Precision trajectory reconstruction

A precision trajectory reconstruction technique based on photoscoring has been developed to evaluate the airborne accuracy performance of guidance and navigation systems. The sensors include a reference inertial navigation system (INS) and a motion picture camera. The camera is mounted in the aircraft at a known position and attitude with respect to the inertial system and is used to photograph marker panels placed at precisely surveyed locations on the ground. The camera includes a time display device which is driven by a clock associated with the inertial data. The image data from the camera are processed with a modern Kalman filter/smoother to estimate the inertial system errors. The trajectory is then reconstructed by correcting the inertial system data with the estimated errors. It is shown using covariance analysis that the precision photoscoring technique can be used to reconstruct the flight trajectory with a position error of 0.4 m under baseline conditions. In addition, flight tests were used to evaluate the accuracy of the photoscoring process