Research On Passive Moving Target Positioning Technology In Mine Based On Phase Difference Ranging

With the development of intelligent equipment and Internet of Things,the process of mine safety production is gradually becoming unmanned and less human.The accuracy,real-time and reliability of moving target positioning is of great significance to safety production management,coordinated work of machines and intelligent unmanned production in coal mines.However,the positioning environment of the underground roadway is complicated,and there is a dense multipath interference phenomenon,which results in poor positioning accuracy.Therefore,based on the analysis of the existing anti-interference and positioning methods,a passive harmonic backscatter anti-interference model is established,and a passive moving target positioning technology in mine based on phase-difference ranging is proposed.Firstly,the complex positioning environment of coal mine and the dense multipath phenomenon caused by it are analyzed.The shortcomings of the current null matrix anti-interference technology are studied.In order to solve the problems of dense multipath and large phase errors caused by frequency reflection and scattering of electromagnetic waves in mine,a downhole anti-multipath interference model based on passive harmonic backscatter is proposed which is used to generate an available harmonic signal.It realizes frequency diversity of uplink and downlink to suppress dense multipath interference of the mine.The experimental simulations and comparisons indicate that passive harmonic backscatter tags have good anti-interference ability.Secondly,in order to overcome the shortcomings of traditional multi-frequency continuous-wave phase difference ranging algorithms such as low positioning accuracy and limited frequency selection,a Coherent Sending broadband Multifrequency Continuous-wave(CSMCW)phase difference ranging algorithm is proposed.In order to maximize the tolerance of the phase error,the genetic algorithm is used to generate the optimal frequency combination suitable for the mine.The range ambiguity is solved by coherent sending multi-frequency continuous-waves and a constrained minimum mean square error,which achieve ranging,positioning and recognition under the condition of large phase error.The feasibility of the CSMCW algorithm was verified through experimental simulations and comparisons.The simulation results indicate that compared with the quadratic phase difference ranging algorithm and the staggered frequency difference ranging algorithm,the CSMCW ranging algorithm based on the harmonic backscatter anti-interference model is more robust,and the positioning range can reach the centimeter resolution under the condition of low signal-to-noise ratio,and can achieve high-precision positioning of moving targets in mine.Finally,take the pose recognition of the roadheader as an example.The application effect of passive moving target positioning technology in mine is studied.The CSMCW phase difference ranging algorithm based on harmonic backscatter is used for pose recognition of roadheader.The simulation results show that the above algorithm guarantees a better recognition effect of the roadheader’s attitude and posture angle,and can meet the application requirements of the positioning of underground moving targets in the future.There are 36 pictures,5 tables,and 82 references in the paper.