Disturbance Observer based Backstepping for Position Control of Electro-hydraulic Systems

Abstract

We propose a disturbance observer (DOB) based backstepping control which improves the position tracking performance in the presence of both friction and load force in an electro-hydraulic systems. The DOB is designed to estimate the disturbance including friction and load force, while avoiding amplification of the measurement noise. We use an auxiliary state variable to avoid the use of the derivative of the measured signal. This results in the avoidance of the amplification of the measurement noise. For position tracking with compensation of disturbances, a backstepping controller is design. The backstepping controller guarantees the ultimate boundedness of the tracking error in the presence of both friction and load force. The closed-loop stability is proven using Lyapunov’s theory.