机械振动干扰下人体目标识别技术研究

Research of human target recognition technology under mechanical vibration interference

目的:探索在大型工程机械作业振动干扰下,基于集合经验模态分解(ensemble empirical mode decomposition,EEMD)的熵识别方法用于超宽带(ultra-wideband,UWB)生物雷达识别压埋人体的可行性。方法:使用中心频率为500 MHz的UWB生物雷达采集装载机怠速、挖掘挥铲和移动3种常规作业的振动信号,并分析振动信号的时频特性。对雷达回波信号矩阵中的慢时间信号进行EEMD,分析本征模态函数能量分布复杂度的熵值,根据熵特征及探测区域凹口宽度识别人体目标。分别在室外自由空间和穿墙条件下进行机械振动干扰下的人体目标探测实验以验证该方法。结果:作业机械和人体目标的EEMD熵值明显低于其他区域的熵值,机械振动信号的熵谱图凹口宽度大于人体目标的熵谱图凹口宽度,可据此分别识别作业机械和人体。结论:该方法在一定程度上提升了机械作业振动干扰下人体目标的识别效率,为复杂条件下UWB生物雷达探测人体目标提供了有意义的借鉴。

Objective To explore the feasibility of the ensemble empirical mode decomposition(EEMD)entropy recognition method to identify buried people by ultra-wideband(UWB)bio-radar under the interference of construction mechanical vibration.Methods A UWB bio-radar with a center frequency of 500 MHz was used to acquire vibration signals of the loader during three conventional operations:idling,digging and shovel swinging as well as moving,and to investigate the time-frequency characteristics of the vibration signals.The EEMD of the slow time signals in the radar echo signal matrix was carried out to analyze the entropy value of the energy distribution complexity of the eigenmode function,and human targets were identified based on the entropy characteristics and the notch width of the detection area.Experiments on human target detection under mechanical vibration interference were carried out in outdoor free space and through-wall conditions respectively to validate the method proposed.Results The EEMD entropy values of the operating machine and human targets were significantly lower than those of the other regions,and the notch width of the entropy spectra of the mechanical vibration signals was greater than that of the human targets,whereby the operating machine and the human body could be identified separately.Conclusion The method proposed enhances to some extent the identification efficiency of human targets under mechanical vibration interference,and provides references for human target detection by UWB bio-radar under complex conditions.[Chinese Medical Equipment Journal,2021,42(6):21-25,31]