摘要:
A space debris remover aiming to remove a space debris object in earth orbits. Angular thrust calculation unit calculates angular thrust. Radial thrust calculation unit calculates radial thrust based on the angular thrust, estimated angular momentum and estimated space debris mass. A foam bonding mechanism connects the space debris remover and the space debris object. A space debris removal controller calculates firing time, and sends a space debris removal control signal comprising the radial thrust, the angular thrust and the firing time. A plurality of first stage thrusters generate the radial thrust and the angular thrust after the firing time. After the stage separator separates a first stage and a second stage of the space debris remover, a plurality of second stage thrusters generate the radial thrust and the angular thrust, and propel the space debris object towards the sun.
摘要:
Methods and apparatus are presented for spacecraft operation using non-Eigen axis attitude transitions via control momentum gyroscopes (CMGs) to avoid or mitigate singularities by providing a time-varying attitude command vector including a plurality of time-varying attitude command signals or values representing a plurality of spacecraft states and control trajectories as a guidance command input to an attitude controller of the spacecraft without modifying the spacecraft feedback control law.
摘要:
A method, apparatus and system is provided for reducing an amount of information transmitted to a vehicle in order to implement attitude control of the vehicle. In accordance with the present invention, data corresponding to at least one time-varying attitude command trajectory defining an attitude of the vehicle is reduced, for example, into a vector of polynomial coefficients. The vector of polynomial coefficients then are transmitted to the vehicle, where they are used to reconstruct the at least one time-varying attitude command trajectory via a polynomial interpolation operation.
摘要:
Techniques are provided to determine an initial quaternion transform that is used to transform measurements received from accelerometer, rate sensor and inertial reference subsystems from a vehicle coordinate frame to an inertial navigation frame. Methods disclosed determine corrective angular rates to use as a feedback signal to rotate the quaternion transform to counter errors that result when transforming a gravity vector and an inertial reference vector (e.g., a magnetic North reference vector) that are being measured by the accelerometer and an inertial reference subsystems, respectively. The initial quaternion determination is performed during a time period when the only substantial acceleration on the vehicle is due to gravity. The initial quaternion can be used for processing various guidance, navigation and control functions.
摘要:
Provided are an attitude control system and method of a spacecraft of an artificial satellite that may enhance a maneuverability and a controllability by simultaneously applying a reaction wheel and a thruster among drive units used to maneuver an attitude of the spacecraft of the artificial satellite. The attitude control system may include: a thruster-based attitude controller which control firing time of thrusters mounted on the spacecraft; and a reaction wheel-based attitude controller controlling driving of a reaction wheel mounted on the spacecraft. The spacecraft may include a plurality of reaction wheels. When a defect occurs in the spacecraft due to a partial malfunction of the reaction wheels, an attitude maneuverability of the spacecraft may be corrected by simultaneously applying the thruster-based attitude controller and the reaction wheel-based attitude controller.
摘要:
A method of providing attitude and antenna steering for a spacecraft having a number of reaction wheels and a number of antennas is disclosed. The method includes determining a beta angle, the beta angle being the angle between a sun vector and an orbit plane of the spacecraft, and engaging either a first mode or a second mode in an alternate manner to provide attitude and antenna steering based on the beta angle. A target frame generator for generating information usable to provide attitude and antenna steering for a spacecraft is also disclosed.
摘要:
Methods and systems are provided for reorienting an agile vehicle, such as a satellite or spacecraft, using a control moment gyroscope (CMG) array. The CMG array comprises a plurality of CMGs onboard the agile vehicle. A method comprises obtaining an input torque command for reorienting the vehicle using the CMG array and, when the angular momentum of the CMG array violates or is approaching a momentum boundary criterion, decreasing the input torque command in the kinetic momentum direction, resulting in a modified torque command, and operating the CMG array using the modified torque command.
摘要:
A system for providing attitude control with respect to a spacecraft is provided. The system includes a reaction wheel control module configured to control a number of reaction wheel assemblies associated with the spacecraft in order to control attitude, and a maneuver control module configured to use a number of gimbaled Hall Current thrusters (HCTs) to control the total momentum associated with the spacecraft during an orbit transfer. The total momentum includes the momentum associated with the reaction wheel assemblies and the angular momentum of the spacecraft. Using the gimbaled HCTs to control the momentum associated with the reaction wheel assemblies during the orbit transfer results in minimal HCT gimbal stepping.
摘要:
A control system for adjusting the attitude of a spacecraft comprises a set of control moment gyroscopes (CMGs) configured to allow null space maneuvering. The control system further comprises a momentum actuator control processor coupled to the set of CMGs and configured to determine a mandatory null space maneuver to avoid singularities and determine an optional null space maneuver to increase available torque. The mandatory null space maneuver can be calculated based upon certain gimbal angles, and can be implemented by augmenting the inverse-Jacobian control matrix.
摘要:
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 ω pixels per star sensor integration period τ, collecting star sensor data while slewing the star sensor according to the selected star sensor angular slew rate ω, and filtering the collected star sensor data according to a frequency determined by the selected star sensor angular slew rate.