The following error groups
are distinguished with strain gauge-based force transducers:
TCzero and linearity
Errors relative to the full scale value:
Errors generating a specific output signal independent of the force applied, for example the temperature effect on the zero point (TCzero) or non-linearity.
Errors relative to the actual value:
Errors whose magnitude is proportional to the force applied at the time of evaluation.
often are of vital importance. These errors are relative to the full scale value
, i.e. to the output signal at full nominal (rated) force. This measurement uncertainty
has a specific value, irrespective of how big the measured force is.
When measurements are taken in the upper sensor range, i.e. at high force levels
, an error relative to the full scale value is uncritical
, since its relative proportion is small compared to the high output signal. The situation looks quite different when a small force
is measured using the same force transducer. In this case, the effect of an error
relative to the full scale value is significantly greater: The value is the same, however, it needs to be related to a smaller force: The relative proportion increases.
and the zero point's dependency on temperature
) are major error influences relative to full scale. Every improvement in these characteristic values enables the force transducer - assuming given accuracy requirements - to be used for ever smaller forces: Errors relative to the full scale value determine the force transducer's permissible measurement range.
Small errors relative to full scale expand the possibility of measuring in the partial load range.
Errors relative to the actual value
always take effect relative to the currently measured force. When small forces are measured, the influence
of these error quantities therefore is rather small