Abstract: Provided are an earth satellite attitude data fusion system and method, applicable to an earth satellite space environment to estimate attitude data of a satellite. When the earth satellite attitude data fusion system of the present invention is used to perform the earth satellite attitude data fusion method, the first step is to perform a body rates/quaternion attitude data processing operation. Then, the next step is to perform an attitude/rates data fusion processing operation, wherein an attitude data fusion algorithm module receives a first IAE result data from a first EKF, and a second IAE result data from a second EKF, and performs an attitude/rates data fusion algorithm in a subsystem level to evaluate an attitude estimation IAE performance based on the first IAE result data, and the second IAE result data.

Abstract: A satellite attitude data fusion system and method is disclosed, applicable to the earth satellite environment to estimate attitude data of the satellite. When the satellite attitude data fusion system of the present invention is used to perform the satellite attitude data fusion method, the first step is to perform a body rates quaternion attitude data processing operation. Then, the next step is to perform an attitude/rates data fusion processing operation, wherein an attitude data fusion algorithm module receives the first IAE result data from the first EKF, and the second JAE result data from the second EKF, and performs an attitude/rates data fusion algorithm in a subsystem level to evaluate an attitude estimation JAE performance.

Abstract: A microelectromechanical gyroscope system is provided. The system includes a first substrate, a second substrate, and a third substrate. The substrates respectively have a first fixing, a second fixing, and a third fixing surfaces. The system further includes a first sensing, a second sensing and a third sensing module boards respectively fixed to the fixing surfaces. Each sensing module board has several microelectromechanical gyroscopes. A signal processing control board is electrically connected to the first sensing module board, the second sensing module board, and the third sensing module board. Wherein the first substrate, the second substrate, and the third substrate are perpendicular to each other. With the above structure, on each system coordinate axis of the microelectromechanical gyroscope system, at least one gyroscope is aligned with it for data acquisition and measurement. Accordingly, the measurement accuracy of the system is improved.

Abstract: Provided are an earth satellite attitude data fusion system and method, applicable to an earth satellite space environment to estimate attitude data of a satellite. When the earth satellite attitude data fusion system of the present invention is used to perform the earth satellite attitude data fusion method, the first step is to perform a body rates/quaternion attitude data processing operation. Then, the next step is to perform an attitude/rates data fusion processing operation, wherein an attitude data fusion algorithm module receives a first IAE result data from a first EKF, and a second IAE result data from a second EKF, and performs an attitude/rates data fusion algorithm in a subsystem level to evaluate an attitude estimation IAE performance based on the first IAE result data, and the second IAE result data.

Abstract: A satellite attitude data fusion system and method is disclosed, applicable to the earth satellite environment to estimate attitude data of the satellite. When the satellite attitude data fusion system of the present invention is used to perform the satellite attitude data fusion method, the first step is to perform a body rates quaternion attitude data processing operation. Then, the next step is to perform an attitude/rates data fusion processing operation, wherein an attitude data fusion algorithm module receives the first IAE result data from the first EKF, and the second JAE result data from the second EKF, and performs an attitude/rates data fusion algorithm in a subsystem level to evaluate an attitude estimation JAE performance.

Abstract: A method for controlling an actuator of a vehicle comprises providing a dynamic condition sensor generating a vehicle movement signal and a position sensor for generating a reported position. A processor is coupled to the inertial sensor and the position sensor and comprises an estimator, a position measurement predictor having a filter, a comparator and a control shaping block, said estimator generating a vehicle position based upon the dynamic condition sensor, said position measurement predictor generating an estimated position measurement in response to the reported vehicle position and a matched frequency response to the movement signal, said control shaping block generating an actuator control signal in response to a comparison of the estimated position measurement and the reported vehicle position.

Abstract: An airborne radio frequency (RF) antenna terminal system includes a two-axis gimbals control system and a phased array antenna. The phased array antenna electronically steers the receive and transmit beams using phase shifters. The electronically steered beams provide a virtual third-axis for the two-axis gimbals control system. The combination of the electronically steered beams and the two-axis gimbaled system provides accurate beam steering for the keyhole region of the two-axis gimbals control system so that the RF communication link is prevented from being lost in the keyhole region.

Abstract: A method and apparatus for reducing centroiding error of a star sensor having a plurality of pixels is disclosed. The method comprises the steps of computing a star sensor angular slew rate of ? pixels per star sensor integration period ?, collecting star sensor data while slewing the star sensor according to the selected star sensor angular slew rate ?, and filtering the collected star sensor data according to a frequency determined by the selected star sensor angular slew rate.

Abstract: A method of estimating the alignment of a star sensor (20) for a vehicle (12) includes generating star tracker data. A vehicle attitude and a star sensor attitude are determined in response to the star tracker data. A current alignment sample is generated in response to the vehicle attitude and the star sensor attitude. A current refined estimate alignment signal is generated in response to the current alignment sample and a previously refined estimate alignment signal via a vehicle on-board filter (38).

Abstract: In accordance with an embodiment of the present invention, a resolver system has at least one resolver and at least one amplifier in electrical communication with each resolver. A reference circuit is in electrical communication with the amplifiers. The reference circuit provides reference signals to the amplifiers. A non-linearity calibration and compensation circuit in communication with each amplifier uses the amplified reference signals to provide scale factors, so as to enhance a precision of the resolver system.

Abstract: A vehicle (12) including a control system (18) is used for controlling vehicle attitude or angular velocity (38). The processor (24) is coupled to a star sensor or tracker (22) and a memory (30) that may include a star catalog (32), and an exclusion list (36). The exclusion list (36), a list of stars to be temporarily excluded from consideration when determining attitude or angular velocity or relative alignment of star sensors or trackers, is calculated on-board. Such a calculation prevents the necessity for a costly, periodic, ground calculation and upload of such data. By manipulating the star catalog, or sub-catalogs derived from said catalog, based upon the exclusion list (36), measurements of such excluded stars are prevented from corrupting the attitude or angular velocity or alignment estimates formulated on board.

Abstract: A vehicle (12) including a control system (18) is used for controlling vehicle attitude or angular velocity (38). The processor (24) is coupled to a star sensor or tracker (22) and a memory (30) that may include a star catalog (32), and an exclusion list (36). The exclusion list (36), a list of stars to be temporarily excluded from consideration when determining attitude or angular velocity or relative alignment of star sensors or trackers, is calculated on board. Such a calculation prevents the necessity for a costly, periodic, ground calculation and upload of such data. By manipulating the star catalog, or sub-catalogs derived from said catalog, based upon the exclusion list (36), measurements of such excluded stars are prevented from corrupting the attitude or angular velocity or alignment estimates formulated on board. The system uses multiple stayout zones for excluding stars from the exclusion list.

Abstract: A system (18) includes: a) A vehicle (12) includes an attitude or angular velocity control system (38), a plurality of star trackers or star sensors (22) each having a field of view (28); b) a memory (30) having a star catalog (32), a star pair catalog (58) and a reference table (56) stored therein; and c) a processor (24) coupled to the attitude or angular velocity control system (38), the star trackers or star sensors (22), and the memory (30). The processor (24) determines the vehicle inertial attitude or angular velocity or sensor alignment, based, in part, on the star pair catalog (58) and reference table (56). The design of the star pair catalog (58) and reference table (56) is suitable for rapid determination of attitude or angular velocity or sensor alignment, and an efficient use of memory.

Abstract: A system (18) includes: a) A vehicle (12) includes an attitude or angular velocity control system (38), a plurality of star trackers or star sensors (22) each having a field of view (28); b) a memory (30) having a star catalog (32), an allocated area for a star pair catalog (58) and a reference table (56) stored therein; and c) a processor (24) coupled to the attitude or angular velocity control system (38), the star trackers or star sensors (22), and the memory (30). The processor (24) populates the star pair catalog (58), using the method described herein. The processor (24) then periodically determines the vehicle inertial attitude or angular velocity or sensor alignment, based, in part, on the star pair catalog (58) and reference table (56). The novel ability of the software to autonomously populate the star pair catalog (58) allows users to avoid uploading a large amount of data, and the problems associated with such an upload.

Abstract: A method and apparatus for refining a spacecraft state estimate, such as an attitude estimate or an angular velocity estimate, is disclosed. The method computes a plurality equations using residuals describing the difference between observed star positions and predicted positions based on inertial measurements, and solves those equations to generate refined estimates of the spacecraft state estimates.

Abstract: A method, apparatus, article of manufacture, and a memory structure for compensating for optical sensor data corrupted by angular acceleration is disclosed. The method comprises the steps of determining an angular acceleration of the optical sensor and modifying the optical sensor data according to the determined angular acceleration of the optical sensor. The apparatus comprises a sensor for determining an angular acceleration of the optical sensor and a navigation system for modifying the optical sensor data according to the determined angular acceleration of the optical sensor.

Abstract: A method and apparatus for estimating a slave payload attitude is disclosed. The method comprises the steps of 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.

Abstract: A method, apparatus, article of manufacture, and a memory structure for compensating for optical sensor data corrupted by angular acceleration is disclosed. The method comprises the steps of determining an angular acceleration of the optical sensor and modifying the optical sensor data according to the determined angular acceleration of the optical sensor. The apparatus comprises a sensor for determining an angular acceleration of the optical sensor and a navigation system for modifying the optical sensor data according to the determined angular acceleration of the optical sensor.

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.

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.