High Precision Laser Dust Detecting System

With the rapid development of science and technology and continuous promotion of the industrialization process, more and more damage of the natural environment is created. Dust, as an important pollution source of environmental degradation, takes severe harm to our living environment and people’s physical and mental health. Therefore, the timely and effective measures should be taken to test the dust concentration in the environment and then remove dust, which can effectively improve the life safety coefficient and the environment quality. In recent years, the national related departments attach great importance to the problem of dust pollution and independently research and develop a lot of dust detection equipments, which are applied plentiful to monitor, prevent and control the dust of the environment. In the existing dust detecting equipment, the poor stability of sensors, which make the measuring accuracy lower and calibration control difficulty bigger, cause inconvenience for the products’promotion and later maintenance. Thus, we need to research a high precision dust detecting system with independent intellectual property rights by ourselves on the basis of the existing dust detecting equipment.As for referring to a large number of literatures, this article adopts light scattering method which can obtain very high precision of the dust concentration by on-line monitoring dust concentration. Based on this method, we design the laser dust concentration detecting system which includes four parts:the overall structure design, optical design, hardware circuit design and software programming design. Then, we calibrate data and analyze the stability of this system using a serial port communication module. Finally, by this system, we measured the field environment’s dust concentration through Origin software analyzing the measured data compared with the released data of national control point. The results show that the stability of the system is also very good. The research content of this article is divided into several parts, as following:The first part:The optical part design of dust detecting system. By comparing the advantages and disadvantages of various dust detecting methods, based on the overall requirements of the performance of the dust detecting system, we finally design out the overall structure of optical part by laser scattering method, including laser light source, the design of the air chamber and the probe selection.The second part:The hardware circuit design of dust detecting system. The Altium Designer software is applied to design circuit diagram of dust collection and processing module, and complete the PCB circuit layout for producing PCB circuit boards.The third part:The software programming design of dust detecting system. We mainly utilize Keil software for design of dust collection program, data filtering program, dust calculating program.The fourth part:The optimization of dust detecting system. A mini fan is added in the side of dust sensors circuit, which can simulate the impact of PM2.5 and PM10 concentration in the dust by environment change in advance.The fifth part:Debugging and field measurements of dust detecting system. After connecting the dust detecting system to the computer using a serial port communication module, we debug the dust detection system. Then, using the dust detecting system measures PM2.5 and PM10 density of environment gas.The sixth part:The performance evaluation of dust detecting system. The field measured data is processed and compared with the released data of national control point,and analyzed by Origin software. Finally, we comprehensively evaluate the stability and reliability performance of the dust detecting system.The dust detecting system developed by this paper breaks through two points in the structure:one is overcoming the low precision and poor stability shortcomings compared with infrared dust concentration measurement; the other is designing a fan channel for the sensor, which makes the measurement accuracy more precise. The dust detecting system can be applied to measure dust concentration changes of the construction site, and its measurement range can achieve a few mg per cubic meter of dust. In contrast detection, it can realize on-line calibration. Its detection precision and stability can be improved when using the adaptive filtering method.