Robust Nonlinear Attitude Tracking for Rigid Spacecraft with Constrained Control Inputs

A robust nonlinear attitude tracking controller for rigid spacecraft subject to constrained control inputs and modeling uncertainties is proposed in this paper. Control input constraint in the controller is guaranteed by using continuously differentially hyperbolic tangent function and bounded properties of attitude parameters. The spacecraft inertia parametric uncertainties and bounded external disturbances are attenuated by bounded robust control term. It is proved via Lyapunov method that attitude tracking errors in closed-loop system are all uniformly ultimately bounded. The numerical simulation is presented to demonstrate the controller performance.