Feedback linearization control for electro-hydraulic servo system based on nonlinear disturbance observer

Feedback linearization control based on nonlinear disturbance observer is investigated for an electro-hydraulic servo system with external disturbances and system uncertainties. Firstly, a mathematical model of electro-hydraulic servo system is developed and a single input-output affine system form is obtained. Then the technique, based on the feedback linearization, is employed to transform the nonlinear system to an equivalent linear form, the controller of which is designed by the pole placement algorithm. Finally, a nonlinear disturbance observer is developed, which is a useful method for improving the system robustness and reducing the effects of disturbances and system uncertainties. The simulation example shows that the proposed strategy can suppress parameter variation and exterior disturbance as well as obtaining good dynamic response.