Non-linear compensation algorithm of LOS locating in aerial remote sensor

A non-linear light-of-sight(LOS) locating compensation algorithm for certain aerial remote sensor is presented in this paper. The LOS locating system is composed of two main components, which are an inertial reference frame to provide coarse LOS locating and a 2-axis Fast Steering Mirror to remove the frame´s residual error. The azimuth and elevation of LOS are both affected by the FSM two-degree-of-freedom rotation, which should be dealt with to raise the accuracy of LOS location. This paper extrapolates LOS locating algorithm of FSM by coordinate transformation, and gives corresponding deviation analysis for different LOS poiting angles. It is found that the angle deviation grows rapidly with range of FSM´s travel enlarging, so the deviation must be eliminated. Through the data analysis for deviation, a non-linear compensation algorithm is proved effective to reduce the error of LOS significantly. Taking LOS changing in [-3 deg, 3 deg] as an example, two analytic expressions are given, and the LOS locating accuracy rises by 34 times compared with non-linear compensation unused, and the cross coupling of LOS loating is 0.08%.