Patent ID: 8265804

Claim:
A method for controlling a vehicle, comprising: sensing a position of each of a plurality of stars relative to the vehicle; determining an attitude of the vehicle using the sensed positions of the plurality of stars, and either with or without using information from a sensor measuring angular velocity; implementing a set of strategies to optimize determination of the attitude of the vehicle when using only the sensed positions of the plurality of stars, without information from the sensor for measuring angular velocity, wherein implementing the set of strategies comprises determining if a lost-in-space (LIS) solution is invalid by applying at least one of a plurality of tests to the LIS solution, the plurality of tests comprising: a trajectory test comprising determining if the LIS solution is inconsistent with a vehicle trajectory, as estimated by two previous LIS solutions, from which an estimated attitude is determined; and a convergence test comprising determining if the LIS solution is inconsistent with a spacecraft attitude and angular velocity estimates, as determined by processing of attitude estimates from multiple previous LIS solutions, or attitude estimates based on other sources; and controlling the vehicle based on the determined attitude of the vehicle.