TERRAIN-AIDED NAVIGATION USING THE VITERBI ALGORITHM

Without some form of correction, an inertial navigation system's (INS' s) positional error grows without bound over time. Several techniques have been used to reduce the INS's positional error. One of these tech niques, terrain-aided navigation (TAN), has been widely researched ove r the last several decades with the research focusing on two methods: Sandia inertial terrain-aided navigation (SITAN), which is based on an extended Kalman fitter (EKF), and terrain. contour matching, which is based on correlation techniques, These methods are applied most succe ssfully to fixed-wing aircraft dying over specific types of terrain; t hey perform poorly for low-velocity, highly maneuverable aircraft such as helicopters, especially when dying over hat or very rough terrain In this paper, we introduce VATAN, a new TAN method based on the Viter bi algorithm (VA), and compare its performance to an implementation of SITAN based on a single EKF,Simulation results show that the VA in VA TAN overcomes divergence problems associated with the EKF in SITAN and provides position estimates with smaller average-squared error. These results show that VATAN has the potential to provide good performance for low-velocity aircraft dying over all types of terrain.