| Summary: | 碩士 === 朝陽科技大學 === 工業工程與管理系碩士班 === 98 === In manual materials handling, the lifting and lowering operations for the common handling tasks, and handling time may not be the same object size, thus affecting the position and muscle force on the body, resulting in musculoskeletal disorders. The purpose of this study is to investigate the effects of the hand exertion and muscle activity of upper limbs when dimension change of objects during handling operations.
An experiment was conducted to collect the biomechanical behavior of upper extremities in the laboratory where two 3-component force transducers and EMG system were performed. Fifteen subjects were recruited and 6 task patterns, which were the combinations of 3 dimension change of objects, 2 handling tasks (lifting and lowering), were designed and performed in the experiment. The software of Motion Processor developed in the laboratory was used to compute the root mean square and percentage of maximum voluntary contraction (MVC) for the tested muscles. The resultant and peak forces obtained from 3-component force transducers were also calculated and observed.
The results show that for lifting task when the dimension change of objects, the right brachioradialis muscle EMG %MVC were significantly affected, for lowering task, the left biceps muscle EMG %MVC were significantly different. Lifting length 56cm box, the left and right upper trapezius muscle activity on greater than 50% MVC, when lowering task, the left and right biceps muscle activity also exceeded 50% MVC, therefore not suitable for handling tasks. When lowering length 18cm box, the four muscles EMG %MVC was less than 40% MVC, for the three kinds of dimension in the better one. No significant d ifference for 3-component forces was shown when the task were changed.
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