NavShoe is a position tracking system, small enough to truck into shoe laces. It is much more accurate than head mounted inertia orientation tracker because the higher foot acceleration enables the use of transfer alignment from GPS. InterSense InertiaCube3 was used to get multisensory data such as gyro, accelerometer, and magnetometer.

Calibration of sensors is conducted after inserting the sensors in shoelaces. This calibration is done by wiggling the sensorized shoe for 30 seconds. When the user takes first steps, the calibration mode terminates and the system enters navigation mode. An algorithm was developed to detect the stance phase of walking and apply zero-velocity updates to the Extended Kalman Filter.

One indoor and outdoor experiment was conducted to test the system. In the indoor experiment, a user walked through a typical wood-frame house, starting at position (0,0,0) and moving along a pre-defined path and then coming back to the origin. The results show 0.3 percent error in the indoor environment. In an outdoor experiment, a user walked along a closed loop and backed to its origin, indicating the same error rate, 0.3 percent.

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