Autonomous Fault Detection on a Low Cost GPS-Aided 3-Axis Attitude Determination System

Arcelio C. Louro, Roberto V.F. Lopes, and Helio K. Kuga

Abstract:	This paper presents a three-axis attitude determination procedure based on the Global Positioning System (GPS) with special emphasis to the autonomous integrity monitoring issue. One envisages a class of low cost navigation applications requiring low accuracy (around 0.5 degrees) but continuous attitude knowledge. A snapshot algorithm first estimates the three-axis attitude from interferometry on double differences of GPS carrier phase L1. Then, the attitude estimate is improved by fusing it with angular rate measurements from low cost, MEMS gyros. The procedure is especially designed to detect single faults on either the GPS or the gyros autonomously from residuals monitoring. Both GPS and gyro measurements are assumed as corrupted by colored Gaussian noises whose effects are mitigated by a stochastic dynamic compensation model. The state vector, which includes the attitude quaternion and parameters of the error model, is estimated from a bank of extended Kalman filters with different time delays. Attitude propagation model between GPS sampling times is based on the gyro output after drift calibration. One defines the fault modes of each sensor and some control parameters to the fault detection procedure. The algorithm is tested with numerical simulation and real data. The simulation scenarios include LEO micro-satellites with different orbit inclinations and three different failure modes: complete loss of track from the whole GPS constellation; temporary abnormal interference on a single GPS satellite; and gyro drift higher than its specified level. The results show that the algorithm is suitable to cope with different fault types and intensity levels.
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:	2658 - 2667
Cite this article:	Louro, Arcelio C., Lopes, Roberto V.F., Kuga, Helio K., "Autonomous Fault Detection on a Low Cost GPS-Aided 3-Axis Attitude Determination 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. 2658-2667.
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