Posted by Deliverator on 27th February 2007
I had a busy day today, as I am trying to finish up a recent avalanche of work from clients before I head off to Portland this Thursday to take members of the TRC to the Pacific Northwest FIRST Robotics Competition, but took five minutes to glance through Craigslist to see if there was anything I absolutely needed (so sue me, I am a gadget freak). I spotted an interesting item offered free by a kind gentlemen named Tom Humphreys, a SmartNAV 3 EG from NaturalPoint.
This neat little doohickey allows for hands free control of a mouse cursor. I have one friend with CP who has motor coordination issues which make using a conventional mouse difficult. The International School is also unfortunately amongst many schools in America to see former students return home from Iraq with serious injuries. I know of at least one student who has been left substantially paralyzed from the neck down. I figured one of the two were likely to make good use of the device, so in a break between jobs, I went over and picked it up. I brought it home this evening and have been experimenting with it.
The unit consists of an emitter/sensor device which sits on top of your monitor, plugs into a USB port and accepts click input from foot pedals (what this unit came from) or a variety of other simple switches. Newer versions of the software which comes with the device support voice clicking as well. The emitter/sensor device seems to be a combination of a CCD camera and a few near IR LED emitters. You are supposed to stick an adhesive dot to your forehead, glasses, boom microphone, etc to reflect the IR back at the sensor. Unfortunately, I didn’t have any of the special dots (made by 3m out of the stuff I am sure is used for jogging reflectors), but still wanted to experiment. I found that coins, watch batteries and other similarly reflective round objects made a poor substitute for the real thing. I tried a jogging reflector and found the camera tracked it much better using the test application, but was too unwieldy for actual use. I noticed that NaturalPoint sells a special baseball cap with a reflector mounted on the brim in their accessories section on their website.
The idea is with the reflector on the brim being farther in front of the point of rotation (your neck), the reflector describes a greater arc due to small neck movements than a reflector mounted on your forehead, making it even easier to track. I decided to imitate this simple solution by taping a rectangle of tinfoil to the front of my FIRST cap. I found a rectangle of foil about an inch tall by two inches wide worked best. Afterwards, my tinfoil hat and I spent about twenty minutes surfing the web, checking email and doing other routine tasks with relative ease. I am sure an official dot would do even better.
Given that the tracking unit simply relies or reflected light, I figured that an emissive target would be even better. I pulled out a 1 watt Luxeon and taped it and a coin cell to the end of my FIRST cap. The tracking was even better than with my tinfoil cap. Unfortunately, taping an LED to one’s forehead isn’t very practical for real world use. I think I will get some reflective tape from the hardware store and see if I can make a better passive reflector hat. If I can’t come up with a better solution on my own, I guess I will just buy some from NaturalPoint, but the hacker in me wanted to see what I could cobble together. Hopefully one of the two above mentioned individuals will be able to make good use of this neat little device. I may just have to pick one of these up in a few years when my wrists are completely shot (my wrists currently make clicking noises which annoy everyone around me and my hands are pretty useless when I first awake in the morning, but I figure they still have a couple good years of use in them).