SMOOTH SLIDING-MODE CONTROL FOR SPACECRAFT ATTITUDE TRACKING MANEUVERS

A sliding-mode control (SMC) algorithm is derived and applied to quaternion-based spacecraft attitude tracking maneuvers. Based on some interesting properties related to the spacecraft model, a class of linear sliding manifolds is selected. Significantly, a Lyapunov function is introduced in the SMC design, which can avoid the inverse of the inertia matrix and thus simplify the controller design. To improve the transient response before reaching the sliding manifold, the smoothing model-reference sliding-mode control (SMRSMC) is further developed, which requires well-estimated initial conditions. Simulation results are included to demonstrate the usefulness of the SMRSMC method.