Analysis of the dynamic characteristics of pressure sensors using ARX system identification

While most analyses on hydraulic systems focus mainly on their static characteristics, a good understanding of their dynamic characteristics is of equal importance. Using a self-developed square pressure wave generator (SPWG), this study explores the dynamic characteristics of pressure sensors in hydraulic systems using system identification analysis. As a replacement of the traditional directional control valve, the developed SPWG can achieve high-frequency switching by the differential effect between the revolving shaft and fixed ring. The square pressure waves generated serve as inputs into the hydraulic system. With the high-sensitivity piezoelectric pressure sensor as the reference sensor, tests are conducted concurrently using a strain gauge pressure sensor, a piezoelectric pressure sensor and a piezoresistive pressure sensor. The output signals obtained from the pressure sensors are analyzed using the auto-regressive exogenous (ARX) system identification and the common pole–zero principle to reveal important dynamic characteristics including frequency response, transfer function, resonant frequency and damping ratio of the pressure sensors.