Patent ID: 7606665

Claim:
A method for aligning an inertial reference system that is coupled to a moveable body, the method comprising: (a) obtaining from an unaided source unaided navigation state information, wherein the unaided source generates the unaided navigation state information using navigation information provided by an inertial reference; (b) obtaining from an aiding source aiding state information, wherein the aiding source generates the aiding state information using navigation information provided by at least one external reference; (c) determining an unaided navigation solution using the unaided navigation state information; (d) determining an aided navigation solution using a combination of the unaided and aiding state information; (e) providing the unaided navigation solution for navigating the movable body; (f) performing an integrity check to determine whether the aided navigation solution provides a better navigation solution than the unaided navigation solution for navigating the movable body; and (g) replacing the unaided navigation solution with the aided navigation solution when the aided navigation solution provides a better navigation solution for navigating the movable body, wherein (i) the unaided navigation solution is an outcome of a reversionary-attitude alignment, and (ii) the aided navigation solution is an outcome of an in-motion alignment.