GPS-Denied Pedestrian Tracking in Indoor Environments Using an IMU and Magnetic Compass

摘要

This paper presents an approach for pedestrian tracking based solely on the integration of a boot-mounted industrial grade inertial measurement unit (IMU) and colocated digital magnetic compass (DMC). The system is self-contained, small and requires only passive sensors (no infrastructure to set up) mounted to the heel of the operator’s boot. During each footstep, there is a rest period that is detected and used to perform a zero-velocity update (ZUPT) to significantly constrain the position, velocity, roll and pitch errors through the use of an extended Kalman filter (EKF), leaving heading errors as the dominant source of position error. Heading errors accumulate with time due to integrated gyro errors and lead to computing motion in the wrong direction and hence, horizontal position errors. This paper shows that improved positioning accuracy can be achieved through the use of magnetic heading updates and a compass filter to successfully extract compass data whose measurements of the Earth’s magnetic field have not been significantly distorted by the ferrous infrastructure in a typical indoor office environment. rnUse of the magnetic compass filter is shown to reduce 95% horizontal position accuracies by several meters for multiple operators walking for periods of up to 15 minutes.