Development of a Projection Moiré System for Measuring large deformation of a compressed air cell - Advancing a smart air cushion system for preventing pressure ulcers

• Main Authors: Sheng-Lin Cheng, 鄭聖霖
• Other Authors: Chih-Kung Lee
• Format: Others
• Language: zh-TW
• Published: 2016
• Online Access: http://ndltd.ncl.edu.tw/handle/4chdem

碩士 === 國立臺灣大學 === 工程科學及海洋工程學研究所 === 104 === Pressure ulcer is one of the common problems for wheelchair patients with spinal cord injury. It has become not only a physical and economic burden on wheelchair patients, but also a big challenge to health care system. In order to fundamental overcome this problem, we developed a smart air cushion system made by air-cell array. By providing the capability to adjust pressure of each air cell, localized stress can be decreased dynamically. To identify the characteristic profile of air cell and use it for controlling air cell function, we develop a Fringe Projection System to measure the large deformation of a compressed air cell. Thus, the characterized performance of air cell and internal pressure can be correlated. This characteristic curve will be used as a reference to operate the smart air cushion system and provide weight value for diagnostic purposes. Thus, the purpose of this study is to understand the behavior of the air cell of a smart air cushion system. . Fringe projection method is used to measure the surface profile of a air cell, the large deformation under different applied weight is measured. Physical parameters of air cells volume, height and amount of expansion are studied to correlated to specific trends in cross section analysis. Under the two-dimensional measurement, it is confirmed that the expanded behavior of the air cell under different weights has an elliptical deformation and is fitted by a bivariate quartic polynomial equation. Subsequently, COMSOL multiphysics is used to perform finite element method to simulate surface pressure distribution of an air cell and deformation of the sidewall. In addition, by comparing with fringe projection measured data, the results of the optical measurement and consistency are verified. Finally, using an open access Arduino controller to control a single air cell inflation and deflationfor studying the performance of the air call under different loading. Based on the quantified characteristic curve, it can be applied to selectively reduce the local buttock tissue pressure by using the smart air cushion system. In addition, it can take a patient’s weight measurement for diagnosing purposes.