Abstract:
An attitude control device for space station with system parameter uncertainties and on-orbit dynamic disturbances. A plurality of state sensors measure a plurality of states of the space station. An identification frequency selecting device selects an identification frequency. A moment of inertia identification operator calculation unit calculates a moment of inertia identification operator. A moment of inertia identification device calculates moment of inertia of the space station. A disturbance torque identification device calculates disturbance torque. A control torque calculation unit calculates a control signal. A plurality of thrusters generate a control torque based on the control signal.
Abstract:
A vehicle having a plurality of thruster components, wherein each of the thruster components includes a plurality of sub-thrusters, each sub-thruster being grouped into one of a plurality of control groups. The vehicle including a control system receiving information related to the vehicle, wherein the control system selects one of the control groups and activates the sub-thrusters of the selected control group.
Abstract:
An aircraft having propulsion units for both conventional aircraft flight in the atmosphere and for high-altitude operation as a rocket. The aircraft is divided into a payload compartment and a compartment containing rocket propulsion unit propellant or fuel, and includes a long transverse wing with a small back-sweep to favor lift in the dense layers of the atmosphere and to thus make it possible to climb to high altitudes at a subsonic speed before using the rocket propulsion units. The return flight portion is performed by gliding or controlled as for a conventional aircraft.
Abstract:
A satellite longitude and drift control method is provided that includes providing a satellite that has a continuously or a quasi-continuously firing thruster, where the thruster is disposed to apply accelerations which counter a tri-axiality displacement in an orbit of the satellite, and the satellite thruster is disposed to achieve optimal ΔV performance in the presence of orbit determination and orbit propagation errors. The method further includes targeting an optimal two-phase continuous acceleration target cycle using the continuously or the quasi-continuously firing thruster, providing a closed loop and a hybrid loop implementation of the thruster firing, where the hybrid loop implementation includes an open and closed loop implementation, and where the closed loop and the hybrid loop implementations are disposed to provide quasi-continuous implementations of an optimal continuous control program.
Abstract:
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. 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 results in minimal HCT gimbal stepping.
Abstract:
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.
Abstract:
Systems and methods are disclosed employing electric propulsion stationkeeping in a cyclical manner to better match the cyclical pattern of power generated by the solar array system. For a typical orbit design, e.g. a geostationary orbit, North-South stationkeeping can be intermittently suspended, tolerating some additional drift but yielding in a very significant reduction in the required solar power system. If necessary, stationkeeping can be supplemented with a chemical thrusters during off periods for the electric propulsion. Because of this, the overall electrical power margin for the solar array system design can be reduced without compromising the mission performance.
Abstract:
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.
Abstract:
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.
Abstract:
Enhanced translational thrusting is provided by reaction engines configured to permit translational thrusting off or through the center of gravity of a spacecraft or other vehicle. Among other applications, this approach is useful for a Satellite Life Extension System (SLES) that provides maintenance services to orbiting satellites. By attaching to the satellite and conducting maneuvers to maintain its operational orbit and attitude, the SLES increases the working lifetime of the satellite. Since the engines of the SLES are redundant, the failure of a single engine will not jeopardize the overall success of the mission.