Adaptive steering law design for single gimbal control moment gyroscopes with parameter uncertainty

Physical parameters of single gimbal control moment gyroscopes (SGCMGs) are often assumed to be known exactly when steering law is designed by taking gimbal servo characteristics into account. However, exact physical parameters are not available due to system complexity. In order to reduce the effect of parameter uncertainty on steering performance, an adaptive steering law is presented. This steering law can estimate physical parameters on line and calculate the control torque for each SGCMG gimbal directly according to the momentum (or torque) command. Since it has no arithmetic singularity, steering error can be made converge to zero asympotically when kinematic singularities do not appear. Meanwhile, the steering law is guaranteed to have excellent adaptability to parameter variations. Comparatively, it has a simple form and is easy to be implemented. Simulation results of a SGCMG system indicate that steering law stated above is feasible.