Wii+Sensor+Bar

= Wii sensor bar = Through our inititial testing we found that the sensor doesn't allow for enough range of movement. You can only move your arm in a small arc before the screen cursor leaves the screen. To simulate the real motion of something such as spray painting, the users need to be able to move their arms in a much larger and more natural arc.

Our first thoughts were that we needed to somehow alter the signal coming out of the Wiimote using a filter of glass in a convex or concave shape. We thought this would allow us to tighten the range so you could move your arm more and still keep the aim on the screen. We tried a couple of things like standard glass, reading glasses, and then a magnifying glass. Alas this was a bit silly and doesn't work.

After some deeper research we discovered that the Wii sensor bar is not in fact a sensor that reads an incoming signal. You would assume it is as it is titled a Wii **SENSOR** bar. It is the Wiimote that is actually the sensor. The sensor bar is made of a pair of infrared lights seperated horizontally by approximately 15cm. These two infrared LEDs are what enables the Wiimote to detect whether you are moving left or right. The Wiimote that you hold in your hand is actually detecting where you are pointing by using the sensor bar as a point of origin for the centre of the screen. When you point directly at the bar you are in the centre of the screen. When you point away from it your mouse pointer moves away from that centre point on the screen.

So for the Wiimote to work you really don't need a Wii sensor bar... all you really need is two infrared lights that are positioned on the same horizontal plane and separated by a distance. The Wiimote will then orient the screen cursor to these two infrared lights. This has already been done by hobbyists, who have wired their own LED emitters, used the infrared emitters from a remote control, or in some cases candles in a darkened room. These are all great ways to build your own "sensor bar", but a little tedious for testing purposes considering I don't have the soldering expertise...and I would probably burn my fingers and it would take me all day to finish!

The same effect could be achieved by using two battery powered sensor bars and taping up one of the emitting windows on each bar so that each bar emits only one light, then place these close together or far apart to see what affect this has on the range of movement allowed by the user before the screen pointer leaves the screen.

With this new information it was now a lot easier to adjust the range of the Wii sensor, but this needed to be tested. The test would indicate if changing the distance between the pair of infrared lights would change the range of left to right motion available, and also the accuracy.

After trialling an unwired Wii sensor powered by batteries, with the standard 15cm distance between each LED, and a gadget that we wired up with two LEDs only 5cm apart, we found that the distance between the two LEDs does not really improve your range of movement. This does allow you to be closer or further away from the screen and match accurately where you point with the corners of the screen. If you have ever used a large projector screen you will know that the accuracy is poor as you can only point at a small region of the screen to get the movement, and you are not pointing where you want the cursor to be.

A larger screen like a projector or 50inch television is a case where you would move the two LEDs further apart to get improved accuracy and less jitters in the cursor. Ideally you would build your own separate LED emitters with a larger array of LEDs to get a stronger signal over the distance, or use two battery powered sensors as described previously.

Note: If you are only using a standard 40 inch screen or smaller, just stick with the standard sensor bar and stand 1-3 metres from the screen.

So we did some testing and found that the two LEDs in the sensor bar serve three purposes:
 * 1) They register the cursor location at the beginning of use.
 * 2) They measure the rotation of your wrist, this makes the cursor rotate in a limited range.
 * 3) They evaluate the distance between the sensor bar and the Wiimote camera.