The Effect of Load Stiffness and Inertia on the Frequency Response of a Higher Order Servo System

Abstract

This study considers a fifth order theoretical model for an electrohydraulic servo system. The experiments were conducted with various values of load stiffness and inertia of the electrohydraulic servo system to compare with the fifth-order theoretical model. It was found that the theoretical results showed good agreement with the experiments. The load stiffness was found to give little influence on the frequency response at the frequency where the phase lag is less than 180 degrees. The higher stiffness ratio gives more damping to the servo system at the frequency where the phase lag is over 180 degrees: however, its influence on the response becomes less when the stiffness ratio exeeds 2, 6. The higher inertia ratio of the load to the servo drive gives more damping as well as slower speed of response.