Robustness analysis of PDF control for elect-hydraulic servo system

The robustness of a controller can decide the quality of the overall system, especially when high precision and high frequency response are required. Commonly control systems are built upon simplified mathematical models and those nonlinear or less influential factors are neglected. However, they exist as noises and external load making the system uncertain. This paper focuses on the robustness of pseudo-derivative feedback (PDF) controlled hydraulic servo system. two criteria are set for analyzing and comparing its performance with that of the PID controlled system. Both theoretical and simulation results are presented to show how PDF controller reacts to system structure and parameter change. The results clearly shown the insensitivity of PDF controller in both time and frequency domain responses to system changes and also prove its robustness.