Study of Spacecraft Attitude Tracking Using Variable Speed Control Moment Gyros

The attitude tracking problem of spacecraft using VSCMG(Variable Speed Control Moment Gyros) as actuators is studied.The attitude dynamic model of spacecraft with VSCMG attached is built,and an angular velocity filter state governed through the stable liner differential equation is introduced.Based on the Lyapunov stability theory,the adaptive control law is designed. In order to determine the attitude control vector of the VSCMG,a weighted minimum norm solution is applied.A new singularity measurement is constructed which describes the configuration singularity. The null motion of the VSCMG,is designed using the gradient method based on the singularity measurement,and is employed to avoid the singularity,as well as to make the rotary speed of rotors to tend to their expected values.In the end,the VSCMG with four-pyramid configuration is applied in the simulation,and the simulation results validate the feasibility and efficiency of the VSCMG systems on the spacecraft attitude tracking.