Wiimote Project

Hi, Ben,

Your Smoothboard is really great. There is only one feature my service users and I would like you to create. See, the original Smoothboard program assumes all the users have the ability to access the whole projector screen. That is why your calibration screen makes use of the whole computer screen. However, with users sitting on wheelchairs and a large projector screen hanging up 2 to 3 meters above the ground, there is no way the users can access the upper part of the computer screen. Elongating the handle of the IR-pens is one of the solutions but it would be much better if Smoothboard can call-up a small window, which duplicates the entire computer screen and responses to the mouse clicks. In this case, we would do the calibration and play the games with only a small part of the entire screen. Mouse sensitivity will be lowered, but, be frank, our service users really do not need such high resolution like we do. Please kindly help to make it happen.

Gordon from Hong Kong

Hi, folks. I’m from Hong Kong but unfortunately cannot buy a high power IR LED to build an IR pen. Here’s the approach I used to solve the problem.

First of all, my projected computer image (~1.3m X 1m) on the wall was set such that the center of the image was at the same height from the ground (~1.6m) as normal eye-sight.

Then, I modified an ordinary LED torch light (~10cm long) such that it consisted of 4 low-power IR LED (1.5V, 100mA working at >250mA with no resistor). Unlike most of you, I didn’t use the tip you called pointing at the screen. I simply stood right in front of the screen, held the IR pen like holding a pencil in the way that the LEDs pointed towards you and the Wiimote.

Lastly, my Wiimote was set right in front of the center of the screen 3m apart.

If you’ve studied Ergonomics good enough, you’d have noticed that human tend to hold a pencil pointing slightly upwards if the drawing point is higher than their eye-sight. Whereas, we tend to hold a pencil slightly downwards if the drawing point is below our eye level. This tilt angle was noticed to compensate the cursor position error generated by not using LEDs as the tip. Besides, since the length of the IR pen was much smaller than the distance between Wiimote and the screen, it provided resolution good enough for normal Windows applications.

This approach differs from the traditional method in the way that you can stand right in front of the screen and hold the IR pen like a pencil but not a magic wand. In addition, LED power is fully utilized because the LEDs are pointing directly at Wiimote. The drawback is that the center of the projected image and Wiimote must be set in a straight line at the eye level for the best result, and the Wiimote cannot be placed at the left or right of the screen.

This is the third IR pen I built with low-power IR LED and I wish all of you enjoy my findings.