Automatic Compensation And Calibration System For Pressure Sensor Based On Virtual Instrument Technology

The fundamental of diffused silicon pressure sensor is piezoresistive effect. This type of pressure sensor has good performance in sensitivity and linearity. But because the IC manufacturing technology and temperature characteristic property of Semiconductor materials, this pressure sensor has problems such as zero point error, sensitivity error and thermal drift, and the error values of different sensors are different. Sensors are required to calibrate their errors and compensate their thermal drifts.To solve these problems, this paper derived a formula relating sensor module's output, pressure and temperature, presented a method for improving the performance of pressure sensor and a compensation and calibration system based on virtual instrument technology. The system can automatically compensate and calibrate the pressure sensor's zero point error, sensitivity error and thermal drift. With the virtual technology and LabVIEW language program development environment, this paper illuminates the functions about each part of this system and explain how to achieve the functions. The system consists of the sensor module, multiplexer, programmable temperature experimental box, programmable supply source, programmable pressure controller, PCI6221 data acquire card, PCI-GPIB card and PC workstation. Experiment results show that this system can greatly improve the accuracy of the sensor. After the compensation and calibration, the thermal drift of sensor falls from 0.151% to 0.0238%, the zero point error falls form 3.98% to 1% and the sensitivity error falls from 6.23% to 0.52%. It is high efficient in compensating and calibrating the pressure sensor, and is suitable for calibration large number of pressure sensors.