摘要:
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.
摘要:
Methods and apparatus to methods and apparatus for performing propulsion operations using electric propulsion system are disclosed. An example method includes deploying a space vehicle including an electric propulsion system; and using the electric propulsion system for attitude control and orbit control, no other propulsion system provided to enable the attitude control and the orbit control.
摘要:
A satellite system includes a chassis, an avionics package included within an upper portion of the chassis. The avionics package includes a main system board, a payload interface board, at least one daughter board and a battery board. The main system board, the payload interface board, the at least one daughter board, and the battery board reside in substantially parallel planes. The payload interface board, the at least one daughter board, and the battery board are coupled to the main system board through one or more stackable connectors. A method of operating a satellite is also described.
摘要:
A method of controlling inertial attitude of an artificial satellite in order to perform a navigation function and to maximize terrestrial coverage of the Earth by the satellite. The method includes deploying the artificial satellite in an orbit about the poles of the Earth; applying gyroscopic precession to the artificial satellite spin axis to precess and maintain the satellite near the ecliptic pole; deploying the artificial satellite so that the spin axis is initially perpendicular to or substantially perpendicular to sun lines; and applying gyroscopic precession to the artificial satellite spin axis to precess the spin axis away from an initial deployed attitude at a selectively-variable precession rate and to maintain the spin axis perpendicular to or substantially perpendicular to the sun lines.
摘要:
Systems, apparatuses, and methods for removal of orbital debris are provided. In one embodiment, an apparatus includes a spacecraft control unit configured to guide and navigate the apparatus to a target. The apparatus also includes a dynamic object characterization unit configured to characterize movement, and a capture feature, of the target. The apparatus further includes a capture and release unit configured to capture a target and deorbit or release the target. The collection of these apparatuses is then employed as multiple, independent and individually operated vehicles launched from a single launch vehicle for the purpose of disposing of multiple debris objects.
摘要:
A method for reducing the angular momentum of a spacecraft comprises a propulsion device able to generate a torque along a Z axis corresponding to an axis of maximum inertia or minimum inertia of the spacecraft, an X axis and a Y axis forming with Z an orthogonal frame; an angular momentum accumulating device, able to generate an angular momentum and a torque along the three axes; and a set of sensors able to measure the angular velocities and estimate the angular momentum of the spacecraft. The method comprises a first step of aligning the angular momentum of the spacecraft along the Z axis, consisting in slaving the angular momentum of the angular momentum accumulating device to the angular velocity of the spacecraft, and a second step of reducing the angular momentum of the spacecraft using a torque generated by the propulsion device.
摘要:
Embodiments of the invention relate to systems and methods for a self-deploying vehicle drag device. In one embodiment, a drag device for a vehicle can be provided. The drag device can include a chute body, wherein the chute body is connected to the vehicle. The drag device can also include at least one collapsible member mounted to the chute body, wherein the at least one collapsible member and chute body are maintained in respective compressed configurations until deployed. Furthermore, the drag device can include at least one device adapted to release the chute body from the vehicle, wherein the chute body and the at least one collapsible member are deployed in expanded configurations with respect to the vehicle.
摘要:
Methods and systems are provided for controlling attitude of a vehicle using a reaction wheel onboard the vehicle. One exemplary method involves receiving a torque command for adjusting the attitude of the vehicle using the reaction wheel, determining a phase error of the reaction wheel based at least in part on the torque command, and determining a motor torque command for the reaction wheel based on the phase error. The motor torque command is provided to an electric motor of the reaction wheel to apply a corresponding torque to the rotor of the reaction wheel. The relationship between the magnitude of the motor torque command and the magnitude of the phase error is nonlinear. In exemplary embodiments, the magnitude of the motor torque command exceeds the stiction torque, at least instantaneously, when the reaction wheel has fallen behind an expected position by more than a threshold amount.
摘要:
A method of controlling attitude of a spacecraft during a transfer orbit operation is provided. The method includes providing a slow spin rate, determining the attitude of the spacecraft using a unified sensor set, and controlling the attitude of the spacecraft using a unified control law. The use of a unified set of sensors and a unified control law reduces spacecraft complexity, cost, and weight.
摘要:
A method for calibration of a digital celestial sensor is disclosed. First, an integrated mathematic model for imaging of a celestial sensor is established according to external and internal parameters of the calibration system of the celestial sensor. Second, by rotating two axes of a rotator by different angles, calibration points data are acquired and sent to a processing computer through an interface circuit. Finally, a two-step calibration program is implemented to calculate the calibration parameters by substituting calibration points' data to the integrated mathematic model. An application device of the calibration method is also provided. The device may include a celestial simulator to provide simulated sunlight or starlight, a two-axis rotator to acquire different calibration points' data, and a processing computer to record the calibration points' data and calculate the calibration parameters.