Geldhart:
Thanks Chagrin for the options. I just looked at the encoder, and while I don't understand everything right now, that will probably change in a few weeks once I learn a bit more about these kinds of things.Angelo - thanks for explaining why the gyro won't work. Much appreciated. As for the turns, my plan is to have the user manually indicate a turn is coming up before the chair actually turns. Just like in a car, you (supposed to anyway) activate the turn signal prior to actually turning the wheel.
Depending on my time and materials, I might just make use of the turn detection to turn OFF the turn signal rather than just using a constant time. That method would be even more like a car with an automatic deactivation of the turn signal, but this will be a fine tuning of stuff that is already there.
Looks like the Pololu encoder can detect forwards and backwards motion as well. Once I learn a bit more, I will revisit the datasheet, as the price is certainly in my budget.
Feel free to keep the ideas coming. I'm likely going to learn more with this project than anything else I do.
I think you are on the right track when you say the user will manually press to use the turn signal. There's no way to program which way the user INTENDS to go, only where he is currently going.
If I am not mistaken, a wheel encoder counts the number of spokes that passes through its sensors. The encoder itself is below:
It says that the two sensors produce wave forms out of phase with each other, which allows you to know which direction the wheelchair is going. I don't know if this particular sensor would be good for your application, to be honest. It seems that the wheel encoder caters specifically to the wheel included in the set. If you look at the wheels and the encoder itself, they go hand in hand. The encoder is made to count the spokes on that specific wheel. You may need to find another wheel encoder or make one yourself.