Laser collimation beam expanding systems improve the collimation of the beam by improving the spatial divergence angle of the laser beam and have important applications in laser ranging, aerospace, rail transportation and intelligent manufacturing. In order to meet the needs of 100 meters laser ranging, a set of coaxial optical system for receiving and sending has been designed in this paper. The system is mainly composed of fiber collimator and Galileo beam expanding system. Based on the transformation theory of Gaussian beam through thin lens and ZEMAX software, simulation and analysis are carried out. At the same time, the relations of the exit beam waist position and diameter with the distance between the lenses as well as the size changes of the returned beam spot with the measured distance are further analyzed. The results show that the coaxial system for receiving and sending can meet needs of 100 meters laser ranging, which can decrease the size of optical elements and has the advantages of simple structure and compactness compared with the common expanding system of minimum divergence angle. It can provide a more accurate reference for the collimation and expanding operation part in related scientific research and engineering practice activities.
Aiming at the visual measurement requirements of space manipulators for grasping non-cooperative targets, a space target docking ring recognition and center point positioning method based on Tiny Darknet YOLOv3 fusion CenterNet is proposed. First, training network model based on open source ImageNet VOC 2007 and self-built spatial non-cooperative target data set and use optimized Tiny Darknet YOLOv3 fusion CenterNet deep learning algorithm to identify space target docking and obtain two-dimensional pixel coordinates of the docking center point; secondly, using the EnsensoN10-408-18 depth camera to obtain the 3*3 neighborhood data of the depth value corresponding to the center point and calculate the neighborhood weighted optimal value to get docking center spatial coordinates in the camera coordinate system. Combined with the hand-eye calibration relationship, the docking center spatial coordinates are converted to the UR5 manipulator base coordinate system. A ground verification system for manipulator to capture the target was built to test the target docking ring identification and center point positioning, and the accuracy error evaluation is completed based on the OptiTrack motion capture global measurement benchmark system. The experimental results show that target positioning accuracy is better than 10mm, and real-time data update rate is better than 2Hz in the dynamic approximation process from 1.5m to 0.2m, which can effectively solve the slow speed and poor accuracy caused by the influence of environmental lighting, target surface material, target attitude scale changes and other factors in traditional feature extraction methods. It lays a foundation for the safe arrival, capture and other manipulator fine operations.
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