IMPROVED METHOD AND APPARATUS FOR OBTAINING ATTITUDE UPDATES IN A STRAPDOWN INERTIAL NAVIGATION SYSTEM

摘要

The invention is a method and apparatus for updating the attitude of a body by utilizing a plurality of gyros to measure as a function of time the angular rate vector or the integrated angular rate vector for the body. The method comprises the steps of (1) obtaining measured values of the angular rate vector at a plurality of readout intervals, (2) obtaining a smoothed value of each of one or more smoothed representations of the angular rate vector at the end of each of a plurality of smoothing intervals, and (3) obtaining the updated attitude of the body at the end of an update interval by utilizing the attitude at the beginning of the update interval and the smoothed values of the smoothed representations of the angular rate vector obtained during the update interval. A smoothed representation is a weighted sum of the measured values obtained during a smoothing interval. The attitude is updated at the end of an update interval by applying a rotation vector to the attitude at the end of the prior update interval, the rotation vector being a weighted sum of (1) a plurality of the smoothed values and (2) the values of a plurality of cross-products of the smoothed values, the smoothed values having been obtained during the update interval.