The Optimal Relationship between Load Structure and Servo Drive in a Higher-Order Servo System : The Effect of the Natural Frequency Ratio of Load Structure to Servo Drive on the Degree of Stability of a Servo System

Abstract

In this study, a hydraulic servo system is considered to be theoretically expressed in the fifth-order, and the gain margin of the fifth-order hydraulic servo system was calculated in terms of the natural frequency ratio of load to servo drive with various values of load-damping ratios and inertia ratios of load to servo drive. The experiments were conducted with various values of load stiffness and inertia of the hydraulic servo system to compare with the fifth-order theoretical model. It was found that the theoretical results showed good agreement with those of the experiments. It was also found from the theoretical model that the natural frequency ratio of load to servo drive must be greater than unity for a servo system to be stable. The relationship between the natural frequency ratio and the inertia ratio for a servo system to have optimal response was qualitatively clarified.