How UAV environmental monitoring technology came into being
At present, many regions in China are facing great pressure to improve the quality of atmospheric environment. In this regard, industry insiders said that only by accurately finding the local pollutant emission sources and comprehensively analyzing many reasons such as geography, meteorology and environmental derivation, can we achieve accurate decision-making and rapid response to air pollution control.
However, due to the characteristics of large regional scope, large pollutant transmission between regions, many types of pollution sources and relatively complex pollution factors, environmental supervision is very difficult. The traditional automatic air monitoring station has a large land area, and its cost and later operation cost are high, so it is difficult to carry out large-scale and precise distribution, And basically “can’t tell the source of pollution”. Even if the air monitoring station is encrypted for monitoring at a high price, the monitoring data arranged at points is always difficult to judge the migration and diffusion of pollution sources, let alone determine the direct source of pollution.
Local governments need a fast and efficient monitoring system for real-time monitoring to overcome the problems of insufficient data support in manual, video and monitoring stations, so as to achieve accurate monitoring to meet the needs of air pollution control and prevention.
“Large area”, “accurate”, “efficient and fast”, UAV technology seems to be born in the face of such keywords.
At present, the application of UAV in atmospheric environment monitoring mainly includes the following three directions:
1、 UAV + visible camera
At present, the most widely used in environmental protection is the traditional UAV + Visible PTZ. It is undeniable that a simple camera or even a zoom camera has been able to bring new ideas to environmental monitoring. However, the observation of air pollutants by the visible camera only stays in the stage of photography and video, lacks accurate monitoring data as support, and is affected by light, rain and fog Due to the low resolution of the camera and other factors, it can only monitor the visible pollution sources with high pollution concentration, such as black chimney and straw incineration. Conventional visible light load can only be regarded as icing on the cake in terms of environmental protection. It is difficult for environmental supervision personnel to use it effectively. If they buy it back, they don’t need it. In the end, they will only become display props.
2、 UAV equipped with infrared imager
In terms of environmental protection application, the UAV equipped with infrared imager can enable the UAV to monitor at night. The heat distribution visualization, temperature measurement and other characteristics of the thermal imager can effectively find the enterprises producing at night, which can be used as a means to curb the illegal emission at night. The fan images of an enterprise during the day (visible light) and at night (thermal imaging), but the thermal imager is also greatly affected by environmental conditions. In addition, different types of enterprises have different forms of heat distribution, there is no inevitable correlation between emission temperature and emission, and the relevant models are complex, which requires long-term comparison and monitoring to draw detection conclusions, which is difficult to meet the urgent needs of environmental supervision.
3、 UAV + gas sensor
“UAV + gas sensor” means that the UAV carries high-precision gas monitoring sensors or gas acquisition devices with various factors (such as VOCs, SO2 and PM2.5) to conduct a wide-range patrol in the survey area to find the monitoring mode of pollution characteristic factors. With the progress of technology, the accuracy of portable sensor has reached an acceptable level, especially the sensor based on photoionization detector (PID) method, its detection limit and accuracy can even reach ppb level, which is enough to meet the requirements of measuring the concentration of air pollutants.
The UK alphensense sensor recommended by isweek industrial mining network has launched ambient air quality sensors specifically for the field of atmospheric monitoring, including toxic gas sensor A4 / B4 series, photo ion gas sensor pid-ah and PM2 5. The n3-10 sensor has been widely used in the field of atmospheric monitoring.
In terms of theoretical support, the intelligent transportation and UAV application research center of Shanghai Jiaotong University, led by Professor Peng Zhongren, a Changjiang Scholar, has studied the application of UAV in air monitoring as early as 2011 Many papers such as “Research on the vertical distribution law of PM2.5 based on UAV observation” have been cited for many times.
In terms of practical application, at present, Chengdu, Tangshan, Ningxia and other regions take the lead in using UAVs for monitoring and assisting environmental supervision and law enforcement. At the same time, the Environmental Supervision Brigade has investigated and dealt with many illegal enterprises according to the discovery of UAVs.
According to the current development trend of UAV environmental monitoring, UAV equipped with gas sensor is the fastest development defense line.
In the presentation of monitoring results, the visualization of UAV + gas sensor data is not enough.
Environmental supervision and law enforcement pay great attention to timeliness. The illegal discharge of enterprises may only occur in a certain period of time, or even just a moment, which is also one of the reasons why it is difficult for environmental supervision to obtain evidence and law enforcement. The UAV gas sensor will get a large amount of measured data in the air pollution investigation. The traditional method of data analysis and management using Excel can not intuitively show the spatial distribution form of pollutants. A large amount of data needs processing and analysis for multiple working days to draw relevant conclusions, which is difficult to provide decision support for the next monitoring, management and treatment work. Visual processing can fully mine the implicit spatial correlation of data and reveal the migration and transformation law of gas pollutants, which is helpful for scientific researchers, supervision institutions and scientific and intuitive interpretation and analysis of air pollution. Efficient and fast detection methods can provide support for a series of subsequent treatment measures and save labor costs.
Responsible editor: CT