Tether disconnect


#1

I have been using a tether disconnect on my ROV for a while now and I have had no problems. I have gone a deep as 208 m. So I figured i would post the connector I have been using in case any one else wants to try it. It makes it WAY more convenient to carry your ROV around.

I put a drop of mineral oil in just to be sure, but when I did “depth test 2” I tested one dry and one with oil and they both stayed free of water. The larger size, which I tested at the same time, had a tiny bit of water in the ‘dry’ one.

http://www.dx.com/p/maitech-2-copper-core-waterproof-connector-terminal-head-black-314033#.VXHGtc9VhBc

The first one I use was from Lee’s electronics, a local electronics store, but they haven’t had them the last few times I was in.


Waterproof connectors - any suggestions?
First dive. 2.8. West of Scotland
#2

Hey Darcy. I’m using the same connectors on my rig for both the tether and the battery tubes. They work great for the OpenROV limited depth range. I have been using silicone grease in mine. They stay completely dry. No problems with them so far. I purchased mine on Amazon. I think they were listed as waterproof LED connectors…


#3

Thanks Darcey :thumbsup:

I had been wondering what you had been using for some of those deeper dives


#4

Thanks for the tip, I ordered one right away! If you have any suggestions to make a waterproof utp ethernet connection let me know.


#5

Niels:
Adafruit sells a 4 pin connector that looks quite like the ones Darcy is using:
( http://www.adafruit.com/products/744?gclid=CK_kqJ32_sUCFdg8gQod0zUAOQ ) which might work for your Ethernet connection. I bought a couple of them but I was uncertain about how long the tiny o-ring would stay water tight for my sensors, so I built some diy four wire connectors using pex plumbing:
http://edwardmallon.wordpress.com/2015/01/29/a-simple-diy-underwater-connector-system/

Deans 1241 connectors just fit inside 1/2 inch pipe, and are satisfyingly solid when they click together. ( http://www.rcplanet.com/W_S_Deans_1241_Micro_4B_Plug_p/wsd1241.htm ) If you need more wires, they make 5 & 6 pin versions of these connectors, but they are hard to find at a good price, so I would probably just stack two of the 4 pin connectors.

I have not done any tests of this connector past 30m yet, and I still have many weeks before I go to retrieve the first prototypes using this system (deployed in March) but I will report back to the OpenRov forum then to let you know how they survived in a marine environment.


#6

Thanks Edward for you suggestion,
However since soldering creates electric magnetic interference on my TCP/IP connection, I suppose the 4 wire connector doesn’t work for me. I will move on to the Tenda adaptor for communication. Makes the tether less sensitive to small damage and enables these kind of waterproof connectors.


#7

I actually use a 4 pin connector just like the one Edward link to above, to connect my raspberry pi tether cam to my rov. it works great for Ethernet.

Aslo the other connector would work for ethernet as well since it will encase any plug (that fits in the 1/2" tube) so you could use a regular ethernet plug. :smile:
But I think you might be right that the tenda version could be more robust.

So did you just use 2 wires with no other modification, to connect? I didn’t realise it was as simple as that. cool!


#8

The price of the connector on Adafruit is quite good, though there would be shipping. Originally I was using a 3pin connector. Because that is what the available connector had.

I do recommend using some oil or grease with whichever connector people use. I use oil because in my minds playthrough of what happens when water gets in, the oil is less thick and so is pushed into the connector and fills the space between the oring and the pins, keeping water from reaching them. The grease will do a better job of keeping water out, but (I imagine) would maybe not fall back against the enemy as well. :smile:

The second link, though I wouldn’t use it for the tether, looks like a really great way to make a seal for any connector. Super cool!


#9

Darcy_Paulin, Thanks for sharing your experience with these tethers, trial and error costs so much time! I like that container if it can contain a regular RJ45 plug. My experience is that if you use a 4 wire economy wiring UTP cable (=2 pairs) and solder connectors to it, the bare soldered ends create a lot of noice (=don’t work for long distances). Remember I don’t use the Tenda adaptor at this point yet (waiting on mail), the lines are really used as patch cable directly between the laptop and the raspberry in my case. I saw your tether cam is nearby the ROV, my cable is 100m long: that’s the difference.

I will use little grease for the connector, since oil might pollute the swimmingpool I am testing mine in :).
First test run of my ROV in a lake nearby:


#10

Hey Niels,

I like your design very much - I guess those are PVC pipes from a hardware store?

Currently I’m working on my own design, using a Raspberry Pi 2. Did you manage to get a video stream from the picam with little camera lag? How does your solution work?

Kind regards,

Stefan


#11

Hi Stefan, thanks. I am using the picam for the video. I have learned the hard way that you need to use the full FOV with low resolution and not the cropped view. Further I have about half a second lag with 0.5Mbps. The camera doesn’t respond very quickly in case the image changes a lot: I would like to have hardware compression.
I use two command to run the stream (with Vplayer on webpage):
One to record and stream simultaneously:
raspivid -t 9999999 -md 4 -fps 5 -b 1000000 -o - | tee /data/stream.h264 | ffmpeg -i - -vcodec copy -an -r 25 -f flv -metadata streamName=myStream tcp://0.0.0.0:6666
and one to stream only:
raspivid -t 9999999 -md 4 -fps 5 -b 1000000 -o - | ffmpeg -i - -vcodec copy -an -r 25 -f flv -metadata streamName=myStream tcp://0.0.0.0:6666
I didn’t get the openrov cockpit working yet, therefore built my own interface.
[please note i updated the code, now wide angle and higher bitrate 9-jun-15]


#12

Do you have a wide angle lens on your raspberrypi camera? I got some for a reasonably good price from dx.com. you would think I was a sales rep. heh. It is too bad that full HD is cropped on raspi cam. Even with a wide angle lens (2.8) the 1080p has only the field of view equal to the full sensor resolutions (640x480,etc). Actually it is still a little less.

I would like to record and stream at the same time too! Do I need to install anything to use tee?


#13

For as far as I know the tee is std. I was also surpriced when I discovered it was so simple and the raspberry could handle it. I am also using a wide angle from DX. I measured the angle of the camera and found 40 degrees for the cropped full HD setting (1080x1900), 60 degrees for the -md 4 setting see above and 80 degrees for the ‘clipon macro wide angle lens, 195460’. When I used the fish eye I only got enormous distortion. By the way: the video is recorded in .h264 format. Maybe this is familiar for you, I had to Google and found MP4box to convert it to MP3. (I am actually very new in all this, I started dec 2014 with my ROV).


#14

THX Niels for sharing your experiences. I’ll try your raspivid/ffmpg solution as soon I find the time. Meanwhile, I get decent results for streaming (low latency) with the raspicam and a modified version of mjpg-streamer: https://github.com/jacksonliam/mjpg-streamer
It works at least at 10 fps and 640x480 size.
-Stefan


#15

what you guys think about the this : https://www.youtube.com/watch?v=s4z8QMgTEA4


#16

Hi All,
Anyone had an experience with this two pin waterproof connector on Amazon?
Regards,
TCIII AVD


#17

We have used there around the lab and they work very well for the price. At depth they do compress and water can enter into the connector. In fresh water it is not a big issue. In salt water it continues to work but over time will begin to fail. It is possible to grease pack them to help avoid this.


#18

Hi Brian,
Thanks for the heads up, much appreciated.
By the way, can you recommend a two pin waterproof connector of a responable price and quality?
Regards,
TCIII AVD


#19

Just made mine plug&play


#20

Nice work! Let us know how it does in the field!