Planning the Chair

It's one thing to have the idea, it's another to get out there and build it, and finally its another thing all together to spend some money to get the parts you need. Since there aren't any real local electronic stores around here, I will be buying my parts from http://www.solarbotics.com since they are Canadian, eh?

Prior to actually getting the parts, and maybe ordering stuff I don't need, or missing stuff I DO need, I need to plan the build carefully.



Makes perfect sense? Actually it isn't really all that complicated.

On the rear view of the chair you see the main display screen in green. This will show the active turn signals, brake lights, reverse indicator, and the Quote of the Day (not all at the same time). Next to it in grey is the speaker system which at this point will provide both an audible reverse signal along with proximity alarms (someone's standing too close).

The white rectangle is the breadboard. A handy little device that allows wires to be connected without the need for soldering. I'm not very good at soldering so this is a life saver. It is attached with a bunch of data wires to the Arduino UNO (in blue) which is the brains of the whole operation. The Arduino is an open source micro-controller that allows easy hacking of electronics. It can read input from sensors or humans, process that input, and send output to various other devices. For example, if the user taps the yellow touch sensor on the left side of the chair, the Arduino will know that the sensor was triggered, then tell the LED display to blink the left arrow for 5 seconds. If the proximity sensor (orange diamond on the bottom of the chair) notes there is a "something" within 1.5 meters, the Arduino will show a "You are walking too close" message on the LED display, and beep the speaker to alert the user that someone or something is behind them.

The user will signal left and right turns by tapping on the yellow circles on the sides of the chair. Tapping both at the same time will also "power down" or "power up" the system. A combination of a magnet attached to the spokes of the chair (red), and a pair of Hall-effect sensors (pink) will continuously calculate the speed and direction of the chair. If the chair slows down suddenly, the LED display will show the brake light, and if the chair goes in reverse, the reverse indicator will light up, and an audible alarm will sound.

The entire system will be powered by 5 AA batteries on the rear of the wheelchair (brown with gray stripes).

There you go, all you need to know. Simple really. Maybe I should have gone with something more complicated.

The Project

The Class

My CS 207 (Building Gadgets) class at the University of Regina is going to simply be, without exaggeration, the most thrilling, the most educational, the most exciting class I have ever taken. Why? Because of final projects like these:

http://www.youtube.com/playlist?list=PL4849EB387901168D

Who doesn't want to build a motion sensing, automatic paintball gun security system?

Ok, I don't want to, but I did think about a bull made out of Lego that would charge only at red things.

Then I remembered the misery daughter had with her wheelchair, and thought, "There has to be something I can do to make it better." After all, that's what dads do, isn't it.

What I Hope to Accomplish

In this project, I will be solving a problem that users of manual wheelchairs face on a daily basis - they are invisible to able bodied people walking near them. This leads to collisions, and squished toes, as people don’t see the person in the wheelchair as they make turns, stop, and back up. This becomes even more important in more crowded areas like schools and shopping malls where traffic becomes stupider the more people added. The proposed solution borrows from another well known facet of Western Civilization that suffers from stupid people -- traffic.

The Current Chair

I will be using a typical manual folding wheelchair. Now that my daughter is using a walking boot cast and seems to be recovering, I have the chair all to myself.

Complete with Cat

The Tricked Out Chair

We will create a system that will show turn signals, break lights, reverse gear indication (along with the Beeeeep, Beeeeep, Beeeep sound) so that others will know to get out of the way of the person in the chair.  In addition to the turn signals, it can also display custom messages (easily updated in the source code), and rotate them on a regular basis. For example:

I heard what you said about my chair
It wasn’t very nice.

I’m only 11 and have my own wheels.
U Jelly?

You can’t hurt my toes.
My wheels can hurt yours - stay clear.

Sit down for what you believe in!

The system should be able to get input from the user or the environment so that the turn signals and brake signals do not have to be complicated to signal. Preferably, it should be able to read the body language of the owner, KNOW that the owner is turning left, and put on the Left Signal automagically without requiring specific input from the user. (Unlike turn signals in a car that are manually activated).

Signals will turn off automatically after a few seconds. The user should also be able to easily turn off the system so that you don’t have distractions when settling into a classroom or other things where small, tight, maneuvers are required.

Sketch (c) 2012,  Elizabeth Johnston, used with permission