Attitude control of rigid body via input-to-state stability and small-gain theorem

A robust nonlinear attitude control approach is proposed based on input-to-state stability (ISS) and small-gain theorem. The angle rate command profiles are designed via ISS, which provide desired angle velocities to achieve robust tracking of the expectable attitude angles. Then, an attitude control law is designed by utilizing small-gain theorem to enforce the commands and guarantee that the closed-loop system is input-to-state practically stable (ISpS) with respect to the bounded uncertainties and unknown disturbances. Finally, the algorithm is tested using computer simulations.