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Sensors 2016, 16(5), 682;

Coupled Integration of CSAC, MIMU, and GNSS for Improved PNT Performance

1,2,* , 1,2
Department of Precision Instrument, Tsinghua University, Beijing 100084, China
State Key Laboratory of Precision Measurement Technology and Instruments, Tsinghua University, Beijing 100084, China
Author to whom correspondence should be addressed.
Academic Editor: Assefa M. Melesse
Received: 21 March 2016 / Revised: 18 April 2016 / Accepted: 9 May 2016 / Published: 12 May 2016
(This article belongs to the Section Remote Sensors)
Full-Text   |   PDF [7375 KB, uploaded 12 May 2016]   |  


Positioning, navigation, and timing (PNT) is a strategic key technology widely used in military and civilian applications. Global navigation satellite systems (GNSS) are the most important PNT techniques. However, the vulnerability of GNSS threatens PNT service quality, and integrations with other information are necessary. A chip scale atomic clock (CSAC) provides high-precision frequency and high-accuracy time information in a short time. A micro inertial measurement unit (MIMU) provides a strap-down inertial navigation system (SINS) with rich navigation information, better real-time feed, anti-jamming, and error accumulation. This study explores the coupled integration of CSAC, MIMU, and GNSS to enhance PNT performance. The architecture of coupled integration is designed and degraded when any subsystem fails. A mathematical model for a precise time aiding navigation filter is derived rigorously. The CSAC aids positioning by weighted linear optimization when the visible satellite number is four or larger. By contrast, CSAC converts the GNSS observations to range measurements by “clock coasting” when the visible satellite number is less than four, thereby constraining the error divergence of micro inertial navigation and improving the availability of GNSS signals and the positioning accuracy of the integration. Field vehicle experiments, both in open-sky area and in a harsh environment, show that the integration can improve the positioning probability and accuracy. View Full-Text
Keywords: integration; CSAC; MIMU; GNSS; precise time aiding; Kalman filter integration; CSAC; MIMU; GNSS; precise time aiding; Kalman filter

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Ma, L.; You, Z.; Liu, T.; Shi, S. Coupled Integration of CSAC, MIMU, and GNSS for Improved PNT Performance. Sensors 2016, 16, 682.

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