Spacecraft Adaptive Sliding Mode Attitude Tracking Control using DGCMG

This investigation is concerned with the non-linear multi-in-multi-out tracking control of a spacecraft with Double-gimbaled control moment gyros as actuators. An attitude dynamic model of rigid spacecraft with DGCMG and a kinematics model in terms of Modified Rodriguez parameters are given for the controller development. Then the control objective and system uncertainties in tracking problem are analyzed considering the major elements which work on the control performance such as moment of inertia change, wheel speed drift and external torque. A adaptive sliding mode controller is designed and is proved stable later in which the sliding mode control are used to compensate external torque and un-modeled dynamics while the adaptive parameters are used to estimate inertia and wheel speed on line. And a steering law of parallel mounted DGCMG is illuminated. Finally Monte Carlo simulation is carried out to prove the effectiveness of the controller.