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A system (18) includes: a) A vehicle (12) includes an attitude or angular velocity control system (38), a plurality of star trackers or star sensors (22) each having a field of view (28); b) a memory (30) having a star catalog (32), an allocated area for a star pair catalog (58) and a reference tabl

A system (18) includes: a) A vehicle (12) includes an attitude or angular velocity control system (38), a plurality of star trackers or star sensors (22) each having a field of view (28); b) a memory (30) having a star catalog (32), an allocated area for a star pair catalog (58) and a reference table (56) stored therein; and c) a processor (24) coupled to the attitude or angular velocity control system (38), the star trackers or star sensors (22), and the memory (30). The processor (24) populates the star pair catalog (58), using the method described herein. The processor (24) then periodically determines the vehicle inertial attitude or angular velocity or sensor alignment, based, in part, on the star pair catalog (58) and reference table (56). The novel ability of the software to autonomously populate the star pair catalog (58) allows users to avoid uploading a large amount of data, and the problems associated with such an upload.

대표청구항 ▼

The invention claimed is: 1. A method for autonomously generating a star pair catalog on-board a vehicle, comprising: generating a master star pair catalog at a remote location, wherein entries of said master star pair catalog include the values of at least one metric, and said master star pair cat

The invention claimed is: 1. A method for autonomously generating a star pair catalog on-board a vehicle, comprising: generating a master star pair catalog at a remote location, wherein entries of said master star pair catalog include the values of at least one metric, and said master star pair catalog is ordered according to said values of said at least one metric, generating a reference table at said remote location, populating said reference table using the indices of said master star pair catalog at said remote location, transmitting said reference table from said remote location to said vehicle, determining, on-board said vehicle, suitable star pair catalog locations using said reference table and said values of said at least one metric, determining, on-board said vehicle, a plurality of star pair catalog entries for said star pair catalog from a star catalog; storing said plurality of star pair catalog entries in said star pair catalog. 2. A method as recited in claim 1 wherein determining a plurality of pair catalog entries comprises determining a first entry of the plurality of pair catalog entries by: a) determining whether the star pair catalog contains an entry corresponding to a first star of a star pair; b) terminating the method without a star pair catalog entry, when no possible first star exists; otherwise, selecting the first star; c) determining whether the star catalog contains an entry corresponding to a second star of the star pair; d) eliminating the first star from future consideration as the first star, then returning to step a), when no possible second star exists; otherwise, selecting the second star; e) determining whether the first star and second star form an acceptable star pair; f) eliminating the second star from future consideration as the second star, when a current first star is used as first star, then returning to step c), should the first star and second star fail to form an acceptable star pair; g) determining a set of potential pair catalog locations which may be occupied by the pair catalog entry representing the star pair formed by the first and second star; h) determining whether one of the act of potential pair catalog locations is currently not occupied by a previously determined pair catalog entry; i) eliminating the second star from future consideration as a second star, when the first star is used, then returning to step c), should a suitable unoccupied pair catalog location not exist; otherwise, populating the pair catalog location with a pair catalog entry representing the star pair formed by the first and second star. 3. A method as recited in claim 2 wherein any star referenced by a star catalog entry maybe chosen to serve as the first star of the star pair. 4. A method as recited in claim 2 wherein any star referenced by a star catalog entry may be chosen to serve as the first star of the star pair, on the condition that the star satisfy a plurality of constraints, as determined by the corresponding star catalog entry. 5. A method as recited in claim 4 wherein the plurality of constraints comprise the star have a magnitude equal to, or brighter than, a specified magnitude threshold. 6. A method as recited in claim 4 wherein the plurality of constraints comprise the star occupy a position within a specified range of a specified position. 7. A method as recited in claim 2 wherein any star referenced by a star catalog entry can be chosen to serve as the second star of the star pair, on the condition that the star satisfy a plurality of constraints, as determined by the corresponding star catalog entry. 8. A method as recited in claim 7 wherein the plurality of constraints comprise the star have a magnitude equal to, or brighter than, a specified magnitude threshold. 9. A method as recited in claim 7. wherein the plurality of constraints comprise the angular separation between the first star and the second star, as determined from the positions of each star as derived from the corresponding star catalog entries, be less than or equal to a specified value. 10. A method as recited in claim 7 wherein the plurality of constraints comprise the angular separation between the first star and the second star, as determined from the positions of each star as derived from to corresponding star catalog entries, be greater than or equal to a specified value. 11. A method as recited in claim 7 wherein the plurality of constraints comprise the star catalog index of the entry corresponding to the second star not be equal to the star catalog index of the entry corresponding to the first star. 12. A method as recited in claim 11 wherein the plurality of constraints comprise the star catalog index of the entry corresponding to the second star must be greater than the star catalog index of the entry corresponding to the first star. 13. A method as recited in claim 7 wherein the plurality of constraints comprise the magnitude difference between first and second star being less than or equal to a specified value. 14. A method as recited in claim 2 wherein the specified value of a metric is calculated for a star pair formed by a first star and second star. 15. A method as recited in claim 14 wherein the metric is a mathematical function of the angular separation between the first and second star, as determined by the positions of the stars as determined using information from the star catalog entries for the stars. 16. The method as recited in claim 1 for determining suitable pair catalog locations comprising: determining a reference table index using the value of the metric; determining the appropriate pair catalog locations for the star pair using the reference table entry referenced by the aforementioned reference table index. 17. A method as recited in claim 1 wherein determining a plurality of star pair catalog entries comprises: determining a first star; determining a second star having a predetermined angular distance and separation representation; in response to a separation representation least significant bit, storing the pair in a pair bucket of the pair catalog. 18. A system comprising: a) a vehicle comprising, an attitude control system or angular velocity control system; and a plurality of star trackers or star sensors each having a field of view; said star tracker or star sensors generating observations; b) a memory having a star catalog and a star pair database, comprising a star pair catalog and reference table stored therein, said reference table having a plurality of star pair catalog entries; c) a processor coupled to said attitude or angular velocity control system and said memory, said processor determining a vehicle inertial attitude or angular velocity, star tracker or star sensor observations, and the contents of the memory, wherein said processor determines said star pair catalog located within said memory following the steps comprising: generating a master star pair catalog at a remote location, wherein entries of said master star pair catalog include the values of at least one metric, and said master star pair catalog is ordered according to said values of said at least one metric, generating said reference table at said remote location, populating said reference table using the indices of said master star pair catalog at said remote location, transmitting said reference table from said remote location to said vehicle, determining, on-board said vehicle, suitable star pair catalog locations using said reference table and said values of said at least one metric, determining, on-board said vehicle, said plurality of star pair catalog entries for said star pair catalog from said star catalog, storing said plurality of star pair catalog entries in said star pair catalog. 19. A system as recited in claim 18 wherein the vehicle comprises a spacecraft. 20. A system as recited in claim 18 wherein the processor determines a star pair catalog entry, and stores the entry at a location in memory by: a) determining whether the associated star catalog contains an entry corresponding to a first star of a star pair; b) terminating the method without a star pair catalog entry, when no possible first star exists; otherwise, selecting a first star; c) determining whether the star catalog contains an entry corresponding to a second star of a star pair; d) eliminating the first star from future consideration as a first star, then returning to step a), when no possible second star exists; otherwise, selecting to second star; e) determining whether the first star and second star form an acceptable star pair; f) eliminating the second star from future consideration as the second star, when the current first star is used as first star, then returning to step e), should the first star and second star fail to form an acceptable star pair; g) determining a set of potential pair catalog locations which may be occupied by the pair catalog entry representing the star pair formed by the first and second star; h) determining whether one of the set of potential pair catalog locations is currently not occupied by a previously determined pair catalog entry; i) eliminating the second star from future consideration as a second star, when the first star is used, then returning to step c), should a suitable unoccupied pair catalog location not exist; otherwise, populating the pair catalog location with a pair catalog entry representing the star pair formed by the first and second star. 21. A system as recited in claim 20 wherein any star referenced by a star catalog entry may be chosen to serve as the first star of the star pair. 22. A system as recited in claim 20 wherein any star referenced by a star catalog entry can be chosen to serve as the first star of the star pair, on the condition that the star satisfy a plurality of constraints, as determined by the corresponding star catalog entry. 23. A system as recited in claim 22 wherein the plurality of constraints comprise the star have a magnitude equal to, or brighter than, a specified magnitude threshold. 24. A system as recited in claim 22 wherein the plurality of constraints comprise the star occupy a position within a specified range of a specified position. 25. A system as recited in claim 20 wherein any star referenced by a star catalog entry can be chosen to serve as the second star of the star pair, on the condition that the star satisfy a plurality of constraints, as determined by the corresponding star catalog entry. 26. A system as recited in claim 25 wherein the plurality of constraints comprise the star have a magnitude equal to, or brighter than, a specified magnitude threshold. 27. A system as recited in claim 25 wherein the plurality of constraints comprise the angular separation between the first star and the second star, as determined from the positions of each star as derived from the corresponding star catalog entries, be less than or equal to a specified value. 28. A system as recited in claim 25 wherein the plurality of constraints comprise the angular separation between the first star and the second star, as determined from the positions of each star as derived from the corresponding star catalog entries, be greater than or equal to a specified value. 29. A system as recited in claim 25 wherein the plurality of constraints comprise the star catalog index of the entry corresponding to the second star not be equal to the star catalog index of the entry corresponding to the first star. 30. A system as recited in claim 29 wherein the plurality of constraints comprise the star catalog index of the entry corresponding to the second star must be greater than the star catalog index of the entry corresponding to the first star. 31. A system as recited in claim 29 wherein the plurality of constraints comprise the star catalog index of the entry corresponding to the second star must be less than the star catalog index of the entry corresponding to the first star. 32. A system as recited in claim 20 wherein any first star and second star are considered to form an acceptable star pair. 33. A system as recited in claim 20 wherein any first star and second star are considered to form an acceptable star pair, on the condition that the star pair satisfy a plurality of constraints. 34. A system as recited in claim 33 wherein the plurality of constraints comprise the magnitude difference between first and second star equal or exceed a specified value. 35. A system as recited in claim 33 wherein the plurality of constraints comprise the magnitude difference between first star and second star being less than or equal to a specified value. 36. A system as recited in claim 20 wherein a value of a metric is calculated for a star pair formed by a first star and second star. 37. A system as recited in claim 36 wherein the metric is a mathematical function of the angular separation between the first star and second star, as determined by the positions of the stars as determined using information from the star catalog entries for the stars. 38. A system as recited in claim 36 wherein suitable pair catalog locations are determined for the star pair using a value of the metric. 39. A system as recited in claim 18 wherein the pair catalog entry data is accessed by a user with a pair handle supplied by the software upon request. 40. A system as recited in claim 39 wherein the pair handle is provided to the user through a function with a plurality of arguments, or the equivalent. 41. A system as recited in claim 40 wherein the aforementioned function, or its equivalent, may include a pair handle as one of the arguments. 42. A system as recited in claim 41 wherein the user may obtain a plurality of pair handles, allowing access to data associated with a set of pair catalog entries, through repeated invocations of the aforementioned function, or equivalent using the pair handle returned front an earlier invocation as an argument. 43. A system as recited in claim 39 wherein the specific pair handle provided to the user depends on a user-supplied value for a metric, associated with pair catalog entries. 44. A system as recited in claim 39 wherein the pair handle provided to the user may be a null pair handle, having a value indicating that the pair handle may not be used to access pair catalog data. 45. A system as recited in claim 44 wherein the null pair handle is provided to the user on occasions when the user attempts to access pair catalog data during a period while the pair catalog is being populated. 46. A system as recited in claim 39 wherein a plurality of users may simultaneously access pair catalog data, each with separately provided pair handles.