In some cases, compensation can also improve the overall performance of sensors in applications. Reasonable error compensation of pressure sensors is the key to their application. Pressure sensors mainly have offset error, sensitivity error, linear error, and hysteresis error. Currently, there are a wide variety of sensor types on the market, which allows design engineers to choose the pressure sensors required for the system. These sensors include both basic transformers and more complex high integration sensors with on-chip circuits. Due to these differences, design engineers must strive to compensate for measurement errors in pressure sensors, which is an important step in ensuring that the sensors meet design and application requirements. The following introduces the mechanisms of four types of errors and their impact on test results, as well as pressure calibration methods and application examples to improve measurement accuracy.
Taking pressure sensors as an example, the concepts involved are applicable to the design and application of various pressure sensors.
A pressure sensor is a single-chip piezoresistive device that has three types:
1. Basic or uncompensated calibration;
2. Calibrated and temperature compensated;
3. There are calibration, compensation, and amplification.
Offset, range calibration, and temperature compensation can all be achieved through thin film resistor networks, which use laser correction during the packaging process.
This sensor is usually used in conjunction 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 a pressure measurement value through the transformation of the analog-to-digital converter.
The simple mathematical model of a sensor is the transfer function. The model can be optimized throughout the entire calibration process, and its maturity will increase with the increase of calibration points.
From a metrological perspective, measurement error has a fairly strict definition: it characterizes the difference between measured pressure and actual pressure. However, it is usually not possible to directly obtain the actual pressure, but it can be estimated by using appropriate pressure standards. Metrologists usually use instruments with an accuracy at least 10 times higher than the measured equipment as measurement standards.
Due to the fact that uncalibrated systems can only convert output voltage to pressure using typical sensitivity and offset values, the measured pressure will result in errors in the weighing sensor.