Page 1 of 2

ROV project, yet to be named

Posted: Dec 6th, 2012, 6:28 am
by Wanderer
Hello Everybody,

After few weeks of research, now comes the time of ordering ( got a very happy banker now.. :-D ) and assembling the ROV. It is also time to start a thread about the ROV project, we're running with a friend. No name yet, but it will come... ;-)

From all the research I've done so far, the design I took inspiration from is this one: http://www.instructables.com/id/How-to-make-a-ROV/ . We're not planning to build the exact same ROV, much more using this design as guideline for ours.

Here are the specifications we're aiming to. I'm well aware, it is not the easiest path, therefore some of the features we're planning might not get implemented in the earlier stages but will be added as the project moves on. We try, as much as possible, to have an "easily" upgradable design which will not involve re-designing the whole system for the future.

The ROV will run on 12V, powered from the surface, we'll use 24V dc power supply which will be converted at 12V using linear converters.
It will be driven by 2 arduinos (Surface and onboard) tethered via serial (Tx and Rx).
I choose to use an arduino to drive and communicate with the ROV as I want to avoid as much as possible carrying a laptop with me when operating the ROV (it's going to be possible to connect one to the box via USB anyway as to get a more detailed datas via a GUI for instance).
Here's the Wiring for the Control Box:
Wiring_Control_Box.pdf
(27.15 KiB) Downloaded 779 times
The leds are for indicating switches status and alarms (temperature, and water in enclosure) as well.
The 2 video outputs:
There's going to be a screen for the pilot on the box, which will have datas from the sensors displayed.
the second video output will get the videos without the OSD on it.

The ROV itself:

- 5 Thrusters (2 for Forward, Back and turning, 2 for skidding and 1 to go up and down), we're going to use bilge pump motors and magnetic coupling for the propellers. For the magnetic coupling. For the magnetic coupling, we're following this tutorial: http://www.rcgroups.com/forums/showthread.php?t=1660192 (thanks a lot Antony for sharing this). I'm going to use those H bridges to control the motors: http://www.pololu.com/catalog/product/755

- for the sensors:
1) the IMU: ArduIMU V3: https://code.google.com/p/ardu-imu/ for the time being, I'll only collect the datas Roll, Pitch and Bearing to be displayed on the control box LCD screen and on the video OSD as well), later on we would like to implement stabilisation and Hold position options.
2) Depth sensor: http://www.amsys.info/products/ms5535.htm
3) Temperature: http://www.ti.com/lit/ds/symlink/lm35.pdf

The OSD: https://code.google.com/p/arducam-osd/w ... m_osd?tm=6 which will collect datas from the Arduino (IMU and Depth) and overlay them on one of the video feed for the operator.

The flood light are made with: http://www.led-tech.de/de/High-Power-LE ... 0_138.html

Here's the wiring for the ROV electronics:
ROV electronics.pdf
(22.12 KiB) Downloaded 676 times
Please, feel free to comment, critisize or suggest. I can't wait to read your feed back
Have a great day

Wanderer

Re: ROV project, yet to be named

Posted: Dec 9th, 2012, 11:42 am
by jconduto
I found your project very interesting.
I am building an ROV with two Arduinos, using RS485 Shield on each Arduino.
The subsea Arduino gets information from the depthsensor, Accelerometer and Compass and will transmit the values to the surface Arduino and this one displays on LCD.
Your idea of using the OSD is a step forward.
For the control of thrusthers I will be using Rc ESC connected to a RC receiver using the tether as a antena.

I will send you photos

Re: ROV project, yet to be named

Posted: Dec 10th, 2012, 3:35 am
by Wanderer
jconduto wrote:I found your project very interesting.
I am building an ROV with two Arduinos, using RS485 Shield on each Arduino.
The subsea Arduino gets information from the depthsensor, Accelerometer and Compass and will transmit the values to the surface Arduino and this one displays on LCD.
Your idea of using the OSD is a step forward.
For the control of thrusthers I will be using Rc ESC connected to a RC receiver using the tether as a antena.

I will send you photos
Hello,

Thanks for your interest!
It seems we're following a very similar path with the electronics, I have a question though: why don't using the arduinos to control the ESCs? You could use a gamepad (playstation for intance) on the surface, and the ROV's arduino controlling the ESC. ?

I'm looking forward to see the pictures
have a nice day

Alain

Re: ROV project, yet to be named

Posted: Dec 10th, 2012, 6:19 am
by KR2_Diving
Wanderer wrote:
jconduto wrote: For the control of thrusthers I will be using Rc ESC connected to a RC receiver using the tether as a antena.
I have a question though: why don't using the arduinos to control the ESCs?
Sounds like there are a few people following the same path!

I have completed the code for using an Arduino to control a Brushless ESC if you are interested in having a look. (However, if you have all ready purchased all the hardware, I see no reason to change.)

Jconduto,
Which RS485 shield did you end up using? Do you have a link? Have you been able to do any tests on distance and data reliability? Did you write your own string format?

Thanks,

Ryan
"KR2_Diving"

Re: ROV project, yet to be named

Posted: Dec 11th, 2012, 7:35 am
by CLYON
That is nice! I like the fact that you use all I/O for something if only to light a LED. At first I was going to use a Uno to Uno, but after seeing this I might change. I would also be interested in the 485 shield. Has anybody tried to control using one joystick and drive, say like a plane? Anyway nice!


Chuck

Re: ROV project, yet to be named

Posted: Dec 18th, 2012, 4:09 pm
by jconduto
The RS485 Shield for Arduino you can buy on www.robotshop.com the part number is RB-Lin-33 made by Linksprite.
Only cost me 12.30 Euros.

Re: ROV project, yet to be named

Posted: Dec 18th, 2012, 6:11 pm
by KR2_Diving
jconduto wrote:The RS485 Shield for Arduino you can buy on http://www.robotshop.com the part number is RB-Lin-33 made by Linksprite.
Only cost me 12.30 Euros.
I like the look of this shield! Thanks for the link!

I was looking at the smaller SparkFun breakout:
https://www.sparkfun.com/products/10124

However, I might mix and match! Use the smaller on in the ROV, and the larger one on the surface! Like the place to add a proper 9-Pin D-Sub connector that is available on the shield!

Looks like they use different IC's, but i wouldn't think that would be an issue... Unless someone knows different...

Ryan

Re: ROV project, yet to be named

Posted: Dec 18th, 2012, 9:48 pm
by Vertcnc
Wouldn't you need a full duplex communications. I believe I saw somewhere that there's a different max dip that allows bi-directional com.

Re: ROV project, yet to be named

Posted: Dec 19th, 2012, 4:24 am
by KR2_Diving
Yes... and no...
If you manage your communication properly, you can get away without having full duplex...

That being said... if there are pre assembled packages that allow for full duplex, I would be open to that idea!

Re: ROV project, yet to be named

Posted: Dec 19th, 2012, 8:50 am
by fluxno
KR2_Diving wrote: That being said... if there are pre assembled packages that allow for full duplex, I would be open to that idea!
on only 2 wires its not possible with rs485 full duplex. but with 4wires you get full duplex, at same lengths. look at circuits like MAX488 from maxim.

rs485 4-wire and rs422 is more or less the same, just some small diffrences on the voltages on the line.

futurlec has a small finished board: http://www.futurlec.com/Mini_RS422.shtml