Fuzzy modelling of stresses in manual lifting tasks

Publisher Website
Google Scholar
Abstract
A new approach, based on the theory of fuzzy sets and systems, was proposed to assess the acceptability of stresses involved in manual lifting tasks. Nine male subjects participated in a laboratory lifting experiment. A total of 108 data points (9 subjects .times. 4 levels of frequency .times. 3 replications) were collected. The maximum acceptable weights of lift were determined using the psychophysical methodology. Metabolic energy expenditure and heart rates were also measured. A hypothesis, stating that the combined effect of biomechanical and physiological stresses leads to an overall measure of lifting task acceptability as expressed by the psychophysical stress, was suggested and evaluated. Conditions were found for which the acceptability measures of the combined and the psychophysical stresses were close to one another. A concept of safety index for a particular weight of load lifted was also proposed.