ABSTRACT
This chapter describes the approach of using the finite-difference time-domain (FDTD) numerical simulation approach and synthetic computational experiments to investigate the effectiveness of the ultrawideband (UWB) radar technique for human vital sign detection, known as bioradiolocation. The direct use of bioradiolocation can provide contactless monitoring of human vital signs in security surveillance, biomedical engineering applications, and search and rescue of victims under collapsed building debris caused by catastrophic earthquakes, along with many other applications. The first section summarizes the major features of human vital signs pertinent to UWB radar detection. Next, it discusses the approach to generating of human vital signs for numerical simulation. Then, it gives a brief summary of the FDTD numerical simulation technique. In a sequence from simple to more complicated, it then demonstrates the effectiveness of this modeling approach in three following sections, with each of the three describing a typical scenario in vital sign detection. The first example is the through-wall detection of a single person. It describes the detailed approach for how to embed the model of a living human subject behind a concrete wall into the computational domain. Besides vital sign detection, it also briefly discusses the possibility of imaging the existence of a human being with MIMO interferometric radar in this section. The second example is a search and rescue scenario model at
CONTENTS
7.1 Introduction ........................................................................................................................ 271 7.1.1 Abstract ................................................................................................................... 271 7.1.2 Introduction to Bioradiolocation Radar .............................................................. 272
7.2 Fundamental Observations to Direct Bioradiolocation Signal Modeling ................. 273 7.3 Generation of Human Vital Signs for Numerical Simulation ..................................... 274 7.4 Finite-Difference Time-Domain Modeling Techniques ............................................... 275 7.5 UWB Radar Detection of a Single Person behind a Wall .............................................277 7.6 The Model of Collapsed Building with Two Living Victims ...................................... 282 7.7 Line-of-Sight Vital Sign Monitoring of Three Patients .................................................288 7.8 Summary and Conclusions .............................................................................................. 292 References ..................................................................................................................................... 293
an earthquake disaster site. The model consists of two human beings with different characteristics of vital signs, that is with different cardiorespiration features, posed in different positions, and buried at different depths in the debris. This model of the collapsed building was developed based on a real situation from an earthquake disaster site. Analysis of the synthetic data indicates that the UWB impulse radar can identify and separate the human subjects’ vital sign for a radar record as short as 20 sec. The third example is a scenario of line-of-sight, noncontact detection for the vital signs from three human subjects simultaneously for monitoring purpose. All of the simulation results have been verified with physical experiments using impulse UWB radar with real human subjects in presence.
