming seems to fit our application so well). Not tempted by ROS for the moment :-)
    • Ideally, highly modular, loose-coupling programming pattern
    • Internal communication based on an anonymous publisher/subscriber bus
      • "In-house" (simple solution based on 'events' module)
      • or 3rd party (ØMQ?)
    • General architecture as currently envisioned here (Google presentation). Going to change...
  • Video transmission:
    • Already successfully tested low-latency transmission from RPi to RPi using Gstreamer over TCP (encapsulated h264 straight from the camera module ; no transcoding on the emitter side).
    • Target: embed video in an HTML page. (WebRTC?)
  • Control: probably Xbox gamepad over tcp or over http.
  • Under study:
 

Hope to read from other BlueROV owners (or any ROV enthusiast of course)

 

Jean-Laurent

 


(Harold Scadden) #2

JL … just wanted to supplement some of your comments with additional data.

 

  • Epoxy
    • “Marine epoxy” is recommended by BlueRobotics. In the US, it seems a fairly common product (Locite Marine Epoxy).
    • Otherwise, Rusty told me that “standard” epoxy would do as well.
    • In Hong Kong, where I live, I could not find anything named “Marine epoxy”. So, I browsed many hardware shops, checked many epoxy brands and products until I found one that said to be suitable for boat repairs. This one was pretty thick, and not very easy to apply (impossible to use a syringe like in the documentation) – not sure if it will do. If somebody has some advice…
The big key with the epoxy is to ensure that you get a type that is anaerobic cure (think super glue etc.) and if possible get a low viscosity epoxy. I would also recommend something that is a two part cure system because those, from experience, tend to have better bonding to surfaces such as what you are dealing with ... anodized metal and the polyurethane jacket on the cable.

Silicon sealant

  • The flanges that were shipped with my BlueROV are different from the new ones available on BR’s store. They require the application of silicon sealant between the flange’s flat edge and the end-cap (while the new ones are based on an O-Ring).
  • So if you receive the same flange as the one I have, get some sealant. I’d recommend white colour (not transparent), as it is easier to see that there are no air bubbles. If your flanges are with an o-ring, probably no need.
One thing you could more than likely get away with ... with success is using the RTV gasket dressing material for stuff like your water pump etc. on your car. I know it might sound crazy but this grade of RTV silicone material is good for extreme temperature ranges and will hold a pressure tight seal to a certain degree. Air bubbles in the material are really a low concern. If the material is strong enough you will not have cascade failures between 'bubbles".

Well that is my two cents input. Good luck and hope all of your dives equal your surfaces!

 

 


(JL Picard) #3

Hi Harold,

Thanks for all your advices; I’ve began experimenting with low viscosity, 2 part epoxies.

Fast setting epoxies are really difficult to handle; their viscosity starts to increase sharply after as short as 90 seconds… that leaves only a a minute or so to load a syringe and apply the right quantity at the right location. Plus, the syringe is systematically wasted after each application. I’ll switch to slower cure epoxies (60+ min) in future experimentations.

I didn’t know about RTV / Gasket maker until you mentioned it. It’s great that you point this option out, as this seems perfectly suited for this application. 'will definitively give it a try when I need to disassemble my the end-caps.

Cheers,


(Harold Scadden) #4

I wish I had said … “slow” cure two part epoxy. You are right about the rapid cure stuff. It also is not something that I would recommend. The working time is basically zero and you really want something that will have time to sit and “degas” itself so any bubbles can work themselves out of the mix.

If you have some website links to your standard hardware stores etc. in your area, please post a few and I can go look up the types of stuff that they have and give you some recommendations based on what I can find or, do what you are already doing and experiment.

When you go to use the RTV / Gasket maker style stuff do something along these lines.

Take the material and spread it out over the surface and pretend like you are smoothing out drywall or concrete and use something to make an even height build up. The key is it doesn’t have to be six miles high!

One other thing that I would recommend trying, as crazy as it might sound, is to get an O-ring (BUNA 75 - 90 durometer would be best) and lay that down on the tube surface and use your gasket maker to hold it in place. Once the gasket maker is cured, it will have captured the O-ring and will help to give it some structure during compression.

The O-Ring is going to have to be small in thickness and just inside of the screws and frankly if both surfaces are clean by itself it will be a good seal. The other much cleaner and easier to do option would be to take the cap, flange and O-ring, mate those together … and then from the inside, smooth in the gasket maker.

It is not the prettiest thing, but it can work.

NOTE to Rusty …

In the installation instructions for the Old R1 Style cap it appears that one of the caps in the sequence of photo’s is your new cap. The four photo … you can see an O-ring race in the flange. Just being nit picky. Wouldn’t want someone wondering why their cap doesn’t look like that.

 


(JL Picard) #5

Hardware stores in Hong Kong… how to say? A picture is probably better than a thousand words! This is what our hardware stores look like: https://www.google.com.hk/search?tbm=isch&q=五金店香港

We don’t have large chain stores like in North America or Europe. Used to have a BnQ some years ago, but they closed - not profitable. Our hardware stores are all very small shops, with a very limited choice within one shop, and little difference between shops… And unfortunately, most owners don’t know much about the very products that they sell… Not really a DIYer heaven, is it? :slight_smile:

I probably won’t try the O-Ring-on-flat-edges setup, as it seems to require quite some skills… Here is what my setup looks like after assembly using Bluerobotics recommendations:

https://goo.gl/photos/txHqiDtgGNJTXXWT6

Pretty clean, and looks reliable. Most importantly: easy to do, even for inexperienced people like me :slight_smile:

RTV might be an improvement over silicone, however. If I have a chance to try, I’ll let you know.

JL


(Rusty) #6

Harold,

RTV and gasket compound are a great suggestion. I’m sure that would work well.

I’ll make sure that image is fixed for clarity - thanks for pointing that out!

JL,

Looks great!

-Rusty