物理学报2017，Vol.66Issue(13)：126-135,10.DOI:10.7498/aps.66.134206
基于足印探测的激光测高仪在轨标定
On-orbit calibration of satellite laser altimeters based on footprint detection
摘要
Abstract
The positioning accuracy of the footprint of a satellite laser altimeter is primarily dependent on the accuracy of its laser pointing, e.g., a 30 arcsec pointing bias will induce 87 m horizontal error and 1.5 m vertical error when the altitude is 600 km and the laser incident angle is 1?. In order to achieve the three-dimensional high-precision observation on the Earth surface, on-orbit calibration is needed to remove the systematic pointing bias mainly arising from the thermal effect. The current methods of on-orbit calibration and verification for laser altimeters are the attitude maneuvering and the footprint detection, respectively. However, the attitude maneuvering is not applicable to the existing satellite platform of China, which uses the large platform with a three-axis attitude stabilization system. The current footprint detection method can only achieve on-orbit verification task, i.e., the horizontal and vertical errors can be evaluated by analyzing the captured laser footprints but the systematic pointing bias cannot be estimated and removed. An improved design scenario of energy detector that is used for capturing laser footprint is given in this paper. The quantification level of the captured laser energy is equal to 8, which is bigger than that of the energy detector designed for geoscience laser altimeter systems corresponding to level 2. Benefiting from the new design scenario, fewer detectors are needed to achieve the same precision when calculating the centroid geolocations of captured footprints. A new systematic misalignment estimation model in the laser direction cosines is deduced, and it is used to estimate the systematic bias by using the detected footprints based on the Gauss-Markoff criterion. With the new detectors and bias estimation model, the footprint detection method now can achieve on-orbit calibration, as well as on-orbit verification. According to the presented calculation model, simulation experiments are operated to analyse three effects that may influence the performance of the footprint detection on-orbit calibration, i.e., the laser incident angle on the detector array, the surface roughness of the site where detectors lay out, and the grid density of the detector array. The simulation results indicate that, when the horizontal positioning accuracy of the captured footprint centroid demands better than 1.8 m which corresponds to 0.6 arcsec laser pointing accuracy when the altitude of the satellite is 600 km, the grid distance of the detector array can be 20 m, the laser incident angle on the detector array should be larger than 3?, and the surface roughness of the calibration site should be less than 0.1 m. The designed detectors and calibration method will be used to capture laser footprints and remove the systematic bias for the laser altimeter on China GF-7 satellite, which is one of the upcoming high-resolution satellites for Earth observation.关键词
星载激光测高仪/系统误差/在轨标定/能量探测器Key words
satellite laser altimeter/systematic bias/on-orbit calibration/energy detector引用本文复制引用
易洪,李松,马跃,黄科,周辉,史光远..基于足印探测的激光测高仪在轨标定[J].物理学报,2017,66(13):126-135,10.基金项目
对地高分辨率观测系统国家科技重大专项工程"高分遥感测绘应用示范系统(一期)"(批准号: AH1601-8)、国家自然科学基金(批准号: 41506210, 11574240)、测绘公益性行业科研专项经费资助项目(批准号: 201512016)、中国博士后基金(批准号:2016M600612)和中央高校基本科研业务费专项资金(批准号: 2015212020201)资助的课题. Project supported by National Science and Technology Major Project, China (Grant No. AH1601-8), National Science Foundation of China (Grant Nos. 41506210, 11574240), Public Science and Technology Research Funds Projects of Survey, China (Grant No. 201512016), China Postdoctoral Science Foundation (Grant No. 2016M500612), and the Foundmental Research Funds for the Central University of Ministry Education of China (Grant No. 2015212020201). （一期）
