Economical and Robust Inertial Sensor Configuration for a Portable Navigation System

Zainab Syed, Priyanka Aggarwal, Xiaoji Niu, and Naser El-Sheimy

Abstract:	Land vehicle navigation for civilian sector is challenging as there are few important and contradictory requirements that have to be satisfied. The very first requirement is the accuracy and reliability of the navigation information. The second requirement, which is contradictory to the first, is the navigation unit to be inexpensive. In addition to these two important requirements, the system has to be small, compact and self-contained; otherwise it will not be adopted by civilians. As a result, there are small Global Positioning System (GPS) modules that provide the navigation information on a digital map to the user. These units are inexpensive and compact but reliability and accuracy cannot be guaranteed for difficult urban environments. The reason for such inaccuracy could be primarily attributed to the dependency of GPS modules on direct line of sight to the GPS satellites which is not possible at all times, such as when the vehicle is driving through a tunnel. Similar problems occur when the vehicle is in the downtown core with tall buildings all around or when it is passing under a forest canopy or a bridge. Self contained and miniature Micro-Electro-Mechanical (MEMS) Inertial Measurement Unit (IMU) can be used to bridge GPS signal outages. While IMUs have been used for navigation for decades, MEMS IMUs are quite new. Traditional IMUs are bulky and consist of three orthogonal accelerometers and three orthogonal gyroscopes (gyros). Due to the cost and size factor, a MEMS IMU with minimum number of sensors will be most desirable for civil vehicle navigation. This paper shows the results of using different sensor combinations. The main idea is to find a sensor combination that will require minimum number of sensors to reduce the costs to the user while providing reliable navigation during GPS signal outages. The results for a full sensor module comprised of i) three orthogonal accelerometers and three orthogonal gyros (Full IMU), ii) two gyros and three accelerometers (2G3A), iii) one gyro and iv) three accelerometers (1G3A), v) one gyro and two accelerometers (1G2A) and then with vi) one gyro and one accelerometer (1G1A) are used in the inertial sensor unit. The results show that one vertical gyro with two horizontal accelerometers with non-holonomic conditions will provide the most economical and robust solution.
Published in:	Proceedings of the 20th International Technical Meeting of the Satellite Division of The Institute of Navigation (ION GNSS 2007) September 25 - 28, 2007 Fort Worth Convention Center Fort Worth, TX
Pages:	2129 - 2135
Cite this article:	Syed, Zainab, Aggarwal, Priyanka, Niu, Xiaoji, El-Sheimy, Naser, "Economical and Robust Inertial Sensor Configuration for a Portable Navigation System," Proceedings of the 20th International Technical Meeting of the Satellite Division of The Institute of Navigation (ION GNSS 2007), Fort Worth, TX, September 2007, pp. 2129-2135.
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