| For ATP system of wireless laser communication,the stable spot acquisition,tracking,positioning and detection system platform in atmospheric laser communication is an important part to ensure the stability of communication link.When the communication distance becomes longer,the atmospheric turbulence effect increases,which leads to the obvious intensification of spot drift,beam propagation and light intensity scintillation effect,and the spot distortion detected by the receiver becomes more serious.Therefore,the spot location detection algorithm is an important part of the servo receiving platform of the wireless optical communication system,which determines the stability and reliability of the servo system in the real-time spot acquisition process.In order to improve the accuracy and stability of spot location in laser communication,a sliding weighted center of mass method was proposed to collect and locate distorted spot images in real time.The algorithm was verified theoretically based on atmospheric turbulence phase screen and field experiment images.At the same time,combined with X and Z axis servo motor,a camera spot acquisition tracking and positioning experimental platform equipped with positioning algorithm was designed and developed,and the algorithm was verified.Specific research contents include:(1)Based on the analysis of the classical algorithm of spot location in atmospheric turbulence environment,the sliding weighted center of mass method is proposed.The main principle is to apply sliding compensation to nonlinear weight method.By using the advantages of this method,the center of spot image can be accurately located.The background noise module was added to the pretreatment process,and combined with the reference image captured frame by frame,the background noise of the spot image was effectively removed,the location error caused by the noise was reduced the center noise was compensated and the effective gray value of the center position of the spot was retained.At the same time,the mode threshold method is proposed to improve the positioning accuracy.(2)Simulation images and experimental images are combined to verify the positioning effect of sliding weighted center of mass method theoretically:a.The beam passing through phase screen is simulated and the clear and complete light intensity distribution is obtained.The sliding weighted centroid localization algorithm is used to verify and compare the simulation images.Compared with the traditional mass and centroid method,the proposed algorithm can significantly reduce the spot offset.The maximum theoretical offset value decreased by 21.5%.Moreover,in the same area of registration point mask,the light intensity is high,and the comprehensive positioning effect is better.b.use in 10.2 KM and 2.4 KM in the field test of the continuous image authentication algorithm,and the shape,mass center method and non-linear weighted centroid localization method,the proposed algorithm makes the continuous image positioning offset shrinking,the biggest drop of 11.7%,the algorithm of anchor point inside the mask pixels intensity is higher,the overall positioning effect is better.(3)The experimental verification of the algorithm was carried out by the experimental platform of camera spot real-time acquisition and positioning system equipped with positioning algorithm.The sliding weighted centroid localization algorithm can reduce the deviation variance of the motor to different degrees.In the X-axis motor migration direction,compared with the nonlinear weighted centroid method,the standard variance of the motor continuous migration can be reduced by 1.9%,3.5%and 16.1%respectively,compared with the centroid method.In the z-axis motor offset direction,the deviation standard variance can be reduced by up to 22%compared with the nonlinear weighted centroid method,46.7%compared with the centroid method,and 71.64%compared with the centroid method.The sliding weighted center of mass method has better comprehensive positioning effect. |
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