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The main part of the hydraulic circuit of the hydraulic stabilization platform (HSP) is the electro-hydraulic servo valve (EHSV), which is very expensive due to its manufacturing requirements, so the proper selection for the geometrical configuration of electro hydraulic servo valve (EHSV) and maintaining the system stability are the main goal for establishing HSP. Also improving the performance of (HSP) to achieve the position tracking in two degrees of freedom (2DOF) based on modifying the different parameters of the hydraulic circuit (actuator size - hydraulic servo actuator geometric configuration - different load on the platform) to achieve the best performance. The system offers a proposal for an upper stabilized platform with moving lower base to be used with ships to achieve a stabilization condition for many purposes such as radar. MATLAB Simulink and Simscape-multibody has been used in modeling the system. Changing the different parameters in the program block library input data (orifice area and spool slot width) to achieve best configuration of the system to be stabilized is discussed. The results show that using 0.6 mm² servo valve orifice area and more raises the system pressure and has a bad effect on system stability, also using 4 mm servo valve slot width has more fluctuation in the system pressure in the transient time than using (3, 2 or 1)mm slot width until approaching stable condition but has a better effect on system stability in the running (operation) time.

This paper presents a mathematical model of electro hydraulic servo system (EHS) using two-stage electrohydraulic servovalve (EHSV), by the aim of Matlab-simulink-simscape multibody to predict the flow characteristics (pressure/flow rate) with changing the parametric configuration of (EHSV), these parameters could be used to estimate the error at different operating conditions. It includes establishing mathematical model, controller model and validating the performance of the (EHSV) by experimental result of published work using the data of servovalve labelled B.31.210.12.1000.U2V (mechanical feedback) manufactured by PPT - Trstenik. The effect of changing servovalve orifice diameter (0.25, 0.30, and 0.35) mm, show that increasing the orifice diameter of the servovalve leads to increase the transient time but decrease the system overshoot. The pressure behaviour is plotted and shows that increasing the orifice diameter leads to increasing the pressure inside the system as to reach the relieve pressure.

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