Experimental evaluation on tracking sitting posture with sitting center of pressure and contact area

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Experimental evaluation on tracking sitting posture with sitting center of pressure and contact area


Author: Mak, Sheung Chi Caleb
Title: Experimental evaluation on tracking sitting posture with sitting center of pressure and contact area
Degree: M.Sc.
Year: 2014
Subject: Sitting position.
Hong Kong Polytechnic University -- Dissertations
Department: Interdisciplinary Division of Biomedical Engineering
Pages: vii, 72 leaves : illustrations (chiefly color) ; 30 cm
Language: English
OneSearch: https://www.lib.polyu.edu.hk/bib/b2762589
URI: http://theses.lib.polyu.edu.hk/handle/200/7808
Abstract: Computer cannot act intelligently without user input, so as a chair. A chair cannot sense the sitting posture and intention of the occupant to provide useful information before symptom of body damage comes in prolonged sitting habit. The sitting posture tracking project enables a chair to sense the occupants sitting posture and needs. Using pressure sensing sheet mounted on chair seatpan to capture the center of pressure and contact area data created a Sitting Pressure Distribution Measurement System. Ten volunteers contributed in the experiment, and the subject body weight was measured and compared with sitting contact area in nine sitting postures, which are commonly found in office environment. A positive relationship was found with correlation coefficient R-value from 0.7 to 0.96 between subject’s body weight and sitting contact area. Therefore, a mathematical model can be developed to predict sitting contact area by inputting body weight. In posture tracking, all nine sitting postures in AP/ML center of pressure and sitting contact area were compared in pair, and 34 out of 36 pairs (94.4%) can be found having significant difference (P<0.05). In order to improve performance, 9 sitting postures were divided into 4 big groups with similar AP/ML direction, and the results show that 100% significant difference (P<0.05) between all grouped pairs. As shown in this project, most cross leg sitting posture cannot be distinguished from the same AP or ML direction of sitting posture. Future work should be aimed at improving the performance of sitting posture tracking by inputting various factors from subjects and measurement system. Further development will be toward dynamic posture tracking which means from one sitting posture to another sitting posture.

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