Journal of Astronautics ›› 2011, Vol. 32 ›› Issue (6): 1262-1270.

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The Observability of Clock Error in Orbit Determination Using X\|Ray Pulsar Based Navigation

CHEN Zheng   

  1. Control Theory and Guidance Research Center, Harbin Institute of Technology, Harbin 150001, China
  • Received:2010-07-28 Revised:2010-09-25 Online:2011-06-15 Published:2011-06-29

Abstract: Standard X\|ray pulsar based navigation (XNAV) can provide spacecrafts with autonomous positioning services, but the clock error of spacecraft will cause an approximate static measurement error in XNAV. In the light of the stability of pulsar’s period, a new clock error estimation method taking the clock error as an extended state in orbit determination using XNAV is proposed by fellow researchers. An observability analysis tool specifically designed for the obit determination is given. The observability analysis based on this extended state method is conducted, and the results indicate that only 2 pulsars are required for the total observability of all the 6 orbit element errors and clock error. The simulation results confirm the observability analysis results: when 2 pulsars are used in XNAV a positioning accuracy of 60m and a timing accuracy of 60ns can be acquied. Comparison simulations also show this method can effectively suppress the effect of clock error on navigation accuracy, thus decreasing the positioning error caused by clock error by over 20 times. The analysis and simulations prove that the extended state method can estimate clock error along with orbit element errors, effectively suppress the clock error’s effect and improve the navigation accuracy.

Key words: Pulsar, Clock error, Observability, Satellite, Kalman filter