The Boeing Company

Hanching Grant Wang

Richard A Fowell

Rongsheng Li

Yeong-Wei Andy Wu

Che-Hang Charles Ih

Chih-Chien Hsu

Sadek W Mansour

Bruce Cordell Detterich

Arunkumar Pursayya Nayak

Douglas Bender

Arun Prakash

Umesh Ketkar

Albert A Munoz

A method and apparatus for generating navigation solutions. A global positioning system based navigation solution unit; an inertial navigation solution unit; a correction unit, a limiter, and an adding unit. The global positioning system based navigation solution unit is capable of generating a first navigation solution. The inertial navigation solution unit is capable of generating a second navigation solution. The correction unit is capable of generating a raw correction. The limiter is capable of selectively modifying the raw correction to fall within a selected range of corrections to form a correction. The adding unit is capable of adding the correction to the second navigation solution to form a navigation solution.

Low authority GPS aiding of navigation system for anti-spoofing

An Ultra-Tightly Coupled GPS-inertial navigation system for use in a moving agile platform includes a range residual extractor that uses best curve fitting of a third order polynomial for estimating range residual. The curve-fitted residual is used to update an error Kalman filter. The error Kalman filter includes correction for navigation solution, and IMU and GPS parameters. The navigation solution together with GPS parameter corrections are used in a Tracking Predictor to generate high-sampling-rate carrier and code replicas. The curve-fitting error covariance indicates signal to noise ratio for the tracked GPS signal and may be used for early indication of interference or jamming.

Ultra-tightly coupled GPS and inertial navigation system for agile platforms

A method for spacecraft power acquisition is provided using single-axis slit sun sensors for both wing-stowed and wing-deployed spacecraft configurations. The method for wing-deployed spacecraft includes initializing a solar wing of the spacecraft to search for sun; rotating the spacecraft about a search axis substantially parallel to a slit sun sensor field of view; monitoring the slit sun sensor for a time of arrival signal; and wherein, if the time of arrival signal occurs, the spacecraft is rotated along the search axis to an orientation where the time of arrival signal occurred and the spacecraft is placed in stable rotation about an axis substantially parallel to a solar wing longitudinal axis; and for a non-occurrence of the time of arrival signal, the spacecraft is slewed about a keyhole axis substantially perpendicular to the search axis to move the sun away from a keyhole.

Method and system for spacecraft power acquisition using single-axis slit sun sensor

A method, apparatus for reducing errors in a plurality of beacon beams is disclosed. The method comprises the steps of computing quantized channel weights {tilde over (W)}from channel weights Wfor at least some of the channels; estimating the quantization error &#x394;Bfor each of the beacon beams from a difference between the channel weights Wand the computed quantized channel weights {tilde over (W)}; and adding the estimated quantization error &#x394;Bto the beacon beams. Similarly, a beacon biases equivalent to the beacon asymmetry error can be computed by the ground beacon beam forming software and uploaded to the on-board software for error compensation. The apparatus comprises one or more means, such as a processor communicatively coupled to a memory storing instructions for performing these operations.

Digital beacon asymmetry and quantization compensation

A method and apparatus for controlling a plurality of solar panels of a spacecraft is described. The method comprises the steps of providing a first step command to a first solar panel, and providing a second step command to a second solar panel at a time of a transient zero-crossing of a dynamic response of the spacecraft body to the first step command, wherein the second solar panel is disposed on an opposite side of the spacecraft from the first solar panel. The apparatus comprises a processor; a first solar panel driver, communicatively coupled to the processor, for providing a first step command to a first solar panel, and a second solar panel driver, communicatively coupled to the processor, for providing a second step command to a second solar panel at a time of a transient zero-crossing of a dynamic response of the spacecraft body to the first step command.

Transient cancellation technique for spacecraft solar wing stepping

A method and apparatus for correcting a beam error is disclosed. One embodiment of the method comprises the steps of selecting beamweight coefficients based on the satellite orbital data, evaluating an effect of quantization of the beamweight coefficients on the beam error, and selecting beamweight coefficients based at least in part upon the evaluation of the effect of beamweight coefficient quantization on beam error. One embodiment of the apparatus comprises a beamweight correction module for selecting beamweight coefficients based on satellite orbital data, for evaluating the effect of quantization of the beamweight coefficients on beam error, and for selecting beamweight coefficients based at least in part upon the evaluation of the effect of beamweight coefficient quantization on beam error. The beamweight correction module comprises a beamweight generator and a beamweight quantizer for quantizing beamweights from the beamweight generator.

Method and apparatus for reducing quantization-induced beam errors by selecting quantized coefficients based on predicted beam quality

A method of correcting for beacon pointing errors is disclosed. A desired beacon value and a predicted measured beacon value are computed and used to generate the beacon correction. An antenna pattern calculator can be used to compute the predicted measured beacon value, and a beacon correction value generator can be used to compute the desired beacon value and to generate the beacon correction.

Method and apparatus for correction of quantization-induced beacon beam errors

A method and apparatus for estimating spacecraft momentum is disclosed. The method comprises the steps of generating a plurality of spacecraft momentum measurements, fitting the plurality of spacecraft momentum measurements to a parametric model of a spacecraft momentum profile having a time period of t, determining the momentum of the spacecraft from the parametric model; and generating an estimate of the momentum to be removed from the spacecraft at least in part from the determined momentum of the spacecraft.

Momentum estimator for on-station momentum control

A method and apparatus for estimating a slave payload attitude is disclosed. The method includes accepting a plurality of slave payload attitude measurements, deriving a model of the relative attitude of the slave payload and a master payload attitude at least in part from the plurality of slave attitude measurements, predicting the relative attitude between the slave payload attitude and the master payload attitude using the derived model, and estimating the relative attitude between the slave payload attitude and the master payload attitude at least in part from the predicted relative attitude between the slave payload attitude and the master payload attitude. Furthermore, the absolute attitude of the slave payload is computed using the relative attitude and the master payload attitude.

Relative attitude estimator for multi-payload attitude determination

A method and an apparatus for controlling the attitude and momentum of a spacecraft while deploying an appendage from the spacecraft. The method uses solar tacking and similar techniques to produce differential solar torques that are used to control the momentum and attitude of the spacecraft during the appendage deployment.

Method and apparatus for solar tacking momentum maintenance in long-duration deployment of a large reflector

A method and an apparatus for controlling the attitude and momentum of a spacecraft while deploying an appendage from the spacecraft. The method comprises the steps of predicting an environmental torque the spacecraft will be subjected to during deployment of the appendage, computing a magnitude and a direction of momentum to add to the spacecraft to at least partially oppose the predicted environmental torque, and storing the computed magnitude and direction of momentum in at least one of the momentum wheels before deploying the appendage.

Method and apparatus for reaction wheel dynamic compensation in long-duration deployment of a large reflector

A system and method for performing in-orbit alignment calibration using on-board attitude sensors to improve reflector alignment after deployment to improve spacecraft pointing.

Reflector deployment error estimation

A method, apparatus for reducing errors in a plurality of beacon beams is disclosed. The method comprises the steps of computing quantized channel weights {tilde over (W)} from channel weights W for at least some of the channels; estimating the quantization error &Dgr;B for each of the beacon beams from a difference between the channel weights W and the computed quantized channel weights {tilde over (W)} ; and adding the estimated quantization error &Dgr;B to the beacon beams. Similarly, a beacon biases equivalent to the beacon asymmetry error can be computed by the ground beacon beam forming software and uploaded to the on-board software for error compensation. The apparatus comprises one or more means, such as a processor communicatively coupled to a memory storing instructions for performing these operations.

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Hacienda Heights, CA, United States of America

Hanching Grant Wang