Research on Multitarget Vital Sign Detection Using IR-UWB Radar in Occlusion Scenarios

Impulse radio ultrawide band (IR-UWB) radar has garnered significant attention as a noncontact sensor for vital signs detection, particularly in disaster relief scenarios. However, accurately determining the number and distance of measured targets from radar, especially when occluded by objects, as well as extracting weak respiration and heartbeat information from complex radar echo signals, remains a major challenge. This article proposes a vital signs removal method based on matching tracking (VSR-MP) to eliminate the effects of wall reflections and the diffusion of target vital signs. It is combined with an improved high-precision multisignal classification (IHAMUSIC) algorithm to determine the number and distance of the targets under test from radar. To enhance vital sign extraction, a variational modal decomposition technique based on the sparrow search algorithm (SSA-VMD) is utilized for reconstructing target vital signs. To address weak heartbeat signals, this article introduces a novel approach combining the comb filter and coherent integration (CI) technique. The experimental results demonstrate that the method proposed in this article can effectively and accurately identify targets obscured by obstacles while detecting the vital sign signals of the targets under test. The average respiratory rate (RR) error is 3.98%, and the average heart rate (HR) error is 4.57%, even in the case of multiple targets.