Radar-Based Respiratory Measurement of a Rhesus Monkey by Suppressing Nonperiodic Body Motion Components

Abstract

We propose a method to measure the respiration of a rhesus monkey using a millimeter-wave radar system with an antenna array. Unlike humans, small animals are generally restless and hyperactive in nature, and suppression of their body motion components is therefore necessary to realize accurate respiratory measurements. The proposed method detects and suppresses nonperiodic body motion components while also combining and emphasizing the periodic components from multiple echoes acquired from the target. Results indicate that the proposed method can measure the respiration rate of the target monkey accurately, even with frequent body movements.

Non-contact respiratory measurements of outdoor-housed rhesus macaques (Macaca mulatta) using millimeter-wave radar systems

“…The measurements in this study were limited to resting individuals. Future research should focus on developing measurement techniques capable of withstanding substantial body movements (Sakamoto et al, 2023).…”

Review: Noncontact Sensing of Animals Using Radar

“…The importance of studying non-human primates lies in the possibility of learning the evolutionary history of humans, and the measurement of physiological signals is important to monitoring the cognitive reactions of non-human primates to experimental conditions. Measurements of non-human primates include the measurements of pig-tailed macaques [40], [41], rhe-sus monkeys [42], [43], and chimpanzees [44], [45].…”

“…Recently, mmW (30-300 GHz) radar systems have been widely used because they are available at a low cost and have high sensitivity to small displacements, which makes the mmW radar an attractive option for the physiological measurement of humans and animals. Huang et al [10]- [12] used a 60-GHz radar system; Darlis et al [34] and Wang et al [26], [55] used 77-GHz radar systems; and Tuan et al [4], Matsumoto et al [39], [45], Iwata et al [44], and Sakamoto et al [42] used 79-GHz radar systems. An even higher frequency of 100 GHz was used by Churkin and Anishchenko [9] and Ma et al [50] for radar measurements of rats and rabbits.…”

“…As the accuracy of the radar-based measurement of physiological signals depends on the signal-to-noise ratio (SNR), it is important to set up a measurement system that ensures a high signal power of echoes reflected off the target animals, although the accuracy also depends on the interference of multiple echoes, large body movements [42], and the physiological nature of the target humans/animals. In addition, a low SNR can be acceptable in measuring body movements, whereas a high SNR is required to measure the heartbeat.…”

“…Among studies adopting a larger distance 𝑟 > 2 m, Bao et al [31] set 𝑟 = 2.5 m for a dog, cat, and pig; Ma et al [23] set 𝑟 = 2.5 m for a dog, cat, and rabbit; Yu et al [25] set 𝑟 = 3 m for a dog; Yin et al [22] set 𝑟 = 3 m for a rabbit; Minami et al [43] and Sakamoto et al [42] set 𝑟 > 5 m for a rhesus macaque; Gong et al [51] set 𝑟 = 11.8 m for birds; and van Eeden et al [46] set 𝑟 = 1-3 km for African wild animals. As discussed in this subsection, the distance between the radar antenna and target animal is selected to be less than 3 m in many cases, especially for the measurement of tiny displacements of small animals.…”