On-the-move alignment for strap-down inertial navigation system

The initial alignment of the terrestrial vehicle borne strap-down inertial navigation system (SINS) is investigated. An on-the-move alignment algorithm using the information provided by an odometer, whose scale factor may have an unknown constant bias, is proposed. This algorithm is designed to take the place of the stationary-based fine alignment. The vehicle, during the fine alignment phase, is not necessarily to be kept in stationary state. It can leave for the destination after the stationary-based coarse alignment, and accomplishes fine alignment in the moving state. The alignment formulation of the new algorithm is derived. On the basis of the formulation, a Kalman filter is designed, which uses the difference of the SINS positioning result and the odometer dead reckoning result as the measurement. The results of a nonlinear Monte Carlo simulation show that this algorithm can accomplish initial alignment and odometer scale factor calibration jointly within 10 minutes.