The Boeing Company

Hughes Electronics Corporation

Other

Che-Hang Charles Ih

Kangsik Lee

Richard A Fowell

Hanching Grant Wang

Richard A Noyola

Yeong-Wei Andy Wu

Richard Yining Chiang

Arunkumar Pursayya Nayak

Danny D Howard

Apparatus and methods for attitude control of a space vehicle. The space vehicle includes a reaction wheel subsystem and a propulsion subsystem for attitude control. A slew controller for the space vehicle detects a failure of the reaction wheel subsystem. To perform an attitude slew, the slew controller identifies a pair of thrusters in the propulsion subsystem that will rotate the space vehicle about a desired axis. The slew controller determines burn parameters for the pair of thrusters, and initiates the burns to perform the desired attitude slew.

Attitude slew methodology for space vehicles using gimbaled low-thrust propulsion subsystem

A system and method are disclosed for an innovative spacecraft (S/C) safing methodology. The system and method use wheel momentum to perform a rotisserie rotation so that the spacecraft can slew at a fast rate in a controlled fashion in order to keep the spacecraft power safe and maintain telemetry and command (T&C) coverage. The system and method involve a reaction wheel system and a spacecraft control processor (SCP). The SCP is in communication with the reaction wheel system. The SCP is operable to determine a rotisserie axis, and take the cross product of the rotisserie axis and a momentum vector to result in a unit vector. The SCP is further operable to slowly slew the spacecraft about the unit vector through an angle until the rotisserie axis aligns with the momentum vector, and rotate the spacecraft about the rotisserie axis to keep the spacecraft power safe.

Innovative optimal spacecraft safing methodology

Spacecraft control modules can steer a spacecraft during a slew maneuver. The spacecraft control modules can receive a target attitude for the spacecraft slew maneuver. An angle between a current attitude and the target attitude may be determined. A smooth attitude offset profile with respect to a steering frame may be established from the current attitude to the target attitude. A smooth attitude command may be generated from the smooth attitude offset profile. The smooth attitude command may be applied to an attitude control module of the spacecraft.

Steering logic for spacecraft slew maneuvers

A method for modeling a structure deployed on a spacecraft. The method includes determining a geometric shape that resembles the structure in a fully deployed configuration; generating time functions for a change in shape of at least one structural component of the structure, the change in shape occurring as the structure expands into the fully deployed configuration; and calculating mass properties of the geometric shape as a function of the time functions.

Dynamic modeling technique for the deployment of large satellite antennas

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.

Robust spacecraft controller and method for designing same

A system and method to enhance attitude estimation for transfer orbit maneuvers of a spinning satellite includes a transfer orbit earth sensor that can receive and convert an infrared radiance to an analog signal. The analog signal is provided to a hardware chord processor and an analog-to-digital converter. The hardware chord processor determines an earth chord length based on the analog signal. The analog signal is sampled in the analog-to-digital converter to provide a digital signal to a digital earth sensor pre-processor, which reshapes the digital signal to provide a pre-processed signal having nearly distinct peaks. A software chord processor is provided with the pre-processed signal. The software chord processor locates the peaks in the pre-processed signal and determines an earth chord length.

System and method to enhance attitude estimation for transfer orbit maneuver

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

Autonomous slewing of a spacecraft about a desired axis using reaction wheels permits a maximum slew rate without wheel saturation even with one wheel failure. The slew is carried out if the total angular momentum of the spacecraft is less than a momentum storage threshold determined from reaction wheel availability. The momentum threshold may be found as the radius of a sphere inscribed in a polyhedron in momentum space, the polyhedron based on the maximum single wheel capacity and the geometry of the reaction wheel system as well as the reaction wheel availability. The momentum available for the slew is determined from the total angular momentum and the availability of each reaction wheel. The slew rate magnitude and slew direction are based on the available momentum. The available momentum calculation may include factors to accommodate noise and model uncertainties, to prevent the slew from placing the total angular momentum into a state overly limiting the rate of a subsequent slew, and to avoid numerical problems.

Slew rate direction determination for acquisition maneuvers using

A spacecraft with a reaction wheel system can be autonomously safed by setting the solar wings to continuous tracking, determining a slew rate vector based on the total angular momentum, and slewing the spacecraft using the slew rate vector until commanded to stop autonomous safing. In a typical application, the spacecraft has a reaction wheel assembly with four wheels arranged to form a right regular pyramid. Two reaction wheels on opposite edges of the pyramid form a first pair and the two remaining reaction wheels forming a second pair. The slew axis of rotation is found by determining as a selected pair the first pair if either reaction wheel in the second pair is inoperative, otherwise determining as the selected pair the second pair and determining as the slew axis of rotation the normalized projection of the axes of rotation of the selected pair onto the base. The slew direction is determined by the sign of the total angular momentum component along the slew axis of rotation.

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Rancho Palos Verdes, CA, United States of America

Che-Hang Charles Ih