Tight Coupling of GPS and INS for Urban Navigation

A multi-sensor integrated solution that combines complementary features of the Global Positioning System (GPS), laser scanner, and inertial navigation system (INS) for navigation in challenging urban environments is developed. GPS and the laser scanner-based techniques exhibit complementary features in urban scenarios. The laser scanner-based navigation relies on the availability of structures (lines and surfaces) within the scan range (80 m, typically). Features (such as lines) are first extracted from laser scan images and then used for position and attitude determination. If there is a building wall that blocks the GPS signal, this wall creates a feature in the laser scan image. Vice-versa, for open streets with limited features, the GPS signal is generally unobstructed. Thus the GPS and laser data are combined into an integrated solution architecture. The system architecture developed also exploits INS navigation states for improved solution robustness, e.g., for robust feature association between scan images and for coasting through cases where an insufficient number of combined GPS/laser measurements is available. A tightly coupled GPS/laser scanner INS mechanization is developed and applied for trajectory reconstruction. Actual urban data is used to demonstrate performance characteristics of the multi-sensor integrated solution that is developed.