A robust control of the pressure in a control-cylinder for the variable displacement axial piston pump
ABSTRACT In order to achieve energy-efficient hydraulic systems, an accurate flow rate and pressure required by a load should be supplied to the systems. The discharge flow from the variable displacement swash-plate type axial piston pump is mainly determined by the angle of the swash-plate and it is adjusted by controlling the pressure in the control-cylinder which is a mechanical regulator for the swash-plate. In this paper, a robust pressure control system of the control-cylinder using a direct drive valve is proposed to control the discharge flow from the variable displacement swash-plate type axial piston pump precisely. In order to design a robust pressure control system, a mathematical model of a pressure control system is derived and system parameters are identified by using the signal-compression method. Also, the sliding mode controller is designed based on the identified mathematical model to guarantee the control performance of the pressure control system. Experiments verified the satisfactory performance of the proposed pressure control system that uses a direct drive even with non-linearity and uncertainties such as flow characteristics, unknown discharge coefficient of the valve orifice, variation of the bulk-modulus, leakage and disturbance induced by the pressure fluctuation in the pressure control system.
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ABSTRACT: Experimental verification of a recently developed algorithm, sliding mode control with perturbation estimation (SMCPE), is performed, a two-axes planar SCARA type robot is used as the test platform. The controller is a PC-based microprocessor with transducer and actuator interfaces. The objective of trajectory tracking is achieved by directly controlling the joint torques, despite the modeling deficiencies and unknown disturbances. Two major practical issues are considered. One of them is the measurement noise and the other is the hard/software limitations on the control loop closure speed. Both of these issues affect the parametric selections with the SMCPE algorithm. A sample test result is presented, to compare the performance of SMCPE with the classical SMCIEEE Transactions on Control Systems Technology 02/1996; · 2.52 Impact Factor
- Journal of Dynamic Systems Measurement and Control-transactions of The Asme - J DYN SYST MEAS CONTR. 01/1988; 110(2).
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ABSTRACT: Conventional hydraulic valve-controlled systems that incorporate positive displacement pumps and relief valves have a problem of low energy efficiency. The objective of the research is to implement parallel control of energy-saving control in an electro-hydraulic load-sensing system and velocity control in a hydraulic valve-controlled cylinder system to achieve both high velocity control accuracy and low input power simultaneously. The overall control system is a two-input two-output system. For that, the control strategy of self-organizing fuzzy sliding mode control (SOFSMC) is developed in this study to reduce the fuzzy rule number and to self-organize on-line the fuzzy rules. To compare the energy-saving performance, the velocity control is implemented under three different energy-saving control systems, such as load-sensing control system, constant supply pressure control system and conventional hydraulic system. The parallel control of the velocity control and energy-saving control by the SOFSMC is implemented experimentally.JSME International Journal Series C 01/2003; 46(1):224-231. · 0.12 Impact Factor