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My Wheelchair Robot - Anna

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What you call a "smoothing circuit," most people would call a "RC low-pass filter" :-)
Wikipedia has a cool article on that, if you want to see formulas for cut-off frequencies/response times, etc.

lol jwatte. Thanks! I knew it had a name, I just couldn't pull it out of my butt when I wrote this. All my electronics and programming is self-taught, so I've got plenty of gaps in my knowledge, too.

Thanks for the tip on the article. I'll go check it out.

Update April 9, 2013 - My Wheelchair Robot Becomes a Teleoperated ROV

It’s been a couple of weeks since I posted anything about Anna, my wheelchair robot I’m using for Smart Chair Technology research. I’ve been busy with family obligations, but I’ve still managed to make some great progress. Here’s a very short update. I’ll try to add a video as soon as I can get my hands on a decent camera!First, I found some open-source robotic software from Oculus used to control their “netbook based” tele-robots. Lucky for me, their controller board is compatible with the Arduino that I’m using. I downloaded the source code for their firmware, made some tweaks, and I now have full remote control/tele-operation of Anna via wifi from any internet connection anywhere in the world, and also via an app on my Iphone. This is a far cry from the simple keyboard control of her I had just a few weeks ago!

This is a screen-grab from my laptop. I remoted in to Anna who was on the other side of the house in the basement, and this is what her camera is looking at. If you can manage to read the screen-grab, you’ll see have I full speed and directional control of her, all while she streams full video and audio to my phone or laptop computer. The status display on the top right is great…battery condition, docked or not-docked status, moving or not, ping time (there is a keep-alive timer that will shut down Anna for safety reasons in the event communications are lost), and more. It’s also got pan/tilt control once I hook a servo up to my camera.
On the hardware side, I made some progress, too. I extended the 24 volts from the wheelchair batteries up into her electronics box, and threw in a 24 to 12 volt DC-DC converter (5 amp), and a 24 to 5 volt DC-DC converter at 10 amps. These will give me the power I need for the Kinect sensor and my ultrasonic and IR sensors, as well as some servos. I brought all three of these voltages out to terminal strips for ease of access. In the center of the picture you can see (from left to right) an 8-relay board, my breadboard for prototyping, and her microcontroller, an Arduino Mega 2560. The phone jack you see in the very lower right corner is where I tapped into the wheelchair’s joystick/controller. If I plug in the Arduino, I’ve got computer control of Anna. If I plug in a loopback jack, she reverts to normal wheelchair mode controlled by her joystick. I did this for ease of moving her around, and safety when I have to take her in public to demonstrate some of the technology I’m working on.

And last, but not least, I put a stable platform on Anna to safely house and isolate her electronics. Although it looks hideous, it kept within my budget (zero dollars for scrap wood. lol). One nice feature to this box is that the wheelchair frame had a reclining seat. By mounting the box between the arm brackets, I am able to release 2 levers at the front of the chair, and the entire electronics box raises up and back to the rear. This makes it easier to work on the batteries and other electronics in her base, and it also doubles the space I can use for electronics because the platform raises up enough that I can mount components on the underside of the board you see in the picture above.

I’ve still got some ultrasonic sensors to mount. Then I’m going to work on tweaking her software until I can purchase a copy of RoboRealm and a Kinect sensor.

So far, I've only got $75 invested (total) in Anna. That only puts me...oh....$75 over budget! lol
Thanks again for reading about Anna! Stay tuned for more Adventures with Anna :)


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