Abstract: Embodiments of the present invention include a two-stage blending filter that blends the measurements from two angular sensors to form a single superior high bandwidth measurement for improved disturbance rejection in a satellite systems for increased accuracy in satellite pointing, orientation, and attitude control. Embodiments of the present invention can include a satellite system including a first sensor including or defining a first measurement bandwidth; a first filter connected to the first sensor; a second sensor including or defining a second measurement bandwidth; a second filter connected to the second sensor; and a third filter connected to the first filter and the second filter. The third filter blend the first signal and the second signal into a third signal; and transmit the third signal to a flight controller configured to adjust an orientation of the satellite, a satellite subsystem, or both, relative to a target in response to the third signal.

Abstract: Embodiments of the present invention include a two-stage blending filter that blends the measurements from two angular sensors to form a single superior high bandwidth measurement for improved disturbance rejection in a satellite systems for increased accuracy in satellite pointing, orientation, and attitude control. Embodiments of the present invention can include a satellite system including a first sensor including or defining a first measurement bandwidth; a first filter connected to the first sensor; a second sensor including or defining a second measurement bandwidth; a second filter connected to the second sensor; and a third filter connected to the first filter and the second filter. The third filter blend the first signal and the second signal into a third signal; and transmit the third signal to a flight controller configured to adjust an orientation of the satellite, a satellite subsystem, or both, relative to a target in response to the third signal.

Abstract: An attitude estimator that uses sun sensor outputs as the only attitude determination measurements to provide three-axis attitude information. This is accomplished by incorporating the Euler equation into the estimator. An unscented Kalman filter is employed to accommodate various nonlinear characteristics and uncertainties of the spacecraft dynamics and thus improve the robustness and accuracy of the attitude estimate.

Abstract: An attitude estimator that uses star tracker measurements and enhanced Kalman filtering, with or without attitude data, to provide three-axis rate estimates. The enhanced Kalman filtering comprises taking an average of forward and rearward propagations of the Kalman filter states and the error covariances. The star tracker-based rate estimates can be used to control the attitude of a satellite or to calibrate a sensor, such as a gyroscope.

Abstract: A system and a method for commanding a spacecraft to perform a three-axis maneuver purely based on “position” (i.e., attitude) measurements. Using an “inertial gimbal concept”, a set of formulae are derived that can map a set of “inertial” motion to the spacecraft body frame based on position information so that the spacecraft can perform/follow according to the desired inertial position maneuvers commands. Also, the system and method disclosed herein employ an intrusion steering law to protect the spacecraft from acquisition failure when a long sensor intrusion occurs.

Abstract: An attitude estimator that uses star tracker measurements and enhanced Kalman filtering, with or without attitude data, to provide three-axis rate estimates. The enhanced Kalman filtering comprises taking an average of forward and rearward propagations of the Kalman filter states and the error covariances. The star tracker-based rate estimates can be used to control the attitude of a satellite or to calibrate a sensor, such as a gyroscope.

Abstract: An attitude estimator that uses sun sensor outputs as the only attitude determination measurements to provide three-axis attitude information. This is accomplished by incorporating the Euler equation into the estimator. An unscented Kalman filter is employed to accommodate various nonlinear characteristics and uncertainties of the spacecraft dynamics and thus improve the robustness and accuracy of the attitude estimate.

Abstract: A system for damping nutation and removing wobble of a spacecraft spinning about a given axis is provided. The system includes a sensor configured to determine three dimensional attitude measurements of the spacecraft, a processor operatively coupled to the sensor and configured to execute a process that facilitates aligning the spin axis with a spacecraft momentum vector. The processor, when executing the process, is programmed to receive spacecraft attitude data from the sensor, determine a torque command using the received attitude data, and control a momentum storage actuator on the spacecraft using the determined torque command such that an angular deviation about the given axis is reduced.

Abstract: A system and a method for commanding a spacecraft to perform a three-axis maneuver purely based on “position” (i.e., attitude) measurements. Using an “inertial gimbal concept”, a set of formulae are derived that can map a set of “inertial” motion to the spacecraft body frame based on position information so that the spacecraft can perform/follow according to the desired inertial position maneuvers commands. Also, the system and method disclosed herein employ an intrusion steering law to protect the spacecraft from acquisition failure when a long sensor intrusion occurs.

Abstract: A system and method for gyroless transfer orbit sun acquisition using only wing current measurement feedback is disclosed. With this system and method, a spacecraft is able to maneuver itself to orient its solar panel to its maximum solar exposure spinning attitude. The disclosed system and method involve controlling a spacecraft maneuver using only the solar wing current feedback as the sole closed-loop feedback sensor for attitude control. A spin controller is used for controlling the spacecraft spin axis orientation and spin rate. The spin controller commands the spacecraft spin axis orientation to align with an inertial fixed-direction and to rotate at a specified spin rate by using a momentum vector. In addition, a method for estimating spacecraft body angular rate and spacecraft attitude is disclosed. This method uses a combination of solar array current and spacecraft momentum as the cost function with solar wing current feedback as the only closed-loop feedback sensor.

Abstract: A system and method for gyroless transfer orbit sun acquisition using only wing current measurement feedback is disclosed. With this system and method, a spacecraft is able to maneuver itself to orient its solar panel to its maximum solar exposure spinning attitude. The disclosed system and method involve controlling a spacecraft maneuver using only the solar wing current feedback as the sole closed-loop feedback sensor for attitude control. A spin controller is used for controlling the spacecraft spin axis orientation and spin rate. The spin controller commands the spacecraft spin axis orientation to align with an inertial fixed-direction and to rotate at a specified spin rate by using a momentum vector. In addition, a method for estimating spacecraft body angular rate and spacecraft attitude is disclosed. This method uses a combination of solar array current and spacecraft momentum as the cost function with solar wing current feedback as the only closed-loop feedback sensor.

Abstract: A system and a method for commanding a spacecraft to perform a three-axis maneuver purely based on “position” (i.e., attitude) measurements. Using an “inertial gimbal concept”, a set of formulae are derived that can map a set of “inertial” motion to the spacecraft body frame based on position information so that the spacecraft can perform/follow according to the desired inertial position maneuvers commands. Also, the system and method disclosed herein employ an intrusion steering law to protect the spacecraft from acquisition failure when a long sensor intrusion occurs.

Abstract: A system for damping nutation and removing wobble of a spacecraft spinning about a given axis is provided. She system includes a sensor configured to determine three dimensional attitude measurements of the spacecraft, a processor operatively coupled to the sensor and configured to execute a process that facilitates aligning the spin axis with a spacecraft momentum vector. The processor, when executing the process, is programmed to receive spacecraft attitude data from the sensor, determine a torque command using the received attitude data, and control a momentum storage actuator on the spacecraft using the determined torque command such that an angular deviation about the given axis is reduced.

Abstract: A method, apparatus, article of manufacture, and a memory structure for designing a robust controller. The method comprises the steps of determining a plant model G of the system dynamics; bounding system dynamics unmodeled by the plant model G of the system dynamics by a weighting function W; applying a transform to an augmented plant model T having the plant model G and the weighting function W; defining a controller {tilde over (F)} from the transformed plant model T; and applying an inverse of the transform to the controller {tilde over (F)} defined from the transformed plant model and the weighting function W to generate the robust controller F.

Abstract: A method of analysis to process jitter information by using a window average statistic model to determine a pointing accuracy. The pointing accuracy ultimately determines whether or not a mission can proceed. The process includes the following: collect a signal, process the signal to produce data, insert the data from the signal into a statistical model to produce statistics, compile the statistics using the statistics model to produce a probability density function, integrate the probability density function to produce a probability distribution function, determine a pointing accuracy from the probability distribution function.

Abstract: This invention introduces innovative filtering techniques to recover the instability phase margin loss due to time delay induced from a throughput shortage problem of a spacecraft central processor (SCP). This invention relates to digital control systems and, more particularly, to a phase recovery filtering technique to alleviate spacecraft central computer processor or (SCP) throughput shortages. This filtering technique recovers the unstable phase margin loss due to the time delay caused by the SCP throughput problem. The filtering techniques may be accomplished without schedule slip or extra cost to the project.

Abstract: A method, apparatus, article of manufacture, and a memory structure for designing a robust controller. The method comprises the steps of determining a plant model G of the system dynamics; bounding system dynamics unmodeled by the plant model G of the system dynamics by a weighting function W; applying a transform to an augmented plant model T having the plant model G and the weighting function W; defining a controller {tilde over (F)} from the transformed plant model T; and applying an inverse of the transform to the controller {tilde over (F)} defined from the transformed plant model and the weighting function W to generate the robust controller F.

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.