Axial Movement Sensor Based on Chaotic Oscillator and Planar Coil

Axial movement measurements are required in different technical tasks. At distances up to several centimeters, inductive sensors are widely used. However, cheap on-the-shelf sensors are often not suitable due to their low sensitivity. Instead of them, linear potentiometers, inductive sensors with moving cores, linear magnetic encoders or laser systems are used, but these solutions have their own limitations and higher costs. In this paper, we propose an inductive sensor consisting of a planar coil included in a chaotic circuit based on the fang system. Coil inductance serves as a bifurcation parameter. When the target moves and inductance accordingly changes, the phase volume of system's attractor also changes. Nonlinearity of this system allows obtaining a steeper sensitivity characteristic comparing with a harmonic oscillator. The phase volume can be easily detected using analog means, which results in completely analog sensor design. We show that such a system is able to perform movement measurements with adjustable range and high accuracy.