Personal inertial navigation system employing MEMS wearable ground reaction sensor array and interface ASIC achieving a position accuracy of 5.5m over 3km walking distance without GPS

An accurate personal inertial navigation system under GPS-denied environment is highly critical for demanding applications such as firefighting, rescue missions, and military operations. Location-aware computation for large-area mixed reality also calls for accurate personal position tracking. Position calculation can be accomplished by using an inertial measurement unit (IMU) composed of a 3-axis accelerometer, 3-axis gyroscope, and 3-axis magnetometer. A gyroscope and magnetometer together can provide the orientation information, while the displacement can be obtained by integrating the acceleration data over time. A MEMS-based IMU is attractive for its small size, low power and low cost. However, such devices exhibit a limited accuracy, large offset, and time drift, which can result in an excessive position error over time. To achieve high-performance navigation, it is critical to accurately reset the IMU time-integration during each step when the foot contacts the ground. Furthermore, correcting the IMU inherent inaccuracy, bias, and time drift becomes important for improving system performance.