Complicated Joystick Controller

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.

$30 Lesson

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.

Loads of fun

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.


I have set up some requirements for my robot chassis.

  • run up to 8 hours on a charge. More hours is better
  • mount whatever I want to it so it needs a solid frame and heavy base
  • I don’t want it to be too small to where it might seem like a toy, but I don’t want it so huge that it would be socially cumbersome
  • safely store a laptop on it
  • emergency shutoff switch
  • remote control system for times when I need to take control of it
  • a way to interact with people around it
  • a camera. Stereo vision is ideal
  • Perimeter detection, sensors?

I am thinking I could hack a power chair if it had one of those joysticks on it.
Something like this:

PC control

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.