Posture Assessment and Subjective Scale Agreement in Picking Tasks with Low Masses

Abstract : This study aims at analyzing the relationship between postural assessment and perceived discomfort for picking tasks with low mass (1kg), involving a wide range of positions/postures. We analyzed the agreement of the different postural scores (mean value, integral value, root mean square value, weighted average time at each RULA level and the % of time per RULA level) with the subjective assessments. The statistical analysis showed no correlation between subjective and postural scores. A few negative correlations were also noticed, especially for time spent at specific levels of postural discomfort compared to subjective feedback. The results showed that the subjective assessment was not correlated with the postural assessment in such low discriminant tasks. Although postural assessment enabled to discriminate the more difficult postures with regard to the experimental conditions, the subjects were unable to report coherent discomfort feedback.