Biomedical Engineering Reference
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right side. Totally, the participant needed to change the sleep position five times. Be-
sides, the experimental procedure needed to be done twice, including a condition that
the participants sleep with a thin quilt, and a condition that they sleep with no quilt.
Before each task, participants were reminded not to breathe deliberately.
Experimental Results. The sleep measurement were divided into four different con-
ditions in this experiment, including two sleep positions (side-lying and supine) and
two circumstances (sleep with a thin quilt and sleep with no quilt). For each condi-
tion, the total numbers of correct head detection frames were calculated manually as
well as the total numbers of correct torso detection frames. The average of accurate
rate and standard deviation in each condition are listed below. The experimental re-
sults showed that while participants slept with no quilt, the measurement accuracy of
head detection was 98% (SD = 0.036) while in the side-lying position, and it was
99.3% (SD = 0.018) in the supine position. Moreover, the measurement accuracy of
torso detection was 91.5% (SD = 0.16) in the side-lying position, and it was 99.3%
(SD = 0.01) in the supine position. Besides, while participants slept with a thin quilt,
the measurement accuracy of head detection is 96.7% (SD = 0.11) in the side-lying
position, and it was 99.5% (SD = 0.02) in the supine position. Moreover, the mea-
surement accuracy of torso detection was 94.5% (SD = 0.1) in the side-lying position,
and it was 99.5% (SD = 0.008) in the supine position. Overall, the average accurate
rate was 98.4% in head detection and 96.4% in torso detection. The experimental
results of head and torso detection are shown in Fig. 6.
Head Detection
Torso Detection
100%
80%
99.5%
99.3%
96.7%
98.0%
60%
99.5%
99.3%
94.5%
91.5%
40%
20%
0%
Side lying
Supine
Side lying
Supine
Sleep without quilt
Sleep with a thin quilt
Fig. 6. Results of head and torso detection in experiment I
For breath measurement, the measurement accuracy is defined as the ratio of the
totally breathing cycles we detected to the totally breathing cycles the RIP system
detected. The measurement results of the RIP system was regarded as the ground truth
of the breathing conditions. The experimental results show that while the user sleeps
with no quilt, the measurement accuracy of breathing rate was 81.9% (SD = 0.11) in
the side-lying position, and it was 90.4% (SD = 0.07) in the supine position. Moreo-
ver, while the user sleeps with a thin quilt, the measurement accuracy of breathing
rate was 84.1% (SD = 0.05) in the side-lying position, and it was 88% (SD = 0.08) in
the supine position. Overall, the average accurate rate of breath measurement was
86.3%. The experimental results of the breath measurement are shown in Fig. 7. For
sleep position, the experimental results showed that in the circumstance of sleeping
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