Measurement of respiratory rate with inertial measurement units

Abstract

Demographic changes and increasing air pollution entail that monitoring of respiratory parameters is in the focus of research. In this study, two customary inertial measurement units (IMUs) are used to measure the breathing rate by using quaternions. One IMU was located ventral, and one was located dorsal on the thorax with a belt. The relative angle between the quaternion of each IMU was calculated and compared to the respiratory frequency obtained by a spirometer, which was used as a reference. A frequency analysis of both signals showed that the obtained respiratory rates vary slightly (less than 0.2/min) between the two systems. The introduced belt can analyse the respiratory rate and can be used for surveillance tasks in clinical settings.

An Overview of Wearable Piezoresistive and Inertial Sensors for Respiration Rate Monitoring

“…In [109], A. Shabeeb et al used an ADXL345 digital accelerometer interfaced with an Arduino UNO board to collect raw data concerning chest movement during breathing, passed to the LabVIEW platform for data processing and visualization. A Butterworth band-pass filter with 0.1 Hz low cut-off frequencies and 1 Hz high cut-off frequencies was applied to the collected raw data [109,110]. The derived signal was amplified 200 times; a Wavelet Analysis (WA) multiscale peak detection function was used.…”

A Respiratory Motion Estimation Method Based on Inertial Measurement Units for Gated Positron Emission Tomography

“…Therefore, there is need for further development of respiratory motion measurement technology, and in particular, the use of MEMS motion sensors has been investigated intensively in the recent years; for a selection of recent and notable papers on this subject, cf. [6][7][8][9][10][11][12][13][14][15][16][17][18][19][20].…”

“…Some ( [7][8][9][10]) articles consider only the use of a single accelerometer to estimate the breathing rate or the respiratory motion. More recent articles typically consider using an IMU which contains an accelerometer and a gyroscope ( [11][12][13][14][15][16]), or an accelerometer, a gyroscope and a magnetometer ( [6,17,18]). In addition to these, a method for estimating respiratory motion using only a magnet and a MEMS magnetic sensor is presented in [19].…”

“…The number of MEMS sensors used form estimating respiratory motion varies between studies. Methods utilizing multiple IMU sensors apply common mode filtering [6,13,14,17,20], independent component analysis (ICA) [7], or a kinematic joint model [18] to achieve position independence or to mitigate motion artifacts during exercise.…”

“…For example, if an IMU is attached to the chest of a subject, it is used to measure the changes of the thoracic angle according to the phase of the respiration cycle. Such a measurement is sufficient for estimating the breathing rate (including inspiratory and expiratory time) [6,13,17], flow waveform [7], and relative changes in tidal volume [14], but it cannot be used to measure the absolute position of the sensor in relation to a fixed zero level without additional assumptions (such as rigid joints in the sensor constellation [18]). In fact, to the best of the authors' knowledge, in the current literature there is only one article [11] besides this work, which has considered the estimation of absolute respiratory motion using a MEMS motion sensor.…”