Aircraft heading for dead reckoning applications using Airborne Laser Scanner range measurements

This paper presents a technique to determine aircraft heading using an airborne laser scanner (ALS) and surveyed ground features. Accurate heading estimation has several important applications for airborne navigation. It can be used for periodical in-flight calibration of heading biases in tactical grade inertial measurement units (IMU), for ALS / IMU calibration prior to a terrain aided landing, or for stabilization of inertial heading measurements when GPS is unavailable. The primary focus will be on dead reckoning navigation applications where GPS is unavailable and where a heading accuracy of at least a few mrad is required. A step-by-step description of the algorithm will be presented along with graphical illustrations of each step. Simulation results will be presented to show the theoretical performance of heading determination from synthesized ground feature geometry using typical ALS parameters. An empirical sensitivity analysis will be used to show the effect of range noise, heading bias, and position noise on the heading accuracy. This theoretical performance assessment will then be compared with flight test data. The results will show that the proposed technique can provide heading bias calibration accuracy at the milliradian level and that this accuracy can be estimated based on the laser range residuals.