INS Aided Ambiguity Resolution for GPS/INS Integrated Kinematic Positioning

Yihe Li and Yunzhong Shen

Abstract:	The performance of RTK (Real Time Kinematic) with long baseline is much degraded compared to conventional short-range RTK. One of the major challenges is to real-time resolve the ambiguities on the baselines between reference and rover stations in the presence of considerable ionospheric and tropospheric biases. Traditionally, the network ambiguities are solved by fixing the wide-lane (WL) ambiguities firstly. With the fixed WL ambiguities as constraint, the narrow-lane (NL) ambiguities are then solved using the ionosphere-free observations. However, such conventional algorithm to the long baseline RTK is subjected to slow convergence of the estimated ambiguities. In this paper, no linear combination is formed and only original observables of carrier-phases and pseudo-ranges are used, then the ionospheric and tropospheric terms, which are not canceled by double differential (DD) observation equations, are explicitly estimated as unknown parameters. In addition, a set of ionosphere-constrained fictitious equations are used to enhance the strength of ambiguity resolution (AR) model. To further improve AR efficiency, GPS alone Least-Square (LS) model is alternated with GPS/INS tightly integrated Kalman filter to resolve the ambiguities. Finally, to verify and demonstrate the proposed algorithm, a static data is accessed from IGS and a GPS/INS integrated field experiment is conducted, both of them are processed with proposed ambiguity resolution algorithm. The results demonstrate that the efficiency of ambiguity resolution is significantly improved with the aid of INS data. The initialization time within 100 epochs is up to 99.5% in the GPS/INS integration scenario, however in the GPS alone scenario it is only 83.5%.
Published in:	Proceedings of the 24th International Technical Meeting of the Satellite Division of The Institute of Navigation (ION GNSS 2011) September 20 - 23, 2011 Oregon Convention Center, Portland, Oregon Portland, OR
Pages:	2350 - 2361
Cite this article:	Li, Yihe, Shen, Yunzhong, "INS Aided Ambiguity Resolution for GPS/INS Integrated Kinematic Positioning," Proceedings of the 24th International Technical Meeting of the Satellite Division of The Institute of Navigation (ION GNSS 2011), Portland, OR, September 2011, pp. 2350-2361.
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