Spacecraft attitude tracking based on almost disturbance decoupling

The problem of spacecraft attitude tracking under bounded disturbances is addressed based on almost disturbance decoupling. The modified Rodrigues Parameter (MRP) is adopted as attitude representation. A feedback linearization control scheme based on differential geometry for nonlinear systems is used to design the controller, by which the tracking and the almost disturbance decoupling performances can be easily achieved. Lyapunov theory is employed to prove that the influence of disturbances on the L₂ norm of output tracking error can be arbitrarily attenuated by changing some adjustable parameters in the controller, and that spacecraft attitude tracking system is globally uniformly ultimately bounded stable. Simulation results demonstrate the effectiveness and feasibility of the proposed control scheme.