Aircraft Heading Measurement Potential from an Airborne Laser Scanner Using Edge Extraction

This paper explores some considerations for making aircraft heading measurements by using an airborne laser scanner (ALS). Laser range measurements are very low noise and high accuracy, so there is potential for high accuracy heading measurements that are not susceptible to broad interference. This heading could stabilize other sensors even when GPS is unavailable. Heading measurements are emphasized since they are often the most sought after quantity for inertial alignment and other applications. The traditional ALS configuration is capable of estimating heading from extracted ground feature edges with degree-level accuracy. Furthermore, the paper discusses two techniques for increasing the laser ground pulse density (by rotating the scanner about the aircraft vertical axis (yaw) and by modifying the scanner parameters). Estimates are provided on how much theoretical accuracy can be expected from each technique and a hybrid technique. The results suggest that it is possible to improve the theoretical heading measurement accuracy by at least one order of magnitude. The second half of the paper discusses sensor stabilization limitations to attaining a high accuracy orientation measurement. This sensitivity analysis describes how noise and bias errors from uncompensated motion and/or sensor stabilization in pitch, roll, and yaw will effect the laser ground pulse positions. The results show that it is better to have stabilization noise than uncompensated motion errors.