Study on command attitude law for refracted starlight observation in SINS/RCNS integrated navigation

To ensure the validity of refracted starlight observation, a command attitude law for maneuver is built for strapdown star sensor. The constraint relations between the relative attitude angles and the constant boresight apparent height are first established, by which attitude control command is generated, and the following attitude maneuver enables the star sensor FOV (Field of View) to keep covering the stratosphere during the midcourse. The simulating environment is set up, which involves the schema trajectory designing, the simulating algorithm of refracted star map and the modeling of the complete autonomous SINS/RCNS (Strapdown Inertial Navigation System/Refraction Celestial Navigation System) integrated navigation system. In the SINS/RCNS integrated navigation, the star sensor boresight is directed to the stratosphere in a suitable height with the command attitude law. The test simulation results show that the SINS/RCNS system prominently increases the precision of position and velocity at reentry point by 87.8% and 39.5% respectively than the sole SINS, and using of wide FOV helps to increase the positioning accuracy.