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Quantitative prediction of overall seat discomfort

Quantitative prediction of overall seat discomfort
Quantitative prediction of overall seat discomfort
Static seat characteristics (seat stiffness) and dynamic seat characteristics (vibration magnitude) can both influence judgements of seat comfort. It is proposed that seat comfort can be predicted on the basis of Steven's psychophysical law: psi = kphialt n, where psi is a sensation magnitude, phialt is the stimulus magnitude and k is a constant. The law is modified to: psi = a + bphialt n s + cphialtn v, where s v phialts and phialtv represent seat stiffness and vibration magnitude, ns and nv are exponents determined by the rate of increase in discomfort associated with the stiffness and vibration magnitude, and a , b and c are constants. The stiffness of foam loaded to 490 N may indicate static seat comfort, while the vibration dose value (VDV) on the seat surface may indicate vibration discomfort. Two experiments with 20 subjects investigated this approach. The first experiment with five magnitudes of vibration, three foams and a rigid wooden flat seat yielded 0.929 for the exponent, nv, for VDV. In the second experiment subjects judged the overall seat discomfort while exposed six vibration magnitudes with the same four seating conditions. This experiment yielded 1.18 for the exponent, ns, for seat stiffness. The overall prediction of seat discomfort was given by: psi = -50.3+ 2.68 phialts 1.18+ 101 phialt v0.929. The prediction equation provided more accurate estimates of subject discomfort than models using either the VDV alone or the stiffness alone, especially when the vibration magnitude was low or the seats were similar. An interaction variable between the VDV and the stiffness slightly improved the prediction. The equivalence of the two stimuli was given by log10 (stiffness) = 0.787 log10 (VDV)+ 1.34, or log10 (VDV) = 1.27 log10 (stiffness)- 1.70
1366-5847
791-806
Ebe, K.
647db990-ef51-49d3-b196-dfedc41c2281
Griffin, M.J.
177c1940-086f-4486-aad2-36e4a6ab9499
Ebe, K.
647db990-ef51-49d3-b196-dfedc41c2281
Griffin, M.J.
177c1940-086f-4486-aad2-36e4a6ab9499

Ebe, K. and Griffin, M.J. (2000) Quantitative prediction of overall seat discomfort. Ergonomics, 43 (6), 791-806.

Record type: Article

Abstract

Static seat characteristics (seat stiffness) and dynamic seat characteristics (vibration magnitude) can both influence judgements of seat comfort. It is proposed that seat comfort can be predicted on the basis of Steven's psychophysical law: psi = kphialt n, where psi is a sensation magnitude, phialt is the stimulus magnitude and k is a constant. The law is modified to: psi = a + bphialt n s + cphialtn v, where s v phialts and phialtv represent seat stiffness and vibration magnitude, ns and nv are exponents determined by the rate of increase in discomfort associated with the stiffness and vibration magnitude, and a , b and c are constants. The stiffness of foam loaded to 490 N may indicate static seat comfort, while the vibration dose value (VDV) on the seat surface may indicate vibration discomfort. Two experiments with 20 subjects investigated this approach. The first experiment with five magnitudes of vibration, three foams and a rigid wooden flat seat yielded 0.929 for the exponent, nv, for VDV. In the second experiment subjects judged the overall seat discomfort while exposed six vibration magnitudes with the same four seating conditions. This experiment yielded 1.18 for the exponent, ns, for seat stiffness. The overall prediction of seat discomfort was given by: psi = -50.3+ 2.68 phialts 1.18+ 101 phialt v0.929. The prediction equation provided more accurate estimates of subject discomfort than models using either the VDV alone or the stiffness alone, especially when the vibration magnitude was low or the seats were similar. An interaction variable between the VDV and the stiffness slightly improved the prediction. The equivalence of the two stimuli was given by log10 (stiffness) = 0.787 log10 (VDV)+ 1.34, or log10 (VDV) = 1.27 log10 (stiffness)- 1.70

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Published date: 2000
Organisations: Human Sciences Group

Identifiers

Local EPrints ID: 10472
URI: http://eprints.soton.ac.uk/id/eprint/10472
ISSN: 1366-5847
PURE UUID: 2c28327b-1616-4e62-972c-71b83197a811

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Date deposited: 21 Jul 2005
Last modified: 27 Apr 2022 12:16

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Contributors

Author: K. Ebe
Author: M.J. Griffin

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