im not sure the best way to accomplish this. Would it be best to hack the donor controller, cut the traces of the joystick and put the arduino in line with that?
The controls on the wheelchair is a joystick that is very sensitive an not too user friendly. I have tried to use it and it jerks around when you start to move the chair. The problem is when you move the joystick slightly the chair does not move so you got to lean more on the joystick and by that time the motor catches up and takes off. One of the main contributing factors is that the two front tires rotate 360 degrees. So it depends on which direction those tires are facing which determines the amount of force needed to get the chair moving.