초록 ▼

Various embodiments of the present invention provide methods, systems, apparatus, and computer program products for providing integrated attitude determination and attitude control for slewing of a satellite. In one embodiment a method is provided. The method comprises after receiving a repointing r

Various embodiments of the present invention provide methods, systems, apparatus, and computer program products for providing integrated attitude determination and attitude control for slewing of a satellite. In one embodiment a method is provided. The method comprises after receiving a repointing request, selecting a guide star sample comprising one or more guide stars from a guide star catalog; determining current attitude information; selecting and retrieving at least one point spread function (PSF) image from a PSF library; estimating an expected position for at least one guide star, the at least one guide star being one of the guide stars of the guide star sample; acquiring at least one star tracker image; calculating a cross-correlation function (CCF) to determine shifts in position of the at least one guide star compared to the expected position; and determining updated current attitude information based at least in part on the determined shifts in position.

대표청구항 ▼

1. A computer-implemented method for providing integrated attitude determination and attitude control for slewing of a satellite, said method comprising the steps of: after receiving a repointing request, selecting, via one or more processors, a guide star sample comprising one or more guide stars f

1. A computer-implemented method for providing integrated attitude determination and attitude control for slewing of a satellite, said method comprising the steps of: after receiving a repointing request, selecting, via one or more processors, a guide star sample comprising one or more guide stars from a guide star catalog, wherein each guide star selected for the guide star sample has a measured brightness brighter than a predetermined value; determining, via the one or more processors, current attitude information; selecting and retrieving, via the one or more processors, at least one point spread function (PSF) image from a PSF library, the selection based at least in part on the current attitude information; estimating, via the one or more processors and based at least in part upon the current attitude information, an expected position for at least one guide star, the at least one guide star being one of the guide stars of the guide star sample; acquiring, via one or more processors and at least one image capture device on the satellite, at least one star tracker image; calculating, via the one or more processors, a cross-correlation function (CCF) based on a sub-image of the selected and retrieved PSF image, the star tracker image, and the expected position for the at least one guide star, the calculation determining shifts in position of the at least one guide star compared to the expected position; and determining, via the one or more processors, updated current attitude information based at least in part on the determined shifts in position. 2. The computer-implemented method according to claim 1, wherein the method further comprises the steps of: upon receipt of the satellite repointing request and prior to acquiring the at least one star tracker image, calculating, via the one or more processors, a planned slew trajectory; and selecting, via the one or more processors, the one or more guide stars of the guide star sample based at least in part on the planned slew trajectory. 3. The computer-implemented method according to claim 2, wherein the guide star sample includes one or more guide stars located within a buffer zone of approximately two degrees surrounding the planned slew trajectory. 4. The computer-implemented method according to claim 2, wherein the method further comprises the steps of: based at least in part upon the planned slew trajectory, selecting a slew-mode sensor integration time; and prior to acquiring the at least one star tracker image, creating, via the one or more processors and based at least in part on the selected slew-mode sensor integration time, the at least point spread function (PSF) image and storing the PSF image in the PSF library. 5. The computer-implemented method according to claim 4, wherein the selected slew-mode sensor integration time is configured to provide image smearing of less than six pixels per frame. 6. The computer-implemented method according to claim 4, wherein the selected slew-mode sensor integration time is configured to provide image smearing of less than one pixel per frame. 7. The computer-implemented method according to claim 4, wherein resolution of the created PSF image is between 0.5 pixels per frame smearing and one pixel per frame smearing. 8. The computer-implemented method according to claim 4, wherein the steps of (a) calculating the planned slew trajectory, (b) selecting the one or more guide stars for the guide star sample, the one or more guide stars located along the planned trajectory and/or a within a buffer zone surrounding the planned trajectory, (c) selecting the slew-mode sensor integration time, and (d) creating the at least one point spread function (PSF) image and storing the PSF image in the PSF library are performed subsequent to receipt of a satellite repointing request and prior to acquiring a star tracker image. 9. The method according to claim 4, wherein the steps of (a) calculating the planned slew trajectory, (b) selecting the one or more guide stars for the guide star sample, the one or more guide stars located along the planned trajectory and/or a within a buffer zone surrounding the planned trajectory, and (c) selecting the slew-mode sensor integration time are performed subsequent to receipt of a satellite repointing request and prior to acquiring a star tracker image and require less than one half of a second of computation time. 10. The computer-implemented method according to claim 9 wherein the step of creating the at least one point spread function (PSF) image and storing the PSF image in the PSF library is performed further prior to receiving the satellite repointing request. 11. The computer-implemented method according to claim 1, wherein the recited configuration enables slewing of the satellite at a slew rate of up to ten degrees per second. 12. The computer-implemented method according to claim 1, wherein the recited configuration enables slewing of the satellite at a slew rate of approximately three to four degrees per second. 13. The computer-implemented method according to claim 1, wherein the current attitude information includes angular velocity obtained from at least one of inertial mass units or from an optical detector. 14. The computer-implemented method according to claim 1, wherein the calculated CCF not only determines shifts in position of at least one guide star compared to the expected position of the at least one guide star, but also determines a correlation amplitude, the correlation amplitude being representative of a quality of the position determination. 15. The computer-implemented method according to claim 14, further comprising the steps of: determining, via the one or more processors, that the calculated correlation amplitude is less than a predetermined value representative of a minimum quality level; and triggering, via the one or more processors, a re-calculation of the CCF using a larger PSF image to recover an acceptable lock quality. 16. The computer-implemented method according to claim 15, wherein the larger PSF image is a full-image PSF, so as to attempt to recover the acceptable lock quality. 17. The computer-implemented method according to claim 1, wherein determining the updated current attitude information, based at least in part upon the determined shifts in position and a quality thereof is performed with an accuracy of at least one arcsecond. 18. The computer-implemented method according to claim 1, wherein the at least one image capture device on the satellite uses at least one of a high speed CCD or a CMOS star tracker sensor. 19. The computer-implemented method according to claim 18, wherein the high speed CCD is at least one of a frame-transfer CCD or an Electron-Multiplication CCD (EMCCD). 20. An integrated attitude determination and attitude control system for use on a satellite, said system comprising: a memory configured to store information associated with the satellite; and one or more processors configured to: upon receipt of a repointing request, select a guide star sample comprising one or more guide stars from a guide star catalog, wherein each guide star selected for the guide star sample has a measured brightness brighter than a predetermined value; determine current attitude information; select and retrieve at least one point spread function (PSF) image from a PSF library, the selection based at least in part on the current attitude information; estimate, based at least in part upon the current attitude information, an expected position for at least one guide star, the at least one guide star being one of the guide stars of the guide star sample; acquire, via at least one image capture device on the satellite, at least one star tracker image; calculate a cross-correlation function (CCF) based on a sub-image of the selected and retrieved PSF image, the star tracker image, and the expected position for the at least one guide star, the calculation determining shifts in position of the at least one guide star compared to the expected position; and determine updated current attitude information based at least in part on the determined shifts in position. 21. The system according to claim 20, wherein the one or more processors are further configured to: upon receipt of the satellite repointing request and prior to acquiring the at least one star tracker image, calculate a planned slew trajectory; and select the one or more guide stars of the guide star sample based at least in part on the planned slew trajectory. 22. The system according to claim 21, wherein the guide star sample includes one or more guide stars located within a buffer zone of approximately two degrees surrounding the planned slew trajectory. 23. The system according to claim 21, wherein the one or more processors are further configured to: based at least in part upon the planned slew trajectory, select a slew-mode sensor integration time; and prior to acquiring the at least one star tracker image, create, based at least in part on the selected slew-mode sensor integration time, the at least point spread function (PSF) image and storing the PSF image in the PSF library. 24. The system according to claim 23, wherein the selected slew-mode sensor integration time is configured to provide image smearing of less than six pixels per frame. 25. The system according to claim 23, wherein the selected slew-mode sensor integration time is configured to provide image smearing of less than one pixel per frame. 26. The system according to claim 23, wherein resolution of the created PSF image is between 0.5 pixels per frame smearing and one pixel per frame smearing. 27. The system according to claim 23, wherein the steps of (a) calculating the planned slew trajectory, (b) selecting the one or more guide stars for the guide star sample, the one or more guide stars located along the planned trajectory and/or a within a buffer zone surrounding the planned trajectory, (c) selecting the slew-mode sensor integration time, and (d) creating the at least one point spread function (PSF) image and storing the PSF image in the PSF library are performed subsequent to receipt of a satellite repointing request and prior to acquiring a star tracker image. 28. The system according to claim 23, wherein the steps of (a) calculating the planned slew trajectory, (b) selecting the one or more guide stars for the guide star sample, the one or more guide stars located along the planned trajectory and/or a within a buffer zone surrounding the planned trajectory, and (c) selecting the slew-mode sensor integration time are performed subsequent to receipt of a satellite repointing request and prior to acquiring a star tracker image and require less than one half of a second of computation time. 29. The system according to claim 28, wherein the step of creating the at least one point spread function (PSF) image and storing the PSF image in the PSF library is performed further prior to receiving the satellite repointing request. 30. The system according to claim 20, wherein the recited configuration enables slewing of the satellite at a slew rate of up to ten degrees per second. 31. The system according to claim 20, wherein the recited configuration enables slewing of the satellite at a slew rate of approximately three to four degrees per second. 32. The system according to claim 20, wherein the current attitude information includes angular velocity obtained from at least one of inertial mass units or from an optical detector. 33. The system according to claim 32, wherein the current attitude information further includes angular roll data. 34. The system according to claim 20, wherein the calculated CCF not only determines shifts in position of at least one guide star compared to the expected position of the at least one guide star, but also determines a correlation amplitude, the correlation amplitude being representative of a quality of the position determination. 35. The system according to claim 34, wherein the one or more processors are further configured to: determining, via the one or more processors, that the calculated correlation amplitude is less than a predetermined value representative of a minimum quality level; and triggering, via the one or more processors, a re-calculation of the CCF using a larger PSF image to recover an acceptable lock quality. 36. The system according to claim 35, wherein the larger PSF image is a full-image PSF, so as to attempt to recover the acceptable lock quality. 37. The system according to claim 20, wherein the determining of the updated current attitude information is based at least in part upon the determined shifts in position and a quality thereof is performed with an accuracy of at least one arcsecond. 38. The system according to claim 20, wherein the at least one image capture device on the satellite uses at least one of a high speed CCD or a CMOS star tracker sensor. 39. The system according to claim 38, wherein the high speed CCD is at least one of a frame-transfer CCD or an Electron-Multiplication CCD (EMCCD). 40. The system according to claim 20, wherein the satellite is a small-scale satellite. 41. The system according to claim 40, wherein the small-scale satellite is configured for at least one of remote sensing, defensive military sensing, or astronomy-oriented applications. 42. A non-transitory computer readable medium comprising: at least one computer-readable storage medium having computer-readable program code portions embodied therein, the computer-readable program code portions comprising: an executable portion configured for, after receiving a repointing request, selecting a guide star sample comprising one or more guide stars from a guide star catalog, wherein each guide star selected for the guide star sample has a measured brightness brighter than a predetermined value; an executable portion configured for determining current attitude information; an executable portion configured for selecting and retrieving at least one point spread function (PSF) image from a PSF library, the selection based at least in part on the current attitude information; an executable portion configured for estimating, based at least in part upon the current attitude information, an expected position for at least one guide star, the at least one guide star being one of the guide stars of the guide star sample; an executable portion configured for acquiring, via at least one image capture device on the satellite, at least one star tracker image; an executable portion configured for calculating a cross-correlation function (CCF) based on a sub-image of the selected and retrieved PSF image, the star tracker image, and the expected position for the at least one guide star, the calculation determining shifts in position of the at least one guide star compared to the expected position; and an executable portion configured for determining updated current attitude information based at least in part on the determined shifts in position. 43. The non-transitory computer readable medium of Concept 42, the computer-readable program code portions further comprising: an executable portion configured for, after receiving the repointing request and prior to acquiring the at least one star tracker image, calculating a planned slew trajectory; an executable portion configured for selecting the one or more guide stars of the guide star sample based at least in part on the planned slew trajectory; an executable portion configured for, based at least in part upon the planned slew trajectory, selecting a slew-mode sensor integration time; and an executable portion configured for, prior to acquiring the at least one star tracker image, creating, based at least in part on the selected slew-mode sensor integration time, the at least point spread function (PSF) image and storing the PSF image in the PSF library.