ROV design

Hello,
I am working on a ROV that will hopefully clean ducts. I'm going to have 2 variable speed drive motors, a turret motor that I can control
the position of, a variable speed motor for a rotating brush, and maybe some sort of cleaning agent sprayer. It will also have a camera that sends video information back to the operator.
My problem is that I want the cable between the ROV and operator panel to consist of just two power wires and a communication cable. Does anyone have any suggestions on a low cost method to send the user outputs and video back and forth on a single communication cable (maybe a CAT5 cable)?
Thanks, any ideas are appreciated,
Joe McKibben
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make the cat5 a crossover
put a mini ITX motherboard on your robot
have a laptop computer at the other end of the cable.
run a video server on the bot.
Rich
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On Oct 13, 3:55 pm, snipped-for-privacy@gmail.com wrote:

That is an interesting idea. But a little more expensive than I was thinking of.
Thanks, Joe McKibben
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Joe McKibben wrote:

It's far cheaper than the alternatives you are talking about.
Used pentium II laptop: $50 on eBay
Mini-ITX board: $100
Webcam: $40
Your 4 variable speed drive motors and controllers, tracks, brush, sprayer, etc. will cost *far* more.
In addition, it won't actually clean ducts. You will be spraying the dirt and then moving it around with the brush.
Free Clue: if your robot comes out of the duct and you don't have to empty out a couple of pounds of dirt, the dirt is still in the ducts.
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Thanks for catching me on this. But I just didn't mention it would be connected to a commercially available duct cleaning vacuum system that has a spinning brush on it. The robot would carry this up the duct and also have the chemical sprayer.
Joe McKibben
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On Oct 14, 12:55 pm, snipped-for-privacy@example.com wrote:

I do understand how the laptop would save me money by not having to use the case and all of the mechanical pots., switches, also it would have a screen already. It would be pretty compact also.
But I am wanting to make more than just one of these robots. So, hoping on good laptop prices on E-bay isn't going to help me with this. Also, I want the system to be more robust and be able to withstand a little abuse. I don't know how many drops a laptop might take.
The communication between the robot and operator panel I was hoping to base on a couple inexpensive ICs.
Thanks for your ideas. It gives me something to chew on.
Joe McKibben
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Video: Camera baluns on each end the type thats used for CCTV
Outputs depend on what they are...Protocol, voltage etc etc
I wouldn't send power and (outputs and video) over the same cable as you'll get interference. Look at using two cables with one shielded. As far as I know there isn't a cable where separate conductors are shielded though I must admit I haven't looked.....
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wrote:

What I am probably going to do is get a custom cable made up, it will probably have two or three cables in it. There are some companies that do it. The video camera will be like a back up camera for cars.
Joe McKibben
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The way I am going to control it is with a two-axis potentiometer joystick for the drive, probably a dial for turret position and a dial for brush speed. A single switch for the spray. It will all be housed in one of those plastic briefcase things. There will be an LCD for viewing the video from the robot.
So, I need a way to gather all of my analog(4) and digital(1) signals in to a single serial signal that I can convert into the PWM and Relay signals I need on hte robot.
Joe McKibben
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Stick a uC at either end and use RS-232.
Remember voltage drops over wire considerably if you've got a long length.........
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Have you considered RF? and eliminating the cable?
XBee might do well, although you'd probably have to put an antenna inside the duct at the point of entry. I'm not certain, but I'm thinking the inside of the duct might act as a fair conduit, or wave chamber, getting the signal well distributed everywhere inside the metal ducting. A XBee link would take care of bidirectional command and reporting. However, your video is another matter. At XBee speeds, you'd have a picture every ~2 or 3 seconds, and it would dominate the whole channel/bandwidth to get that. 801.11 might make a good path for video, and maybe control as well.
At those high frequencies it could go either way, a really tight enclosed wave guide, or a squelching faraday cage around ever corner. A little experimentation might tell you which.
Randy
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When I first was given the idea for this project that was my first inclination. But the person who gave me this project thinks it will interfere with wirless communications in hospitals were he does a lot of duct cleaning. Also though the robot is going to be carrying a vacuum hose so carrying a cable along with it probably will not hurt to much.
Joe McKibben
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RMDumse wrote:

That's a heck of an RF transmitter if it can eliminate a caple that supplies power to run several electric motors...
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On Oct 14, 9:24 pm, snipped-for-privacy@example.com wrote:

That would be wouldn't it. That much RF, and you could just burn out the dust off the metal surfaces, and skip the whole ROV thing, huh?
No, I meant the communications cable. The power cable or alternative of batteries would still be required.
Randy
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Yeah if you used RF you would have to use a battery or still a cable but just with the power wires.
Joe McKibben
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On Sat, 13 Oct 2007 14:58:19 -0000, Joe McKibben

Duct/pipe bots seem to be popular things to try to construct. From my simple experience, you probably could control it from a laptop thru a single piece of cat3 phone wire. One conductor for rs232 to a controller, one conductor for video, one conductor for + power for the controller, cam, and servos, and a common ground (the bot would need to have batterys for the large motors, lights and such). Would be easy to test. From what I've seen of the homebrew duct/pipe bots, I think most were eventually abandoned for various reasons.
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On Oct 14, 1:35 pm, shb*NO* snipped-for-privacy@comporium.net (Si Ballenger) wrote:

I like this idea of carrying a battery on board so I wouldn't have to use larger gauge power wires in the cable. But, I already have some pretty tight space requirements for the robot.
Thanks, Joe McKibben
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wrote:

I personally would use an on-board battery, and run everything else through a single CAT-5.
Oh, and use RS-485, not RS-232. You need an RS-485 transceiver at each end, but you can run RS-485 reliably through thousands of feet of cable.
Later, Jon
-------------------------------------------------------------- Jon Hylands snipped-for-privacy@huv.com http://www.huv.com/jon
Project: Micro Raptor (Small Biped Velociraptor Robot) http://www.huv.com/blog
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I did some research on RS-485 and found some Maxim RS-485 tranceiver ICs. I get how they comunicate between each other but how do I add my Outputs to the circuit? Also could I transmit the video over the RS-485?
Thanks for the help, Joe McKibben
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Jon Hylands wrote:

I'm not sure RS-485 has enough bandwidth for video.
100MB ethernet has the required bandwidth for video.
-Wayne
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