Research status and direction of ultra-wide band radar technology for borehole rescue

In the mine rescue process, the current video and audio based borehole life information identification technology has the problems of video obstacle failure and fast speed of sound wave attenuation. In order to solve the above problems, the ultra-wide band (UWB) radar technology that can penetrate coal rock bodies, brick walls and other obstacles for non-contact measurement and realize life information identification is studied. The application status and existing problems of UWB radar technology in mine borehole rescue are analyzed from three aspects, including UWB electromagnetic wave transmission attenuation characteristics, clutter filtering and optimization, and the target life identification method. ① UWB electromagnetic waves can detect and locate the life information of people behind obstacles. Its attenuation is related to the electric field, magnetic field strength, frequency and medium. However, the current research on the attenuation characteristics of UWB electromagnetic wave transmission lacks the research on the law relationship between various coal and rock masses and UWB electromagnetic wave transmission attenuation at different temperatures, detection frequencies, and metamorphic degrees. There are few researches on the relationship between UWB electromagnetic wave frequency, incident angle, polarization form and other key parameters and change characteristics and UWB electromagnetic wave attenuation. ② The methods such as empirical mode decomposition method and MUSIC method can filter the clutter in UWB electromagnetic waves. But the methods lack accurate extraction and scientific representation of effective wave characteristics and information after clutter filtering, which makes it difficult to improve the speed and accuracy of life information characteristics extraction and identification. ③ UWB electromagnetic waves can capture the life signs of multiple target people behind obstacles, such as breathing or heartbeat. The use of multiple radar observation points can improve the accuracy of life information detection in a low signal-to-noise ratio environment. However, the current research lacks systematic identification and quantitative analysis of breathing, heartbeat, chest undulation, body temperature in multiple directions and from multiple angles. And the current research lacks an optimized method for life information identification models. In order to solve the existing problems, the research directions of UWB radar technology for borehole rescue application are pointed out as follows. ① It is proposed to study the influence of the properties of coal and rock masses and electromagnetic wave related parameters on the transmission attenuation of UWB electromagnetic wave in coal and rock masses under different conditions. The law of transmission attenuation is obtained. ② It is suggested to study on clutter filtering optimization and echo characteristic extraction algorithms suitable for mine environment, and use the effective characteristics in the echo to establish a learning sample database. ③ It is proposed to construct the personnel life information identification model applicable to the mine environment, and continuously optimize the model with the sample database to improve the accuracy and speed of life information identification.