Recent research projects in hydraulics

Abstract

In this article, the IHP's research activities in four different fields are described. An adaptive control will be treated of which is capable of changing the controller parameters of a state controller with the sudden changes in the open-loop behaviour by means of a quick on-line-identification. Furthermore, two new circuit concepts for the saving of energy will be treated of. Electrohydraulic load-sensing serves to supply multiple consumers from one pressure sources. If only one consumer is fed by a variable pump, the control of a differential piston through a hydrotransformer and a pressure-ratio-valve serves to improve the static and dynamic transfer function of the system. The investigation of the contamination sensitivity of pressurecontrolled variable pumps and the analysis of the resulting increase in the leakage flow serves to increase the wear resistance and the lifetime of the components involved.