ROV design

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

That is an interesting idea. But a little more expensive than I was thinking of.

Thanks, Joe McKibben

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.....

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

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

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.

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

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.

Stick a uC at either end and use RS-232.

Remember voltage drops over wire considerably if you've got a long length.........

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

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

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

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

That's a heck of an RF transmitter if it can eliminate a caple that supplies power to run several electric motors...

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

Yeah if you used RF you would have to use a battery or still a cable but just with the power wires.

Joe McKibben

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

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

I'm not sure RS-485 has enough bandwidth for video.

-Wayne