| Summary: | 碩士 === 國立臺灣科技大學 === 工業管理系 === 102 === With the development of science, technology, and the improvement of wireless network, the handheld mobile devices became popular. Following the invention of tablets, people can acquire the information needed at any time people without the need to sit in front of desktop or laptops typing or using the mouse. However, tablet is still considered as a hand-held device that requires human’s hand(s) to hold it while using or operating this device. When a tablet is used for a specific long period of time, it may cause discomfort or even damages to upper-extremity muscle and/or other parts of human muscle.
The main purpose of the study is to explore effects and loadings on the upper-extremity when different body postures are used to hold a tablet. The experiment is designed into two stages. While the first stage has the subjects to use tablet in both sitting and standing positions and acquiring their subjective Rapid Upper Limb Assessment (RULA) evaluations regarding both these positions, the second stage measures the physical load on the upper-extremity muscle based on the signal strength of electromyography and the angle of wrist. Three independent variables, including number of hand(s) used, elbow angle, and tablet direction, and two dependent variables, are considered in our experiment. Borg scale and post-experiment questionnaire were used to access the subjects’ view of loading and fatigue feeling.
Experimental result shows that loading of upper-extremity muscle is lower in sitting position than in standing position. Furthermore, all three independent variables have significant effect in standing position. To summarize, a more suitable and lower physical loading position to operate the tablet is to use both hands with 100°in elbow flexion against frontal plane and with a vertical grip of tablet direction.
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