Ebe K, Griffin M J
Human Factors Research Unit, Institute of Sound and Vibration Research, University of Southampton, UK.
Ergonomics. 2000 Jun;43(6):791-806. doi: 10.1080/001401300404751.
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 = kphi(n), where psi is a sensation magnitude, phi is the stimulus magnitude and k is a constant. The law is modified to: psi = a + bphis[n(s)] + cphiv[n(v)], where phis and phiv represent seat stiffness and vibration magnitude, n(s) and n(v) 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, n(v), 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, n(s), for seat stiffness. The overall prediction of seat discomfort was given by: psi = -50.3 + 2.68phis1.18 + 101phiv0.929. 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.
静态座椅特性（座椅刚度）和动态座椅特性（振动幅度）都会影响对座椅舒适性的判断。有人提出，可以根据史蒂文斯心理物理学定律来预测座椅舒适性：ψ = kφⁿ，其中ψ是感觉强度，φ是刺激强度，k是常数。该定律修改为：ψ = a + bφsⁿ(s) + cφvⁿ(v)，其中φs和φv分别代表座椅刚度和振动幅度，n(s)和n(v)是由与刚度和振动幅度相关的不适感增加率确定的指数，a、b和c是常数。加载到490 N的泡沫刚度可能表明静态座椅舒适性，而座椅表面的振动剂量值（VDV）可能表明振动不适感。对20名受试者进行的两项实验研究了这种方法。第一项实验采用了五种振动幅度、三种泡沫和一个刚性木制平板座椅，得出VDV的指数n(v)为0.929。在第二项实验中，受试者在相同的四种座椅条件下暴露于六种振动幅度时，判断整体座椅不适感。该实验得出座椅刚度的指数n(s)为1.18。座椅不适感的总体预测公式为：ψ = -50.3 + 2.68φs¹.¹⁸ + 101φv⁰.⁹²⁹。与单独使用VDV或刚度的模型相比，该预测方程能更准确地估计受试者的不适感，尤其是当振动幅度较低或座椅相似时。VDV和刚度之间的相互作用变量略微改善了预测效果。两种刺激的等效关系为log₁₀（刚度） = 0.787 log₁₀（VDV） + 1.34，或log₁₀（VDV） = 1.27 log₁₀（刚度） - 1.70。
