Patents by Inventor Rongsheng Li

Rongsheng Li 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).

  • 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: 6512979
    Abstract: A method, apparatus, article of manufacture for determining the attitude of a spacecraft having at least one star sensor. The method comprises the steps of selecting a first reference star sensor from among the star sensors; designating two stars observed by the first reference star sensor as a primary star pair; identifying a candidate star pair corresponding to the primary star pair, wherein the candidate star pair is selected from a star catalog having a plurality of entries; estimating an inertial orientation of the first star sensor at least in part from the identified candidate star pair; and determining the spacecraft attitude from the estimated inertial orientation of a reference star sensor selected from a group comprising the first star sensor.
    Type: Grant
    Filed: June 21, 2002
    Date of Patent: January 28, 2003
    Assignee: The Boeing Company
    Inventors: David D. Needelman, Yeong-Wei A. Wu, Rongsheng Li, William L. Burkett, Jr.
  • Publication number: 20030009284
    Abstract: A method, apparatus, article of manufacture for determining the attitude of a spacecraft having at least one star sensor. The method comprises the steps of selecting a first reference star sensor from among the star sensors; designating two stars observed by the first reference star sensor as a primary star pair; identifying a candidate star pair corresponding to the primary star pair, wherein the candidate star pair is selected from a star catalog having a plurality of entries; estimating an inertial orientation of the first star sensor at least in part from the identified candidate star pair; and determining the spacecraft attitude from the estimated inertial orientation of a reference star sensor selected from a group comprising the first star sensor.
    Type: Application
    Filed: June 21, 2002
    Publication date: January 9, 2003
    Inventors: David D. Needelman, Yeong-Wei A. Wu, Rongsheng Li, William L. Burkett
  • 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: 6470270
    Abstract: A method, apparatus, article of manufacture for determining the attitude of a spacecraft having at least one star sensor. The method comprises the steps of selecting a first reference star sensor from among the star sensors; designating two stars observed by the first reference star sensor as a primary star pair; identifying a candidate star pair corresponding to the primary star pair, wherein the candidate star pair is selected from a star catalog having a plurality of entries; estimating an inertial orientation of the first star sensor at least in part from the identified candidate star pair; and determining the spacecraft attitude from the estimated inertial orientation of a reference star sensor selected from a group comprising the first star sensor.
    Type: Grant
    Filed: November 7, 2000
    Date of Patent: October 22, 2002
    Assignee: The Boeing Company
    Inventors: David D. Needelman, Yeong-Wei A. Wu, Rongsheng Li, William L. Burkett, Jr.
  • 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: 6441776
    Abstract: A method, apparatus, and article of manufacture for directing a payload coupled to a spacecraft substantially at a target location is disclosed. The method comprises the steps of determining spacecraft orbital parameters and spacecraft payload attitude parameters; and directing the payload at the target location by applying a spacecraft bus steering law determined at least in part from the orbit and attitude parameters. The apparatus comprises a navigation system for determining spacecraft orbit parameters and spacecraft attitude parameters, and for applying a spacecraft bus steering law to direct the payload substantially at the target location. The spacecraft bus steering law is determined at least in part from the determined spacecraft orbital parameters, the determined spacecraft attitude, and determined payload attitude parameters. In one embodiment, the apparatus includes a payload attitude control system for directing the payload relative to the spacecraft bus.
    Type: Grant
    Filed: January 7, 2000
    Date of Patent: August 27, 2002
    Assignee: Hughes Electronics Corporation
    Inventors: Douglas H. Hein, Rongsheng Li
  • Patent number: 6362464
    Abstract: An apparatus for determining stellar inertial attitude based upon a plurality of stars includes a star tracker and a controller. The star tracker is used to sense the positions of stars and generate signals corresponding to the positions of the stars as seen in its field of view. The controller checks a star catalog and actively determines which stars to track. The controller does this determination in terms of each star's relative geometry. The controller then commands the star tracker to track these stars and uses them to determine the spacecraft attitude.
    Type: Grant
    Filed: February 15, 2000
    Date of Patent: March 26, 2002
    Assignee: Hughes Electronics Corp.
    Inventors: Yong Liu, Yeong-Wei A. Wu, Rongsheng Li, Christopher L. Rice
  • Patent number: 6356815
    Abstract: Stellar attitude-control systems and methods are provided with enhanced accuracy because they recognize that important star tracker errors exhibit a boresight symmetry and that these errors can be accurately defined by weighting a measurement-noise covariance matrix R(tn) with variances that are functions of off-boresight angles of detected stars. A method of the invention derives off-boresight angles &thgr; from star-tracker signals of detected stars. These off-boresight angles &thgr; are combined with variance coefficients &agr; to generate off-boresight variances rob(tn) that are functions of the off-boresight angles &thgr; and, in particular, correspond to star tracker color shift errors. A gain matrix K(tn) is then calculated with a weighted measurement-noise covariance matrix R(tn) that includes the off-boresight variances rob(tn). This gain matrix is used to generate an attitude estimate matrix X*(tn) for use in spacecraft attitude control.
    Type: Grant
    Filed: August 25, 2000
    Date of Patent: March 12, 2002
    Assignee: Hughes Electronics Corporation
    Inventors: Yeong-Wei A. Wu, Rongsheng Li, Yong Liu
  • Patent number: 6330988
    Abstract: An apparatus for star catalog equalization to enhance attitude determination includes a star tracker, a star catalog and a controller. The star tracker is used to sense the positions of stars and generate signals corresponding to the positions of the stars as seen in its field of view. The star catalog contains star location data that is stored using a primary and multiple secondary arrays sorted by both declination (DEC) and right ascension (RA), respectively. The star location data stored in the star catalog is predetermined by calculating a plurality of desired star locations, associating one of a plurality of stars with each of the plurality of desired star locations based upon a neighborhood association angle to generate an associated plurality of star locations: If an artificial star gap occurs during association, then the neighborhood association angle for reassociation is increased.
    Type: Grant
    Filed: July 29, 2000
    Date of Patent: December 18, 2001
    Assignee: Hughes Electronics Corporation
    Inventors: Yong Liu, Yeong-Wei Andy Wu, Rongsheng Li
  • Patent number: 6317662
    Abstract: The stability of a recursive estimator process (e.g., a Kalman filter is assured for long time periods by periodically resetting an error covariance P(tn) of the system to a predetermined reset value Pr. The recursive process is thus repetitively forced to start from a selected covariance and continue for a time period that is short compared to the system's total operational time period. The time period in which the process must maintain its numerical stability is significantly reduced as is the demand on the system's numerical stability. The process stability for an extended operational time period To is verified by performing the resetting step at the end of at least one reset time period Tr whose duration is less than the operational time period To and then confirming stability of the process over the reset time period Tr.
    Type: Grant
    Filed: July 24, 2000
    Date of Patent: November 13, 2001
    Assignee: Hughes Electronics Corporation
    Inventors: Rongsheng Li, Yeong-Wei Andy Wu
  • Patent number: 6304822
    Abstract: Methods are provided for dynamically processing successively-generated star tracker data frames and associated valid flags to generate processed star tracker signals that have reduced noise and a probability greater than a selected probability Pslctd of being valid. These methods maintain accurate spacecraft attitude control in the presence of spurious inputs (e.g., impinging protons) that corrupt collected charges in spacecraft star trackers. The methods of the invention enhance the probability of generating valid star tracker signals because they respond to a current frame probability Pfrm by dynamically selecting the largest valid frame combination whose combination probability Pcmb satisfies a selected probability Pslctd. Noise is thus reduced while the probability of finding a valid frame combination is enhanced. Spacecraft structures are also provided for practicing the methods of the invention.
    Type: Grant
    Filed: August 1, 2000
    Date of Patent: October 16, 2001
    Assignee: Hughes Electronics Corporation
    Inventors: Yong Liu, Yeong-Wei Andy Wu, Rongsheng Li
  • Patent number: 6298288
    Abstract: A system and method of estimating the attitude of a spacecraft is disclosed. A three-axis inertial-based estimate of spacecraft attitude is produced and is compared to a stellar-based estimate of spacecraft attitude. A Kalman filter having states associated with gyro scale factor and/or misalignment errors compares the stellar-based attitude estimate to the inertial-based estimate of attitude and apportions the total error into three time varying matrices. A first time varying matrix is associated with gyro scale factor and misalignment errors, a second time varying matrix is associated with gyro bias errors, and a third time varying matrix is associated with attitude errors. The time varying matrices are applied as corrective feedbacks to the inertial-based estimate of spacecraft attitude and are adaptively adjusted to minimize the error therein.
    Type: Grant
    Filed: December 16, 1998
    Date of Patent: October 2, 2001
    Assignee: Hughes Electronics Corp.
    Inventors: Rongsheng Li, Yeong-Wei A. Wu, Garry Didinsky
  • Patent number: 6288671
    Abstract: Control systems and methods are provided which enhance acquisition range, transient response and offset pointing accuracy in beacon-assisted orientation of a spacecraft to a desired spacecraft attitude Adsrd. The methods receive a beacon signal with antennas that are arranged in a fixed angular relationship to thereby form an attitude error signal Serr whose magnitude is a measure of the attitude difference between a current spacecraft attitude Acrnt and the desired spacecraft attitude Adsrd. A sum power P&Sgr; that is the sum of the signal powers from the antennas is sensed and a signal modifier Smod is generated that increases with decreases in the sum power P&Sgr;. The attitude error signal Serr is then modified with a term (1+Smod) to form an enhanced attitude error signal Serrenhd. In one embodiment, the signal modifier Smod is n|Pmax−P&Sgr;|m wherein n and m are positive numbers and Pmax is the sum power P&Sgr; when the attitude error is zero.
    Type: Grant
    Filed: April 25, 2000
    Date of Patent: September 11, 2001
    Assignee: Hughes Electronics Corporation
    Inventors: Yeong-Wei Andy Wu, Umesh S. Ketkar, Rongsheng Li, Richard Y. Chiang
  • Patent number: 6289268
    Abstract: A star tracker coupled to the spacecraft having a star catalog associated therewith. A sun sensor is coupled to the spacecraft. A control processor is coupled to the star tracker and the sun sensor. The processor obtains star data using a star tracker and an on-board star catalog. The processor generates a coarse attitude of the spacecraft as a function of the star data, and establishes a track on at least one star in the on-board star catalog. The processor calculates a sun tracking rate, and obtains a normal phase attitude as a function of the star data and the coarse attitude. The information is used to slew the spacecraft to a desired attitude.
    Type: Grant
    Filed: March 2, 2000
    Date of Patent: September 11, 2001
    Assignee: Hughes Electronics Corp.
    Inventors: Garry Didinsky, Arunkumar P. Nayak, Rongsheng Li, Yeong-Wei A. Wu, Jeffrey A. Kurland, David D. Needelman
  • Patent number: 6285927
    Abstract: A method and system for minimizing attitude errors resulting from dynamic spacecraft maneuvers or time-varying mismatched attitude sensor measurements. The method includes time-tagging a primary attitude value from a primary attitude sensor and storing the value and associated time stamp in a buffer. A secondary attitude value, generated by a secondary attitude sensor, having a different associated time-stamp is then time-matched to the primary attitude valve. The corrected spacecraft attitude is then calculated as a function of the time-matched primary and secondary attitude values. In one aspect of the invention, the primary attitude sensor generates attitude data at a faster rate than the secondary attitude sensor. This primary attitude data is stored in a buffer such that, when the secondary attitude data becomes available, several nearest-in-time primary attitude data points are retrieved from the buffer. These data points are then used to interpolate a higher time-matched resolution data point.
    Type: Grant
    Filed: May 26, 1999
    Date of Patent: September 4, 2001
    Assignee: Hughes Electronics Corporation
    Inventors: Rongsheng Li, Yeong-Wei Andy Wu
  • Patent number: 6272432
    Abstract: A system and method of estimating the attitude of a spacecraft compares a three-axis inertial-based estimate of spacecraft attitude to a stellar-based estimate of the spacecraft attitude. A Kalman filter having some states associated with low spatial frequency errors compares the stellar-based attitude estimate to the inertial-based estimate of attitude and apportions total attitude error into two time varying matrices. A first time varying matrix is associated with star tracker low spatial frequency errors, a second time varying matrix is associated with gyro bias errors and attitude errors. The time varying matrices are used to apply corrective feedbacks to the stellar-based attitude estimate and the inertial-based estimate of spacecraft attitude, and are adaptively adjusted to minimize total estimated attitude error.
    Type: Grant
    Filed: May 10, 1999
    Date of Patent: August 7, 2001
    Assignee: Hughes Electronics Corporation
    Inventors: Rongsheng Li, Yeong-Wei A. Wu, Douglas H. Hein, Garry Didinsky
  • 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