I like‎ > ‎

An infrared glove for the Wiimote Whiteboard

Wiimote whiteboard is one of the wiimoteprojects originated from Johnny Chung Lee's original ideas.
In a few words, it allows using a wiimote and an infrared light emitting source to write directly on a screen as if you were using a whiteboard.

Several designs for the light source have been made by various users. The most common is a whiteboard marker in which the tip has been replaced by an I.R. led. This is a great design when you are using the application with a projector. However, if you want to use the application on an LCD screen, this design has a fundamental flow: dragging a led around the screen will eventually leave marks on it, and/or damage the led.

Trying to overcome this limitation, I (as several others) have designed a glove with a finger mounted I.R. led. This design makes your fingertip the only thing touching the screen, while the led stays at some distance. Now you don't need to worry about leaving marks on your lcd... apart from fingerprints! :)

You can see a video of the glove in action at http://www.youtube.com/watch?v=oO8l4bPTiHs.

Tracking precision limitations
Because the led is not exactly on the fingertip, the precision is not very high. Flexing the finger, or touching the screen at different angles, will affect the position of the mouse cursor relative to your fingertip. After testing, I would say this is probably not a good setup for operating the OS (although the video shows it is possible, there is a too high error rate for everyday use). However, I found the glove effective in cases where the precision of pointing matters less than the ease of gesture. For example:
  • User interfaces in which objects to click are large
  • Photoshop, especially if you use the "mouse only" setting of the Wiimote Whiteboard application (using the other hand to click)
  • Gesture recognition, where the exact location does not matter as much as the shape of the gesture

Making the glove

The whole design is very cheap and takes less than one hour to build.

Needed components:
  • a pair of gloves, possibly with open fingertips (makes typing possible while using the glove)
  • an I.R. led with a good viewing angle and power
  • a resistor of appropriate value
  • a microswitch
  • a battery holder for two AA or AAA batteries
  • two AA or AAA batteries
  • some strong glue
  • soldering iron, solder, thin electrical wire, electrical tape
  • a large needle and thread if you want the construction to be solid
  • a digital camera or videocamera for testing
You can find extremely cheap fishing gloves with open fingertips (less than 4$ shipped) at www.dealextreme.com .

Buy the led, resistor, microswitch, battery holder and electrical wire and tape at your favourite electric parts supplier. For the resistor, you need to calculate the right value: knowing your led's forward voltage and current, and given that you are using two 1.5V batteries, use this page to calculate it: http://led.linear1.org/1led.wiz

Now the step by step construction. Note: you might want to adapt things, like putting the led or the switch on different places. I am describing what worked for me.

First, cut two long pieces of wire. These should be long enough to go from the first articulation of your index finger to the finger base, then to the first articulation of your middle finger, then back again to your palm, around your wrist up to the back of the hand. This is more than you actually need, but will give you a margin to work with. It is important to choose two wires with different colours, it will help a lot when running wires inside the glove. I advice using red for the positive lead and black for the negative. 

Solder one extremity of the red wire to the led's positive lead; solder one of the resistor's leads to the led's negative lead. The led's negative lead usually is on the side of the led which has a cut in its circumference. Now solder the other resistor's lead to the black wire. put a piece of tape around each led's lead and the resistor, so the uncovered leads do not touch each other.
Bend the led's leads on one side, then bend them again towards the top of the led. You should get a shape like this:

Twist the red and black wire together. Position the led at your first index finger articulation (thumb side), and measure the length of wire it takes to go down your index and back up your middle finger until the first articulation (thumb side). Leave a little margin but not too much otherwise the switch will move. Cut the red wire at this length and uncover its terminal.

Solder this wire to one of the microswitch's leads. Solder the piece you cut to the opposite lead.

This is a good moment to test your wires and solderings. Put the batteries in the battery holder and connect the ends of the wires to it (respecting the polarity). Keeping them together with fingers should be enough for now. Look at the led using a digital camera (it can see infrared light). When you push the switch, it should turn on. If it doesn't work, recheck your solderings, and especially check that you respected the led's and batteries' polarity, that your switch is correctly connected, and that the led is not broken.

Once everything works, twist the remaining wires together. For the moment don't solder them to anything esle, you should fix the led and switch first.

Using the led's bent leads to wrap around the material, put the lead on the glove's index finger tip, on the thumb's side. The led should be facing away from the finger tip, towards the wrist. Let the wires run inside the glove. Use some glue, or needle and thread, even better both, to fix the led in this position.

Now reach inside the glove (or turn it inside out for easier access). Have the wires run down inside the index finger of the glove and up again inside the middle finger. If you cut the lengths right, the switch should just come up at the tip of the glove's finger on the thumb's side. Fix the switch in this position with glue or needle and thread, or both.

Have the remaining wires run down the middle finger again, along the glove's back, and come out from the glove's wrist. If you did things right you should have enough wire coming out to give you a safe margin.

Glue, or otherwise fix, a battery holder in a good position, for example on the glove's back.The holder will probably have wires coming out of it. These wires need to be connected to the red and black wires coming out of the gloves (beware the polarity!). You need to cut all wires to the good length so you don't have too much wire in excess. Solder them together, put some tape around each soldering, and you're good. If your battery holder does not have wires coming out of it, you might need to connect the wires coming out of the glove directly to the battery holder.

Now pop in a couple of batteries and put your glove on. Look at the led with a camera. When you push the switch, the led should come to life.

One last thing, this design is a bit delicate in which the wires are running inside the glove where the hand goes. While this has no danger with respect to electrical current, there is a risk of breaking the wires when putting the glove on or taking it off. It might be advisable to wrap the whole wires couple with tape to make it more solid, and fix it with needle and thread at several points in its course to make sure it stays put.

All you have left to do is download your favourite version of the Wiimote Whiteboard (I advice Uwe Schmidt's Java Wiimote Whiteboard) and you're good to finger your monitor... wait, that came out wrong!