First, the rationale.
Thin-film pressure sensors work on the strain principle, and the pressure value is calculated by measuring the deformation of the film. When the film is subjected to external pressure, it will be deformed, and the magnitude of the deformation is proportional to the pressure. By measuring this deformation, the corresponding pressure value can be calculated.
2. Accuracy calculation method.
1.Linearity error.
Linearity error is a description of the deviation between the output of a sensor and the theoretical output. It is a percentage representation of the sensor's maximum error over the entire measuring range versus the full-scale output. The calculation formula is as follows:
Linearity Error = (Actual Output Maximum - Theoretical Output Maximum) 100% of Theoretical Output Maximum
Among them, the maximum value of actual output refers to the maximum value of the actual output of the sensor in the whole range; The maximum theoretical output is the theoretical output value derived from the sensor specification or design parameters.
2.Non-linearity error.
The nonlinearity error describes how much the actual output of the sensor deviates from the theoretical straight line. The calculation formula is as follows:
Nonlinearity Error = Range Output under Root Number.
Among them, the x-axis error and y-axis error represent the deviation of the actual output of the sensor in the x-axis and y-axis directions, respectively.
3.Repeatability error.
Repeatability error describes the maximum deviation between multiple outputs of a sensor caused by the same input under the same conditions. The calculation formula is as follows:
Repeatability Error = Maximum Output Deviation Measuring Output.
The maximum output deviation is the difference between the maximum and minimum output values measured multiple times under the same conditions.
4.Hysteresis error.
The hysteresis error describes the maximum deviation between the forward and reverse outputs of the sensor at the same pressure input. The calculation formula is as follows:
Hysteresis error = (forward output - reverse output) 100% of the range output
Among them, the forward output refers to the output value of the sensor when the pressure increases; The reverse output is the output value of the sensor when the pressure decreases.
5.Temperature error.
Temperature error is a sensor error due to a change in temperature. It can be reduced by calibrating the sensor at a constant temperature. If the effect of temperature cannot be eliminated, the range of temperature error can be calculated.
3. Measures to improve accuracy.
1.High-precision materials and manufacturing processes are used to reduce initial errors and linearity errors.
2.Regular calibration is carried out during use to reduce errors caused by wear, aging and other factors.
3.Choose the right signal processing circuits and algorithms to reduce the impact of noise and interference on accuracy.
4.The sensor is temperature compensated to reduce the effect of temperature on accuracy.
5.In the design stage, the first analysis and experimental verification are carried out to optimize the sensor structure and parameters to improve its accuracy and stability.
6.Pay attention to avoid overload and impact during use to prevent irreversible damage to the sensor.