Determination of the target LOS direction in the two-star angular distance measure method based on the ORSM system

In allusion to the problem that some redundant solutions are existed in searching for the target LOS (line of sight) direction in the two-star angular distance measure method based on the ORSM (the optics and radar strap-down measuring) system, the relation of the four spots, in which one is the center of the optical platform, the other three are the projective spots of the target and two stars on the surface of the unit-sphere, whose center is the center of the optical platform, in the case that the optics and radar are merged into an organic whole, is studied. The law that the above four spots are relative invariant is found. Making use of the information about the center of the optical platform and the projective spots of the stars, the two temporary coordinate systems based on both star-sensor coordinate system and station-center coordinate system are established. According to the peculiarity that the target coordinate is fixed in these two temporary coordinate systems, the algorithm to eliminate the redundant solution to the target LOS direction is presented. The experimental result proves its effectiveness.