A novel two-dimensional inductive sensor based on planar coils

The precision measurement of two-dimensional displacements is needed in many domains, such as precision fabrication and detection. This paper presents a novel inductive position sensor with the capability of measuring displacements in x- and y- directions simultaneously. The sensor consists of two parts: a ferromagnetic plate with primary windings which are composed of four layers of planar coils, a ferromagnetic plate with secondary windings which are composed of four layers of planar coils. Primary windings are supplied with two orthogonal 20KHz alternating current to generate traveling wave magnetic field along x- and y- directions separately. Secondary windings output two signals whose phases are proportional to linear displacements of X and Y directions respectively. The structure and working principles of the sensor are proposed. Meanwhile, a sensor model is simulated to verify the feasibility of the working principle and a sensor prototype is fabricated for physical experiment. According to the analysis of experiment results, the measurement range is 140mm×140mm, and the maximum linearity in one pitch is 1%. The performance of sensor may be improved by optimizing the layout of primary and secondary windings and signal processing circuit.