Method and system for controlling a vehicle

A system for controlling a vehicle, comprising:

• a processor;
• a module operating on the processor to determine an attitude of the vehicle using a sensed position of each of a plurality of stars relative to the vehicle, and either with or without using information from a sensor measuring angular velocity, wherein a set of strategies are used 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 measuring angular velocity, wherein 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
• an attitude control module, operating on the processor, to control the vehicle based on the determined attitude of the vehicle.

A vehicle, comprising:

• a processor for controlling operation of the vehicle;
• a plurality of star sensors each for capturing star position information relative to the vehicle;
• a module operating on the processor to determine an attitude of the vehicle using the star position information, either with or without using information from a sensor measuring angular velocity, wherein a set of strategies are used to optimize determination of the attitude of the vehicle when using only the sensed position of each of the plurality of stars, without information from the sensor measuring angular velocity, wherein 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
• a module to control the vehicle based on the determined attitude of the vehicle.

A computer program product comprising a hardware computer readable storage medium having computer usable program code embodied therewith for controlling a vehicle, the hardware computer readable storage medium comprising:

• computer usable program code configured to determine an attitude of the vehicle using a sensed position of each of the plurality of stars, and either with or without using information from a sensor measuring angular velocity;
• computer usable program code configured to use a set of strategies to optimize determination of the attitude of the vehicle when using only the sensed position of each of the plurality of stars, without information from the sensor for measuring angular velocity, wherein computer usable program code configured to use the set of strategies comprises computer usable program code configured to determine 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
• computer usable program code configured to control the vehicle based on the determined attitude of the vehicle.