Position-Domain Hatch Filter for Integrated GPS/BeiDou/Altimeter

La Woo Kim, Won Jae Yoo, and Hyung Keun Lee

Abstract:	In this paper, a multi-sensor navigation system for urban positioning is proposed. The system is based on the hybrid position-domain Hatch filter, and utilizes global positioning system (GPS), BeiDou, and a barometric altimeter. The proposed system improves positioning accuracy and availability in urban areas where signal reception condition is very poor. In existing navigation systems using GPS only, positioning is impossible or large error occurs when the number of visible satellites is insufficient. By utilizing both GPS and BeiDou, global navigation satellite system (GNSS) availability is remarkably improved. Some essential considerations for integrating GPS and BeiDou were described; time references and satellite orbits. By utilizing the barometric altimeter, the GNSS availability is further improved because it can replace a single GNSS satellite. In addition, the vertical accuracy is significantly improved. To improve reliability of the proposed system, the hybrid position-domain Hatch filter is proposed. The proposed filter is based on carrier-smoothed-code (CSC) principle like other Hatch filters but utilizes barometric altimeter measurements and considers virtual measurements for continuous positioning. GNSS signals are very low in strength when receiving in the earth surface since satellites transmit signals at a height of about 20,000~35,000 km. Therefore, in urban areas which have many obstructions such as skyscrapers and overpasses, unreliable measurements are often obtained because of a cycle slip or a multipath. In this paper, an L1 doppler shift is utilized to detect the cycle slip and the multipath, called fault detection and isolation (FDI) algorithm. Urban vehicle experiment is performed to evaluate the feasibility of the proposed system. Compared with the existing navigation system using GPS only, the position information availability is improved from 78% to 100%. Also, a trajectory became much smoother.
Published in:	Proceedings of the ION 2019 Pacific PNT Meeting April 8 - 11, 2019 Hilton Waikiki Beach Honolulu, Hawaii
Pages:	691 - 701
Cite this article:	Kim, La Woo, Yoo, Won Jae, Lee, Hyung Keun, "Position-Domain Hatch Filter for Integrated GPS/BeiDou/Altimeter," Proceedings of the ION 2019 Pacific PNT Meeting, Honolulu, Hawaii, April 2019, pp. 691-701. https://doi.org/10.33012/2019.16778
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