Development of a Low-Cost Solution for GPS/Gyro Attitude Determination

Chaochao Wang, and Gérard Lachapelle

Abstract:	The use of low cost GPS receivers for attitude determination can significantly reduce the overall cost of a hardware system. However, compared to the use of high performance GPS hardware, the carrier phase measurements from low cost sensors are subject to additional carrier phase measurement errors, such as multipath, antenna phase center variation and noise. These error sources, together with cycle slip occurrences, severely deteriorate the accuracy and reliability of attitude estimation using low cost GPS receivers. To overcome the limitation of standalone GPS attitude determination systems, an integration solution using low cost GPS receivers and rate gyros is investigated in this paper. By employing this dead reckoning aiding sensor type, the ambiguity search region can be specifically defined as a small cube based on the continuous attitude and inter-antenna configuration information. An extended centralized Kalman filter is implemented to fuse the rate gyro data with GPS carrier phase measurements. The quality control system based on innovation sequences is used in the Kalman filter to identify cycle slip occurrences and incorrect antenna vector solutions. Availability also improves as compared to a GPS standalone system as the attitude parameters can be estimated using angular rate measurements from rate gyros during GPS outages. The hardware used to design and test the integrated system consists of CMC Allstar receivers with OEM AT575-70 antennas and Murata ENV-05D-52 piezoelectric vibrating rate gyroscopes. The performance of the GPS/rate Gyro system was first examined in static mode and further tested under real field kinematic conditions. High performance GPS receivers, namely NovAtel Beeline units were also tested to investigate the advantages of gyro integration with different receiver grades in a kinematic environment.
Published in:	Proceedings of the 2004 National Technical Meeting of The Institute of Navigation January 26 - 28, 2004 The Catamaran Resort Hotel San Diego, CA
Pages:	267 - 276
Cite this article:	Wang, Chaochao, Lachapelle, Gérard, "Development of a Low-Cost Solution for GPS/Gyro Attitude Determination," Proceedings of the 2004 National Technical Meeting of The Institute of Navigation, San Diego, CA, January 2004, pp. 267-276.
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