Gimbaled thruster control system

Abstract

A method for controlling spacecraft velocity. A thruster torque gimbal angle command is calculated to provide a desired thruster torque demand command including a desired momentum adjust torque and a desired attitude control torque. A velocity change error between a commanded velocity change and an actual velocity change, a commanded force vector based on the error to cause the actual velocity change to approach a commanded velocity change, and force gimbal angle commands and force thrust commands to achieve the commanded force vector are calculated; and/or an error between gimbal angles and thrust levels and reference gimbal angles and thrust levels, reference gimbal angle commands and reference thrust commands to drive actual gimbal angles and thrust levels toward reference gimbal angles and reference thrust levels are calculated. A total gimbal angle command is calculated by adding the torque gimbal command with at least one of the force gimbal angle command and the reference gimbal angle command. A total thrust command is calculated including at least one of the force thrust command and the reference thrust command. The thrusters are gimbaled to the total gimbal angle command and a level of thrust produced by the thrusters is varied according to the total thrust command.