Design and implementation of 60MPa high-precision hydraulic calibration system

In the industrial production area, pressure is one of the important measuring parameters. To ensure the measurement accuracy of pressure sensors, it is necessary to carry out a regular calibration on them. In order to obtain the standard value of pressure accurately, rapidly and continuously, a high-precision hydraulic calibration system based on DSP and FPGA was designed. The pressure signal of hydraulic oil was real-time acquired by a high-precision piezoresistive pressure sensor, then the voltage out-putted through the electrical bridge of the piezoresistive pressure sensor was converted to digital signal by 24-bit high-precision AD, after calculating the value of pressure, according to improved PID control algorithm designed for this hydraulic calibration system which realized incremental PID control, control output calculated by DSP was transmitted to FPGA to control the rotating speed of stepping motor to change the displacement of cylinder rod of helicoidal pump, thus the pressure fine regulating was realized. The control process curves real-time acquired by the system show, during testing process of 3 groups of calibration pressure (10 MPa, 30 MPa, 60 MPa), the system was competent for calibrating pressure within the set time ruled by calibration regulation, and steadied the pressure in plusmn0.02% accurate range.