High Precision Position Control of Electro-Hydraulic Servo System Based on Feed-Forward Compensation

The study is focused on an electro-hydraulic servo system which is a position control system. It is a non-minimum phase system when it was discretized with a certain sample time. To improve its tracking performance and extend its bandwidth, based on invariance principle, feed-forward compensation is developed by pole-zero placement theory for the system. The task is accomplished by transforming instable zero of the system into pole of the fitted closed-loop transfer function, forming the zero of feed-forward compensator and completing the compensation of the instable zero for the closed-loop system. The simulation and experimental results show the validity of the analytical results and the ability of the proposed algorithm to efficiently improve the system tracking performance and greatly extend system bandwidth.