Relationship between Objective and Subjective Methods in Evaluating Static Discomfort of Car Driver Seat

Abstract

Objective method alone is insufficient in measuring discomfort of car seats. It is indirect and does not truly convey the perception and feeling of the sitter. A combination of both objective and subjective method gives better evaluation on discomfort. Seat pressure distribution method was adopted to investigate the static characteristic of a seat. The method was found to be statistically repeatable in measuring sitting of fourteen male subjects in static condition. Subjective discomfort through subjective assessment using a valid and reliable self-established questionnaire together with a body pressure map (BPM) showed increasing discomfort as sitting time increase; which is expected. The short term seat pressure distribution was used to be correlated with subjective assessment. Significant and moderate correlation was observed between four local body parts namely the seat pan bolster, thighs, upper back and lower back with overall seat average pressure BPM used in the subjective evaluation. Multiple linear regression model were established; overall discomfort from averaged pressure from BPM can be predicted from right & left buttock, right & left thigh and upper back & lower back. It was found that R-Sq=93.5%, R-Sq (adj) = 83.7% with moderately adequate predictive ability with predicted R-Sq= 46.77%.