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.
High precision, high resolution and absolute position are the key characteristics for linear displacement measurement.This paper proposes an absolute linear displacement sensor which is suitable for harsh environment. The sensor has a primary coil and a secondary coil.The primary coil is composed of two arrays of spiral coils which are arranged orthogonally.The primary coil is supplied with 4 kHz alternating current to generate two arrays of magnetic field that travel orthogonally. Meanwhile, the spatial periods of the magnetic fields are N and (N+1). The secondary coil consists of two sets of spiral coils, and every set of spiral coils induce only one array of magnetic field.With the motion of the secondary coil, two roads of signals are induced. According to the phase comparison, the absolute position is determined.The structure and working principle of the sensor is proposed. The sensor model is simulated by finite element analysis software. A sensor prototype is fabricated to be verified by experiment. The experimental results show that the measurement range is 61.5mm with the linearity 0.54%.