An Improved Personal Dead-Reckoning Algorithm for Dynamically Changing Smartphone User Modes

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

Abstract:	The demand for navigating a user with a hand-held device, especially in GPS denied environments, has tremendously increased over the last few years. Today’s smartphones contain low cost sensors with 3D sensing capabilities for any type of motion experienced by the phones. Accelerometers, gyroscopes, and magnetometers are the most commonly found sensors in the smartphones that provide 3D acceleration and attitude of the phone. In the current state of the art in MEMS technology, the accuracy of gyroscopes is not good enough for getting a heading over longer durations of time. Well calibrated magnetometers, on the other hand, provide absolute heading information, however; they are usually disturbed by nearby ferrous objects, making them unreliable for brief intervals. This calls for the investigation of possible sources of heading error in complementary sensors such as a gyroscope and a magnetometer, and improving the accuracy of the result based on an improved Kalman filter design. Three commonly used modes for hand-held devices, talking over phone, belt-strapped configuration, and reading/texting (compass portrait), are considered in this research. To validate the proposed algorithm, test results are discussed for the cases when the user carefully kept the device in each of the above modes and also for the cases when the user was switching between different modes. As mentioned above, a method is presented to obtain seamless heading information by combining the heading outputs from both magnetometers and gyroscopes in an adaptive weighted average approach. The weights are decided and adjusted based on detections of certain events, such as external magnetometer anomaly, and gyroscope bias drifts to provide an improved and robust heading solution.
Published in:	Proceedings of the 25th International Technical Meeting of the Satellite Division of The Institute of Navigation (ION GNSS 2012) September 17 - 21, 2012 Nashville Convention Center, Nashville, Tennessee Nashville, TN
Pages:	2432 - 2439
Cite this article:	Ali, A. S., Siddharth, S., El-Sheimy, N., Syed, Z.F., "An Improved Personal Dead-Reckoning Algorithm for Dynamically Changing Smartphone User Modes," Proceedings of the 25th International Technical Meeting of the Satellite Division of The Institute of Navigation (ION GNSS 2012), Nashville, TN, September 2012, pp. 2432-2439.
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