Linear Displacement Measurement Based on Image Grayscale Information

Xueling, 刘雪玲 Liu; Jinchun, 胡金春 Hu; Tong, Hao; Aixue, 葛爱学 Ge; Shengwu, 杜胜武 Du; Yu, 朱煜 Zhu

doi:10.3788/aos201939.0412008

Cited by 2 publications

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“…In other words, 25-bit measurement can be achieved. By this, we set 2 m = 2 16 in equation (1). Because there are 2 N = 2 9 lines in the circumference of the grating code disk, the measurement resolution is 360 • /2 9+16 .…”

Section: Positioning Experimentsmentioning

confidence: 99%

“…'Resolution stability' refers to the fluctuation of the output displacement measurement value when the spindle of the angular displacement measuring device is fixed. We imposed 2 m = 2 16 in the subdivision algorithm. The grating circle we used contains 2 N = 2 9 lines, so we synthesized a measurement resolution of 25-bit.…”

Section: Resolution Stability Experimentsmentioning

confidence: 99%

“…Lashmanov et al [15] used a camera to collect and measure a scale ruler with scale lines for measurement accuracy of 1.65 µm. Liu et al [16] measured displacement based on gray value calculation to reach measurement accuracy of 4 µm by using an imaging lens. The magnifying imaging lens readily achieves high-resolution imaging, but it increases the volume of the device and is easily affected by vibration and virtual focus problems.…”

Section: Introductionmentioning

confidence: 99%

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Image-type displacement measurement resolution improvement without magnification imaging

Yu¹

2021

Meas. Sci. Technol.

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The imaging-type displacement measurement (IDM) technique is better-suited to high-resolution measurement than the traditional moiré fringe technique. In Angular displacement measurement, IDM generally requires lens-magnified imaging processes to reach the proper resolution, which depends on overly large imaging lenses and highly complex, generally unreliable equipment, making the technique not conducive to industrial application. The resolution of an IDM device was improved in this study without the use of an imaging lens. The lensless imaging principle was established, then a new algorithm based on multi-line fusion and denoising was developed to improve the displacement subdivision resolution. The proposed algorithm was verified by both simulation and experimentation. The simulation shows that the proposed algorithm effectively reduces positioning operation noise. In the experiment, an angular measurement resolution of 0.039″ (25-bit) was achieved on a 70 mm diameter circular grating. The proposed method lays a foundation for further high-resolution displacement measurement techniques.

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Section: Positioning Experimentsmentioning

confidence: 99%

Section: Resolution Stability Experimentsmentioning

confidence: 99%

Section: Introductionmentioning

confidence: 99%

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Image-type displacement measurement resolution improvement without magnification imaging

Yu¹

2021

Meas. Sci. Technol.

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A New Image Grating Sensor for Linear Displacement Measurement and Its Error Analysis

Fang

Zhou²,

Yu³

et al. 2022

Sensors

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To improve the accuracy of the current vision-based linear displacement measurement in a large range, a new type of linear displacement sensing system, namely, image grating, is proposed in this paper. The proposed system included a patterned glass plate attached to the moving object and an ultra-low distortion lens for high-accuracy image matching. A DFT local up-sampling phase correlation method was adopted to obtain the sub-pixel translation of the patterns onto the target plate. Multiple sets of stripe patterns with different designs were located on the glass plate to expand the measurement range, based on the principle of phase correlation. In order to improve the measurement accuracy, the main errors of the image grating system were analyzed, and the nonlinear error compensation was completed based on the dynamic calibration of the pixel equivalent. The measurement results, after the error compensation, showed that the total error of the proposed system was less than 2.5 μm in the range of 60 mm, and the repeatability was within 0.16 μm, as quantified by standard deviation.

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Linear Displacement Measurement Based on Image Grayscale Information

Cited by 2 publications

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Image-type displacement measurement resolution improvement without magnification imaging

Image-type displacement measurement resolution improvement without magnification imaging

A New Image Grating Sensor for Linear Displacement Measurement and Its Error Analysis

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