Attitude controller design for the advanced upper stage

This paper describes a detailed design method and performance of the digital autopilot for attitude control of the advanced upper stage. The reaction control system (RCS) of the attitude control system (ACS) is used for attitude control, reignition operations and large angle attitude maneuvers. The RCS control laws employ parabolic switch curves in their phase plane logic to obtain fast response with a minimum of firings. The design synthesis which considered the rigid-body stability is presented. The performance of the upper stage control system is summarized using Matlab/Simulink simulation.