Design of an adaptive calibration technique using Support Vector Machine for LVDT

Design of an adaptive calibration technique for displacement measurement using Linear Variable Differential Transformer (LVDT) is proposed in this paper. The objectives of this proposed work are (i) to extend linearity range of LVDT to full scale of input range, (ii) to make system capable of measuring displacement accurately with variations in dimensions of primary and secondary coil, number of primary and secondary windings, and excitation frequency. Output of LVDT is differential AC voltage across secondary coils. It is converted to DC voltage by using a suitable data conversion circuit. Support Vector Machine (SVM) model is added in cascade to data conversion unit replacing the conventional calibration circuit to achieve desired objectives. The system once designed is subjected to test data with variations in physical parameters of LVDT and excitation frequency for particular displacement. Results show the proposed technique has achieved its set objectives. Designed displacement measurement technique using proposed adaptive calibration technique yields a root mean percentage of error of 0.0078, with linearization over the range 0 to 100 mm.