Laser-aided inertial navigation for self-contained autonomous indoor flight

Unmanned Aerial Vehicles are often used for reconnaissance, search and rescue, damage assessment, exploration, and other tasks that are dangerous or prohibitively difficult for humans to perform. Often, these tasks include traversing indoor environments where radio links are unreliable, hindering the use of remote pilot links or ground-based control, and effectively eliminating Global Positioning System (GPS) signals as a potential localization method. As a result, any vehicle capable of indoor flight must be able to stabilize itself and perform all guidance, navigation, and control tasks without dependence on a radio link, which may be available only intermittently. Since the availability of GPS signals in unknown environments is not assured, other sensors must be used to provide position information relative to the environment. This research describes the use of a scanning laser rangefinder for position and heading estimation and the incorporation of that estimate in the overall guidance, navigation, and control system to effectively eliminate the dependence on GPS. The combination of a scanning laser rangefinder, a sonar for altitude, and an Inertial Measurement Unit (IMU) are simulated onboard a quadrotor helicopter for active stabilization and position control. Two different navigation algorithms that utilize a scanning laser with techniques borrowed from Simultaneous Localization and Mapping (SLAM) are eval- uated for use with an IMU-stabilized ying vehicle. Simulation and experimental results are presented for each of the navigation systems.