A new two-position analytic alignment algorithm for SINS

A 2-position analytic alignment method for strapdown inertial navigation system (SINS) is developed to overcome the limit on precision in analytic alignment on stationary base, which mainly comes from the performance of inertial measurement unit (IMU). IMU is successively rest at two positions by rotating the vehicle to measure the earth's rotation rate and gravity, and measurement at one position is subtracted from the other to eliminate constant error of IMU to improve alignment precision. Transformation matrix between two vehicle reference frames is calculated using output of gyros during the vehicle's rotation. An improved method for estimating gesture matrix is developed to avoid matrix nonreversibility. Error analysis is performed to determine the available precision which is demonstrated by computer simulation.