Availability Improvement of RTK-GPS with IMU and Vehicle Sensors in Urban Environment

N. Kubo and C. Dihan

Abstract:	The increasing demand for navigation and automation has led to the development of a number of accurate and precise navigation applications that make use of the Global Positioning System (GPS) and other sensors. However, GPS tends to suffer from multipath error, especially in urban environments. To overcome this problem, a method was developed for improving real-time kinematic GPS (RTK-GPS) using a low-cost inertial measurement unit (IMU) and conventional vehicle speed sensors. In the study, the quality of the complete observation data was assessed based on the carrier-to-noise ratio and satellite elevation angle, and the popular least-squares ambiguity decorrelation adjustment method and the ratio test were used to obtain the fix positions. We used speed information obtained from Doppler measurements as an alternative source of information, while information from the IMU and vehicle speed sensor (integrated with the RTK-GPS via a Kalman Filter) was used during the outage of visible satellites. We also used the IMU and vehicle speed sensors to detect the wrong fixes in the RTK-GPS. A Position and Orientation System for Land Vehicles (Applanix) was used to estimate the reference positions. During GPS outage, it is important to accurately determine the last heading of the car for precise navigation. In this study, it was found that a suitable measurement quality check is required to obtain better direction information. The results of the experiment demonstrate that, to some extent, our proposed method is beneficial as an alternative to the conventional RTK-GPS in an urban environment.
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:	1545 - 1555
Cite this article:	Kubo, N., Dihan, C., "Availability Improvement of RTK-GPS with IMU and Vehicle Sensors in Urban Environment," Proceedings of the 25th International Technical Meeting of the Satellite Division of The Institute of Navigation (ION GNSS 2012), Nashville, TN, September 2012, pp. 1545-1555.
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