A modified technique of displacement measurement of a piston made of magnetic material inside a cylinder

Movement of piston inside a cylinder has many applications in industries and measurement of its displacement inside the cylinder is very much important to study its operation and control. In the present paper a non contact type displacement measurement technique of a piston made of magnetic material inside a cylinder has been proposed. In this technique, the difference of inductances of two identical coils wound outside a cylinder due to movement of piston inside it has been found to be linearly related with the displacement. A modified differential inductance measurement circuit has been designed to develop the proposed displacement transducer. The design of the circuit along with principle of operation has been described in the paper. The operation of the proposed circuit has been experimentally studied and the experimental results are reported in the paper. The proposed transducer has been found to have very good linearity and repeatability.