"This was a few years ago so sensors may have improved" Apparently they're much better than previously. When I first tried this around 3 years ago, I had the s

"This was a few years ago so sensors may have improved" Apparently they're much better than previously. When I first tried this around 3 years ago, I had the same problems you did. The errors get cubed by the double integration. Software Kalman filters and other tricks didn't really help. A lot of the newer sensor chips now do "sensor fusion"[1] on the chip itself, which means that the raw data is much more useful, and requires almost no post-processing. I assume that this, in combination with higher sampling rates, means that the errors are small enough for the output to be useful over "human interaction" scale. [1]: http://en.wikipedia.org/wiki/Sensor_fusion http://en.wikipedia.org/wiki/Sensor_fusion Examples: http://www.kionix.com/sensor-fusion http://www.kionix.com/sensor-fusion http://www.invensense.com/mems/technology.html http://www.invensense.com/mems/technology.html http://www.st.com/web/en/catalog/sense_power/FM89?sc=mems http://www.st.com/web/en/catalog/sense_power/FM89?sc=mems