Noncontact Respiratory Measurement for Multiple People at Arbitrary Locations Using Array Radar and Respiratory-Space Clustering

Koda, Takato; Sakamoto, Takuya; Okumura, Shun; Taki, Hirofumi

doi:10.1109/access.2021.3099821

Cited by 27 publications

(32 citation statements)

References 41 publications

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“…• The proposed method improves the estimation accuracy of respiration by integrating data from multiple radar systems. These issues have not yet been addressed by existing studies, including ours [39], which demonstrates the novelty and innovation of this work. Table I compares this study and other existing studies.…”

Section: Introductionmentioning

confidence: 91%

“…Next, using each radar image |I m (t, r m )| 2 , a point cloud is generated according to [39]. The X-means clustering technique [39], [43] is then applied to the point cloud and the clusters c 1 , c 2 , • • • , c Nm are generated; these clusters correspond to the N m targets. Note that N m is the number of targets detected using the m-th radar system.…”

Section: Imaging and Clustering Of Human Targets Using Multiple Radar Systemsmentioning

confidence: 99%

“…For presentation purposes, we generated a radar cluster image C m (t, r m ) that takes the values {0, 1, 2, • • • , N m }, which correspond to the indices of the clusters c 1 , c 2 , • • • , c Nm except for 0; C m (t, r m ) = 0 indicates that no cluster is associated with r m . Finally, the representative position r (n) m of cluster c n in the m-th radar image is calculated [39]; the clusters' representative positions are then processed in the proposed data fusion algorithm, which combines multiple radar images.…”

Section: Imaging and Clustering Of Human Targets Using Multiple Radar Systemsmentioning

confidence: 99%

“…Another advantage of radar-based respiratory measurement is the possibility of performing simultaneous measurements of the respiration of multiple people using only a single device. There have been numerous studies in which a single-radar system has been used to measure the respiration of multiple people [21]- [39]. For example, Nosrati et al [36], Islam et al.…”

Section: Introductionmentioning

confidence: 99%

“…For example, Nosrati et al [36], Islam et al. [37], Su et al [38], and Koda et al [39] used singleradar systems to demonstrate simultaneous measurement of the respiration of two, three, three, and seven people, respectively. These studies, however, did not consider the effect of the shadowing problem, in which an echo from one target person is blocked by another person located between the first person and the radar system; this results in the radar system being unable to detect a person (or some people) when multiple people are present in the scene.…”

Section: Introductionmentioning

confidence: 99%

See 4 more Smart Citations

Multiradar Data Fusion for Respiratory Measurement of Multiple People

2021

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This study proposes a data fusion method for multiradar systems to enable measurement of the respiration of multiple people located at arbitrary positions. Using the proposed method, the individual respiration rates of multiple people can be measured, even when echoes from some of these people cannot be received by one of the radar systems because of shadowing. In addition, the proposed method does not require information about the positions and orientations of the radar systems used because the method can estimate the layout of these radar systems by identifying multiple human targets that can be measured from different angles using multiple radar systems. When a single target person can be measured using multiple radar systems simultaneously, the proposed method selects an accurate signal from among the multiple signals based on the spectral characteristics. To verify the effectiveness of the proposed method, we performed experiments based on two scenarios with different layouts that involved seven participants and two radar systems. Through these experiments, the proposed method was demonstrated to be capable of measuring the respiration of all seven people by overcoming the shadowing issue. In the two scenarios, the average errors of the proposed method in estimating the respiration rates were 0.33 and 1.24 respirations per minute (rpm), respectively, thus demonstrating accurate and simultaneous respiratory measurements of multiple people using the multiradar system.

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Section: Introductionmentioning

confidence: 91%

Section: Imaging and Clustering Of Human Targets Using Multiple Radar Systemsmentioning

confidence: 99%

Section: Imaging and Clustering Of Human Targets Using Multiple Radar Systemsmentioning

confidence: 99%

Section: Introductionmentioning

confidence: 99%

Section: Introductionmentioning

confidence: 99%

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Multiradar Data Fusion for Respiratory Measurement of Multiple People

2021

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First noncontact millimeter‐wave radar measurement of heart rate in great apes: Validation in chimpanzees (Pan troglodytes)

Matsumoto,

Iwata,

Sakamoto

et al. 2024

American J Primatol

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Heart rate is a crucial vital sign and a valuable indicator for assessing the physical and psychological condition of a target animal. Heart rate contributes to (1) fundamental information for cognitive research, (2) an indicator of psychological and physical stress, and (3) improving the animal welfare of captive animals, especially in nonhuman primate studies. Heart rate has been measured using a contact‐type device; however, the device burdens the target animals and that there are risks associated with anesthesia during installation. This study explores the application of heartbeat measurement techniques using millimeter‐wave radar, primarily developed for humans, as a remote and noninvasive method for measuring the heart rate of nonhuman primates. Through a measurement test conducted on two chimpanzees, we observed a remarkable correspondence between the peak frequency spectrum of heart rate estimated using millimeter‐wave radar and the mean value obtained from electrocardiograph data, thereby validating the accuracy of the method. To the best of our knowledge, this is the first demonstration of the precise measurement of great apes' heart rate using millimeter‐wave radar technology. Compared to heart rate measurement using video analysis, the method using millimeter‐wave radar has the advantage that it is less susceptible to weather and lighting conditions and that measurement techniques for multiple individuals have been developed for human subjects, while its disadvantage is that validation of measurement from long distances has not been completed. Another disadvantage common to both methods is that measurement becomes difficult when the movement of the target individual is large. The possibility of noncontact measurement of heart rate in wild and captive primates will undoubtedly open up a new research area while taking animal welfare into consideration.

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Outdoor noncontact respiratory measurements of unrestricted rhesus macaques (Macaca mulatta) using millimeter‐wave radar

Minami,

Sanematsu,

Iwata

et al. 2024

American J Primatol

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Respiration is an invaluable signal that facilitates the real‐time observation of physiological dynamics. In recent years, the advancement of noncontact measurement technology has gained momentum in capturing physiological activities in natural settings. This technology is anticipated to be found not only in humans but also in nonhuman primates. Currently, the predominant noncontact approach for nonhuman animals involves measuring vital signs through subtle variations in skin color. However, this approach is limited when addressing areas of the body covered with hair or when working in outdoor settings under fluctuating sunlight. To overcome this issue, we focused on noncontact respiratory measurements using millimeter‐wave radar. Millimeter‐wave radar systems, which employ millimeter waves that can penetrate animal fur and estimate respiration‐derived periodic body motion, exhibit minimal susceptibility to sunlight interference. Thus, this method shows potential for conducting noncontact vital measurements in natural and outdoor settings. In this study, we validated a millimeter‐wave radar methodology for capturing respiration in outdoor‐housed rhesus macaques (Macaca mulatta). The radar was positioned beyond the captive enclosure and maintained at a distance >5 m from the target. Millimeter waves were transmitted to the target, and the reflected waves were used to estimate skin surface displacement associated with respiration. The results revealed periodic skin surface displacement, and the estimated respiratory rates weres within the reported range of respiratory rates for rhesus macaques. These results suggest the potential applicability of millimeter‐wave radar for noncontact respiration monitoring in outdoor‐living macaques without anesthesia or immobilization. The continued advancement of noncontact vital measurement technology will contribute to understanding primate mental and physical dynamics during their daily life.

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Noncontact Respiratory Measurement for Multiple People at Arbitrary Locations Using Array Radar and Respiratory-Space Clustering

Cited by 27 publications

References 41 publications

Multiradar Data Fusion for Respiratory Measurement of Multiple People

Multiradar Data Fusion for Respiratory Measurement of Multiple People

First noncontact millimeter‐wave radar measurement of heart rate in great apes: Validation in chimpanzees (Pan troglodytes)

Outdoor noncontact respiratory measurements of unrestricted rhesus macaques (Macaca mulatta) using millimeter‐wave radar

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