Large-Scale Body Movement Cancellation in FMCW Radar Respiration Detection

Detecting respiration using radar is an attractive approach for noncontact health monitoring based on sensing chest displacement. This study addresses the challenge of detecting respiration with frequency-modulated continuous-wave (FMCW) radar under large-scale body movements. In such conditions, the radar detects a mixed chest displacement including respiration and body movements, which might severely distort the detected displacement. To this end, we propose a respiration detection system incorporating a novel iterative displacement alignment method and dual radar devices. First, the iterative displacement alignment method compensates for chest displacement by aligning the signals, enabling the detected displacement with less distortion. Then, dual radar devices further cancel out body movement by combining the chest displacement detected from the front and back of the body. These processes help isolate the respiration and improve detection performance. Numerical simulations and experimental validations demonstrate the effectiveness of the proposed method for respiration detection.