Calculating Normalized Error Scores for Multi Facility Calibration Variance Analysis
Calculating normalized error scores isolates facility bias from measurement noise by evaluating raw offsets against combined expanded uncertainties.
Temperature Coefficient Cross Sensitivity
Parameter Interdependence
Simultaneous dependence of a sensor’s output parameter on both temperature and an additional environmental factor complicates the isolation of the primary measurement variable. In high-performance pressure sensors, temperature coefficient cross sensitivity alters the sensor’s sensitivity to pressure as the temperature fluctuates. This interaction requires multi-dimensional calibration matrices to separate the thermal effects from the pressure changes.
The effect ceases to be a significant error source when the sensor is operated within a narrow, actively controlled thermal chamber.
Calibration Modeling
Sensor designs often use silicon piezoresistors that change resistance with applied pressure. However, these resistors are also inherently sensitive to temperature variations. This dual sensitivity produces a temperature coefficient cross sensitivity that manifests as a change in the sensor’s scale factor over temperature.
Calibration algorithms must use polynomial equations to model and compensate for this multi-variable dependence.
Sensing Impact
Uncompensated cross sensitivity results in measurement errors that vary across the operating temperature range of the sensor. In industrial applications, this error can lead to incorrect process control decisions. By implementing on-chip temperature sensors, modern devices can provide real-time compensation data.
This integration allows the sensor to dynamically adjust its output based on the current temperature.
Performance Validation
Verifying the accuracy of the compensation algorithm involves testing the sensors across a matrix of temperatures and pressures. This testing is performed in automated environmental chambers during factory calibration. Sensors that do not meet the residual error specifications are rejected.