Research On Using Plane Model To Calibration Spatial Positional Relationship Of Sensors In Domestic Airborne Laser Sounding Lidar

Positioning accuracy is one of the key performance indicators of the airborne laser depth radar system.The level of positioning accuracy determines the application field and scope of the system.The calculation and analysis show that the placement error is the main factor that determines the positioning accuracy of the airborne laser depth radar system.Therefore,a reliable calibration model of placement error and a corresponding placement error calibration scheme designed to improve the positioning accuracy of the airborne laser depth radar system is very necessary.This paper takes the domestic airborne laser depth radar system as the research object.Based on the investigation of the calibration method for the placement error of the airborne laser radar system at home and abroad,combined with the characteristics of domestic airborne laser depth radar system,the paper proposes a placement error adjustment based on model plane constraint model.The main research content includes:(1)The geodesic positioning model of airborne laser depth radar is derived.The composition of the domestic airborne laser sounding system is introduced.The coordinate system of each sensor is defined.The formula of the distance measurement and positioning of the scanner is deduced for the system-specific oval scanning structure.The coordinate of laser foot point in the WGS84 system is derived based on the spatial transformation relationship of each sensor.(2)Theoretical analysis and qualitative quantitative calculation of error sources have been made in airborne laser depth radar system.Starting from the geometric positioning model of the laser foot point in the WGS84 coordinate system,the error sources of the system are introduced.The effects of ranging error,angle error,placement error,attitude error,and positioning error on the laser foot positioning accuracy are qualitatively and quantitatively analyzed.Emphasis was placed on the study of the effect of placement angle error on the characteristic features of points,lines,and surfaces,providing a theoretical basis for the calibration of placement errors.(3)A placement error calibration algorithm based on plane constraint model is adopted according to the characteristics of airborne laser depth radar.Plane features with different orientations are extracted from on-board point clouds and ground high-precision surveying data.Then conjugate planes are found from which the extracted planes.Placement errors are calculated based on the laser point formulas and plane constraints by the means of Conditional adjustment with parameters.In the algorithm,plane fitting algorithm based on the eigenvalue method is optimized for the standard deviation of the distance from the point to the fitting plane used to iteratively calculate the fitting plane parameters,and so the robustness of the plane is improved.(4)According to the proposed calibration method,the principle and method for establishing the calibration field are given,the flight route is designed,and the settlement error is calculated.Based on the mechanism of the second-class elevation difference,the features of plane and slope are used to evaluate the accuracy of airborne laser depth measurement lidar.Experiments show that the placement error calibration algorithm based on the plane constraint model can solve the placement error effectively.After error correction,the localization accuracy of the domestic airborne laser depth measurement radar can meet the design requirements and achieve the accuracy index of similar foreign products.