NONLINEAR MODELS OF TEMPERATURE SENSOR DYNAMICS

To describe temperature sensor dynamics, linear models have been widely used in the literature of the subject. These models are derived on the basis of transmittance and they express the sensor response to a unit temperature step. However, such linear models can only be applied for a small temperature increase, ranging from 20 to 30-degrees-C, because the temperature sensor can then be regarded as a linear element. This paper presents non-linear models which adequately describe temperature sensor dynamics within the temperature increase range (of random values) where the sensor can be considered as a linear or a non-linear element. These models are derived on the basis of the Stone-Weierstrass theorem describing uniform approximations of continuous functions. The use of non-linear models in the dynamic method of measuring high temperatures beyond the permissible sensor range is given as an example.