Research On Rapid Extraction And Matching Technology Of Lidar Point Cloud Feature

As a sensor for perceiving the surrounding environment,the lidar has important research significance in its integration with other fields.With the rapid development of science and technology and intelligent manufacturing,lidar technology for measuring the speed of moving objects has also become a hot research topic,especially for measuring the speeds of large equipment during docking,such as ship berthing.Currently,lidar systems used for speed measurement either have large sizes,high cost,and complex system structures,making them impractical for real-world applications,or they lack high precision in speed measurement,such as handheld lidar speed guns.Therefore,this thesis presents the design of a small-sized and cost-effective single-line ranging lidar.Furthermore,an algorithm is also employed to enhance the accuracy of speed measurement for moving objects.This thesis mainly conducts the following research on the single-line distance measurement lidar:(1)To achieve the smaller size and more compact structure for the designed lidar,this thesis first conducted a comparative analysis of different ranging methods and selected the pulse ranging method for ranging.Secondly,an avalanche photodiode was used as a detector to effectively detect weak echo signals.Finally,a fiber laser was used as a transmitting light source to alleviate the problem of heat dissipation.(2)Designed and implemented circuit solutions for various modules of the lidar system.The system mainly comprises a central control,laser driver,receiver circuit,interface,motor scanning,and power modules.The central control module coordinates the operation of all system units and accurately acquires raw time information.The laser driver module not only controls the temperature of the laser with high precision but also improves the laser’s anti-interference capability.The receiver circuit module detects weak echo signals to obtain information about distant targets.The interface module enables faster acquisition of raw point cloud data.The motor scanning module adjusts the rotation speed,thereby improving the scanning range of the laser radar.This results in more accurate distance information and reduced noise.The power module provides a more stable operating voltage,enabling the efficient operation of each module.(3)Design a lidar testing experimental platform.Firstly,install the lidar on the rail platform for mobile testing to obtain point cloud data.Then,the obtained point cloud data was subjected to feature extraction and inter-frame matching using the normal distributions transform(NDT),iterative closest points(ICP),and correlative scan matching(CSM)algorithms.The experimental results of demonstrated that the NDT algorithm outperformed the ICP and CSM algorithms in terms of velocity measurement accuracy and algorithm robustness.Moreover,the velocity measurement results obtained from the NDT algorithm were closer to the rail platform’s actual track speed,with a maximum velocity deviation of lesser than 0.021m/s when compared to the actual speed.The distance measurement lidar based on the NDT algorithm proposed in this thesis provides a valuable reference for improving the speed measurement accuracy of lidar on moving objects.