Applicable to Cat 330D/336D oil pressure sensor EX2CP54-12

The pressure sensor has high precision and reasonable error, and the error compensation of the pressure sensor is the key to its application. The pressure sensor mainly includes offset error, sensitivity error, linearity error and hysteresis error. This paper will introduce the mechanism of these four errors and their influence on the test results, and at the same time introduce the pressure calibration method and application examples to improve the measurement accuracy.

At present, there are many kinds of sensors on the market, which enables design engineers to choose the pressure sensors needed by the system. These sensors include not only the most basic converters, but also more complex high-integration sensors with on-chip circuits. Because of these differences, the design engineer must compensate the measurement error of the pressure sensor as much as possible, which is an important step to ensure that the sensor meets the design and application requirements. In some cases, compensation can also improve the overall performance of the sensor in the application.

Offset, range calibration and temperature compensation can all be realized by thin film resistor network, which is corrected by laser in the packaging process.

The sensor is usually used in combination with a microcontroller, and the embedded software of the microcontroller itself establishes the mathematical model of the sensor. After the microcontroller reads the output voltage, the model can convert the voltage into the pressure measurement value through the conversion of the analog-to-digital converter.

The simplest mathematical model of the sensor is the transfer function. The model can be optimized in the whole calibration process, and the maturity of the model will increase with the increase of calibration points.

From the perspective of metrology, measurement error has a very strict definition: it represents the difference between the measured pressure and the actual pressure. However, the actual pressure can not be obtained directly, but it can be estimated by adopting appropriate pressure standards. Metrologists usually use instruments whose accuracy is at least 10 times higher than that of the measured equipment as the measurement standards.

Because the uncalibrated system can only use typical sensitivity and offset values to convert the output voltage into pressure error.