AUTONOMOUS NAVIGATION FOR HEO SATELLITES BASED ON SINS/GNSS TIGHT INTEGRATION METHOD

摘要

Geostationary and high-earth-orbit (HEO) satellites, which are located above the global navigation satellitesystem (GNSS) constellation, receive only very weak GNSS signals due to the high path loss of these signals.What's more the number of visible satellites is very small, and each satellite is available for only a short period. Thismakes it difficult for the implementation of autonomous navigation. In this paper, for navigation of HEO satellites, akind of acquisition method for weak signal based on Duffing chaotic oscillator was proposed, and a kind ofautonomous navigation scheme was introduced based on tight integration of strap-down inertial navigation system(SINS) and GNSS. For the SINS, the inertial sensors can be calibrated, while the assistance of SINS can help toimprove the trace ability for GNSS and increase the dynamic and anti-jamming performance. The tight integrationmethod uses the ephemeris given by GNSS receiver and the position and velocity value given by SINS to calculatethe pseudo range ρ_I? and the pseudo range rate ρ_I? related to the position and velocity given by SINS, then they arecompared with ρ_G ? and ρ_G ? given by GNSS receiver to get the error. Subsequently, a Kalman filter is used toestimate the error, and then open-loop or feedback correction can be used for the following solution. Theobservability of the measure equation of tight integration method (using pseudo range and pseudo range rate) ismuch better than that of the loose integration method (using position and speed). The simulation results show that theposition and velocity estimation precision of SINS/GNSS tight integration method is better than that of the looseintegration method, and the proposed scheme can satisfy the autonomous demand for HEO satellites.