旋翼无人机载差分光学吸收二维探测系统的研究及应用

Research and application of differential optical absorption two-dimensional detection system for rotorcraft unmanned aerial vehicle

针对机载探测系统的小型化、多角度、多高度、快速同时获取大气多污染物的技术需求,研制了一套融合多传感实现不同高度和不同方位角的轻量化、低成本的小型差分光学吸收二维机载观测系统,并将其搭建于旋翼无人机平台上应用于大气环境污染物的观测.本文详细介绍了研制的旋翼无人机平台和机载差分光学吸收系统构成,开展了系统稳定性研究,机载设备偏航角、翻滚角以及俯仰角的角度偏差均值分别为0.07°,-0.13°,-0.12°,满足监测稳定性要求.将机载系统与商用地基差分光学吸收系统进行比对观测实验,比对结果显示二者监测数据相关系数均大于0.92.最后利用该机载系统开展外场飞行实验,机载差分系统分别飞行距离水平面至30,60,90 m高度进行观测,观测时仰角设置为0°,方位角从0°到360°每隔30°进行一次测量,获得了不同方位角以及不同高度下的NO_(2),SO_(2),HCHO浓度分布信息.研究结果表明该研发系统满足大气多污染物同时快速多角度多高度的探测技术需求.

In order to meet the technical requirements for miniaturization,multi-angle,multi-altitude,and fast simultaneous acquisition of atmospheric pollutants,this study develops an integrated,lightweight,and cost-effective airborne differential optical absorption spectroscopy(DOAS)system.This system is designed in order to be used on a rotorcraft unmanned aerial vehicle(UAV)platform for monitoring atmospheric pollutants.The compositions of the hexacopter UAV platform and the airborne DOAS system are detailed in this work.The system includes a multi axis differential optical absorption spectroscopy(MAX-DOAS)spectral acquisition system,a control system,and a flight environment monitoring system.Commands are sent from a computer via serial communication to drive a gimbal,controlling the azimuth angle and elevation angle of the telescope,with a camera recording the light obstruction.The sunlight scattered by the atmosphere is collected by the telescope and transmitted via fiber optics to the spectrometer,which then transmits the data to the control computer.Additionally,the system captures data of altitude,temperature,humidity,and GPS location during flight,and filters out spectral data obtained under abnormal flight conditions.Stability studies indicate that the mean angular deviations for yaw,roll,and pitch are 0.07°,-0.13°,and-0.12°respectively,which meet the requirements for monitoring stability.Comparative experiments with a commercial ground-based DOAS system show that the correlation coefficients between the monitoring data of both systems are both greater than 0.92,confirming the reliability of the airborne system.In field flight experiments,the airborne DOAS system conducts observations at altitudes of 30 m,60 m,and 90 m,with the elevation angle set at 0°and the azimuth angle measured every 30°from 0°to 360°.The system successfully obtains the concentration distributions of NO_(2),SO_(2),and HCHO at different azimuth angles and altitudes.The results indicate that the concentrations of these three gases decrease with altitude increasing,with higher concentrations observed in the southeast direction,indicating the presence of pollution sources in that direction.Further analysis with considering altitude changes indicates that the rate of decrease in NO_(2) concentration and SO_(2) concentration slow down with altitude increasing,while the rate of decrease in HCHO remains relatively constant.These findings indicate that this system effectively meets the technical requirements for simultaneous,rapid,multi-angle,and multi-altitude detection of atmospheric pollutants,providing essential support for the detailed monitoring of complex urban micro-environments.