Research On Key Technology Of Detecting Missing Persons In School Bus Based On Millimeter Wave Radar

In order to prevent the problem of missing personnel,the technology of personnel detection is studied.Physical sign signal is the physiological signal of human body.When millimeter wave radar is used to detect people,the received echo signal not only contains physical sign signal,but also contains clutter interference.Therefore,how to effectively solve the clutter interference and single-person and multi-person detection problems is of great significance to the research of MMW radar missing personnel detection technology.In this thesis,echo signal preprocessing technology,single-person detection technology and multi-person detection technology are deeply studied.Aiming at the clutter interference in the echo signal,the millimeter-wave radar echo signal is preprocessed.The noise in radar echo signal is analyzed and the echo signal with noise is modeled.In this paper,CA-CFAR algorithm,GO-CFAR algorithm,SO-CFAR algorithm,OS-CFAR algorithm and improved target constant false alarm detection algorithm are used to remove clutter interference of simulated noisy echo signal.Among them,alarm leakage phenomenon occurs when CA-CFAR algorithm,GO-CFAR algorithm and OS-CFAR algorithm are adopted.The application of SO-CFAR algorithm will lead to false alarm phenomenon,while the improved target constant false alarm detection algorithm can avoid false alarm and missed alarm phenomenon,and has the best effect of suppressing clutter interference.For the problem of personnel omission,this paper carries out detection from two aspects: single person and multiple people.When a single person missed,this paper modeled the sign signal of a single person and detected it by using EEMD algorithm,STFT and wavelet transform of improved threshold function.The signal-to-noise ratio(SNR)and root-mean-square error(RMSE)were 15.25 d B,22.63 d B and 23.67 d B,respectively.The root mean square error values are 0.046,0.042 and 0.039,respectively.The results show that the wavelet transform of the improved threshold function has the best detection effect.In the case of omission of multiple people,this paper takes two people as an example to model the sign signal of two people,constructs the cost function of MUSIC algorithm,and estimates the MUSIC spectrum of sign signal of two people under three kinds of signal-to-noise ratio(0d B,-10 d B and-20 d B).Experimental results show that the detection effect is optimal at 0d B.The school bus personnel omission prevention based on millimeter wave radar is verified experimentally.Firstly,the hardware structure of IWR1642 millimeter wave radar is introduced.CCS software is used to compile the program,and Uni Flash is used to write the program into millimeter wave radar.Secondly,the data received by millimeter wave radar is displayed in GUI interface on PC.Finally,the detection of respiratory signal and heartbeat signal is completed,and the feasibility of millimeter wave radar detection technology is verified through experiments.