Control Synthesis Methodology Related to an Advanced Nonlinear Electrohydraulic Servo System

The obtaining of control law for an advanced four-dimensional, nonlinear electrohydraulic servo mathematical model is the main contribution of the paper. This control law ensures the asymptotic stability of references tracking by constructing a Control Lyapunov Function (CLF) on the errors concerning the state variables and theirs desired values. An approach based on partitioning the state system into two subsystems − a first one internal stable, and a second one taken as framework of control synthesis − was developed; this is another main contribution of the present paper. The paper's interest derives also from illustrating the key idea of CLFs synthesis by using of celebrated Barbalat's Lemma. Numerical simulations were reported from viewpoint of assessing the servo time constant performance.