Optimization of a Displacement Controlled Linear Hydraulic Actuator Utilizing Mechatronics Approach

Abstract

Displacement controlled hydraulic systems present an effective approach to improve the efficiency of fluid power systems. This approach prevents fluid throttling, which is a major case of power dissipation, by minimizing the use of control valves in circuits. This approach could play an important role in industry and mobile hydraulics in the near future to overcome the problems associated with fossil fuel especially pollution. The work presented in this thesis describes developing, measuring, modeling, and controlling of a displacement controlled hydraulic linear actuator. A practical hydraulic circuit is developed with a small number of common components, and is suitable for many practical applications. The linear actuator is controlled by changing the swash plate angle of the variable displacement pump which in turn changes the pump delivery. A complete test rig with all necessary instrumentations is designed to measure, monitor, record, and control the hydraulic circuit using mechatronics principals (mechanical, electrical/electronic, and information technology). Model identification is conducted to find the transfer function based on practical measurements. The calculated data were compared with measured results obtained through an extensive experimental program which proved the validity of the model. Two types of controllers are selected and many input signals with different shapes are fed to the system. Good tracking performance is observed between the desired, and the output signals. Experiments are done in different loads to simulate practical conditions and all the data are displayed on line during experiments. Two types of software are used, the first one is made by Visual Basic/Labview packages and the other is done by Matlab Real Time Windows Target toolbox. This work