Electrohydraulic System Design and Control

This paper deals with the position control of a hydraulic actuator regulated by a proportional directional control valve. The control algorithms based on the proportional-derivative controller have been applied to a specially designed two-channel electro-hydraulic servo system, which has the capacity to experimentally simulate common circumstances of a typical fluid power circuit. The first system includes the positioning hydraulic cylinder controlled using the proportional valve, a displacement measuring system and a control device in a closed-loop system. In order to add further realism in the control system a second double acting hydraulic cylinder is used to generate the disturbing load. The effectiveness of the proposed control algorithms is demonstrated for both moving directions as well as for both unloaded and loaded system. The results of the experimental testing have shown that for some industrial applications a relatively good motion control performances can be achieved using a proportional valve as a control component with a simple control algorithm, but for the case of changing operating conditions, some advanced control approaches should be used.