Current Optics and Photonics

Optical Society of Korea (한국광학회)
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Design and Implementation of an Absolute Position Sensor Based on Laser Speckle with Reduced Database

  • Tak, Yoon-Oh (School of Mechanical Engineering, Gwangju Institute of Science and Technology) ;
  • Bandoy, Joseph Vermont B. (Department Biomedical Science and Engineering, Gwangju Institute of Science and Technology) ;
  • Eom, Joo Beom (Department of Biomedical Science, Dankook University) ;
  • Kwon, Hyuk-Sang (School of Mechanical Engineering, Gwangju Institute of Science and Technology)
  • Received : 2021.03.15
  • Accepted : 2021.04.27
  • Published : 2021.08.25
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Abstract

Absolute position sensors are widely used in machine tools and precision measuring instruments because measurement errors are not accumulated, and position measurements can be performed without initialization. The laser speckle-based absolute position sensor, in particular, has advantages in terms of simple system configuration and high measurement accuracy. Unlike traditional absolute position sensors, it does not require an expensive physical length scale; instead, it uses a laser speckle image database to measure a moving surface position. However, there is a problem that a huge database is required to store information in all positions on the surface. Conversely, reducing the size of the database also decreases the accuracy of position measurements. Therefore, in this paper, we propose a new method to measure the surface position with high precision while reducing the size of the database. We use image stitching and approximation methods to reduce database size and speed up measurements. The absolute position error of the proposed method was about 0.27 ± 0.18 ㎛, and the average measurement time was 25 ms.

Keywords

Acknowledgement

This study was supported by the National Research foundation of Korea grant funded by the Korea government (2019R1A2C2090661), GIST Research Institute (GRI) grant funded by the GIST (1711122918).

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