OpenROV # 3440 arrives in the UK


#1

Feel just like a kid on Christmas morning. Even down to not opening it until I’d finished my breakfast! That’s a nice feeling at my age.
Dispatch and shipping was excellent, apart from the tracking information drying up when it reached the UK. Many big commercial companies could learn a lot from these guys.
It is beautifully packed and the red hat is the icing on the cake.
I might do a little bit on the electronics this evening, to get my feet wet. I’m an electronic engineer and Labview programmer but have no experience of Beaglebone and very little of Linux. However, I’m hoping to be able to do some fancy stuff in Labview.
More soon.


#2

Mine’s not quite here yet… arriving before 6!


#3

Haha! That wasn’t the sound of a gauntlet hitting the floor was it?
I won’t start until 6.30.


#4

Well I don’t quite believe it. I had a free afternoon and I have now completed the first 2 guides, up to doing the epoxy.

That part was particularly difficult and messy because I didn’t get epoxy with nozzles, so I mixed it up and then splodged it into a 5ml syringe. I had to fill it about 4 times to pot the wires, but it worked well in the end.

I don’t understand why there are 3 battery tube endcaps. I hope one is a spare, because I have made a mistake on one of them.

Looking forward to doing the electronics, that is definitely in my comfort zone.

Andrew


#5

I managed to finish my kit with a couple of good sessions. I’ve been doing electronics for many years and the one thing that you can usually rely on is that it won’t work first time. This is quite wonderful, plug it in and everything works! I’m astonished. I’ve managed to focus and calibrate the lasers, get the motors working the right way and do a pretend fly.

The only issue I have is that I have done a vacuum test and there is a slight leak somewhere. It won’t hold 300mm H2O but it will just about seal at 100mm H2O. Don’t know where to start looking really.

I suppose I could pressurise and submerge it, but vacuum might fail.

It still seems very weird to have all the exposed wires in the water, counter intuitive and I’m a bit worried that my glue lined heatshrink was a little on the large side so maybe thats where my leak is, up the wire joints, that’ll be a nightmare to find. Eventually I will have to cross fingers and dunk it.

Andrew


#6

First off I would like to say thank you @e4andy for all of your kind words! We are glad to be able to bring that Christmas morning feeling to everyone (even not around the holidays)!

Yes this is a spare in case you were to lose one in the field.

We are glad that it worked on the first time :slight_smile: You can thank @Walt_Holm for all of his hard work to make the electronics as robust as they are.

With regard to the drop in vacuum pressure it might now actually be a leak but how the test is being conducted.

The way the vacuum test is being conducted it is possible to have a small drop in pressure even if there is no drop in pressure in the tube. If the outside 1.5mm white acrylic piece and the larger 6mm clear piece do not have a cementing job that covers the entire surface, air can travel between these layers and thus have the decrease in pressure if you are using a suction cup type connector on the vacuum pump.

This image is of a 2.7 endcap not a 2.8 endcap but the idea is the same

From an operational standpoint there is no issue if this is the cause of the decrease in pressure.

The other place I would check is the fill hole for the epoxy around the DB-25. This level can drop significantly and cause a place water can get in through the layers of acrylic.

With regard to the adhesive lined heatshrink covering the ends of the wires, we have tested it and have not had problems as long as the glue on the inside is fully melted and coming out both sides.

I hope this answers your questions and concerns.


#7

Thanks for your help Brian.
To do the test I inserted a piece of silicon tubing with Molykote sealer on it, into the hole in the end cap, so it shouldn’t register inter-layer leaks, the vacuumed it with a syringe, teed into a gauge. I do this stuff all day at work, we make devices for pressurising the eardrum to measure intra-cranial pressure!

My guess is that my heatshrink is a little too large and the motor connection joints aren’t sound, or it’s getting in through the epoxy’d wire bundle.

However, as I say, I’m used to looking for very small leaks, so it shouldn’t take long.

Thanks again for your help.
Andrew


#8

Finished and tested!

I’ve now tested underwater (minus electronics) and it seems to be leak free. I’ve driven it up and down the bathtub and all functions seem to be good.

Looking forward to my first real open water dive on Thursday.


#9

I’ve done the first dive and it all went well, (I’ll post some video soon). The current was a bit too strong so it seemed impossible to turn to face me, because of the tether being attached to the rear. I also didn’t realise how useful a compass and depth gauge would be, unless you’re on the bottom, you haven’t a clue where you are. We went down to 9m and lost track of position completely. It’s going to be a lot more difficult to fly this thing than I first thought!