DIGITAL SIMULATION OF HYDRAULIC POSITIONAL SERVOMECHANISM CONSIDERING THE HYSTERESIS BACKLASH AND THE HYDRAULIC FLUID COMPRESSIBILITY

Abstract

In hydraulic positional servomechanism the hydraulic fluid compressibility variation due to air bubbles, namely the increase of air volume ratio in oil gives rise to a negative fact in the behavior of the system. The presence of hysteresis backlash brings about the limit cycle in the second-order system, but for a third-order system the backlash ameliorates the condition of system stability, in spite of controlling accuracy. Besides, in this case limit cycle does not occur. The present paper deals with the above problems and gives some interesting conclusions which can be used in engineering practice.