The Japanese Journal of Ergonomics

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Though the human factors approach is important in designing medical devices from the points of view of easy maneuverability, panel simplification, reduction of mistake in handling, etc., it is actually the latest among others. So adopting the “link analysis”, we evaluated the panel design of electrocardiograph, which is the most popular electronic device in medicine.
Results were as follows: (1) sequential link analysis, flow graph, showed that electrocardiographs in the past and on sale were lacking in human factors consideration, especially in arrangement of electronic parts on the panel, (2) corresponding link analysis and link ratio showed that the operator's right hand was used much more frequently than the left one, which would cause fatigue, (3) the shape and the mechanics of those parts were still rough and not refined yet, and (4) there was no standardization of their marks and symbols on the panel.
Considering these results, three improved mock-up panels were designed and equipped in our laboratory. They were actually handled and evaluated by the same analysis. Simplified in outlook and handling, they were proved to be improved in maneuverability and handling balance of both hands. It became clear that the link analysis was an easy and powerful tool for such kind of human factors research.

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A sequence of motions consisting of standing up from a chair and sitting down again to the chair are analyzed from kinematic viewpoints and the influences of aging on the motions are discussed. A 16mm movie camera is employed to take the pictures of the body motions, and the necessary information is fed into a minicomputer with use of a graphic tablet so that forces and torques acting at body joints are computed based on a two-dimensional mathematic model of human body.
Experiments were carried out by nineteen male subjects from 22 years old to 80 years old. The results of the detailed analyses of the motion patterns and the estimated torques at important body joints indicate that the smoothness of the motion is reduced with an increase of age due to lack of close coordinations in motions among different joints. The torque acting at the hip joint is reduced with aging, and it is drastically reduced by supporting body by putting hands on the frontal table during the motions.

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