Improvement of altitude precision in indoor and urban canyon navigation for small flying vehicles

Because of integrating measurements, the Inertial Navigation System (INS) for UAVs or small planes has the great drawback to increase the uncertainty for those entities, as acceleration and angular velocity that are function of time. For this reason, it generally employs GPS in order to correct and calibrate itself. When GPS is not available, typically in environments such as urban canyons or indoor navigation, is necessary to measure the altitude using stored map terrain profile and a LiDAR altimeter: weighting these data through a least square method, we can obtain the altitude of the vehicle non affected by local discontinuities of the ground.