effect results from the fact that all fourSG behave in the same way during temperature
changes with regards to the direction and the amount of change in resistance. As two positive SG and two negative SG feed into the equation, there is essentially no output signal
following a change in temperature.
The remaining, minute residual error
can be corrected by special nickel elements that are connected to the Wheatstone bridge.
The addition of temperature-dependent resistances
(also nickel elements) in the supply line compensates for the temperature dependence of the sensitivity(TCS)
. During temperature changes, the E-modulus of the material
decreases which results in more strain
under the same force application. In addition, the sensitivity of the SG
is dependent on the temperature. The resistances in the supply line compensate for this in that the increase in resistance at higher temperature leads to a greater voltage drop
. This reduces the voltage at the Wheatstone bridge and consequently the output signal decreases
arise from the geometric ratios which change under load. Force transducers can be optimized to produce extremely good linearity through the clever selection of the spring element design
and through precise positioning
of the strain gauges.
shows a summary of compensation options
. In addition to the TKzero and TCS influences described in detail above, it is also possible to compensate the linearity and to achieve the required sensitivity through adjustment.
Figure 2: Connection of a force transducer with TKzero and TCS adjustment. Additional adjusting elements for sensitivity and linearity
The SG technology also permits the compensation of mechanical influences
which should not be measured, e.g. bending moments or lateral forces.