Mitigation of a Heading Drift in Pedestrian Dead-reckoning Caused by the Sensor Bandwidth

In this paper, we analyze the relationship between sensor bandwidth and heading drift, and improve a pedestrian dead-reckoning (PDR) system considering the heading drift by the insufficient bandwidth. The PDR system using foot-mounted inertial measurement unit (IMU) is generally based on an inertial navigation system (INS). In order to reduce the estimated position error, INS is combined with the zero-velocity update (ZUPT), which assumes that the pedestrian shoe velocity is zero at the stance phase. Although the error can be reduced through ZUPT, the estimation errors due to other causes remain. The angular rate and acceleration signals measured from the inertial sensor have various frequency components depending on the motion of the shoe. In the heel strike phase, the signals change sharply due to the impact, and the high frequency components are generated compared to the other phase. Considering only the accuracy of the inertial sensor and using a sensor with insufficient bandwidth, estimation errors occur in the PDR system. In the standard PDR system, loss of information due to narrow bandwidth causes heading drift, which is the unobservable state in the filter. In order to compensate for the heading drift due to the insufficient bandwidth, we analyze the estimation errors according to the bandwidth. Moreover, we propose a PDR system considering the heading drift estimated based on sensor bandwidth. To improve the estimation performance of the PDR system, the proposed system compensates the heading drift according to the sensor bandwidth in the heel strike with the high frequency components. The experimental results show that the improved performance of the proposed system compared with the standard algorithm.