Patent ID: 6481672
Filing Date: 2002-11-19
Classification: B64G

Abstract:
A method for controlling spacecraft velocity, the method comprising:A) calculating thruster torque gimbal angle command to provide a desired thruster torque demand command including a desired momentum adjust torque and a desired attitude control torque; B) performing at least one of 1) calculating a velocity change error between a commanded velocity change and an actual velocity change, calculating a commanded force vector based on the error to cause the actual velocity change to approach a commanded velocity change, and calculating force gimbal angle commands and force thrust commands to achieve the commanded force vector, and 2) calculating an error between gimbal angles and thrust levels and reference gimbal angles and thrust levels, calculating reference gimbal angle commands and reference thrust commands to drive actual gimbal angles and thrust levels toward reference gimbal angles and reference thrust levels; C) calculating a total gimbal angle command by adding the torque gimbal command with at least one of the force gimbal angle command and the reference gimbal angle command; D) calculating a total thrust command comprising at least one of the force thrust command and the reference thrust command; and E) gimbaling the thrusters to the total gimbal angle command and varying a level of thrust produced by the thrusters according to the total thrust command.