I found a PDF that describes how the joystick interacts with the chair. Man, I would have never figured this out with my multi-meter. I wrote a sketch to control the chair with the Arduino, but still allow manual control through the joystick. I needed to smooth out the PWM to analog so I used an ‘RC circuit’ and put it all on a small board and stuck the whole thing in a project box. JoystickBypass.pde
I fried my Arduino today. I was hooking up what I thought was a com line in the chair’s control stalk and it made a ground loop through my computer. I was charging the chair from house mains at the time. There was a loud pop and now I have a hole in my chip. Bummer. I guess they make an Aduino where you can replace just that chip, but that is not the Arduino I have. I will get a replacement.
So far I can’t figure out how to tap this joystick controller. A replacement will be on the order of $150 so I am not willing to mess with it too much. Worst case, I can sell the chair and buy an off the shelf robot chassis. I can’t sell a fried chair.
I can tell I will be losing a lot of time playing with the Arduino. I have a bunch of goodies coming in the mail for it. The FEZ is powerful, supports multi threading, and has a micro SD card slot. The FEZ is more what I was looking for but I have decided to use the Arduino for simplicity sake.
Here is where the rubber meets the road. I need to control this power chair with a computer. I have been poking around online looking for a solution. The Arduino and ARM based boards seem to be most popular. I bought an Arduino UNO and a FEZ Panda II to play with and see what I like better. The Ardunio has a huge fan base and therefore many code examples and help groups. The FEZ runs the .NET micro framework and is closer to the skill-set I already have. http://www.adafruit.com/category/17_64 http://www.ghielectronics.com/catalog/product/256/