Affiliations: [a] Institute of Ergonomics, Department of Mechanical Engineering, Darmstadt University of Technology, Darmstadt, Germany | [b] Department of Industrial Engineering, National Tsing Hua University, Hsinchu, Taiwan
Correspondence:
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Address for correspondence: M. Diaz-Zeledon, Institute of Ergonomics, Darmstadt University of Technology, Petersenstrasse 30, Darmstadt 64287, Germany. E-mail: diaz@iad.tu-darmstadt.de
Abstract: The objective of this study is to investigate the effect of the variations of an objects' instability, on the upper body and trunk locomotion system during self-paced, 3D, and reaching and transport movements performed in a seated position. Unstable objects can be found in many industrial sectors, such as chemical industries or service areas. Due to the deficit in methods of their manipulations and investigations of the related effects has motivated the present study. 30 subjects (15 male, 15 female) participated in this experiment. The physical human responses were measured using (a) self-paced Hand Motion Time, (b) Range of Motion of the trunk, shoulder, and elbow, (c) muscular strain of selected muscle groups in the shoulder, arm, and trunk. The mental workload is measured by subjective assessment, of the unstable moved object. The results of the statistical tests prove that there is an effect of the liquid level and target position on the physical and mental level of the locomotion system. Direction of movement (motion-phase) presents a significant influence on the Range of Motion, the muscular activity and the Hand Motion Time. These results can be applied to evaluate, and develop products for workplaces, where the reduction of musculoskeletal injuries plays an important role.
Keywords: Motion-analysis, unstable objects, workplace design, muscular strain, hand motion time, range of motion
