Abstract
Theoretical analysis in this paper indicates that the accuracy of a silicon piezoresistive pressure sensor is mainly affected by thermal drift, and varies nonlinearly with the temperature. Here, a smart temperature compensation system to reduce its effect on accuracy is proposed. Firstly, an effective conditioning circuit for signal processing and data acquisition is designed. The hardware to implement the system is fabricated. Then, a program is developed on LabVIEW which incorporates an extreme learning machine (ELM) as the calibration algorithm for the pressure drift. The implementation of the algorithm was ported to a micro-control unit (MCU) after calibration in the computer. Practical pressure measurement experiments are carried out to verify the system's performance. The temperature compensation is solved in the interval from −40 to 85 °C. The compensated sensor is aimed at providing pressure measurement in oil-gas pipelines. Compared with other algorithms, ELM acquires higher accuracy and is more suitable for batch compensation because of its higher generalization and faster learning speed. The accuracy, linearity, zero temperature coefficient and sensitivity temperature coefficient of the tested sensor are 2.57% FS, 2.49% FS, 8.1 × 10−5/°C and 29.5 × 10−5/°C before compensation, and are improved to 0.13%FS, 0.15%FS, 1.17 × 10−5/°C and 2.1 × 10−5/°C respectively, after compensation. The experimental results demonstrate that the proposed system is valid for the temperature compensation and high accuracy requirement of the sensor.
Highlights
Pressure is an important monitored parameter in industrial fields for process control and safety, so there is a massive demand for suitable pressure sensors
The pressure error in percentage between linear fit and actual data is shown in Figure 8, which shows a poor linearity of 2.5% FS which is mainly caused by the thermal drift
A smart temperature compensation system is presented in this study
Summary
Pressure is an important monitored parameter in industrial fields for process control and safety, so there is a massive demand for suitable pressure sensors. Because of their good accuracy, high sensitivity and excellent linearity, silicon piezoresistive MEMS pressure sensors are one of most reported and developed micromachined devices [1], and are widely used in various systems like automobiles, biomedical and process control systems for their low cost, small size and mature fabrication technology [2]. Thermal drift caused by the inherent cross temperature sensitivity of silicon sensors [3] has a significant impact on the sensor accuracy, sensitivity and linearity. Some fabrication processes and novel designs have been used for temperature compensation
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