Society of Robots - Robot Forum

General Misc => Misc => Topic started by: CrazyCossack on June 04, 2010, 03:43:57 PM

Title: Underwater ROV controller question
Post by: CrazyCossack on June 04, 2010, 03:43:57 PM
Hey all, I am currently in the design phase of building an hobby PVC type ROV with a bunch of friends, unfortunately my robotics experience is very lacking (i'm in law - maybe I should have been an engineer!).

I do have some basic programming experience but as far as hardware goes I am completely useless. We figure that we'll have the battery on the ROV, as well as some sort of chip. Our current design will have 3 DC motors(likely either 6V or 12V), 2 lights(going to be LED clusters), and a camera (not sure what kind of output) as inputs. We'd like a chip with an ethernet output, since 300ft of Cat5 is relatively inexpensive.

We haven't yet settled on what type of camera we should get, as we're not familiar with what inputs chips can take.

Our problem is that we're looking for some sort of chip that would take some sort of video input from a camera, be able to control 3 DC motors, control some LEDs, and use an ethernet output. If it was easily expandable that would also be excellent because we may want more detail in the next version, such as compass, water sensor, better camera etc.

Thanks for any replies!  :)
Title: Re: Underwater ROV controller question
Post by: SmAsH on June 04, 2010, 06:29:05 PM
Well, any good microcontroller like the arduino or an axon would do for this as you haven't been too specific... The basics you would need is a motor controller per motor, but what do you want the Ethernet part for?

About the camera part, the chance of finding a good microcontroller that can process video would be hard. What most people do is get a camera with on board processing like the blackfin, avrcam or cmucam.
Title: Re: Underwater ROV controller question
Post by: CrazyCossack on June 04, 2010, 09:46:05 PM
Thanks for the reply!

We want an Ethernet as we're hoping to limit the amount of cables to the surface (ie. we plan to have the battery on-board), but we're very open to suggestions. The thinking is that it would be nice to have everything controllable through a single laptop.

Those are good camera suggestions though, I guess we'd probably almost need something closer to a computer if we want any sort of really good video?
Title: Re: Underwater ROV controller question
Post by: Razor Concepts on June 05, 2010, 04:40:01 AM
Do you want the camera to just transmit video? In that case you wont need a cmucam or blackfin, as those are designed for onboard video processing. You can also buy ethernet enabled cameras.
Title: Re: Underwater ROV controller question
Post by: CrazyCossack on June 05, 2010, 10:52:47 AM
Yes, I think that's more along the lines of what we're thinking, since we have a laptop at the surface it may be redundant to do video processing on the ROV as well?

Basically to limit costs we want to be able to have as few cables going to the surface as possible, if we could somehow get a controller that would be able to take commands for 3 motors, leds, and be able to feed the video up to the surface through a single ethernet connection to the laptop that would be ideal. But if another cable would be needed to feed video up to the surface that's ok as long as the cost of the cable does not exceed what the cost of video processing in the controller would be. (Our goal is 100ft deep, but we'll have 200ft of cable at least for more freedom, and the cable will have slack anyway)

So if we were to get an ethernet enabled camera, we would basically be looking at two ethernet cables to the surface? One for the motors/leds and one for the video processing? Would there be a way to bridge these two into a single ethernet? Since laptops generally only have room for one.

So new to all this, I apologize haha.

Thanks
Title: Re: Underwater ROV controller question
Post by: SmAsH on June 05, 2010, 04:29:49 PM
Yes, maybe an Ethernet switch would work?
Title: Re: Underwater ROV controller question
Post by: madsci1016 on June 05, 2010, 05:44:11 PM
Hey Crazy,

Sounds like you are really into this project. Well, lets see if I can help. FYI, I am an engineer for the Navy, building water based robots of course.

It sounds like you have a good plan so far, however I am worried about the depth you want to hit, 100 feet. While that doesn't sound like a lot, that's actually a tremendous amount of pressure for DIY robotics. Its very hard to make shaft seals withstand that pressure. Motors on professional ROVs are separate pressure vessels from the main electronics, and are encased in oil with pressure compensators, that increase oil pressure as the ROV dives deeper, so internal oil pressure = external water pressure and the seals won't blow out.

Also, all cables that enter the ROV go through very expensive wet mate-able plugs that are designed into the ROV housing so there is no way for water to get through.

Anyway, just some food for thought, since you made no mention of your mechanical plans. 

A IP ethernet camera sounds like a good idea, I'd then think about an Arduino with ethernet shield

http://www.ladyada.net/make/eshield/ (http://www.ladyada.net/make/eshield/)

and a Ethernet switch (on the ROV) like Smash suggested. This way, video and control could go down one Ethernet line.
Title: Re: Underwater ROV controller question
Post by: CrazyCossack on June 07, 2010, 12:35:41 PM
We'll look into the sealant issue, as we have no final plans as to how we're going to keep the water from entering the electronics area through where the cables go.

Thanks so much for the ethernet switch idea +  Arduino controller. We'll look into it more. When we have more of a finished product I might post some pictures up here. :)

I'll probably have more questions as times goes on haha, but thanks for the replies!
Title: Re: Underwater ROV controller question
Post by: little-c on June 10, 2010, 09:54:46 AM
sod ethernet, use an ethernet cable to run two usb lines,

 one for a web cam and another for the micro.
cheep web cam from ebay will do fine. can probably use the power lines on the webcams usb to run the LED lights aswell, reducing draw on the battery.

run all your 5 volt systems over USB, and use the battery for the motors.

ethernet cables have four twisted pairs, USB cables have four twisted wires. therefore use a ethernet cable to bring in two usb lines. permanatly attach the wire into the bot.
Title: Re: Underwater ROV controller question
Post by: dunk on June 10, 2010, 10:07:22 AM
sod ethernet, use an ethernet cable to run two usb lines,

 one for a web cam and another for the micro.
cheep web cam from ebay will do fine. can probably use the power lines on the webcams usb to run the LED lights aswell, reducing draw on the battery.

run all your 5 volt systems over USB, and use the battery for the motors.

ethernet cables have four twisted pairs, USB cables have four twisted wires. therefore use a ethernet cable to bring in two usb lines. permanatly attach the wire into the bot.
nope. USB has a maximum cable length:
http://www.usb.org/about/faq/ans5 (http://www.usb.org/about/faq/ans5)
Quote
Q1:  How long of a cable can I use to connect my device?
A1: In practice, the USB specification limits the length of a cable between full speed devices to 5 meters (a little under 16 feet 5 inches). For a low speed device the limit is 3 meters (9 feet 10 inches).


dunk.
Title: Re: Underwater ROV controller question
Post by: madsci1016 on June 10, 2010, 10:11:00 AM
sod ethernet, use an ethernet cable to run two usb lines,

 one for a web cam and another for the micro.
cheep web cam from ebay will do fine. can probably use the power lines on the webcams usb to run the LED lights aswell, reducing draw on the battery.

run all your 5 volt systems over USB, and use the battery for the motors.

ethernet cables have four twisted pairs, USB cables have four twisted wires. therefore use a ethernet cable to bring in two usb lines. permanatly attach the wire into the bot.


Bad idea little,

He wants to go 100 feet. The USB specification limits maximum wire length to 16 feet without active repeaters. And this is just for the data signal. Trying to draw power off the 5V line at 100 feet would also be a very bad idea, as the line loss for such a low voltage would be immense. Professional ROV's send power down 100' tethers at ~800 VAC, the higher voltage is used to avoid line loss.

EDIT: Dunk in for the goal as I was posting, LOL.
Title: Re: Underwater ROV controller question
Post by: little-c on June 11, 2010, 03:21:07 AM
works for smaller scale stuff. Im going to stick to my tracked robots.
Title: Re: Underwater ROV controller question
Post by: Admin on June 14, 2010, 10:46:48 AM
We'll look into the sealant issue, as we have no final plans as to how we're going to keep the water from entering the electronics area through where the cables go.
I use this on my UUV:
http://www.google.com/products?q=water+tight+wire+seal&um=1&ie=UTF-8&ei=ilwWTKKfB8OqlAeX--X5Cw&sa=X&oi=product_result_group&ct=image&resnum=3&ved=0CDUQzAMwAg (http://www.google.com/products?q=water+tight+wire+seal&um=1&ie=UTF-8&ei=ilwWTKKfB8OqlAeX--X5Cw&sa=X&oi=product_result_group&ct=image&resnum=3&ved=0CDUQzAMwAg)
Title: Re: Underwater ROV controller question
Post by: madsci1016 on June 14, 2010, 10:52:30 PM
You have a UUV? .... link?
Title: Re: Underwater ROV controller question
Post by: Admin on June 15, 2010, 04:53:08 AM
You have a UUV? .... link?
You aren't the only person who works for the Navy and can't just post everything on the web :P

That said, you'll find pics of our old first (ghetto) prototype here:
http://www.societyofrobots.com/robottheory/Sensor_Data_Fusion_Submerged_Results_Pectoral_Fin_UUV.pdf (http://www.societyofrobots.com/robottheory/Sensor_Data_Fusion_Submerged_Results_Pectoral_Fin_UUV.pdf)
Title: Re: Underwater ROV controller question
Post by: madsci1016 on June 15, 2010, 08:06:11 AM
Ahh, i thought you meant a home built UUV. Eventually I want to build my own at home.
Title: Re: Underwater ROV controller question
Post by: CrazyCossack on June 19, 2010, 08:23:55 PM
Ok so I'm slightly confused, basically I would order the ethernet shield and something like http://www.leeselectronic.com/catalog/product_info.php?cPath=1236&products_id=7842&osCsid=6429bf3d30a98830af6d6072b94c4991 (http://www.leeselectronic.com/catalog/product_info.php?cPath=1236&products_id=7842&osCsid=6429bf3d30a98830af6d6072b94c4991)?

- Crazy
Title: Re: Underwater ROV controller question
Post by: SmAsH on June 19, 2010, 09:28:18 PM
Yes, pretty much, and a switch if you want to run two streams to the top on one line.
Title: Re: Underwater ROV controller question
Post by: voyager2 on June 20, 2010, 06:57:18 AM
Hi,
Here's a few tips:
*Use only one DC motor, unless you have a pocket deep enough for a motor-driver ;D
*Use BIG servos to control diving planes, rudder, etc...
*Use PVC plumbing pipe, like whats under your bathroom sink
*Use GPS in-case the tether gets cut or something.
*Use an AXON, plenty of room for expansion.
Hope this helps

Also why do you need to use Ethernet cable?
Just use the RX and TX (uart) on the micro to control the ROV and stream video.
Maybe just use Radio? 
Title: Re: Underwater ROV controller question
Post by: madsci1016 on June 20, 2010, 09:09:43 AM
Voyager, there are several things wrong with your suggestions.

He wants to build an ROV, not a UUV. ROVs are directional thrust vehicles, they are not continuously moving through water. You cannot have control surfaces like rudders on a vehicle that is staying stationary in the water, and only making small movements. He needs at minimum 4 motors to be able to maneuver his ROV in the water.

The second thing is water blocks Radio Frequencies very well. There's no point in putting a GPS on it, it will never work underwater. Same goes for any radios for control.

Also, the maximum length for Serial cable is in the tens of meters. where Ethernet can go at least 100m, which is the depth he wants to go at.
Title: Re: Underwater ROV controller question
Post by: CrazyCossack on June 20, 2010, 11:22:07 AM
Yes, pretty much, and a switch if you want to run two streams to the top on one line.

Hey thanks for the quick reply! So what sort of switch would this be?

And Voyager, we are using three small 12v 3amp DC motors (hoping we won't need a fourth!). Our construction, minus the electronics is basically complete, pained and everything, and we have built it out of PVC. We have also leak tested it (not at depth, mabye we'll do a pressure test with air) and it seems to work well. I'm also unsure how well gps works in the water? Though I heard compasses work well for finding the general heading, hopefully we won't have to deal with a cut tether!

Thanks all!
Title: Re: Underwater ROV controller question
Post by: madsci1016 on June 20, 2010, 11:39:33 AM
There's is no point to put GPS on it. Compass is nice though to keep your self oriented correctly.


A switch like this:

http://www.newegg.com/Product/Product.aspx?Item=N82E16833127085&nm_mc=OTC-Froogle&cm_mmc=OTC-Froogle-_-Network+-+Switches-_-D-Link-_-33127085 (http://www.newegg.com/Product/Product.aspx?Item=N82E16833127085&nm_mc=OTC-Froogle&cm_mmc=OTC-Froogle-_-Network+-+Switches-_-D-Link-_-33127085)

Also, did you put some sort of leak sensor that will alert you to the presence of water inside the ROV? If not, I highly suggest it.
Title: Re: Underwater ROV controller question
Post by: CrazyCossack on June 20, 2010, 03:54:49 PM
Thanks madsci. Hmm the dimensions are 5.8" x 4.5" x 1.2", I think we want to fit it all into a 4in PVC, unless we change the design. So I think we need 2/3 dimensions to be below 4". I'll start looking for a smaller one perhaps.... We have looked into a water sensor, but since we're so new to all of this I think we want to just get the basics working first before expanding with fancy gadgets. Once we get the motors/leds properly we'll think about adding a compass and a water sensor.  Hopefully the micro controller will make it a fairly easy add-on. I'll design my UI with room for it though.

Edit: http://www.amazon.com/Cisco-SF-100D-05-Desktop-Switch/dp/B003AVN1LG/ref=sr_1_3?ie=UTF8&s=electronics&qid=1277071026&sr=1-3 (http://www.amazon.com/Cisco-SF-100D-05-Desktop-Switch/dp/B003AVN1LG/ref=sr_1_3?ie=UTF8&s=electronics&qid=1277071026&sr=1-3) Seems to fit the bill.
Title: Re: Underwater ROV controller question
Post by: madsci1016 on June 20, 2010, 04:54:59 PM
Also, when we stuff small off the shelf stuff into our robots, we usually take off the devices enclosure, and just using the raw circuit board. This save even more room.

 I'd be cautious omitting a water sensor from the beginning, as it is a safety measure. I'd hate for you to lose all your electronics on your first dive!
Title: Re: Underwater ROV controller question
Post by: CrazyCossack on June 20, 2010, 05:17:06 PM
Yes, that's a good idea to take off the casing, should free up much needed room in there. Ah what the heck you talked me into it haha. I thought it over and it's a relatively small expense to pay for potentially saving a lot in electronics which would suck to have to buy again. Do you have any recommendations for a good sensor?

Also this camera was brought up, http://www.bhphotovideo.com/c/product/654971-REG/Trendnet_TV_IP501P.html#accessories (http://www.bhphotovideo.com/c/product/654971-REG/Trendnet_TV_IP501P.html#accessories). It seems to have 640x480, which is like 0.3 MP, and 30 FPS. In your view is that pretty standard for the price? And this originally started as a more photography oriented thing, but for the first prototype we're ok with having a crappy camera. When we build our second one, it'll hopefully be able to take some nice pics. :)
Title: Re: Underwater ROV controller question
Post by: madsci1016 on June 20, 2010, 10:09:11 PM
small expense, it's more like pennies. You just need transistors and resistors. here's a circuit:

http://www.discovercircuits.com/DJ-Circuits/h2oalm.htm (http://www.discovercircuits.com/DJ-Circuits/h2oalm.htm)

The sensor probes can just be two bare wires that you should locate at the lowest part of your robot. Tie the 'buzzer' part of the circuit to an I/O pin on your micro-controller, and you have a water alarm. You would also have to increase some of the resistor values a bit and power the circuit at the same voltage as your microntroller logic, 3.3 or 5V.

The camera looks decent. You are not going to find a higher resolution video camera at that price. If your goal is photography, I'd have a real point and shoot camera on your rig as well. You can use a servo to click pictures when commanded from the surface. 
Title: Re: Underwater ROV controller question
Post by: Admin on June 21, 2010, 07:50:36 AM
GPS is only useful if your robot comes to the surface to get a new fix, as dead reckoning underwater builds up in error over time.

I'd be cautious omitting a water sensor from the beginning, as it is a safety measure. I'd hate for you to lose all your electronics on your first dive!
Putting electronics in during the first dive?!  :o

When testing our waterproofing, I fill the inside with lots of weights, drop it in the water at the required depth, and then pull it out after a few hours to check for leaks. This is a great way to test to see how deep your bot can go without frying anything.
Title: Re: Underwater ROV controller question
Post by: madsci1016 on June 21, 2010, 08:58:33 AM
GPS is only useful if your robot comes to the surface to get a new fix, as dead reckoning underwater builds up in error over time.

Also, it's just an ROV, not a UUV. Not much use for GPS either way.
Title: Re: Underwater ROV controller question
Post by: CrazyCossack on June 21, 2010, 10:47:52 AM
Thanks for that schematic, it sadly will probably be a tough build for us considering our weak electronic skills, but we'll give it a shot! I think we will test the ROV for a few hours at depth without electronics for the first dive but it'll be nice to have anyway. (we have tested, and it's watertight, but not yet at depth)

Also I forgot to mention that we'll want the motors to reverse as well, how will that work with the Arduino? I assume we'll need to get a switch that revereses current and then plug that into the serial...or something :P.

And how will power work with the microcontroller, I'd think usually you would feed power to the microcontroller and it would distribute it as needed? In the case of the Arduino it seems to run off of 5v? How will we get around this when we have 3 motors at 12v 3 amps each? I assume LED cluster should be no issue at 4.5v and 1.7amp since we'll just need a resistor.
Title: Re: Underwater ROV controller question
Post by: Admin on June 21, 2010, 11:10:49 AM
get motor drivers from here:
http://www.dimensionengineering.com/ (http://www.dimensionengineering.com/)
Title: Re: Underwater ROV controller question
Post by: CrazyCossack on June 21, 2010, 03:03:14 PM
Thanks for that. These seem suprisingly expensive, is there one that will perhaps work for 3 DC motors? Since this seems like we'll have to buy one that controls 2 motors (Sabertooth dual 5A motor driver ) and one that controls the last motor (SyRen 10A regenerative motor driver) at the cost of over $100?

Also how do these work? They connect into the serials and on the other end onto the motors and can somehow be controlled be controlled through the serial?
Title: Re: Underwater ROV controller question
Post by: madsci1016 on June 21, 2010, 03:07:14 PM
I agree with Admin, Dimension makes really decent motor controllers, for your need, specifically this one:

http://www.dimensionengineering.com/Sabertooth2X5.htm (http://www.dimensionengineering.com/Sabertooth2X5.htm)

Slightly expensive at $60, you would need two to run three motors. (They are dual channel each). They communicate over serial and can be daisy channel in 'packetized' serial mode, so you would just connect both of them to the Arduino's Uart TX pin. The Arduino will send data packets that would tell the motor driver what to do, including reversing direction. The motorcontroller would get power directly off your 12V battery.

Most Arduino's have their own voltage regulator on board, meaning you can connect their "Raw" power pin to 12V and it will step it down to 5V for the Microcontroller's use. I wouldn't power anything else off the microcontroller directly.

If you have other parts that need power at 5V, you can either build yourself a power regulator board, or if you do use the Dimension motor controllers, they provide 5V out for anything you might need it for.
Title: Re: Underwater ROV controller question
Post by: madsci1016 on June 21, 2010, 03:18:33 PM
There are cheaper non-digital alternatives out there, but the trade off is that they are much more complex to integrate. They would require many more IO pins of the Arduino to be used, and would require you to build some additional support circuitry to use.

For example, This one is $23

http://www.pololu.com/catalog/product/1212 (http://www.pololu.com/catalog/product/1212)

But look how many wires it needs:

(http://www.pololu.com/picture/0J1816.350.jpg)

And that's just for one motor.

While the Sabertooth would just be serial and ground to both.
Title: Re: Underwater ROV controller question
Post by: Admin on June 21, 2010, 04:11:07 PM
I agree with madsci1016.

They may be more 'expensive', but if you pay twice the price for twice the quality and capability, then its worth it.

This is an example of me using a DE motor driver:

How to Make a Robot with Axon II MCU (http://www.youtube.com/watch?v=51TgbvcNwCQ#)
Title: Re: Underwater ROV controller question
Post by: CrazyCossack on June 21, 2010, 09:55:15 PM
Makes sense, we'll definitely go with the Dimension controllers then. Thanks so much guys, really invaluable help! It would have taken me eons to figure this all out if I did it without asking questions (and a lot of wasted money buying the wrong stuff too).
Title: Re: Underwater ROV controller question
Post by: CrazyCossack on June 23, 2010, 09:35:48 PM
Hey guys, just a small update, we've *basically* finished the build except for the electronics. The only thing that remains is to find a good propeller, a local hobby store sold one that seemed decent but was slightly too small so we're going to go back and test a larger one. Issue is even the small propeller need a much larger shaft than the bilge pump motor's shaft was, and the larger ones are even more so. We need a propeller about 2.5-3in in diameter, they might not have one at the hobby store that large and might need to look online (unless we want to pay 3X $45 (no way) for a big fancy metal one).

Just to run it past you guys one more time before I do a massive amount of online purchases, here is what I plan to get:

Overview of parts:

Robotics:
E-shield: http://www.robotshop.ca/adafruit-ethernet-xport-shield-kit-arduino-6.html (http://www.robotshop.ca/adafruit-ethernet-xport-shield-kit-arduino-6.html)
Arduino: http://www.robotshop.ca/arduino-usb-microcontroller-board-1-4.html (http://www.robotshop.ca/arduino-usb-microcontroller-board-1-4.html)
2X motor control: http://www.robotshop.ca/Sabertooth-2x5-en-1.html (http://www.robotshop.ca/Sabertooth-2x5-en-1.html)

Camera: http://www.bhphotovideo.com/c/product/654971-REG/Trendnet_TV_IP501P.html#accessories (http://www.bhphotovideo.com/c/product/654971-REG/Trendnet_TV_IP501P.html#accessories)

10/100 switch: http://www.amazon.ca/TRENDnet-5-Port-100Mbps-Switch-Plastic/dp/B000M2TAN4/ref=sr_1_1?ie=UTF8&s=electronics&qid=1277240876&sr=8-1 (http://www.amazon.ca/TRENDnet-5-Port-100Mbps-Switch-Plastic/dp/B000M2TAN4/ref=sr_1_1?ie=UTF8&s=electronics&qid=1277240876&sr=8-1)

Cat6 cable:
http://www.deepsurplus.com/Network-Structured-Wiring/Ethernet-CAT6-Patch-Cables-300ft/300ft-Yellow-Cat-6-Patch-Cable-Molded;jsessionid=0a0105531f4330b4b62fbc61470c8cadbe10d24accee.e3eSc3uRax8Te34Pa38Ta38Rc350 (http://www.deepsurplus.com/Network-Structured-Wiring/Ethernet-CAT6-Patch-Cables-300ft/300ft-Yellow-Cat-6-Patch-Cable-Molded;jsessionid=0a0105531f4330b4b62fbc61470c8cadbe10d24accee.e3eSc3uRax8Te34Pa38Ta38Rc350)
Title: Re: Underwater ROV controller question
Post by: madsci1016 on June 23, 2010, 10:11:29 PM
Looks like your Ethernet Shield you linked is just a breakout, and actually requires you to buy another circuit, the actual ethernet chip, to be completed.

This looks like a complete Shield.

http://www.robotshop.ca/arduino-ethernet-shield-4.html (http://www.robotshop.ca/arduino-ethernet-shield-4.html)
Title: Re: Underwater ROV controller question
Post by: CrazyCossack on June 24, 2010, 07:41:39 AM
Ah-ha, thanks again, good catch. Good thing I posted to confirm. I'll probably be asking a lot more questions once we figure out a circuit diagram haha.

Cheers.
Title: Re: Underwater ROV controller question
Post by: madsci1016 on June 24, 2010, 02:14:59 PM
Crazy

How much programming experience do you guys have? Have you thought about what is going to be on the surface that sends commands to the ROV? A computer program, another Arduino?

Just things to think about while the stuff ships.
Title: Re: Underwater ROV controller question
Post by: CrazyCossack on June 24, 2010, 05:57:17 PM
We've planned to use a laptop on the surface that'll be running a program/as well as showing video.

We've got some basic experience in java, C++ and Visual Basic (doesn't really count). Been a while since we've programmed though so all the syntax runs together in my head haha. I've checked out some programming with the Arduino and I'm not too worried, seems like there are good online ressources for the syntax but I'm not sure how we're going to network this with the 10/100 switch. I'm not sure how much GUI capability there is with the Arduino as I've only seen command prompt-type UI.

But I think making a GUI with the video feed from the camera embedded in the GUI might be a little of a nightmare with the switch, if I do that it'll be later after we have the basics down. I'm sure the camera has a crappy little program that should let us at least do the basics: see what we're doing, and record video for later.

At the moment I'm more worried about how the electronics are going to work as that's the area that we really don't have much experience (except basic stuff we can barely remember from grade 10 physics haha).

So we have:
3X motors at 12v 3amps each.
Camera at 12v 9amp.
Edit: and LEDs at 4.5v at 1.7amp
Arduino 5v...and ????
And no idea if the motor controllers, e-shield, and the 10/100 switch take any power.

So basically we have to decide on what batteries we're going to buy for this. Moreover, how will they be configured? I've read putting the microcontroller on a separate battery from the motors is a good practice? I'm really lost as to how power is going to work with the Arduino, usually I'd expect the Arduino to directly be feeding the motors power....not sure how one could get them running on a separate battery and taking orders from the Arduino...

Title: Re: Underwater ROV controller question
Post by: Razor Concepts on June 24, 2010, 09:16:30 PM

....not sure how one could get them running on a separate battery and taking orders from the Arduino...



Arduino runs on separate 5v source. Motors and motor driver runs on separate 12v source.
Connect ground of the 5v source to the ground of the 12v source.

This way, they are on separate batteries, but the Arduino can still talk to the motor controller.
Title: Re: Underwater ROV controller question
Post by: madsci1016 on June 24, 2010, 11:34:12 PM
Alright, Lets break down your power system a bit.

First off, the battery. My suggestion would be a Hobby Li-poly battery like This One (http://www.hobbyking.com/hobbyking/store/uh_viewItem.asp?idProduct=8934&Product_Name=Turnigy_2200mAh_3S_25C_Lipo_Pack). The reasons are they are cheap, and support large currents. You mentioned you are using bilge pumps, which can draw large currents. I know the 12V one I have for my saltwater change system can draw 3-4Amps under load. So worst case for you, 3 pumps at full load would be 9-12 Amps, which other battery types would have a hard time sourcing. However, they can be dangerous, and you should definitely have a something like a 15Amp fuse in-between your battery and ROV electronics.

I tried having separate batteries for electronics and motors before, but got tired have having issues on which battery was dead, and having to keep two different chargers around. For the folks around here, it's just a matter of opinion. I reduced my SAGAR robot to one system battery and had no problems.

For the devices:

The motorcontrollers are self powered, they just required a direct connection to the battery (through a fuse), a connection to the motor, and Serial in and signal ground.

The Arduino can also be powered from 'raw' battery voltage, as it has it's own power regulator that can take up to 20V. The Arduino has nothing to do with motor power, that's all taken care of by the Motor Controllers. The Arduino just commands them to give a certain amount of power to the motors.

The network switch will take power. If it runs of 12V, you should be ok powering it off the battery voltage. If it's 5V, you will need to see how much it draws. If it draws less then 100ma, you could run it off the 5V output of one of the motorcontrollers. Same for the camera. If you end up having a lot of equipment (or servos) that runs off 5V, you might consider a switching regulator like this (http://www.dimensionengineering.com/DE-SW050.htm). The would give you a 5V source up to 1 Amp.

For the LED, another adjustable voltage regulator Like This (http://www.dimensionengineering.com/DE-SWADJ3.htm) would let you dial in the right voltage for your LED array, and support the large current it draws.

All these switching regulators are expensive compared to cheaper Linear regulators, but the trade off is much better efficiency performance and longer run times.


You really don't need to worry about the 10/100 switch as far as programming. It is invisible to all the devices connected to it, all it does is make sure all the device can talk to each other. So you could use the camera software running on your topside computer to bring up the camera. Then you would just need a program that opens up a TCP or UDP connection to the Arduino, and sends commands to it. You just need to make sure all devices are on the same subnet, IE all have IP address like 192.168.1.x .

I think I got it all. Man that was a long post. You are making me want to build an ROV now, it's a shame the waters near me are about to be all dark with oil. Stupid BP.
Title: Re: Underwater ROV controller question
Post by: Ro-Bot-X on June 25, 2010, 05:39:50 AM
You can power your Arduino (and all 5V electronics) from a 5V switching regulator by plugging the output from the regulator to the 5V pin (and GND to GND) if you are using a 12V battery. This way the electronics are not influenced by the motors starting up as the switching regulator will output a steady voltage until the battery is completely depleted. You need to make a battery sensor to be able to command your ROV to come back to shore before the motors can't push it any more.

Also, you can use the 3A adjustable switching regulator as madsci recommended to power your servos and adjust it to 6V, instead of using a second battery on the robot. A second battery plus charger will be more expensive anyway and will complicate charging.
Title: Re: Underwater ROV controller question
Post by: CrazyCossack on June 25, 2010, 04:13:57 PM
Thanks for the info guys, that was very helpful. What about capacitors? With a quick discharge battery like that perhaps they won't be needed? I'll probably also throw in a few transistors here and there to make sure things don't go boom.

I'll try to get back to you all with a shitty circuit diagram you can all tear apart haha, eventually we'll get it right though.
Title: Re: Underwater ROV controller question
Post by: madsci1016 on June 25, 2010, 04:29:08 PM
No problem.

Most of these devices already have power cleaning caps already, no need to add more. Arduino cleans it's own power. The camera and switch will expect to get dirty power from dirty wall warts. LEDs won't care.


I'll probably also throw in a few transistors here and there to make sure things don't go boom.

What do you mean by this? Did you mean fuses instead of transistors?
Title: Re: Underwater ROV controller question
Post by: CrazyCossack on June 25, 2010, 07:57:56 PM
My bad, I mean to say diodes, but then realized that the motor controllers/micro controller can probably deal with that on their own circuits, though switching the direction of current is probably unlikely.

We'll get back to you guys with a circuit diagram soon!
Title: Re: Underwater ROV controller question
Post by: madsci1016 on June 25, 2010, 08:09:16 PM
The battery I linked for you has a polarized connector, so it's physically impossible to connect your battery backwards. There's no need for an energy wasting diode.
Title: Re: Underwater ROV controller question
Post by: CrazyCossack on June 25, 2010, 08:37:12 PM
Thanks for such a quick reply. We've been trying to figure out how long one battery would last us in this setup. I think we'lll run the microcontroller off the main battery afterall. There doesn't seem to be any figures provided on battery life at any given current draw. If we were to have a camera running at 9amps + 1.7 amp LED, both on constantly, so 10.7 amp base, plus a variable average of probably 4.5-6 amps on the motors - how long would the battery last? This is in addition to the unkown current draw of the 10/100 switch and the Arduino.
Title: Re: Underwater ROV controller question
Post by: madsci1016 on June 25, 2010, 08:57:27 PM
I'm running out the door so I will have to come back with the math, but there's no way your camera is drawing 9Amps. Double check that.
Title: Re: Underwater ROV controller question
Post by: CrazyCossack on June 25, 2010, 10:06:28 PM
Ah-ha, 9 Watts, completely misread that thanks for the correction. I thought that was a little much. And with it being 12v, that is 0.5 amp. Edit: though the web page actually says 12V, 1.5A on further checking.
Title: Re: Underwater ROV controller question
Post by: madsci1016 on June 25, 2010, 10:54:58 PM
Back.

I don't see your ROV moving all the time during your dives.

Really, with the price and size of that battery, i'd say get two and put them in parallel, for a total of 4.4 Amp Hours. That would power 4.4 Amps, for an hour. or 2.2 Amps for two hours, you get the idea.

There's really no telling how much average power your ROV is going to consume, and it will also vary mission by mission, if you are fighting a current you will use more power. My gut tells me that with 4.4Ah at 11.1 Volts, you would get 45-60 mins of run time, but that's a WAG (Wild A$$ Guess).

How about some pictures of what you have built already?
Title: Re: Underwater ROV controller question
Post by: CrazyCossack on June 26, 2010, 09:18:10 AM
That was our best guess as well since the life of the battery at any Ah was not stated by the manufacturer. We'll probably end up buying three in case one craps out. So 15amp fuse still seems to be the best bet then. Would it make sense to put a large capacitor after the fuse to regulate the current? Or would that be counter productive?

Man I had totally forgot that you hadn't seen anything from the design, next time I'm at m buddies house I'll bring my camera and I'll take some pics.
Title: Re: Underwater ROV controller question
Post by: madsci1016 on June 26, 2010, 09:27:50 AM
Would it make sense to put a large capacitor after the fuse to regulate the current? Or would that be counter productive?

I wouldn't. Power cleaning caps only work well when placed near the device that's using the power, and all those devices already have those caps built into them. Just make sure you use decent wire, sized appropriately, and make good connections.
Title: Re: Underwater ROV controller question
Post by: CrazyCossack on June 27, 2010, 11:54:57 AM
Alright good stuff then, should be a pretty easy circuit then, just plug-and-play basically. Only thing that remains is getting a (or a couple) switching regulators for the LED and maybe the 10/100 switch.
Title: Re: Underwater ROV controller question
Post by: Admin on June 28, 2010, 07:52:27 AM
Quote
We've planned to use a laptop on the surface that'll be running a program/as well as showing video.
Reminds me of a funny story I heard where a guy didn't secure his electronics/laptop, and the tethered ROV decided to take everything into the pool with it . . . :P
Title: Re: Underwater ROV controller question
Post by: CrazyCossack on June 29, 2010, 03:16:25 PM
Yeah I'll be sure to check to make sure that never happens to us!



First off, the battery. My suggestion would be a Hobby Li-poly battery like This One (http://www.hobbyking.com/hobbyking/store/uh_viewItem.asp?idProduct=8934&Product_Name=Turnigy_2200mAh_3S_25C_Lipo_Pack). The reasons are they are cheap, and support large currents. You mentioned you are using bilge pumps, which can draw large currents. I know the 12V one I have for my saltwater change system can draw 3-4Amps under load. So worst case for you, 3 pumps at full load would be 9-12 Amps, which other battery types would have a hard time sourcing. However, they can be dangerous, and you should definitely have a something like a 15Amp fuse in-between your battery and ROV electronics.


Hey, I'm having difficulty finding a good charger for this battery - would you guys have any recommendations?
Title: Re: Underwater ROV controller question
Post by: waltr on June 29, 2010, 03:56:18 PM
Quote
I'm having difficulty finding a good charger for this battery
To buy or build?

To build check out the MCP7383x charge control chips from Microchip. These need a minimum of external parts.
Title: Re: Underwater ROV controller question
Post by: CrazyCossack on June 29, 2010, 04:15:36 PM
At the moment I'm thinking buy, building something like that may be beyond our current capabilities haha.
Title: Re: Underwater ROV controller question
Post by: madsci1016 on June 29, 2010, 04:35:13 PM
Crazy,

I personally own and use This One. (http://www.hobbyking.com/hobbyking/store/uh_viewItem.asp?idProduct=8247&Product_Name=Turnigy_2S_3S_Balance_Charger._Direct_110/240v_Input) Seems to work fine charging the battery I linked, since I own that too.

Good for those on a budget, but the expensive ones take batter care of your batteries.

And before you ask Here's the connectors to mate to the battery.  (http://www.hobbyking.com/hobbyking/store/uh_viewItem.asp?idProduct=10254)
Title: Re: Underwater ROV controller question
Post by: CrazyCossack on June 29, 2010, 06:01:17 PM
Ah-ha, thanks very much. To my credit (or lack thereof) I did realize I needed connectors! Cheap is always good.

We're currently trying to find CAT5/6 available in Ottawa, most American retailers want to charge $40-$60 for shipping 300ft of cable, which is more than the price of the cable (~$40). We've not had any luck yet, seems like it's either 100ft or 1000ft, not sure that connecting three 100ft together would be a good idea, connectors might actually bump the price up to even with the 300ft, and might not fit in the tether. I will keep you guys posted though.

We're thinking of making the tether as done here (http://www.hobbyrov.com/index.php?option=com_content&view=article&id=47:umbilicals-and-tethers&catid=39:umbilicals&Itemid=29 (http://www.hobbyrov.com/index.php?option=com_content&view=article&id=47:umbilicals-and-tethers&catid=39:umbilicals&Itemid=29)). Though finding that length in hollow braided rope might be tricky.

On the propeller front we've tested small (and cheap) propellers 3/16" size, they worked well, but our cover for the thrusters allows for 3in diameter blades. We also tried plane props with the full size 3in, and interestingly the smaller 3/16" props meant for water vastly outperformed them. The local hobby place had metal ones, but for a lot of money, like $40 each. Seeing as we have 3 thrusters that is quite expensive, I think we would rather pay like $5 for plastic ones with probably less power, than pay $120 for slightly more power. So if anyone knows any place that sells cheapy plastic props with a 2-3in diameter that would be so helpful.

And suprisingly, that's about all the materials we need before we're done material wise. The only issue that really remains is getting the wires into the electronics area, we'll probably use a threaded plumbing fitting. Looking forward to getting this all setup! And I haven't forgot about pictures.

Title: Re: Underwater ROV controller question
Post by: chelmi on June 29, 2010, 06:38:43 PM
We're currently trying to find CAT5/6 available in Ottawa

Yay! I didn't know there were other people from Ottawa on SoR!

Where do you plan to test you ROV? The Rideau canal? ;)
Title: Re: Underwater ROV controller question
Post by: CrazyCossack on June 29, 2010, 06:56:15 PM
Haha I always seem to find people from Ottawa on every forum, small world. Testing in the canal would be pretty epic, I could probably get away with it too!
Title: Re: Underwater ROV controller question
Post by: madsci1016 on June 29, 2010, 08:37:12 PM
Your propeller problem reminds me of an idiosyncrasy at work.

One of my jobs at work is an operator for Unmanned Underwater Vehicles for the Navy. The vehicles we use were originally invented by an Oceanographic Institute for scientific purposes. The Navy saw how they could be used for anti-mine warfare, and placed an order for more. Sine the institute couldn't mass produce them, a private company was spun off (that's now foreign owned, for crying out loud) to start production. Now the Navy is chained to that company for it's UUV needs. The propeller on them is machined out of a single piece of metal, bends easily and costs the government $1000 for each new replacement.

The original Institute that invented the vehicles started with, and still use today $5 plastic airplane props. They keep several in their spares kit, when one breaks, they just replace it on the spot. There vehicles swim just as well as ours do.

It hurts my head to think about sometimes....
Title: Re: Underwater ROV controller question
Post by: CrazyCossack on June 30, 2010, 03:32:42 PM
Woot found some cheap propellers on Ebay, way to go Hong Kong - they seem to have everything! That is a pretty crazy inefficiency, maybe a lesson in not privatizating? Does anyone know how Cat 5/6 cable fairs if it is just left in the water, like if we just attached it to a tether, but not actually inside anything. Would there be too much noise from the water and kill the signal?
Title: Re: Underwater ROV controller question
Post by: dunk on July 01, 2010, 05:02:38 AM
Does anyone know how Cat 5/6 cable fairs if it is just left in the water, like if we just attached it to a tether, but not actually inside anything. Would there be too much noise from the water and kill the signal?
my hunch is it will be fine as long as the plastic coating on the individual strands is in tact.
it might be worth being careful about kinking the cable to prevent wear on the plastic insulators.

the space between the outer plastic sheath and the inner 8 cores will fill up with water but that shouldn't matter.

out of interest: salt or fresh water?


dunk.
Title: Re: Underwater ROV controller question
Post by: CrazyCossack on July 02, 2010, 01:34:16 PM
Yeah, I guess we'll look at how expensive each kind of rope is to procure and take it from there. It'll be running in fresh water basically exclusively (just due to us being far from salt water).
Title: Re: Underwater ROV controller question
Post by: CrazyCossack on July 25, 2010, 01:52:06 PM
Hey all, haven't posted in a while so just a little update, and pictures as promised

We're still waiting on the batteries before we do anything else. As requested are some pictures of our design.

http://img839.imageshack.us/img839/3016/dsc4557.jpg (http://img839.imageshack.us/img839/3016/dsc4557.jpg)

http://img842.imageshack.us/img842/8355/dsc4558.jpg (http://img842.imageshack.us/img842/8355/dsc4558.jpg)

For reference the smaller PVC is 2in and the larger is 4in. The little motor looking things are thrusters, converted bilge pumps. The skids and ballast (2in at bottom and 4in at top) aren't yet attached to the rest of the frame, and they will be closer to the edges. The electronics area/camera place with the plexi-glass window is a little large, but we'll cut it down when we know exactly how large the electronics area will be. There will be one thruster on the grate pointed upwards, and the other two facing back on either side. We have an option for a 4th if we need one more but I doubt it. We also have two lights which I forgot to put in the picture.

We're still looking for a length of 300ft ethernet locally, rather than buy one from the States or China which costs like $70+ after shipping.
Title: Re: Underwater ROV controller question
Post by: dunk on July 26, 2010, 06:18:25 AM
We're still looking for a length of 300ft ethernet locally, rather than buy one from the States or China which costs like $70+ after shipping.
RS Supplies have branches worldwide and will have it although they are not always the cheapest.

they seem to go by the name of http://www.alliedelec.com/ (http://www.alliedelec.com/) in CA.
Offices in Ottawa.


try any local trade electrical suppliers as well.
an electrician will definitely know where to source this locally.


dunk.
Title: Re: Underwater ROV controller question
Post by: madsci1016 on July 28, 2010, 05:21:42 PM
A suggestion:


http://www.societyofrobots.com/robotforum/index.php?topic=11724.0 (http://www.societyofrobots.com/robotforum/index.php?topic=11724.0)
Title: Re: Underwater ROV controller question
Post by: CrazyCossack on August 06, 2010, 06:59:36 PM
That seems like a great deal, thanks for the link! We may just end up settling on 100ft for now, or try to string 3 lengths of 100ft together although might be trickier with the tether.

Madsci, we bought four of those batteries you recommended, would there be any sort of problem with having four on the ROV instead of the two? ie, is it more unstable? We are going to go with the 15amp fuse still I think.
Title: Re: Underwater ROV controller question
Post by: madsci1016 on August 06, 2010, 08:37:04 PM
The trick to stability underwater is a large difference between CB / CG. (Center of balance, Center of gravity)

You want your dead weight to stay towards the bottom of your ROV, and keep the floats high.  The larger the distance between CB/CG, the more stable the ROV will in the water.

So more batteries are OK, just keep them towards the bottom of the ROV as possible, and keep your floats as high as possible.
Title: Re: Underwater ROV controller question
Post by: CrazyCossack on August 07, 2010, 06:36:11 PM
Ah sorry I should have been more specific, I'm not really concerned with the weight, but more of the stability of the circuit. If the batteries are less stable then conventional ones, will be putting four batteries in there instead of two make it twice as likely that the 15amp fuse breaks at any given point? Should we perhaps put two of them through a 15amp, then the other two through another 15amp...so if one fuse breaks we'll still have the power from the other two batteries? Or is this just overkill?
Title: Re: Underwater ROV controller question
Post by: madsci1016 on August 07, 2010, 07:42:42 PM
O, oops.

No, there will be no difference in your electrical system other then if things go horribly wrong, it will make a bigger boom. Just keep your fuse inline as close to the batteries as possible, to keep the 'unprotected' part of the circuit as small as possible.

And remember, don't EVER throw water on a lithium fire, nor throw a burning battery into water.
Title: Re: Underwater ROV controller question
Post by: CrazyCossack on August 08, 2010, 01:48:09 PM
Got it, I'll keep that in mind - thanks!
Title: Re: Underwater ROV controller question
Post by: CrazyCossack on September 05, 2010, 06:29:37 PM
Hey guys, we've been very busy but we have made some pretty decent progress considering. The ROV is almost completely assembled minus some small issues with attaching the propellers properly, securing the tether and the electronics.

We have the electronics all ready to go, we'd just like to confirm that this circuit will work, and what we've done is not completely crazy or something (this is our weakest area).

Once you guys have OK'd it we'll throw it all together and have some pictures for you all. :)

Here is the diagram: http://img693.imageshack.us/img693/2893/rovschem.png (http://img693.imageshack.us/img693/2893/rovschem.png)


Cheers!
Title: Re: Underwater ROV controller question
Post by: madsci1016 on September 05, 2010, 07:12:13 PM
How is the LED array wired? You show it as directly connecting to the Arduino. The pins of the Arduino do not handle enough current to drive those LEDs directly.
Title: Re: Underwater ROV controller question
Post by: CrazyCossack on September 05, 2010, 08:22:09 PM
Thanks for the quick reply, how much current is the Arduino able to output in one pin? Because we've got two sets of 3 LEDs. If the Arduino can't power the LEDs we're really not sure how wire this so that the LEDs get the 5v power from the switch regulator while still being controlled by the Arduino.
Title: Re: Underwater ROV controller question
Post by: madsci1016 on September 05, 2010, 08:37:23 PM
an Arduino pin can only handle about 20mA.

But never fear, that's why we have transistors.

(http://www.arduino.cc/playground/uploads/Learning/multiple_leds2.jpg)

Something like this would allow you to switch the LEDS on or off. just make sure whatever transistor you use can handle the current. A regular 2n2222 will do about 1Amp, so you could use two, one per LED chain and be ok. Just tie both base resistors to the same Arduino pin.
Title: Re: Underwater ROV controller question
Post by: CrazyCossack on September 05, 2010, 09:51:25 PM
Excellent that makes sense, so we just put a transistor before each LED cluster on our diagram and that ought to do the trick?
Title: Re: Underwater ROV controller question
Post by: madsci1016 on September 05, 2010, 10:22:07 PM
yup. I'd also have a resistor in line with the LEDS like the diagram, just to protect the LEDs, since 5v is higher then there 4.5V need. A 1W or greater 1 ohm resistor should do the trick.
Title: Re: Underwater ROV controller question
Post by: Admin on September 06, 2010, 08:34:20 AM
yup. I'd also have a resistor in line with the LEDS like the diagram, just to protect the LEDs, since 5v is higher then there 4.5V need. A 1W or greater 1 ohm resistor should do the trick.
The resistors are required for limiting current, doesn't matter the voltage involved. :P


I'd use a MOSFET here instead of a transistor simply because they are more efficient, can operate at much higher currents, can switch on/off much faster, and don't require a resistor at the gait. ::)
Title: Re: Underwater ROV controller question
Post by: madsci1016 on September 06, 2010, 08:45:15 AM
The resistors are required for limiting current, doesn't matter the voltage involved. :P

It matters when calculating the needed resistance.  :P

I'd use a MOSFET here instead of a transistor simply because they are more efficient, can operate at much higher currents, can switch on/off much faster, and don't require a resistor at the gait. ::)

Works either way. MOSFETs tend to be more expensive then BJTs, no? Switching times don't matter for this application. And regular BJTs should handle his current just fine.

Also, you spell 'gate' funny.
Title: Re: Underwater ROV controller question
Post by: Admin on September 06, 2010, 09:05:11 AM
Oops, I was thinking of 'robot walking gait' vs 'MOSFET gate' lol


MOSFET's do cost more, but for a one-off thing, only like 50 cents more. You'd only save if you were to make a few hundred/thousand of them.
Title: Re: Underwater ROV controller question
Post by: CrazyCossack on October 05, 2010, 04:26:48 PM
Hey all, so a short update and a little question. We have the electronics mostly assembled but the damn camera crapped out on us, we could never get a connection. Either the camera was defective or we damaged it some way by opening it up/modifying it so many times. We really want a different model of camera as this one was a pain to deal with and really quite bulky. It is hard to fine a good ethernet bullet camera to fit our dimensions that won't run us $300.

I was looking at this webcam http://www.logitech.com/en-ca/webcam-communications/webcams/devices/6816 (http://www.logitech.com/en-ca/webcam-communications/webcams/devices/6816). The camera has decent quality and autofocuses very well which is key. And using a usb-rj45 adapter. Question is, after using the rj45 adapter, then running that through a 10/100 switch to the laptop, will we be able to use the Logitech software to control it?

Thanks,

John
Title: Re: Underwater ROV controller question
Post by: madsci1016 on October 05, 2010, 05:00:07 PM
Depends, what's this USB to ethernet adapter you talk about? Is it an accessory for that camera or some third party thing?
Title: Re: Underwater ROV controller question
Post by: CrazyCossack on October 05, 2010, 07:59:21 PM
Third party adapter, was thinking of just buying a cheapy from ebay.
Title: Re: Underwater ROV controller question
Post by: madsci1016 on October 05, 2010, 08:21:47 PM
You have to give us a link; datasheet, something.  I've never heard of a USB to ethernet camera adapter, so I want to make sure it does what you think it does.
Title: Re: Underwater ROV controller question
Post by: CrazyCossack on October 07, 2010, 01:02:11 PM
Something like: http://cgi.ebay.ca/USB-RJ45-Ethernet-Card-10-100-LAN-Network-Adapter-/390245465376?pt=LH_DefaultDomain_0&hash=item5adc713d20 (http://cgi.ebay.ca/USB-RJ45-Ethernet-Card-10-100-LAN-Network-Adapter-/390245465376?pt=LH_DefaultDomain_0&hash=item5adc713d20)

I'm not sure it would work power wise either, presumably I'd have to get some POE going. I don' think the 10/100 switch does POE, but I'll have to confirm later.
Title: Re: Underwater ROV controller question
Post by: chelmi on October 07, 2010, 01:41:11 PM
Something like: http://cgi.ebay.ca/USB-RJ45-Ethernet-Card-10-100-LAN-Network-Adapter-/390245465376?pt=LH_DefaultDomain_0&hash=item5adc713d20 (http://cgi.ebay.ca/USB-RJ45-Ethernet-Card-10-100-LAN-Network-Adapter-/390245465376?pt=LH_DefaultDomain_0&hash=item5adc713d20)

I'm not sure it would work power wise either, presumably I'd have to get some POE going. I don' think the 10/100 switch does POE, but I'll have to confirm later.

I'm pretty sure this is not what you think it is. This is a network card, and it needs a USB host (like a PC) to work. Your webcam is a USB device as well (not a host), to have the two work together you will need a PC.

Chelmi.
Title: Re: Underwater ROV controller question
Post by: madsci1016 on October 10, 2010, 04:24:00 PM
I agree with Chelmi, this is not want you want. That's a device side USB to ethernet chip. You would need some sort of host-side USB to ethernet server that was specially coded to work with a logitech USB camera.

Your best bet is to buy a real IP video camera. The alternative would be to buy a Video over IP converter box and a analog camera, but that would cost more then a standalone IP video camera.
Title: Re: Underwater ROV controller question
Post by: CrazyCossack on October 10, 2010, 09:37:04 PM
Ok guys, thanks for that! We'll keep searching for an IP network camera that'll do the trick.

In other ROV related news we finally got our patch ethernet cable working but it took a lot of troubleshooting, the cable is about 275ft, down from 333ft which was too unreliable. It seems not to work unless it's set to 10 MB/s, which hopefully will still work when we text it next with the 10/100 switch. We have a special coating on it and it performed without any loss in water.

We also have the ROV almost all assembled (minus electronics bay and motors everything is mounted). It's just barely on the side of positive buoyancy, when I push it to the frigid depths of my pool (12ft), it takes ~10 seconds to get to the surface, so we're very happy with that. The ROV is looking pretty worse for wear right now after all the tests haha, I think we'll soon have to give it another paintjob. Right now it's yellow, which is good for visibility, but really shows all the scrapes. Maybe black instead, although that decreases the odds of finding it in a lake haha.
Title: Re: Underwater ROV controller question
Post by: CrazyCossack on July 24, 2011, 08:33:58 PM
Hey all, I hope you guys have no problems if I necro this post! :) I thought it might be better if I keep it all to one thread, but let me know if I should make a new one.

So we have been working on the ROV for a few months and the construction is now mostly complete. We disassembled the ROV and repainted it and have made a new electronics bay that should be big enough for all the electronics and our new camera. We have also got a new thruster. We've also done a new light aray I would take pictures but I think we'll wait on the electronics to reassemble it. For those of you who remember I have no clue about electronics and we'll really need help!

So the current list of electronics for a refresher is:
- 4X batteries (http://www.hobbyking.com/hobbyking/store/uh_viewItem.asp?idProduct=8934)  in parallel: together 11.v at 8800mAh
- 1X voltage regulator (http://www.dimensionengineering.com/DE-SWADJ3.htm)
- 2X sabertooth 2x5 motor controllers (http://www.dimensionengineering.com/Sabertooth2X5.htm)
- a 10/100 switch
- Arduino Duemilanove (http://www.arduino.cc/en/Main/ArduinoBoardDuemilanove)
- a Arduino eshield (http://www.arduino.cc/en/Main/ArduinoEthernetShield)
- Two leak sensors kindly provided by madsci!
- Camera 12v 1.5A
- 3X thrusters 12v at 3amp each
- 1 thruster 12v at 5amp
- 4X LED cluster, 4.5 and 50ma for each cluster

Right now, we're very confused about what pins are currently used by the eshield and what are available to hook up the s1 of the motor controllers to. We'd like to power 2 motors for each motor controller, and have forward/reverse/stop etc. on each one. What mode should we use?

I'm working on an updated version of the circuit diagram since I showed the one we had to an engineer friend and it needed major revisions haha. I'll post it as soon as I'm able to draw it.
Title: Re: Underwater ROV controller question
Post by: CrazyCossack on July 24, 2011, 09:42:31 PM
Here is the schematic. The ????? areas represent where we are confused about which pin to connect the motor controllers, LED, and the leak sensor to the arduino eshield.

(http://img196.imageshack.us/img196/2917/65281943.png)

http://img196.imageshack.us/img196/2917/65281943.png (http://img196.imageshack.us/img196/2917/65281943.png)
Title: Re: Underwater ROV controller question
Post by: madsci1016 on July 24, 2011, 09:52:31 PM
Gee, that leak sensor circuit looks familiar.   :P :P

So you are asking how to hook the sabertooth controllers to the Arduino? The sabertooth's you have are serial controlled (right?), so you would have to create two software serial ports. You can create them on any pins, even analog ones; just as long as they aren't already used by your other hardware.

Looking at the eshield page:

"Arduino communicates with both the W5100 and SD card using the SPI bus (through the ICSP header). This is on digital pins 11, 12, and 13 on the Duemilanove and pins 50, 51, and 52 on the Mega. On both boards, pin 10 is used to select the W5100 and pin 4 for the SD card. These pins cannot be used for general i/o"

So any pins except 10-13 and 4 are open for any of the uses you mentioned.

Title: Re: Underwater ROV controller question
Post by: CrazyCossack on July 24, 2011, 10:06:52 PM
Yes thanks so much for the leak sensor circuit! :)

That's what we were wondering, it seems from the product documentation there are 4 modes we could put the sabertooths in: Analog, R/C, Simplified serial and packetized serial. I would assume we want simplified serial?

Thanks for that, we couldn't figure out which ports were a being used by the eshield.

Any tips on how we could power the led array without overdrawing the current? And how do your leak sensors attach?

Cheers!

Title: Re: Underwater ROV controller question
Post by: madsci1016 on July 24, 2011, 10:16:02 PM
Simplified serial is easier, but the creation of software serial ports on the Arduino is taxing on it's processor and uses up memory.

You could use packitized serial and then connect both sabertooths just use one pin on the Arduino, it's hardware UART TX pin and not have the overhead of software serial.

You should look to see if anyone has made an Arduino library to talk to the sabertooth's using packetizied serial, that would be your best option. If not, I'll help you with the code.

Easy way to drive the LEDs is using a MOSFET that can handle the current.

I'll help you you out in better detail tomorrow if no one else does. It's off to bed for me now.
Title: Re: Underwater ROV controller question
Post by: madsci1016 on July 25, 2011, 07:48:44 PM
Sigh, 10 hour days at work are killer.

So, to drive the LEDS, you need a 'logic level' MOSFET.You will wire it like the middle circuit below.

(http://www.blogcdn.com/www.diylife.com/media/2008/01/fet-diagram2.png)

The FETswitch line can be tied to an Arduino pin directly, or through a 100 ohm resistor just to be safe. Wire it so every LED has it's own current limiting resistor, and they all connect to the drain pin on the MOSFET. A MOSFET like this (http://search.digikey.com/scripts/DkSearch/dksus.dll?Detail&name=ZVN4206A-ND) will let you switch 600mA currents.

I didn't see any easy Arduino libraries for the sabertooth, but we should be able to do it. So for now, the wiring plan should be to wire BOTH sabertooth RX pins to the Arduino's TX pin (pin 1).

The leak sensors can be connected to any available IO pin, except pin 0, 4, 10-13 since those are used by other things.
Title: Re: Underwater ROV controller question
Post by: CrazyCossack on July 27, 2011, 01:32:46 PM
Cool thanks for the help! Packetized serial it is! I'm currently working on how to run the Arduino through the e-shield. So far I have been unable to really contact it at all, I think I have an older version, so the MAC address is not posted on the bottom of the device and it isn't. I've read I have to assign one which is no biggie. I have had a hard time figuring out what the IP address of the device is, if I plug it in directly to my laptop ipconfig doesn't show anything running on the LAN. I'll probably post something on the Arduino forums, but thus far I have been unable to even compile their sample ethernet sketches.
Title: Re: Underwater ROV controller question
Post by: madsci1016 on July 27, 2011, 04:24:47 PM
Yeah, can't help you there. Never used any such thing.

Though I bet you need to use a router to get an IP address assigned. Just plugging straight into your PC means you would have to set static IPs on both devices first.