A Robust Sensor Fusion Algorithm for Pedestrian Heading Improvement

S. Siddharth, A. S. Ali, N. El-Sheimy, C.L. Goodall, Z.F. Syed

Abstract:	Pedestrian Dead Reckoning (PDR) combined with the knowledge of initial coordinates and user modes, can potentially deliver the accuracy required for pedestrian navigation applications. An improved PDR logic that works in different user activities is described first followed by novel techniques for heading estimation for a robust navigation solution. Improvement in the heading of the user for walking cases, especially in GNSS denied environments and urban canyons, is a difficult problem in pedestrian navigation that needs investigation. The heading observability considerably degrades in low speed walking, making this problem even more challenging. The goal of this work is to improve the heading solution when handheld personal/portable devices such as cellphones are used for positioning. Most of the smart phones are now equipped with self-contained, low cost, small size, and power-efficient sensors, such as a magnetometer, a gyroscope, and an accelerometer. For an absolute heading computation, a suitable choice is using a magnetometer in combination with a gyroscope. Recognizing the user modes is indispensable for optimal working of the proposed PDR algorithm. To this end, most common user activity, such as detection of stationary and walking cases with a hand-held device is described briefly. By recognizing a suitable mode the switching of fusion filter is furnished seamlessly. The fusion filter needs calibrated magnetometer readings, and helps in initializing the gyroscope in the fusion filter described. Gyroscopes work accurately over short time intervals, and assist in compensation for loss in heading information during magnetic anomalies and are also used to smooth the coarse magnetic heading derivations. A walking person is expected to make slow turns with the device. Our observations and frequent field tests have shown an improvement in PDR solution if, gyro derived heading is updated from magnetometer heading during these slow turns. The results show that good pedestrian navigation solutions can be obtained ubiquitously, if the heading derived by using the techniques described above along with an appropriate pedestrian dead reckoning algorithm is implemented.
Published in:	Proceedings of the 24th International Technical Meeting of the Satellite Division of The Institute of Navigation (ION GNSS 2011) September 20 - 23, 2011 Oregon Convention Center, Portland, Oregon Portland, OR
Pages:	1337 - 1345
Cite this article:	Siddharth, S., Ali, A. S., El-Sheimy, N., Goodall, C.L., Syed, Z.F., "A Robust Sensor Fusion Algorithm for Pedestrian Heading Improvement," Proceedings of the 24th International Technical Meeting of the Satellite Division of The Institute of Navigation (ION GNSS 2011), Portland, OR, September 2011, pp. 1337-1345.
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