Absolute planar two-dimensional time-grating displacement sensor with multi-frequency magnetic field coupling
Aiming at the problem that incremental planar two-dimensional(2-D)time-grating displace-ment sensors need to be zeroed when they are powered up,an absolute planar 2-D time-grating displacement sensor based on multi-frequency magnetic field coupling was designed,which adopts time-driven excitation signals of different frequencies to reduce the power consumption of the sensor circuit and at the same time make the decoupling of signals in the X and Y directions and the 2-D absolute position solving simpler and more reliable.Firstly,a mathematical model of magnetic field distribution of the excitation coil was estab-lished,and the relationship between the width of the excitation coil and the height of the coupled air gap was analyzed according to the characteristics of the spatial magnetic field distribution;based on the incremental 2-D time-grating displacement sensor structure of the differential structure,an absolute planar 2-D time-grating measurement model of the opposite poles reciprocal structure was established,and a new scheme for the 2-D absolute position solution based on the look-up table method was proposed,which avoided the influence of the measurement error on the solution result in the practical application;the feasibility of this solution was verified by electromagnetic field simulation,and the optimal installation gap of the sensor was determined to be 0.8 mm;finally,the sensor prototype was fabricated,and the 2-D precision experimental platform was constructed for performance testing.The experimental results show that the sensor prototype in the effective measuring range of 147 mm×147 mm,the original measurement errors in the X and Y directions are±20.4 μm and±21.1 μm,respectively,and it has the advantages of no need to find the zero point on pow-er-on,which realizes the all-in-one 2-D absolute displacement measurement and positioning.
multifrequency magnetic fieldantipolar primeabsolute two-dimensionaltime-grating dis-placement sensor
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