Research on feed-forward PIDD2 control for hydraulic continuous rotation motor electro-hydraulic servo system with long pipeline

In the applications of hydraulic continuous rotation motors used in the valve control electro-hydraulic servo system, the long distance between the electro-hydraulic servo valves and the hydraulic motors causes long pipeline effect, which results in a decreased natural frequency and delayed dynamic response of the hydraulic system. This paper presents the mathematical model and characteristic analysis of the dynamic characteristic of the system, as well as the long pipeline effect. A second order differential term is added to the traditional PID control method to decrease/eliminate the load torque fluctuation of the hydraulic motor, which is denoted by PIDD
²
. Based on the mathematical model and analysis of the system, a control strategy combining PIDD
²
and feed-forward of velocity and acceleration is proposed. Both the traditional PID control method and the above-mentioned control method for the electro-hydraulic servo system were simulated in the simulation environment AMESim. The experiment results show that the PIDD
²
control with feed-forward of velocity and acceleration will reduce the time delay and stability margin decline of the system response to some extent, and improve the dynamic performance of the system.