Measurement principle and structure optimization of two-dimensional time grating displacement sensor

High-precision position measurement and detection technology are more and more needed in the process of precision machining. This paper proposes a two-dimensional displacement sensor based on planar coil. The sensor is composed of excitation and induction coils. Two groups of excitation coil array are arranged in the x and y directions respectively, then two groups of magnetic fields which travel orthogonally are generated. The induction coil induces the variation of the magnetic field to generate two electrical signals whose phases are related to x and y respectively. The displacements are obtained after phase comparisons and calculations. A sensor model based on the principle is built and simulated in the finite element analysis software. According to the simulation results, the measurement error is traced back to the source and the structure of the sensor is further optimized. A sensor prototype is fabricated and the experiment is carried out. The experimental results show that the measurement range is 140mm × 140mm with the resolution of 1. μm, and the nonlinearity is 0.5 % in one pitch.