Contactless linear position transducer based on reluctance variation

A novel form of electromagnetic transducer for continuous position sensing in linear drive systems is described. The transducer relies on a repetitive variation of inductance with position caused by the change of reluctance between moving and static saliences of a magnetic circuit. The novelty feature of the transducer is seen in terms of its design which is distinguished by a simple cylindrical modular form and allows a large sensing range. The transducer’s accuracy and sensitivity are independent of the sensing range. The investigations presented are focused on studying the magnetic circuit design and the excitation of the transducer, with the aim to accomplish a linear relationship between the transducer output and position. A consideration of the effects of core losses and motional EMF on the transducer output has been made. Results obtained with an experimental prototype transducer are included.