Attenuation of nonlinearly state-dependent uncertainties: robust control design and its application to robotic manipulators

Attenuation of nonlinear uncertainties using robust control is considered. A system under investigation has a linear nominal part and a nonlinear lumped uncertainty. Robust control is designed using Lyapunov direct method. It is shown that the proposed control is continuous, guarantees global stability without knowledge of nonlinear dynamics expect their size bounding function, and ensure a finite upper bound on attenuation performance index over infinite horizon. As an application, it is shown that the proposed control can directly applied to robotic manipulators and many other nonlinear systems.