Temperature compensation of a load cell under heterogeneous heating

The occurrence of bias drift due to temperature effects in a load cell is a source of measurement error that deeply impacts experimental tests, and cannot be avoided in all cases. In wind tunnel tests with installed propulsion, for instance, the force sensor may be positioned close to an electric motor, resulting in heat being conducted through the load cell. As a result, the temperature varies during the test and its effect cannot be removed by a simple offset measurement, in which case a compensation of temperature effects is suggested. However, there’s a current lack of an in-depth description of the calibration procedure and its validation, as well as a discussion on less known effects such as heterogeneous temperature distributions. This work addresses these topics, by explaining the procedure behind a new approach based on two thermocouple readings in strategic regions of the load cell and the study of different heating scenarios in a controlled environment, which results in an improved compensation that considers the strain caused by both homogeneous and heterogeneous heating of the sensor. This method is then later validated by a test case, in which the resulting compensation reduced the bias error from 7.1 to 0.3N$$0.3~\text {N}$$ for a 18∘C$$18~ ^{\circ } \text {C}$$ temperature increase.