Direct positioning and autonomous navigation algorithm based on dual cone-scanning horizon sensor/star sensor

One method using the pure attitude sensors, Infrared Scanning Horizon Sensors (ISHS) and Star Sensor (SS), to determine the absolute position in inertial frame is developed. With the absolute position from the ISHS/SS, the Autonomous Integrated Navigation System (AINS) filter could be simplified. Based on the common nadir vectors from ISHS and absolute attitude from SS, a new direct positioning algorithm for ISHS/SS is constructed. The positioning error model is derived, too. Different the common method using the nadir vector/angle of ISHS to construct the observation, the inertial position from ISHS/SS is chosen as the observation of the AINS filter to estimate the absolute position and velocity. The Jacobin matrix of observation equation could be simplified greatly because the observation would not include the complex trigonometric function caused by the nadir vector/angle of ISHS. Simulation with the data from STK validates the correction of the direct positioning algorithm of ISHS/SS and the corresponding error model. The new AINS filter is tested to be convergence. The AINS position and velocity precision is about 500m (3a) and 0.5m/s (3a) if the measurement precision of ISHS and SS are 0.1° (3a) and 0.005° (3a), respectively.