Method of calibration and precise measurements for temperature dependent signals from the Wheatstone bridge strain gauge sensors

Progress in digital electronic and arrival of new generation of the high precision and sufficiently fast analog-to-digital converters made a software based thermal compensation of the strain gauge sensors more attractive than traditional hardware thermal compensation. For many type of the strain gauge sensors with a Wheatstone bridge it is possible to organise a measurement circuitry so that from the bridge two output signal can be measured. One of these signals (U₁) is mostly depend on the value of the strain gauge deformation but also is depending on the temperature variation. The second of these signals (U₂) is depending mostly on the value of the temperature but also is influenced by strain gauge deformation variation. Calibration procedure is providing the two sets of the curves. One set (isotherms) is corresponding to the constant value of the temperature and varied parameter proportional to the deformation (load, pressure, etc...). Second set of the curves is corresponding to the varied temperature under the constant value of parameter proportional to deformation. Mathematical algorithms and software program are developed for the fast and precise computation of the parameter proportional to the deformation and value of the temperature.

This method was tested successfully on the different type of the sensors. As a result not only thermal compensation problem of the sensors was solved without any additional hardware component but sensors became the sensors of the two parameters, for example pressure and temperature, that is useful for the many practical application.