Tele-presence robot

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Nick Fryer
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Tele-presence robot

Post by Nick Fryer » Tue Dec 13, 2011 3:03 am

I've recently started a project to create a telepresence robot out of an old wheelchair. I plan on using an Arduino to output to the wheelchair controller. However how should I go about controlling it remotely and how would I go about setting and receiving video.

https://plus.google.com/u/0/b/107243143 ... 6720/posts

Thanks
Nick

LukeW
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Re: Tele-presence robot

Post by LukeW » Sat Dec 17, 2011 9:15 am

Sending and receiving video through an Arduino isn't really very practical.

You should be able to get relatively common cameras off the shelf that output composite video, and transmitters that take composite video and transmit it wirelessly (commonly in the 2.4 GHz spectrum) to a receiver that outputs composite video to a display.

Would that provide sufficiently high resolution and quality for your application?

For wireless communications with the Arduino, you want RF, right?

What kind of RF range? What kind of communications speed/bandwidth do you think is required?

You might use Bluetooth, 802.11 Wifi, 802.15.4 with a chip like an ATmega128RFA1 or a module like an XBee, or you might use those Nordic 2.4 GHz bidirectional chips, or you might use those low-cost single-direction low-bandwidth 433 MHz modules.

Nick Fryer
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Re: Tele-presence robot

Post by Nick Fryer » Sun Dec 25, 2011 7:36 am

Thanks for the reply.

I have purchased an wireless IP camera it should work quite well.

For the control I was thinking of using one of your 433 MHZ recievers, how would I go about transmitting too the robot.

Nick

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jonoxer
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Re: Tele-presence robot

Post by jonoxer » Wed Dec 28, 2011 3:59 am

Hey Nick, great to see you on the forum!

If you wanted to use the 433MHz receiver shield, you could use the Jaycar transmitter module I mentioned in this thread:

viewtopic.php?f=12&t=122&p=382#p382

However, I suggest you go for something bidirectional. It would be really handy being able to put a battery charge monitor, collision detection, proximity detection, etc on the bot and then send that data back to you. As @LukeW suggested, there are a number of options including XBee that would be worth looking at.
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Jon

Nick Fryer
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Re: Tele-presence robot

Post by Nick Fryer » Fri Dec 30, 2011 4:49 am

Thanks Jon,

I think I will use the transmitter from jaycar for simplicity. I will have a look at upgrading it once I get it working. Thanks for the advice though I will eventually have to do use something bio directional like the XBee.

To control the wheelchair we figured out it would easest to mimic joystick but we will need to output a true analog variable voltage between positive 2.5 to negative 2.5. We will need to 2 of these signals one for forwards and backwards and one for turning. How would you suggest going about this.

Thanks Merry Christmas and a happy New Year.

Nick

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jonoxer
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Re: Tele-presence robot

Post by jonoxer » Fri Dec 30, 2011 9:17 am

There are a few solutions to that, but the first thing I'd start looking into is digital potentiometers. The joystick in the wheelchair is most likely a pair of interlocked potentiometers, so it may be as simple as disconnecting the existing pair of pots and putting a pair of digital pots into the same position.

Digital pots are typically controlled via I2C or SPI, but I don't have any specific recommendations. These tutorials may get you heading in the right direction though:

http://www.arduino.cc/en/Tutorial/SPIDigitalPot
http://arduino.cc/en/Tutorial/DigitalPotentiometer

Do you know the specs of the existing joystick? Is it a pair of pots, and if so, do you know what values they are and whether they're linear or logarithmic?
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Jon

Nick Fryer
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Re: Tele-presence robot

Post by Nick Fryer » Sat Dec 31, 2011 6:09 am

2 pots is what we expected to see when we pulled the thing apart, but what we got was 5 electromagnets. I've managed to find the documentation on the joystick.

http://www.pennyandgiles.com/Multi-Axis ... 04,3,,.php

Cya
Nick

Nick Fryer
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Re: Tele-presence robot

Post by Nick Fryer » Sat Dec 31, 2011 1:14 pm

I managed to find a pdf of exactly what I was looking for.

http://nebula.ece.iastate.edu/files/mpfp_doc.pdf
Last edited by Nick Fryer on Mon Apr 23, 2012 1:54 am, edited 1 time in total.

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jonoxer
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Re: Tele-presence robot

Post by jonoxer » Sun Jan 01, 2012 11:06 am

Wow, that really is just what you're looking for! I haven't seen those inductive joysticks before.

I'd love to see how you go, so please keep us updated. If you need any help putting together that circuit they documented to emulate the joystick, just let me know.
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Jon

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