vision bot questions

I'd like to mount two cameras on a robot and transfer their video wirelessly. I'd prefer using WLAN, as I'll be using a PC to
process the data and the range of the robot would then be anywhere a wireless network is available. Does anyone have any experience or ideas with something like this? Could it be done with as little as a microcontroller? I'd like to keep it as simple, small, and energy efficient as possible. I've seen several modules for converting Ethernet to serial, like the XLAN, but I have not seen any for wireless. Also, what cameras do you recommend and where can I purchase them.
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godavemon wrote:

In this case, I would use a PC for your robot. It may not be the bottom line most efficient way to do it, but if you use something Linux and a cheap EPIA motherboard, it may end up cheaper then going the same route with a simpler micro-controller, and certainly has a lot more software components that will help you accomplish your task. You could probably use two USB cameras.
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godavemon wrote:

You can go one of two ways.
Probably the easiest for two cameras is simply to go with a small micro-itx or similar motherboard with one or two USB ports. You can either use two usb webcams, or (if you have the space and power) two usb frame grabbers, and the cameras of your choice. The latter is a nice option, since often webcams have a rather narrow FOV. It does add to your size and power requirements, however. If transfering dual video frames via wireless lan, you'll almost certainly want to to some compression on board prior to sending the data over the lan, since uncompressed video eats a lot of bandwidth. There are a number of jpeg compression libraries available, or you can look around for h.263 or other related video compression libraries. You should also be able to do wlan with the micro itx.
The second possiblity is to use two wireless cameras or video transmitters and transmit back to dual frame grabbers on a remote host. This lowers your power and size requirements, but means that you'll need transmitters capable of transmitting on two different frequencies (not too hard to find). You also need a separate means of wireless control of your robot. There are a number of cheap wireless tranceivers available, however, which may or may not be suitable, depending on your needs. The major drawback of going this route is that it isn't very "plug and play" -- if you move the robot to another site, you have to lug two framegrabbers, receivers and a bunch of other stuff along with you. This option uses relatively little power and done be done in a very small form factor fairly cheaply, but tends to be limited if you are going to be running your robot much outside of your lab.
Personally for two cameras I think I'd probably go with the first option if size and power consumption aren't an issue.
Hope that helps -- m
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Wow, thanx. The mini-itx boards make the idea of putting a PC onboard seem a lot less cumbersome. Does anyone have any recomendations of a board I should use and what kind of battery pack I'll need to supply it? Also, what version of linux would be good for this type of application, and where can i learn more about making or obtaining software to send two compressed video streams over the internet?
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godavemon wrote:

I have two Mini-ITX boards for my robots.
The VIA M10000 (1 GHz C3) uses a 12V 9 amp-hour SLA battery for the electronics alone.
The iBase 890c (2.0 GHz Pentium M) uses 2 12V 7 amp-hour batteries in serial for 24 V going through a switching converter to 12V. -- D. Jay Newman
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How long will these run on a charge?
Rich
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If possible, always try to have a socket/cable which will plug into some constant power supply (eg. mains) so that you can do all your testing without the batteries dying.
snipped-for-privacy@gmail.com wrote:

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l3 wrote:

Agreed. I have such connectors to both charge the batteries and to run the system without having to worry about battery life. -- D. Jay Newman
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snipped-for-privacy@gmail.com wrote:

The VIA M10000 (1 GHz C3) uses a 12V 9 amp-hour SLA battery for the electronics alone.
This gets over an hour, but I haven't pushed it to the limit in a while.
The iBase 890c (2.0 GHz Pentium M) uses 2 12V 7 amp-hour batteries in serial for 24 V going through a switching converter to 12V.
My test, without sensors (but with WiFi) got three hours. I'll post better results once I put Groucho together again. -- D. Jay Newman
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I need some help deciding which mini/micro itx board to get as I don't know much about them. Do you have any recomendations? I need it to have atleast 2 usb ports, have or be able to easily add wireless internet, and be as fast as possible for little money, so I can do some minor video compression. I haven't found much on the internet about them. Where do you guys go for your info on these boards and where do you go to buy them? Thanx
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godavemon wrote:

I look at Logic Supply http://www.logicsupply.com /
From there you can get the specs of the various boards they sell. -- D. Jay Newman
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"godavemon"

I'm in the exact same stage as you, and I'm going to go mini-itx too.
I'm going to buy from www.mitxpc.com for the simple reason that it was the only supplier that I called where I didn't get a voice mail or an electronic answering systems. The guy who talked to me was very helpfull, he stayed on the phone with me for almost an hour. He was really interested in knowing about my project and then he got me the board that was perfect for my application. Not very common these days.
http://www.mitxpc.com/proddetail.asp?prod=MBVMII12000CM1&cat1
This board is fast (1.2GHz) and includes cardbus and cf. Both will be very usefull for my application. The cardbus will carry a wi-fi card for testing and debugging. The CF slot will hold a 2GB CF card in lieu of a hard drive. My robot will navigate rough terrain, and I don't like the idea of a hard drive being shaken to death in such environments. The system can be booted from the CF card. The other advantage is that I can have as many systems as I want. For example, in one card I may have my system running on linux with a given set of behaviors, while another CF runs windows xp with another completely different set of behaviors. If I want to test one or another, just replace the card and reboot.... simple as that.
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That looks pretty sweet. I kinda like the previous model http://www.mitxpc.com/proddetail.asp?prod 180012&cat1
It seems to be the same thing only a 1.0GHz processor instead of 1.2 and for $40 cheaper. I talked to some guys at work that lead me to this.
http://www.newegg.com/app/searchProductResult.asp?Submit=Go&Range=1&InnerCata (0&DEPA=0&bop=and&description=micro%2Datx&Order=rating
What is the difference between a micro-itx board and macro-atx? The macro-atx seem to be a lot cheaper. PC/104 boards were also recomended by someone at work but thought they're cool looking and modular they seem somewhat more difficult to opperate.
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