An Intelligent Instrument for Measuring Liquid Level

In this paper, we propose a scheme to increase the linearity range of the capacitance level sensor (CLS) and make independent of the permittivity of the liquid used. The capacitance from the CLS is first converted to frequency by a timer circuit and then frequency is converted to voltage by a frequency to voltage converter. The relation is nonlinear and depends on permittivity of liquid. Artificial Neural network (ANN) model is used in cascade with the frequency to voltage converter. This arrangement has the effect of linear relation between level to be measured and the output of the ANN model. Further this is independent of permittivity of liquid used. The proposed ANN-based scheme incorporates intelligence into the sensor. Using Matlab environment the training has been done to design a model of ANN.