대표
청구항
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What is claimed is: 1. A method of controlling a gimbaled platform, comprising the steps of: computing an acquisition phase gimbal angle rate command ωcmd--Acq from a measured LOS angle error ΔθLOS for an initial control period T; computing an estimated LOS angle rate {circumflex over (ω)}LOS at least in part from the acquisition gimbal rate command ωcmd--Acq; computing a tracking phase gimbal angle rate command ωcmd--Trk using a controller initialized with the estimated LOS angle rate {circumflex over (ω)}LOS; and com...
What is claimed is: 1. A method of controlling a gimbaled platform, comprising the steps of: computing an acquisition phase gimbal angle rate command ωcmd--Acq from a measured LOS angle error ΔθLOS for an initial control period T; computing an estimated LOS angle rate {circumflex over (ω)}LOS at least in part from the acquisition gimbal rate command ωcmd--Acq; computing a tracking phase gimbal angle rate command ωcmd--Trk using a controller initialized with the estimated LOS angle rate {circumflex over (ω)}LOS; and commanding the gimballed platform according to an angle rate command ωcmd, wherein the angle rate command ωcmd is the acquisition phase angle rate command ωcmd--Acq during the initial control period T and the tracking phase gimbal angle rate command ωcmd--Trk after the initial control period T. 2. The method of claim 1, wherein the initial control period T ends when the measured LOS angle error ΔθLOS is below a threshold value for a number N of consecutive LOS angle error ΔθLOS measurements. 3. The method of claim 1, wherein the estimated LOS angle rate {circumflex over (ω)}LOS is computed after the control period T ends. 4. The method of claim 1, wherein the estimated LOS angle rate {circumflex over (ω)}LOS is computed after the control period ends from data matrices populated during the initial control period. 5. The method of claim 1, wherein the acquisition phase gimbal rate command ωcmd--Acq is computed as a non-linear mapping of the measured LOS angle error ΔθLOS to the gimbal angle rate command ωcmd. 6. The method of claim 1, wherein the estimated LOS angle rate {circumflex over (ω)}LOS includes an estimated azimuth LOS angle rate {circumflex over (ω)}az,LOS and an estimated elevation LOS angle rate {circumflex over (ω)}el,LOS is estimated according to: Δti=ti-t0, and t0 is an initial time; Δθel,payload,sensor,i is a change in elevation of the measured LOS angle error ΔθLOS in a platform reference frame within the time Δti; Δθaz,payload,sensor,i is a change in azimuth of the measured LOS angle error ΔθLOS in a platform reference frame within the time Δti; {circumflex over (K)}1az is an estimate of a cross coupling of an azimuth channel of a sensor used to measure the elevation of the LOS angle error ΔθLOS; and {circumflex over (K)}2az is an estimate of a gain of an azimuth channel of the sensor used to measure the azimuth of the LOS angle error ΔθLOS; and Δti=ti-t0, and t0 is an initial time; Δθel,payload,sensor,i is a change in an elevation of the measured LOS angle error ΔθLOS in a platform reference frame within the time Δti; Δθaz,payload,sensor,i is a change in an azimuth of the measured LOS angle error ΔθLOS in a platform reference frame within the time Δti; {circumflex over (K)}1el is an estimate of a gain of an elevation channel of a sensor used to measure the elevation of the LOS angle error ΔθLOS; and {circumflex over (K)}2el is an estimate of a gain of an elevation channel of the sensor used to measure the azimuth of the LOS angle error ΔθLOS. 7. The method of claim 1, further comprising the step of low pass filtering the acquisition phase angle rate command ωcmd--Acq before commanding the gimballed platform. 8. The method of claim 1, wherein the measured LOS angle error ΔθLOS is measured by an acquisition sensor. 9. The method of claim 1, wherein the tracking phase gimbal angle rate command is computed by a linear controller. 10. The method of claim 9, wherein the linear controller comprises a digital filter the output of which is initialized to the estimated LOS angle rate {circumflex over (ω)}LOS. 11. The method of claim 1, wherein an estimated cross coupling is computed when the estimated LOS angle rate {circumflex over (ω)}LOS is computed and is used to initialize the controller. 12. The method of claim 1, wherein the initial control period T is predetermined. 13. The method of claim 1, wherein: the gimbaled platform is controlled to acquire and track a target; the first phase is an acquisition phase; and the second phase is a tracking phase. 14. The method of claim 1, wherein the LOS angle error ΔθLOS is an angle between a target and a boresight of the gimbaled platform. 15. An apparatus for controlling a gimbaled platform, comprising: means for computing an acquisition phase gimbal angle rate command ωcmd--Acq from a measured LOS angle error ΔθLOS for an initial control period T; means for computing an estimated LOS angle rate {circumflex over (ω)}LOS at least in part from the acquisition gimbal rate command ωcmd--Acq; means for computing a tracking phase gimbal angle rate command ωcmd--Trk using a controller initialized with the estimated LOS angle rate {circumflex over (ω)}LOS; and means for commanding the gimballed platform according to an angle rate command ωcmd, wherein the angle rate command ωcmd is the acquisition phase angle rate command ωcmd--Acq during the initial control period T and the tracking phase gimbal angle rate command ωcmd--Trk after the initial control period T. 16. The apparatus of claim 15, wherein the initial control period T ends when the measured LOS angle error ΔθLOS is below a threshold value for a number N of consecutive LOS angle error ΔθLOS measurements. 17. The apparatus of claim 15, wherein the estimated LOS angle rate {circumflex over (ω)}LOS is computed after the initial control period T ends. 18. The apparatus of claim 15, wherein the estimated LOS angle rate {circumflex over (ω)}LOS is computed after the initial control period ends from data matrices populated during the initial control period. 19. The apparatus of claim 15, wherein the acquisition phase gimbal rate command ωcmd--Acq is computed as a non-linear mapping of the measured LOS angle error ΔθLOS to the gimbal angle rate command ωcmd. 20. The apparatus of claim 15, wherein the estimated LOS angle rate {circumflex over (ω)}LOS includes an estimated elevation LOS angle rate {circumflex over (ω)}az,LOS and an estimated azimuth LOS angle rate {circumflex over (ω)}el,LOS is estimated according to: Δti=ti-t0, and t0 is an initial time; Δθel,payload,sensor,i is a change in an elevation of the measured LOS angle error ΔθLOS in a platform reference frame within the time Δti; Δθaz,payload,sensor,i is a change in an azimuth of the measured LOS angle error ΔθLOS in a platform reference frame within the time Δti; {circumflex over (K)}1az is an estimate of a cross coupling of an azimuth channel of a sensor used to measure the elevation of the LOS angle error ΔθLOS; and {circumflex over (K)}2az is an estimate of a gain of an azimuth channel of the sensor used to measure the azimuth of the LOS angle error ΔθLOS; and Δti=ti-t0, and t0 is an initial time; Δθel,payload,sensor,i is a change in an elevation of the measured LOS angle error ΔθLOS in a platform reference frame within the time Δti; Δθaz,payload,sensor,i is a change in an azimuth of the measured LOS angle error ΔθLOS in a platform reference frame within the time Δti; {circumflex over (K)}1el is an estimate of a gain of an elevation channel of a sensor used to measure the elevation of the LOS angle error ΔθLOS; and {circumflex over (K)}2el is an estimate of a cross coupling of an elevation channel of the sensor used to measure the azimuth of the LOS angle error ΔθLOS. 21. The apparatus of claim 15, further comprising the step of low pass filtering the acquisition phase angle rate command ωcmd--Acq before commanding the gimballed platform. 22. The apparatus of claim 15, wherein the measured LOS angle error ΔθLOS is measured by an acquisition sensor. 23. The apparatus of claim 15, wherein the tracking phase gimbal angle rate command ωcmd--Trk is computed by a linear controller. 24. The apparatus of claim 23, wherein the linear controller comprises a digital filter having a delay element including an output initialized to the estimated LOS angle rate {circumflex over (ω)}LOS. 25. The apparatus of claim 15, wherein an estimated cross coupling is computed during the initial control period and used to initialize the controller. 26. The apparatus of claim 15, wherein the initial control period T is predetermined. 27. The apparatus of claim 15, wherein: the gimbaled platform is controlled to acquire and track a target; the first phase is an acquisition phase; and the second phase is a tracking phase. 28. The apparatus of claim 15, wherein the LOS angle error ΔθLOS is an angle between a target and a boresight of the gimbaled platform. 29. A method of controlling a gimbaled platform, comprising the steps of: computing an acquisition phase gimbal angle rate command ωcmd--Acq from a measured LOS angle error ΔθLOS for an initial control period T; computing an estimated LOS angle rate {circumflex over (ω)}LOS; computing a tracking phase gimbal angle rate command ωcmd--Trk using a linear controller initialized with the estimated LOS angle rate {circumflex over (ω)}LOS wherein the linear controller comprises a digital filter the output of which is initialized to the estimated LOS angle rate {circumflex over (ω)}LOS; and commanding the gimballed platform according to an angle rate command ωcmd, wherein the angle rate command ωcmd is the acquisition phase angle rate command ωcmd--Acq during the initial control period T and the tracking phase gimbal angle rate command ωcmd--Trk after the initial control period T. 30. The method of claim 29, wherein the initial control period T ends when the measured LOS angle error ΔθLOS is below a threshold value for a number N of consecutive LOS angle error ΔθLOS measurements. 31. The method of claim 29, wherein the estimated LOS angle rate {circumflex over (ω)}LOS is computed after the control period T ends. 32. The method of claim 29, wherein the estimated LOS angle rate {circumflex over (ω)}LOS is computed after the control period ends from data matrices populated during the initial control period. 33. The method of claim 29, wherein the acquisition phase gimbal rate command ωcmd--Acq is computed as a non-linear mapping of the measured LOS angle error ΔθLOS to the gimbal angle rate command ωcmd. 34. The method of claim 29, wherein the estimated LOS angle rate {circumflex over (ω)}LOS is estimated at least in part from the angle rate command. 35. The method of claim 34, wherein the estimated LOS angle rate {circumflex over (ω)}LOS includes an estimated azimuth LOS angle rate {circumflex over (ω)}az,LOS and an estimated elevation LOS angle rate {circumflex over (ω)}el,LOS is estimated according to: Δti=ti-t0, and t0 is an initial time; Δθel,payload,sensor,i is a change in an elevation of the measured LOS angle error ΔθLOS in a platform reference frame within the time Δti; Δθaz,payload,sensor,i is a change in an azimuth of the measured LOS angle error ΔθLOS in a platform reference frame within the time Δti; {circumflex over (K)}1az is an estimate of a gain of an elevation channel of a sensor used to measure the elevation of the LOS angle error ΔθLOS; and {circumflex over (K)}2az is an estimate of a gain of an elevation channel of the sensor used to measure the azimuth of the LOS angle error ΔθLOS. and Δti=ti-t0, and t0 is an initial time; Δθel,payload,sensor,i is a change in an elevation of the measured LOS angle error ΔθLOS in a platform reference frame within the time Δti; Δθaz,payload,sensor,i is a change in an azimuth of the measured LOS angle error ΔθLOS in a platform reference frame within the time Δti; {circumflex over (K)}1el is an estimate of a gain of an elevation channel of a sensor used to measure the elevation of the LOS angle error ΔθLOS; and {circumflex over (K)}2el is an estimate of a gain of an elevation channel of the sensor used to measure the azimuth of the LOS angle error ΔθLOS. 36. The method of claim 29, further comprising the step of low pass filtering the acquisition phase angle rate command ωcmd--Acq before commanding the gimballed platform. 37. The method of claim 29, wherein the measured LOS angle error ΔθLOS is measured by an acquisition sensor. 38. The method of claim 29, wherein an estimated cross coupling is computed when the estimated LOS angle rate {circumflex over (ω)}LOS is computed and is used to initialize the controller. 39. The method of claim 29, wherein the initial control period T is predetermined. 40. The method of claim 29, wherein: the gimbaled platform is controlled to acquire and track a target; the first phase is an acquisition phase; and the second phase is a tracking phase. 41. The method of claim 29, wherein the LOS angle error ΔθLOS is an angle between a target and a boresight of the gimbaled platform. 42. An apparatus for controlling a gimbaled platform, comprising: means for computing an acquisition phase gimbal angle rate command ωcmd--Acq from a measured LOS angle error ΔθLOS for an initial control period T; means for computing an estimated LOS angle rate {circumflex over (ω)}LOS; means for computing a tracking phase gimbal angle rate command {circumflex over (ω)}cmd--Trk using a linear controller initialized with the estimated LOS angle rate {circumflex over (ω)}LOS wherein the linear controller comprises a digital filter the output of which is initialized to the estimated LOS angle rate {circumflex over (ω)}LOS; and means for commanding the gimballed platform according to an angle rate command ωcmd, wherein the angle rate command ωcmd is the acquisition phase angle rate command {circumflex over (ω)}cmd--Acq during the initial control period T and the tracking phase gimbal angle rate command {circumflex over (ω)}cmd--Trk after the initial control period T. 43. The apparatus of claim 42, wherein the initial control period T ends when the measured LOS angle error ΔθLOS is below a threshold value for a number N of consecutive LOS angle error ΔθLOS measurements. 44. The apparatus of claim 42, wherein the estimated LOS angle rate {circumflex over (ω)}LOS is computed after the initial control period T ends. 45. The apparatus of claim 42, wherein the estimated LOS angle rate {circumflex over (ω)}LOS is computed after the initial control period ends from data matrices populated during the initial control period. 46. The apparatus of claim 42, wherein the acquisition phase gimbal rate command ωcmd--Acq is computed as a non-linear mapping of the measured LOS angle error ΔθLOS to the gimbal angle rate command ωcmd. 47. The apparatus of claim 42, wherein the estimated LOS angle rate {circumflex over (ω)}LOS is estimated at least in part from the angle rate command. 48. The apparatus of claim 47, wherein the estimated LOS angle rate {circumflex over (ω)}LOS includes an estimated azimuth LOS angle rate {circumflex over (ω)}az,LOS and an estimated elevation LOS angle rate {circumflex over (ω)}el,LOS is estimated according to: Δti=ti-t0, and t0 is an initial time; Δθel,payload,sensor,i is a change in an elevation of the measured LOS angle error ΔθLOS in a platform reference frame within the time Δti; Δθaz,payload,sensor,i is a change in an azimuth of the measured LOS angle error ΔθLOS in a platform reference frame within the time Δti; {circumflex over (K)}1az is an estimate of a cross coupling of an azimuth channel of a sensor used to measure the elevation of the LOS angle error ΔθLOS; and {circumflex over (K)}2az is an estimate of a gain of an azimuth channel of the sensor used to measure the azimuth of the LOS angle error ΔθLOS; and Δti=ti-t0, and t0 is an initial time; Δθel,payload,sensor,i is a change in an elevation of the measured LOS angle error ΔθLOS in a platform reference frame within the time Δti; Δθaz,payload,sensor,i is a change in an azimuth of the measured LOS angle error ΔθLOS in a platform reference frame within the time Δti; {circumflex over (K)}1el is an estimate of a gain of an elevation channel of a sensor used to measure the elevation of the LOS angle error ΔθLOS; and {circumflex over (K)}2el is an estimate of a cross coupling of an elevation channel of the sensor used to measure the azimuth of the LOS angle error ΔθLOS. 49. The apparatus of claim 42, further comprising the step of low pass filtering the acquisition phase angle rate command ωcmd--Acq before commanding the gimballed platform. 50. The apparatusof claim 42, wherein the measured LOS angle error ΔθLOS is measured by an acquisition sensor. 51. The apparatus of claim 42, wherein an estimated cross coupling is computed during the initial control period and used to initialize the controller. 52. The apparatus of claim 42, wherein the initial control period T is predetermined. 53. The apparatus of claim 42, wherein: the gimbaled platform is controlled to acquire and track a target; the first phase is an acquisition phase; and the second phase is a tracking phase. 54. The apparatus of claim 42, wherein the LOS angle error ΔθLOS is an angle between a target and a boresight of the gimbaled platform.
