This project shows you how to build a Wireless Accelerometer Mouse Pointer (Look here). I think in time these types of input devices will be in everything allowing for added functionality. I can think of lots of great applications on cell phones for example, I would like to have a Google Maps up on my phone and simply tilt it in the direction I want to go. Looks like the site is still being updated since there is a code link but no schematic yet.
"Human Interfacing Device is key area in modern electronics era. Gesture recognition can be well introduced in modern day computers to play 3D games. Virtual Reality is not far away from our doorsteps. Simple inertial navigation sensor like accelerometer can be utilized in getting Dynamic or Static acceleration profile of movement to move cursor of mouse or Gyroscope to even rotate 3D object. We propose a technique on same principle to convert acceleration profile of accelerometer into distance with double integration. Accuracy might be issue as errors keeps on adding in double integration but with robust signal processing it would not create problems. Only limitation will be in movements that cause little acceleration which puts upper limit on sensitivity of sensor. (In mill volts per g, g= 9.8m/s2)"
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