Research on self-calibration method of large range absolute linear time-grating displacement sensor based on splicing technology
With the contradiction between extended measuring range and absolute positioning of large range linear displacement sensor, and a lack of efficient installation of high-precision reference devices in its application field, it is difficult to frequently calibrate online to maintain its measurement accuracy.This paper proposes a new error continuation self-calibration method for linear time-grating displacement sensor based on splicing technology.First, the complex large range absolute measurement is divided into the absolute displacement measurement on a single grid scale and the absolute position judgment after the grid scale is spliced.Then, the absolute position data is employed as the basis of position judgment and the double probe structure is built to realize the smooth transition of the induced signal at the joint.Finally, the original two-probe structure is employed to obtain the range measurement sequence, the periodic error function is built with the error continuation method, and the amplitude spectrum reconstruction error function is obtained by the fast Fourier transform method.To verify the feasibility and effectiveness of the above method, a sensor prototype with a single segment grid ruler length of 600 mm is made for experiment.Our results show the absolute position measurement is realized within the measuring range of 903 mm after the two grid scales are splicing together.After the self-calibration method is adopted, the average peaking error of the sensor in a single cycle decreases from 2.00 μm to 0.59 μm, and the error compensation effect is 70 .50％.The peak value of large-range error decreases from 18 .93 μm to 0.75 μm, and the error compensation effect is 96.04％.Moreover, the calibration effect comparison experiment demonstrates our self-calibration method is superior to the traditional comparison calibration method based on Fourier harmonic compensation, and the error calibration effect is improved by about 76.20％.Our research may provide some references for range expansion and error self-calibration for absolute linear displacement sensor.
large rangeabsolute formdisplacement sensorerror calibrationtime grating
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