Motion-Tolerant Radar-Based Heart Sound Detection

This paper presents a novel motion-tolerant heart sound (HS) detection approach using a millimeter-wave (mmWave) Frequency-Modulated Continuous Wave (FMCW) radar sensor. Recent works demonstrate, in ideal stationary scenarios, radar-based HS detection from chest surface vibrations due to sound pressure waves. However, similar to the known motion distortion problem for radar-based vital signs detection, we have observed that HS measurement is severely affected by other motion artifacts as the HS-induced skin vibration is extremely small (a few micrometers) compared to body motion. Therefore, we develop a phase-tracking-based motion cancellation technique to mitigate the effect of body motions and thus radar-based HS detection is feasible. Simulation and measurement results validate the motion-tolerant radar-based HS detection in the presence of random body motions (RBM).