ROS control for robosapien

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ROS control for robosapien

Postby ENKI-][ » February 16th, 2011, 6:01 pm

I have a Robosapien V1. I'm not too keen on cracking the case, since this is the only Robosapien V1 I have, but it's not actually terribly useful. Between the piles of non-rechargable D batteries and the IR control, it doesn't please me as much as I thought it might.

For instance, I set it up for telepresence:
http://www.youtube.com/watch?v=F8-EAhvzYtk
This was not terribly useful, since I could only tele-commute about six feet, and only within line-of-sight.

The obvious solution is to set up a simple RF transmitter and receiver, and hook an IR-filtered photovoltaic on the transmitter and an IR LED on the receiver, which will sit behind the robot's head. That would, trivially, extend the range to that of my own RF circuitry or that of the wireless camera module, whichever is shorter (previous experiments with the camera module indicate that it can go more than two hundred feet before the signal becomes unusable). However, that doesn't sufficiently pique my interest, and I can't be arsed to do it.

More interesting would be to make each side a transceiver, encode with DTMF tones (I can rip the circuitry out of old touch-tone phones, or maybe shell out for actual DTMF encoder/decoder ICs), add sensors, design some protocol by which I can broadcast full-duplex over a homemade radio with DTMF tones something resembling a fairly complex set of sensor values and motor control (since my video transmitter is out-of-band I don't need to worry about THAT mess). There are, if I recall, twelve DTMF tones on a touch tone phone (0-9, star, and octothorpe), and if I decode to binary I can bitmap four bits and have some values unrepresentable, or I can encode twelve separate signals.

I understand that there exists an ROS/AVR bridge. If I use an AVR to control the signals sent via the radio and to process those signals it receives, I can plug this into ROS (and if I can get my tuner card working properly, I can plug the video in as well).

That said, I'm not terribly well-versed in electronics, I've never used ROS, the extent of my hands-on experience with RF circuits is building an AM radio from a kit in fifth grade, and I've never generated DTMF tones with ICs (nor have I decoded them).
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Re: ROS control for robosapien

Postby eresonance » February 21st, 2011, 4:20 pm

This is a pretty complicated little project you're thinking of doing! Maybe I'll add a few of my suggestions to your project.

ROS is super cool, and I've only just begun to get to know it. The major problem with it is its complexity. It has a pretty steep learning curve and you'll def. need to know how to code in python or C++ before you delve into that one.

Super cheap wireless transmitters that spit out digital would be a lot easier than worrying about tones and filters and all that. You can buy them from sparkfun (http://www.sparkfun.com/products/9582 or something like http://www.sparkfun.com/products/8768) or get them with unregulated output power from china via seeedstudio (2km range). Either way it would be a lot easier to interface with a micro controller.
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Re: ROS control for robosapien

Postby ENKI-][ » February 21st, 2011, 5:15 pm

Thanks :-). I'm already quite familiar with both C++ and Python, though I have yet to use ROS. I expect the hardware to be the bottleneck here.

Thanks for the heads up on the cheap digital RF transceiver modules. I'm always on a shoestring budget (which is why I mostly do software), so I'll take a look to see if those are something I can afford.

EDIT: That thing from seeedstudio looks like the ticket! Cheap, and no surfacemount soldering. Cheers!
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Re: ROS control for robosapien

Postby eresonance » February 21st, 2011, 5:58 pm

I bought one of those seeedstudio ones a while back but haven't used it for anything yet. I also bought a bunch of microchip based zigbee modules for super cheap but I don't know what I'll use em for either :P
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Re: ROS control for robosapien

Postby ENKI-][ » February 21st, 2011, 6:20 pm

It looks like I'd need to get two of them for them to be of any use, and I'd probably also need a spare arduino on the robot side to handle the translation to IR. I like the idea that it'll blow up if you bend the antenna, though. Depending on the pin spacing, I may be able to fit it in and use it like a shield (since it takes 5v).

The one thing I'm worried about is that it might jam the signal from the camera.
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