Robust model following controller applied to positioning of pneumatic control valve with friction

Addresses the robust model following control problem for a class of uncertain nonlinear systems with friction. A nonlinear controller is developed where Lyapunov´s direct method is used to show the robust global convergence of the error dynamics between the reference model and the uncertain system. To design the control law, exact friction force is not required, but only the upper bound for the level. An application of the proposed controller to a pneumatic control valve with static friction is shown and the experimental results are given