The influence of the motion of powered ceiling hoists on the subjective sense of safety

Abstract

This paper deals with the human sense of safety affected by the motion of electric ceiling-hoist. The effect of motion was examined by the subjective evaluation. Subjects were 35 handicapped persons who regularly used wheelchair and 20 persons over 60 years old. The hoist was capable of controlling the transfer speed and the acceleration. The angular acceleration of spreader bar for hanging of the human body was measured to take quantitatively the degree of body swing in the direction of hoist movement. Subjects were asked to rate the sense of safety in 5-grading scale about nine patterns of motion, compared with the typical motion of hoist on the market. The results revealed the followings. (1) The number of subjects who feel safe increases as the transfer speed and acceleration decreases. (2) 95% of subjects didn't feel danger for the transfer speed below 0.33m/s, the acceleration below 0.24m/s², and the maximum of angular acceleration below 0.59deg/s².