Saturday, September 17, 2005
How the Nintendo Revolution Controller detects Motion
How does it work? well, they could us RF or IR and have a receiver measuring deltas in time of packets received at a receiver, but that is too expensive and not likely how they did it. Instead, its likely they put a potentiometer in the controller. A potentiometer is very cheap: 4 wires standing straight up within a liquid stuck onto the circuit board. As the liquid moves, the current across the 4 poles changes and you can detect roll, pitch, and yaw (position will likely be controlled with the standard d-pad on the top of the control). This info is transmitted via IR back to the console. So, with a $.50 device, Nintendo will open up new forms of gameplay. Don’t disappoint us Obi-wan.
A simple 2D example is shown above. As the liquid moves around the current on each of the two wires is measured and motion can be detected, the amount of change in current is proportional to the movement that has taken place. Technically, you can probably get away with only 3 poles in 3D, but for robustness there will probably be at least 4 poles, and maybe multiple potentiometers at the front and back of the controller, for example. Note, i'm just guessing on all of this :)