Modeling and experimental evaluation of variable speed pump and valve controlled hydraulic servo drives

Çalışkan, Hakan
In this thesis study, a valveless hydraulic servo system controlled by two pumps is investigated and its performance characteristics are compared with a conventional valve controlled system both experimentally and analytically. The two control techniques are applied on the position control of a single rod linear actuator. In the valve controlled system, the flow rate through the actuator is regulated with a servovalve; whereas in the pump controlled system, two variable speed pumps driven by servomotors regulate the flow rate according to the needs of the system, thus eliminating the valve losses. To understand the dynamic behaviors of two systems, the order of the differential equations defining the system dynamics of the both systems are reduced by using the fact that the dynamic pressure changes in the hydraulic cylinder chambers become linearly dependent on leakage coefficients and cylinder chamber volumes above and below some prescribed cut off frequencies. Thus the open loop speed response of the pump controlled and valve controlled systems are defined by v second order transfer functions. The two systems are modeled in MATLAB Simulink environment and the assumptions are validated. For the position control of the single rod hydraulic actuator, a linear state feedback control scheme is applied. Its state feedback gains are determined by using the linear and linearized reduced order dynamic system equations. A linear Kalman filter for pump controlled system and an unscented Kalman filter for valve controlled system are designed for estimation and filtering purposes. The dynamic performances of both systems are investigated on an experimental test set up developed by conducting open loop and closed loop frequency response and step response tests. MATLAB Real Time Windows Target (RTWT) module is used in the tests for application purposes.


Dynamic modelling of a backhoe-loader
Kılıç, Boran; Balkan, Raif Tuna; Department of Mechanical Engineering (2009)
The aim of this study is to develop a dynamic model of the loader system of a backhoe-loader. Rigid bodies and joints in the loader mechanism and loader hydraulic system components are modelled and analyzed in the same environment using the physical modelling toolboxes inside the commercially available simulation software, MATLAB/Simulink. Interaction between the bodies and response of the hydraulic system are obtained by co-operating the mechanical and hydraulic analyses. System variables such as pressure,...
Design and performance analysis of a pump-turbine system using computational fluid dynamics
Yıldız, Mehmet; Albayrak, Kahraman; Çelebioğlu, Kutay; Department of Mechanical Engineering (2011)
In this thesis, a parametric methodology is investigated to design a Pump-Turbine system using Computational Fluid Dynamics ( CFD ). The parts of Pump-Turbine are created parametrically according to the experience curves and theoretical design methods. Then, these parts are modified to obtain 500 kW turbine working as a pump with 28.15 meters head. The final design of Pump-Turbine parts are obtained by adjusting parameters according to the results of the CFD simulations. The designed parts of the Pump-Turbi...
Acoustical analysis of exhaust mufflers for earth-moving machinery
Olğar, Tarık; Çalışkan, Mehmet; Department of Mechanical Engineering (2009)
This study concerns with acoustical analysis of exhaust mufflers for earth-moving machinery. The study arises from the fact that there is a need for further noise reduction emitted by earth-moving machinery produced by Hidromek Inc. in order to be on the safe side of the limits stated in European Noise Directive 2000/14/EC. The acoustical performance of the muffler is investigated both experimental and numerical means. A three-dimensional finite element method is performed to calculate the transmission loss...
Development of an electrical machines analysis and optimum design software package
Göynük, Yılmaz; Ertan, Hulusi Bülent; Department of Electrical and Electronics Engineering (2008)
In this study, three different programs are developed for the analysis of the three-phase induction motor, single-phase capacitor type induction motor and switched reluctance motor. The programs are developed by using Pascal and C++ programming languages. In the performance calculations of motors, analytical methods are used and these methods are tested for accuracy. These programs have also capabilities to design an optimum motor, which meets a set of performance, material and manufacturing constraints whi...
Dynamic modeling of an excavator during digging and simulating the motion
Özünlü, Özcan Mutlu; Söylemez, Eres; Department of Mechanical Engineering (2009)
The aim of this study is to perform the dynamic force analysis of a 3-degrees-of-freedom excavator during digging the soil and to simulate the motion on computer screen. Standard load calculations are done statically, therefore the effects of forces changing with time on the system cannot be observed. The dynamic analysis method used in the thesis is Recursive Newton – Euler Method and the numerical analysis method for simulation is 4th Order Runge – Kutta Method. After this study, the effects of sudden vel...
Citation Formats
H. Çalışkan, “Modeling and experimental evaluation of variable speed pump and valve controlled hydraulic servo drives,” M.S. - Master of Science, Middle East Technical University, 2009.