MEMS-IMU Based Pedestrian Navigator for Handheld Devices

Jani Kappi, Jari Syrjarinne and Jukka Saarinen

Abstract:	A typical problem with MEMS-IMU is that the orientation information of the inertial navigator degrades rapidly with time causing large error in position estimate. Pedestrian navigation provides ways to restrict navigation solution so that the error in position estimate grows at a lower rate. The object of this work is to create a pedestrian navigator using low cost MEMS inertial sensors. This type of system can extend the operation period of the GPS integrated navigation system in the unaided mode. This paper presents a new method to estimate the step lengths and the travelled distance using low cost MEMS inertial measurement unit. The sensor assembly consists of MEMS gyroscopes and accelerometers capable of 1 mrad/s and 0.7 mg rms noise levels, respectively, and also of magnetic compass and barometric altimeter. The pedestrian navigator has been realised and algorithms tested using MATLAB with real sensor data. The system implements footfall and motion state recognition from inertial measurements. IMU signals are fused with magnetic compass and barometer signals by applying Kalman filter. Step length estimations are made using acceleration measurements from a single handheld IMU. There is no need for a priori knowledge of the step length and the IMU doesn’t have to be fixed in any particular orientation. By applying this method INS operation in pedestrian navigation can be extended to several minutes without external aiding which is a critical issue for handheld devices. The longer the unaided operations of the INS the better the power consumption can be achieved. The pedestrian navigator shows improvement on navigation accuracy and power consumption of the integrated navigation system in an urban environment.
Published in:	Proceedings of the 14th International Technical Meeting of the Satellite Division of The Institute of Navigation (ION GPS 2001) September 11 - 14, 2001 Salt Palace Convention Center Salt Lake City, UT
Pages:	1369 - 1373
Cite this article:	Kappi, Jani, Syrjarinne, Jari, Saarinen, Jukka, "MEMS-IMU Based Pedestrian Navigator for Handheld Devices," Proceedings of the 14th International Technical Meeting of the Satellite Division of The Institute of Navigation (ION GPS 2001), Salt Lake City, UT, September 2001, pp. 1369-1373.
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