Identification of electro-hydraulic load-sensing servo system
2021
Mitov, A., Technical Univ. of Sofia (Bulgaria) | Slavov, T., Technical Univ. of Sofia (Bulgaria) | Kralev, J., Technical Univ. of Sofia (Bulgaria) | Angelov, I., Technical Univ. of Sofia (Bulgaria)
The paper presents the results of the identification procedure for obtaining a model of an electrohydraulic load-sensing servo position system for power steering of mobile machinery. The studied system consists of an axial-piston variable displacement pump that supplies the load-sensing electro-hydraulic power steering system. The pump is equipped with a hydro-mechanical pressure controller type DR, which makes it possible to realize a meter-in flow control circuit with the load-sensing function. When the external resistance force acting on the cylinder piston increases, the pump controller limits the displacement volume, and hence the flow rate supplied to the system. The purpose of the identification is to reach a linear state-space model that accurately describes the dynamic behaviour of the system. The system is represented with one input and two outputs. The output signals are measurable variables: the spool position in the proportional valve and the piston position of the servo cylinder. To evaluate the parameters of the model, open-loop experiments were performed with the studied system, which was realized on a laboratory test rig. The input signal for identification experiment is a random binary signal (RBS) to achieve good excitation of the plant. Validation of the model obtained has been carried out based on independent data-set. The aim of the present work is to reach a model that is suitable for the design of embedded controllers for the electro-hydraulic load-sensing servo systems.
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