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

摘要

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.

主权项

1. A space vehicle comprising:
a bus having a nadir side and a zenith side opposite the nadir side; a reaction wheel subsystem that includes a plurality of reaction wheels for controlling attitude of the space vehicle; a propulsion subsystem that includes a plurality of thrusters installed on the zenith side of the bus each having a thrust less than 0.1 Newton, wherein each of the thrusters is coupled to the bus by a two-axis gimbal assembly; and a slew controller coupled to the reaction wheel subsystem and the propulsion subsystem; the slew controller is configured to detect a failure in the reaction wheel subsystem; in response to the failure, the slew controller is configured to:
determine a target attitude for the space vehicle;identify a first thruster and a second thruster of the plurality of thrusters that produce an attitude slew of the space vehicle about an axis toward the target attitude;determine start parameters for the first thruster and the second thruster to initiate the attitude slew about the axis;direct the first thruster at first gimbal angles based on the start parameters so that thruster forces from the first thruster are spaced by a first moment arm from a center of mass of the space vehicle;direct the second thruster at second gimbal angles based on the start parameters so that thruster forces from the second thruster are spaced by a second moment arm from the center of mass;initiate a burn of the first thruster for a first burn duration based on the start parameters; andinitiate a burn of the second thruster for a second burn duration based on the start parameters.