National Textile Center

Year 8 Proposal

Project No.: F99-S02

Competency: Fabrication

Sensory (Kansei) Engineering of Aesthetics in Textile Fabrics

Project Team:

Leader: Roger L. Barker/ NCSU/ Perception, instrument correlation analysis

Email: roger_barker@ncsu.edu Phone: 919-515-6577

Members: Moon W. Suh/ NCSU/ Process control, probabilistic modeling (Professor)

Jae L. Woo/ NCSU/ Measurement, fluctuations analysis (Visiting Research Professor)

Marian G. McCord/ NCSU/ Brainwave techniques, (Assistant Professor)

Itzhak Shalev/ NCSU/ Human textile interaction analysis

Collaborators: John C. Russ/ NCSU/ Image analysis & fractile surfaces

Yoshio Shimizu/ Shinshu University, Japan/ Kansei engineering

Tomoyuki Yoshida/ National Institute of Bioscience & Human Technology (MITI), Japan/ Brain wave measurement & analysis

Barry L. Whitsel/ UNC, Chapel Hill/ Human physiology & psycho-physiological measurement (Professor)

Objective:

To establish a scientific basis for applying the "1/f" concept – a revolutionary, mathematically definable framework for determining and quantifying sensory preference, developed as part of the Japanese "Kansei Engineering" effort - for designing universally sensorially pleasing textile fabrics.

To design optical and tactile/mechanical measuring systems and software tools for converting textile fabric designs, textures and color combinations into electronic waveforms which can be transformed to reveal 1/f patterns and other frequency domain analyses.

To design a physiological measurement system, based on known scalp electro-potentials methods, for quantifying human sensation and perception generated by pleasing visual and tactile stimuli from textile fabric designs, patterns, textures and color combinations.

Relevance to NTC Mission:

Translation of the "1/f" concept into textile fabric production specifications will essentially create a new, all encompassing design guideline for all textile products, allowing the manufacturer to continually match consumer preference and compete with "non 1/f" designed fabrics. Our interdisciplinary team, in collaboration with Japanese researchers and industrial scientists, is well positioned to go beyond what has been done to date in Japan and to build the extensive theoretical and empirical groundwork required to formulate universal Kansei design rules for fabrics. Kansei engineering, by providing a window into the heart and mind of the consumer, may be the key to designing and producing a new class of textile fabrics and products. In a consumer driven market, systematically engendering user preference at a fundamental sensorial level can be the categorical competitive edge.

State of the Art:

Sensory (Kansei) engineering of aesthetics into consumer products has received considerable attention in Japanese national R&D projects including the Human Sensory Measurement Application Technology (HSMAT) project and the Ministry of International Trade and Industry (MITI) Technology Frontier Program. Nara, Tsukuba, Hiroshima and Shinshu universities all have Kansei related programs. Kansei engineering seeks to "improve human well-being by optimizing physiological and psychological environments. It is a tool to design products with an eye on observable physiological responses to stimuli. The goal is to tailor products to the preference of every consumer (Nakano). Kansei can be simply defined as "sensory tailoring" (Nagamachi).

An important outcome of Kansei research is the discovery that stimuli that obey a 1/f relationship on a log/log plot of power spectral density versus stimulus frequency (f) engender well-being and harmony, while brain alpha wave fluctuations of a comfortable/content individual are also found to obey the 1/f relationship. In other words- though the exact interaction is yet undetermined- the human body prefers 1/f pattern sensory inputs and correspondingly outputs 1/f type signals in response to such inputs. There is evidence that this relationship holds true for visual, auditory, tactile, olfactory and taste stimuli. The 1/f relationships have been reported to exist in the song of a nightingale, the murmur of a stream, a Mozart serenade, a beautiful painting, the heart beat and in voltage variations in nerve fibers. This discovery is especially meaningful because the 1/f pattern is found to exist both on the stimulus side and on the physiological response side. Advances have been made in the methods of extracting 1/f patterns from optical and mechanical stimuli and in measuring 1/f brain alpha wave fluctuations in response to pleasing stimuli. There is a strong case for investigating the applicability of 1/f as the most promising "Universal Kansei Tool" which can be utilized for designing 1/f stimuli engendering products on the one hand and for interpreting physiological response to monitor favorable reaction on the other hand.

Examples of 1/f Power Spectra [from Concepts of Fluctuations, Musha]

Frequency (Hz) Frequency (Hz)

J.S. Bach Mozart Symphony

Brandenburg Concerto, No. 1, 1^st Movement No. 40, 1^st Movement

Approach:

Textile fabric surfaces are inherently different than other commonly sensorially experienced surfaces such as metal, wood, stone and plastic. Woven or knit structures always consist of fibers, loosely bound in yarns which are then interlaced to create a fabric. Textiles are therefore innately sensorially bi-modal giving rise to at least two distinct levels of tactile sensorial stimuli. Since yarns diameters are generally two to three orders of magnitude larger than constituent fiber diameters, a finger scanning a fabric surface at a constant velocity and direction will encounter low frequency stimulus as the finger collides with successive yarns and at the same time, the finger will encounter a high frequency stimulus at it collides with the much finer individual yarn surface fibers. The same holds true for a visual scan. If one considers the physical meaning of a linear 1/f stimulus in the frequency domain in its simplest sense of two points defining a straight line in the power spectral density versus stimulus frequency plane, one can visualize an abundance of a low frequency stimulus and concurrently a scantier stimulus at a higher frequency. Indeed, the 1/f relationships shown by Koga et al, Musha and Yoshida et al for natural phenomena and brain alpha wave olfactory response were indicatory over the frequency range of 1 to 0.01 Hz, i.e., about two orders of magnitude of difference between the low and the high frequency stimuli. This is well within the range of fiber/yarn magnitude differences. Relatively little work has been done on visual and tactile stimulus fluctuations occurring in textiles. A progressive approach is necessary for the fundamental investigation of the 1/f concept in relation to textile fabrics:

1. Development of analytical methods for Kansei 1/f research:

- Development of a measurement system for acquiring visual and tactile information from fabric and fabric-like surfaces.

- Development of analytical and statistical procedures for identifying 1/f patterns in complex optical and mechanical fluctuations.

- Establishment of laboratory techniques for quantitatively characterizing physiological response to stimuli based on scalp electro-potential ("brain wave") measurement at key locations.

2. Fundamental Studies of 1/f patterns and physiological/psychological responses in humans:

- Qualification and calibration of 1/f criteria as dependable benchmarks for an "aesthetically pleased" response.

- Definition of stimulus threshold for 1/f response and separation of inter sensory interference and noise.

- Establishment of relationships between preferred sensory perception (visual and tactile) and physiological and psychological response patterns.

3. Learn how to design and produce textile fabrics that trigger favorable consumer response:

- Link optical and geometrical fluctuations originating from fabric topological characteristics to the visual and tactile preference.

- Prepare textile fabrics with different ratios between fiber diameter, yarn diameter, fiber packing in yarn and yarn spacing based on the established relationships.

This Year’s Goal:

1. Develop measurement systems for acquiring visual and tactile information from fabric and fabric-like surfaces. Install CCD system capable of measuring optical patterns from planar surfaces with minimal loss of information.

2. Develop analytical and statistical procedures for identifying 1/f patterns in complex optical and mechanical fluctuations. Employ techniques of statistical signal analysis to analyze and interpret frequency spectrograms.

3. Establish laboratory techniques for quantitative characterizat physiological response to stimuli based on scalp electro-potential ("brain wave") measurement at key locations. Install brain wave measuring procedures successfully demonstrated in Japan by Yoshida and Shimizu. Techniques will be adapted and enhanced using US cutting edge competency in bio-physiological science, signal/ information processing and computer software.

Outreach to Industry:

Industrial collaborators will supply fibers, yarns and fabrics for constructing samples for this research as well as successful fabric designs for our 1/f analysis.

Resources Required:

A major resource is the research team. The principle investigators in this research group bring a broad expertise in facets of this multidisciplinary work. Suh and Woo are experts in probabilistic modeling and signal analysis (Woo is also proficient in Japanese language). Barker and Shalev have extensive experience in perception/ instrument correlation analysis. McCord is a specialist in biofeedback and brainwave techniques with clinical experience.

The expertise of the team is augmented by a group of internationally recognized experts in areas critical to the research, including Yoshio Shimizu at Shinshu University and Tomoyuki Yoshida at MITI's Institute of Bioscience and Human Technology, two of the leading authorities on sensory (Kansei) engineering and 1/f phenomena in Japan. John Russ, and expert in image analysis and fractile surfaces and Barry Whitsel, a specialist in human psycho-physiological measurements at the University of North Carolina, Chapel Hill, will provide specialized consultation to the project group.

New equipment needed for the project includes:

- Instruments to acquire significant topological and optical information from fabric and fabric-like surfaces.

- Dedicated hardware and software required to manipulate complex waveforms.

- Advanced scalp electro-potential monitoring and electrode placement equipment.

- Automatic subjective sensory assay response gathering hardware and software.

- Special brain imaging equipment (magnetoencephalography and functional magnetic resonance imaging)