| Single-photon lidar is an advanced active photoelectric detection technology that can make full use of every photon signal received by the detector.It has the advantages of high detection efficiency,long distance,and strong ability to detect weak signals.The target signal extraction algorithm,as a data processing technology of lidar,can obtain effective information such as target distance and speed,but the existing signal extraction algorithms are mainly for targets with accurate orbit predictions,and for unknown targets lacking prior information such as target distance,speed,and noise The scene is not fully applicable.Therefore,based on the single-photon lidar ranging system,this article takes the high-speed moving target without prior information as the main research object,studies the lidar data processing technology,and realizes the real-time extraction of the unknown target distance trajectory at the thousand kilometers level.Firstly,the echo characteristics of the received photons under motion conditions are studied in depth,and the analysis shows that the target signal intensity decays rapidly with the increase of detection distance and laser incidence angle.In order to be closer to the real measurement environment,a variety of motion states and detection probabilities of the target are simulated,and the lidar point cloud data under different conditions such as signal loss and jitter error are generated.For high-speed moving targets in typical scenarios,a distance-trajectory extraction algorithm based on the standard Hough transform is proposed,which uses the temporal correlation between target echo points to introduce the straight-line detection algorithm into the extraction of echo signals.The proposed improved real-time distance gate based on motion slope effectively reduces the noise in the distance gate,which is particularly effective for targets with fast motion;the analysis concludes that the algorithm range accuracy and computation in the standard Hough transform increases with the improvement of parameter spatial resolution.The experimental results show that:within the detection distance of 900 km,the noise intensity is within the range of 0-6000 counts/s,for moving targets with a speed of 5-12 km/s and an acceleration of 0-100 m/s~2,the algorithm can achieve real-time extraction of the distance trajectory of unknown targets in typical scenarios,the distance root mean square error is better than 2.72 m,and the same extraction effect can be achieved for the space debris measured target.The distance trajectory extraction algorithms based on improved Hough transform and random Hough transform are proposed for the extended target with certain motion acceleration.Through the analysis of the algorithm principle and calculation parameters,the respective advantages,disadvantages and applicable scenarios of the two algorithms are discussed.The experimental results show that the range accuracy of the two algorithms is not affected by the target motion acceleration,and both can adapt to the non-uniform motion scenario with acceleration-500-500 m/s~2,and the root mean square error of distance is better than 2.48 m and 0.75 m,respectively.In this paper,the single-photon laser ranging distance trajectory extraction algorithm is studied in depth,and the proposed standard Hough transform algorithm can accurately extract the distance trajectory of high-speed non-accurate forecast targets in real time,with the advantages of strong noise immunity and fast extraction speed.The improved Hough transform and random Hough transform distance trajectory extraction algorithm effectively solves the problem of large distance error of standard Hough transform algorithm in non-uniform motion scenarios.The research content of this paper expands the application scenario of single-photon laser ranging system and provides a new way for the subsequent laser ranging data processing of spatial non-cooperative targets. |
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