Patents by Inventor Yeong-Wei Wu

Yeong-Wei Wu has filed for patents to protect the following inventions. This listing includes patent applications that are pending as well as patents that have already been granted by the United States Patent and Trademark Office (USPTO).

  • Patent number: 6566640
    Abstract: A method and apparatus for post processing a star tracker measurement to remove a systematic error characterizable at least in part by a pixel phase is disclosed. The method comprises the steps of computing the pixel phase along a first axis from a measured star position and a star tracker characteristic, computing a first axis error correction according to the computed pixel phase, and computing a compensated first axis star tracker measurement according to the measured star position and the first axis error correction.
    Type: Grant
    Filed: September 24, 2001
    Date of Patent: May 20, 2003
    Assignee: The Boeing Company
    Inventors: Yeong-Wei Wu, Rongsheng Li
  • Publication number: 20030093194
    Abstract: A method and apparatus for calibrating rate sensor measurements to compensate for rate sensor scale factor non-linearities. An outer loop compensator compares current rate sensor scale factor estimates with the current scale factor non-linearity compensation, and deviations from the current non-linearity compensation are corrected in an updated compensation.
    Type: Application
    Filed: November 13, 2001
    Publication date: May 15, 2003
    Applicant: THE BOEING COMPANY
    Inventors: Rongsheng Li, Yeong-Wei Wu, David L. Augenstein
  • Publication number: 20030057354
    Abstract: A method and apparatus for post processing a star tracker measurement to remove a systematic error characterizable at least in part by a pixel phase is disclosed. The method comprises the steps of computing the pixel phase along a first axis from a measured star position and a star tracker characteristic, computing a first axis error correction according to the computed pixel phase, and computing a compensated first axis star tracker measurement according to the measured star position and the first axis error correction.
    Type: Application
    Filed: September 24, 2001
    Publication date: March 27, 2003
    Applicant: THE BOEING COMPANY
    Inventors: Yeong-Wei Wu, Rongsheng Li
  • Publication number: 20030029970
    Abstract: The present invention is directed to spacecraft that have, for any reason, lost the spacecraft's service attitude that permits it to carry out the service operations for which it was designed. The invention provides methods and structures for acquiring and determining a power-safe attitude (i.e., one in which wing current is sufficient to support the spacecraft's housekeeping operations) from which the spacecraft can be subsequently returned to a service attitude. The methods are particularly useful because they a) require only a single star tracker for sensing attitude, comprise simple maneuvers, and typically acquire a power-safe attitude that does not significantly differ from the spacecraft's service attitude to thereby reduce the spacecraft's return-to-service time.
    Type: Application
    Filed: January 29, 2001
    Publication date: February 13, 2003
    Inventors: Grant Wang, Yeong-Wei Wu, Rongsheng Li, David D. Needelman
  • Patent number: 6504502
    Abstract: A pointing system and method for directing a first satellite system instrument to a first target is disclosed. The method comprises the steps of computing the orientation of a first satellite system instrument; computing a position of the satellite using measured orbital data; computing a target line of sight (LOS) vector direction from the satellite to the target using the computed orientation and the computed satellite position, and directing the first instrument to the first target according to the computed target LOS vector. The apparatus comprises at least one attitude sensor for the first instrument and a communicatively coupled satellite navigation system. The satellite navigation system determines the satellite position using measured satellite orbital data. The satellite navigation system computes the orientation of the first instrument using the attitude measurements, and computes the satellite position using measured satellite orbital data.
    Type: Grant
    Filed: January 7, 2000
    Date of Patent: January 7, 2003
    Assignee: Hughes Electronics Corporation
    Inventors: Yeong-Wei Wu, Rongsheng Li
  • Patent number: 6460809
    Abstract: Structures and methods are provided for deriving corrected star coordinates Ccrctd from measured star coordinates Cms that include star tracker charge transfer efficiency (CTE) errors. The structures and methods are based on a recognition that measured star coordinates Cms of star image centroids include CTE errors which are functions of the CCD path lengths over which the associated electrical charges traveled. In particular, the errors are substantially a product of a respective path length and a star-coordinate error factor &xgr; which, in turn, is a function of the star image magnitudes msi. Information contained in different measured star coordinates Cms is organized to facilitate the derivation of an estimate &xgr;* of the star-coordinate error factor &xgr; with conventional estimation processes. The measured star coordinates Cms are then corrected with the error factor estimate &xgr;* to realize the corrected star coordinates Ccrctd and, thereby, improve the accuracy of spacecraft attitude control.
    Type: Grant
    Filed: January 25, 2001
    Date of Patent: October 8, 2002
    Assignee: The Boeing Company
    Inventors: Yeong-Wei Wu, Rongsheng Li, James H. Green
  • Publication number: 20020125375
    Abstract: Structures and methods are provided for deriving corrected star coordinates Ccrctd from measured star coordinates Cms that include star tracker charge transfer efficiency (CTE) errors. The structures and methods are based on a recognition that measured star coordinates Cms of star image centroids include CTE errors which are functions of the CCD path lengths over which the associated electrical charges traveled. In particular, the errors are substantially a product of a respective path length and a star-coordinate error factor &xgr; which, in turn, is a function of the star image magnitudes msi. Information contained in different measured star coordinates Cms is organized to facilitate the derivation of an estimate &xgr;* of the star-coordinate error factor &xgr; with conventional estimation processes. The measured star coordinates Cms are then corrected with the error factor estimate &xgr;* to realize the corrected star coordinates Ccrctd and, thereby, improve the accuracy of spacecraft attitude control.
    Type: Application
    Filed: January 25, 2001
    Publication date: September 12, 2002
    Applicant: THE BOEING COMPANY
    Inventors: Yeong-Wei Wu, Rongsheng Li, James H. Green
  • Patent number: 6108594
    Abstract: A method and apparatus for autonomous acquisition of attitude in a stellar inertial spacecraft attitude system is disclosed. The present invention uses star trackers, an on-board star catalog, spacecraft steering and inertial sensors to determine spacecraft attitude. The present invention utilizes pattern match and pattern rejection methods and uses multiple stellar snap-shots in conjunction with spacecraft steering and spacecraft inertial measurements to acquire spacecraft attitude. Spacecraft inertial measurements are used to connect multiple stellar snap-shots to provide adequate star information that can be used to acquire spacecraft attitude. In an attitude determination system using star trackers, the star trackers may have a narrow field-of-view or few stars may be available for viewing. The present invention uses pattern matching and pattern rejection on different sets of stars, thereby allowing attitude acquisition when the number of stars in view is small.
    Type: Grant
    Filed: May 29, 1998
    Date of Patent: August 22, 2000
    Assignee: Hughes Electronics Corporation
    Inventors: Garry Didinsky, Yeong-Wei Wu, Rongsheng Li, Arunkumar Nayak, Douglas Hein