Year: 1994
Type: dissertation
Abstract: This thesis presents experimental studies on the relationship between external surface\npressure and the perceived discomfort in seated body areas, in particular those under\nthe ischial tuberosity and the mid-thigh. It consists of three parts.\nPart one provides a comprehensive review of the existing knowledge concerning\nseated discomfort. The current assessment methods of seated discomfort are\nsummarised, with the emphasis on the validity and reliability of the rating scale\nmethods. The implications of surface pressure to seated people are outlined from the\nperspective of clinical, sensory and perceptual, and ergonomics domains. A brief\nreview of current technologies for pressure measurement is also provided.\nPart two presents the experimental work. It starts with an exploratory assessment\nmodel of seated discomfort, based on pressure measures. Two preliminary\nexperiments were conducted to test the feasibility of the model. Three further\npsychophysical experiments were carried out to test the validity and reliability of the\nselected six rating scales, and to investigate the effects of surface pressure levels on\nperceived pressure intensity and discomfort in the seated mid-thigh and ischial\ntuberosity areas. Surface pressure stimuli were applied to a seated body area of 3,318\nmm2• Subjects judged three items of sensations: pressure intensity, local discomfort,\nand the overall discomfort. The main results are: I) A 50-point category partitioning\nscale was identified to be most sensitive and reliable for scaling pressure intensity and\ndiscomfort; 2) Sensations of pressure intensity and discomfort linearly increase with\nthe logarithm of the pressure stimulus level; 3) Thresholds for pressure intensity and\ndiscomfort in the seated ischium and thigh areas were derived; 4) The sensitivity of\nintensity and discomfort to the stimuli differs between the locations .The mid-thigh is\nmore sensitive to surface pressure than the ischium. It is considered that this is due to\ndifferences in load adaptation, body tissue composition and deformation; 5) Local\npressure discomfort dominates the overall discomfort, and ratings of the local\ndiscomfort are higher than those of overall discomfort.\nPart three discusses the findings from this research. Four integration models of the\noverall discomfort from local discomfort components were proposed. The Weighted\nAverage model asserts that the overall discomfort is a linear combination of local\ndiscomfort components, and that the weight of each local discomfort is the proportion\nof this component out of the arithmetic sum of all local discomfort components. The\nmechanisms of discomfort were analysed.\nThe fundamental research presented herein uniquely contributes to the knowledge on\nthe human perception of seated pressure discomfort. Although this is not application\nbased, the findings contribute to the methods of seating comfort evaluation as well as\nprovide criteria by which seat designers may formulate design requirements.
Author: Wenqi Shen
Language: English
Subfield: Human Factors and Ergonomics
Field: Social Sciences
Domain: Social Sciences
Open Access status: green
Funder: Loughborough University
OpenAlex ID: W2301473785