Mode-Scheduling Steering Law Design for Variable Speed Control Moment Gyroscope

Variable speed control moment gyroscope(VSCMG) is a single-gimbal control moment gyroscope(CMG) with an adjustable speed of the wheel,and has three work modes,i.e.,CMG mode,reaction wheel(RW) mode,and VSCMG mode.In order to command VSCMGs to work in suitable mode,a mode-scheduling steering law is presented.When CMGs are far from the singularities,the CMG mode can be used to generate large output torque.Otherwise,VSCMG mode can be used to escape from the singularities with the help of RWs.When accurate control torque is needed,RW mode can be used.This algorithm has obvious physical meanings and is easy to realize because the pseudo-inverse problem of a 3×2N matrix is decomposed into the pseudo-inverse problem of two 3×N matrices.Simulation results for a certain VSCMG system demonstrate that the steering law presented above is feasible.