The system bandwidth analysis in electro-hydraulic servo system with PDF control

This paper focuses on employing PDF (pseudo derivative feedback control) in electro-hydraulic servo system; especially in reason analysis of improving system bandwidth, approximate calculation for system bandwidth and design method of maximum bandwidth in PDF control. It indicates the main reason extending system bandwidth is due to the improvement of system stability margin by PDF control strategy; an approximate expression between real system bandwidth and controller coefficients is derived and the design method based on maximum system bandwidth of PDF control is given. It was proven that value of real system bandwidth is approximately 0.73 times as much as that value of the system theory design bandwidth by system simulation and experiment. The study and experiment result show that the PDF control not only extends the system bandwidth, but also provides excellent control performance on contrast with PLD control strategy in hydraulic servo position system.