Linearity Metric
Metrological quantification of sensor output deviation relative to a theoretical straight line drawn directly between zero and full-scale calibration points defines transfer function curvature. Calculating terminal-point non-linearity provides an absolute bound on sensor linearity errors without allowing artificial mathematical slope shifts to reduce peak error figures. The metric applies across the full calibrated measurement range, stopping at the physical operational limits of the transducer.
Instrument specifications report this parameter as a percentage of full-scale output.
Endpoint Alignment
Endpoint alignment forces the reference baseline to pass through measured output at zero input and maximum rated input. Unlike best-fit straight line methods that minimize average squared error across all points, terminal-point calculations anchor both ends of the calibration curve. This approach reveals mid-scale displacement errors that best-fit straight line metrics obscure.
Pressure sensors and displacement transducers evaluated under this standard show higher published non-linearity percentages but offer guaranteed endpoint accuracy.
Error Magnification
Physical sensor non-linearities stem from diaphragm deflection mechanics, magnetic saturation, or semiconductor piezoresistive saturation effects. As input stimulus increases toward upper measurement range limits, mechanical stiffness changes cause the output voltage slope to roll off. Microprocessor-based instruments store multi-point lookup tables or polynomial coefficients to correct these systematic curvature errors.
Uncorrected terminal-point deviation directly degrades overall system measurement accuracy.
Verification Standard
Calibration laboratories measure non-linearity using primary calibration standards with accuracy ratios exceeding four to one relative to the sensor under test. Calibration certificates state maximum measured deviation across ascending and descending input steps. Final acceptance requires deviation to remain within factory specification bounds.
