Study on Chest Expansion in Lateral Plane Using Accelerometers

Abstract

The chest expansion measurement is a part of physical therapy to track the progress of rehabilitation for checking the performance of lungs. The chest expansion mechanism in lateral plane moves like a bucket handle. It moves more than one direction. This paper measures the chest expansion by using accelerometers in lateral plane. The MEMS accelerometer measures acceleration in each axis and can use double integral to convert acceleration to displacement. The acceleration in each axis is affected from the Earth gravity and then uses simple trigonometric equation to eliminate the Earth gravity from the acceleration data. Taking deep breath measures chest expansion measuring, therefore the signal has low frequency. This paper improve the accuracy by subtracting the signal with the average data to eliminate offsetting error and using low-pass filter for canceling the noise at high frequency. The result shows the displacement error of acceleration and chest caliper.