Accurate sensing of multiple humans buried under rubble using IR-UWB SISO radar during search and rescue

Abstract

Upon the collapse of man-made structures like buildings, bridges, etc., the search and rescue personnel must locate and rescue the buried people. Considering the radar's beam width, victims may be buried under rubble at the same longitudinal range from the radar and fall into blind spots due to missed detections. Here, we will address this problem efficiently. Experimental work has been undertaken by placing subjects under randomized rubble with an impulse-radio ultra-wideband (IR-UWB) radar placed above the debris. Pre-processing the raw data removes stationary and non-stationary clutter, while the novel variance threshold method proposed herein identified the potential targets. The inter-target dynamic range (ITDR) concept is presented to extract the exact number of targets per range bin by considering the difference in the power level of consecutive dominant target breathing frequencies. Consequently, variable mode decomposition (VMD) is used to extract the breathing signal. An average correlation coefficient of 87.9 % was achieved between the target vital signs from the radar and the respiration belt. Finally, a range compensation algorithm is developed to increase detection efficiency to an average of 7.23 % range error. Thus, multiple targets are successfully extracted with reasonably accurate range and vital signs under varying target postures. � 2022 Elsevier B.V.