Analysis and Validation of a Planar High-Frequency Contactless Absolute Inductive Position Sensor

• Published in: IEEE transactions on instrumentation and measurement Vol. 64; no. 3; pp. 768 - 775
• Main Authors: Aschenbrenner, Bernhard, Zagar, Bernhard G.
• Format: Journal Article
• Language: English
• Published: New York IEEE 01.03.2015; The Institute of Electrical and Electronics Engineers, Inc. (IEEE)
• Subjects: Coils; Couplings; Crosstalk; Displacement measurement; inductors; Mathematical models; mutual coupling; parasitic capacitance; Position measurement; Printed circuit boards; printed circuits; Q factor; Receivers; Resonant frequency; RLC circuits; Sensors; Q factor; Displacement measurement; printed circuits; inductors; position measurement; parasitic capacitance; mutual coupling
• ISSN: 0018-9456; 1557-9662
• DOI: 10.1109/TIM.2014.2348631

This paper presents a low cost precise and reliable inductive absolute position measurement system. It is suitable for rough industrial environments, offers a high inherent resolution (0.1%-0.01% of measurement range), can measure target position over a wide measurement range, and can potentially measure multiple target locations simultaneously. The basic position resolution is improved by adding two additional finer pitched receive channels. The sensor works on principles similar to contactless resolvers. It consists of a rectangular antenna printed circuit board and a passive LC resonant circuit. A mathematical model and the equivalent circuit of this kind of sensor are explained in detail. Such sensors suffer from transmitter to receiver coil capacitive crosstalk, which results in a phase sensitive offset. This crosstalk will be analyzed by measurements. Moreover, the mechanical transducer arrangement, the measurement setup, and the measured results will be presented.