2014 Volume 22 Pages 203-211
Daily continuous measurement and analysis for lung volume are important in establishing early detection of lung diseases. Most e-textile-based wearable spirometers use torso girths to estimate lung volume, including chest girth and abdomen girth. However, if we assume to use only one calibration posture to minimize users’ burden, estimation errors will increase when users assume postures other than ones used for calibration. To resolve this issue, we analyzed movement of torso girths with motion captures at standing, sitting and forward-bending (30, 60, 90 degrees) postures; and found that liner adjustment is suitable for reducing estimation errors depending on forward-bending postures. The adjustment with coefficients optimized with a brute-force method improved the differences of estimation errors between the calibration posture and the others from 0.30±0.12 liter to 0.03±0.05 liter. The adjustment with coefficients yielded from torso-girths’ average values of each posture improved the differences to 0.23±0.09 liter.
