What does the Nike+iPod Sport Kit have in common with the upcoming Nintendo Wii controller? Besides hoping to encourage us to be more active, they’re both designed around the accelerometer.

When Apple first announced the Nike+iPod Sport Kit, there was a lot of speculation about how the system would actually work. Would it work without the special Nike+ shoes? Does it measure the impact of your footsteps? Was it just a fancy pedometer? Even though it’s been out for a few weeks now, and we’ve proven that you don’t need the special Nike shoes, there’s still a bit of confusion about the mechanics of the sensor and some skepticism about whether it “really” works with non-Nike shoes. Thankfully, I’ve found an easy-to-understand introduction to the brains behind the Nike+iPod sensor.

Dimension Engineering’s Beginner’s Guide to Accelerometers is a one page overview that covers the basic functions, mechanics, and types of accelerometers available. In a nutshell: Accelerometers measure acceleration forces, such as the force of gravity and/or the forces produced by movement. In this way, you can use them to measure the tilt and speed of anything they’re attached to at any given moment. By measuring the speed of your foot when it’s moving, and the amount of time it’s at rest between steps, the iPod software can calculate your pace, your speed, and your distance travelled.

Apple and other portable computer makers have used accelerometers to implement their “Sudden Motion Sensor” technology which will automatically park the hard drive heads, helping to protect it if the computer senses a sudden drop. Clever people have found ways to use this built-in functionality to control other computer functions.

It looks like accelerometers will be everywhere soon due to the release of Nintendo’s Wii game console, which lets players interact with games via a pair of motion-sensitive controllers. It will be interesting to see how hackers adapt all of these accelerometers to control other devices and technologies in our lives. If you like to tinker with electronics, this might be a promising area to start looking into.

UPDATE: EE Times found that the sensor actually uses a “piezoelectric disk speaker,” rather than a traditional accelerometer, to measure your food motion.

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