Systematic study of touch-feel perception : surface affective engineering aspects

Abstract

The objective of this Ph.D work is to establish an affective engineering system for general surface tactile evaluation, which fits in the current knowledge gap between the micro-surface physical properties and the customers’ peceptual responses to surface tactile senses as well as their affective preferences. Drawing upon a broad multidisciplinary review, this research identifies the value of such affective system for tactile evaluation in both academic research and industry application. A concept framework of surface tactile evaluation system is specified, including three substructs: instrumentation, sensory evaluation and database construction & mining. The framework is implemented to investigate how surface tribological factors such as topography, hardness and friction against skin affect the tactile attributes and general preference, with regard to 'soft-touch' polymer coatings and patterns. Works were done in three major folds: Firstly, two instrumentation features for tribological test and surface characterisation have been developed. The works include (1) a novel tribometer with flexible configurations of in-vivo friction test by finger touch and dry sliding Roller-on-Block test and (2) a Hot-tip Tribological Probe Microscope (hot-tip TPM) with localized surface thermal measurement. Their novelty in design and performance are presented and discussed in detail. Some preliminary tactile studies on car interior materials and regular machined surfaces are also performed on tribolgical aspects. To help interpreting the data acquired from TPM and to improve the understanding of the limitation of surface characterization at micro/nano scale, fidelity issues are considered on two aspects: (a) finite tip size effect on topography measurement and (b) probe misalignment effect on nanoindentation test. Secondly, a database of ‘soft-touch’ polymer surfaces has been constructed at both physical level and psychophysical level. On one hand, the surface microstrutures are physically characterized by the home-made instruments and other commercial ones, in terms of topography, surface nanohardness and friction coefficient. Internal correlations among the measured surface properties are observed. Attempts have been made to explain these correlations by the aforementioned fidelity issues and classical tribology theory. On the other hand, the tactile perception towards the polymer samples are evaluated and quantified in the four major tactile sensory modes (Smooth-rough , soft-hard , slippery-grippy , cool-warm) and the general preference (Like-dislike). Nonparametric statistical tests such as Kendall’s W test and Wilcoxon test are applied to study the evaluation effectiveness among the subjects and the perceptual difference among the samples. Gender difference is identified in the tactile evaluation effectiveness of polymer coatings. Last but not least, this research further explored the complex relationships among the perceived attributes and measured surface properties by using a range of classical data mining techniques such as cross correlation analysis, factor analysis and regression methods. It was noted that the perceived attributes such as smooth/rough and grippy/slippy are influenced by surface topography with parameters of roughness and average spacing while the perceived softness largely depends on the ratio of hardness to modulus H/E. A regression model is established to describe the psychophysical relationships in relation to surface tactile design of the ‘soft-touch’ polymers.EThOS - Electronic Theses Online ServiceUniversity of WarwickGBUnited Kingdo