Design of teaching experiments based on high-precision laser spot centroid positioning technology
[Objective]Capturing,tracking,and aiming are essential prerequisites for intersatellite laser communication and laser measurement.To achieve precise laser capturing,tracking,and aiming,high-precision detection of the laser spot centroid is crucial.To enhance the accuracy of centroid detection,this paper proposes a high-precision laser spot centroid positioning method based on Otsu combined with weighted least squares.[Methods]First,this method uses filtering to remove most of the noise from the laser spot image incident on the CCD.Then,the Otsu threshold segmentation method is used to separate the target laser spot image from the background in the laser spot image.Second,morphological processing is used to smooth the edges of the laser spot image.Afterward,the edge extraction operator is used to extract the edge of the laser spot image,and the contour of the extracted edge is tracked to obtain the edge coordinates.Finally,the weighted least squares fitting method is used to fit the edge of the laser spot image with iterative reweighting and multiple adjustments of weights to achieve the best fitting effect of the spot and obtain a high-precision centroid of the spot.[Results]This study designed a simulation verification experimental program based on MATLAB software,explored the performance of the proposed algorithm under different factors,and compared it with the grayscale centroid method to verify its effectiveness and feasibility.During the experimental process,the positioning accuracy of this algorithm was found to be higher than that of the traditional gray-level centroid method,achieving subpixel-level high-precision spot centroid positioning.In addition,under different signal-to-noise ratios,compared with the traditional centroid method,the algorithm proposed in this paper had better noise resistance and higher accuracy in spot position detection.When the signal-to-noise ratio of the image was low,the centroid error measured by the grayscale centroid method was relatively large.As the signal-to-noise ratio of the laser spot image increased,the positioning error of the grayscale centroid method gradually decreased.When the light spot was incident at different positions on the CCD,the centroid positioning result of the light spot showed trends of large errors on both sides and small errors in the middle.When the centroid of the spot was close to the edge of the CCD,the spot was incomplete,and the positioning accuracy of the grayscale center of gravity method decreased.When the laser spot was incident on the center of the CCD,the complete spot could be detected,and the detection accuracy of the grayscale center of gravity method gradually improved.Whether at the center or edge of the CCD,the method proposed in this article had better accuracy in detecting the centroid of the spot than the grayscale centroid method as it considered noise filtering,edge smoothing,tracking,and weighted least squares circle fitting.Under different CCD resolutions,both algorithms gradually stabilized and showed a decreasing trend in positioning error as the CCD resolution increased.The positioning accuracy of the spot centroid proposed in this article was superior to that of the grayscale centroid method.The simulation results met theoretical expectations,and the experiment achieved the expected results.[Conclusions]This experiment encourages students to think innovatively,explore boldly,and practice hands-on,applying their knowledge of signal processing to the positioning of intersatellite laser spot centroids.It also trains students in analyzing and solving problems,leading to a deeper understanding and consideration of factors affecting the accuracy of spot centroid positioning.
laser communicationspot centroid localizationweighted least squaresexperimental design
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