Design of Nonlinear Controllers for an Electrohydraulic Velocity Servo-System

This paper addresses the control problem of an electrohydraulic velocity servo-system (EHVSS). Two control schemes are proposed for the stabilization of the system. The first scheme is a dynamic sliding mode controller (SMC), and the second scheme is a linear quadratic regulator-like control law which is based on the state-dependent Riccati equation (SDRE) approach. When applying the SMC technique, the mathematical model of the system is transformed into the controller canonical form via a nonlinear transformation to facilitate the control design. When applying the SDRE technique, the EHVSS dynamics are parameterized to produce a system with a state-dependent coefficient matrix; then the linear quadratic controller technique is carried out to produce a sub-optimal state feedback control law that regulates the system trajectories to their desired values. The effectiveness of the proposed controllers is validated through computer simulations.