Objective assessment of sitting comfort and discomfort

How do you know if the chair you are sitting on is comfortable or not?", is a question I asked my young son ol)e day, to which he replied, "just sit on it and see if it's comfortable!" Counting on his fingers, he ended with "Seriously, Dad, I could have done your PhD in 9 words!" Although measuring sitting comfort using subjective measures (comfort rating questionnaires) appears to be an intuitive, practical and cost effective method, it does have some limitations. For example, with purely subjective feedback it is difficult to reliably distinguish and rank well designed chairs with subtle design differences in terms of their comfort rating. From a chair designer or user perspective, if an objective, valid, sensitive and reliable method was available to assist in the design of the most comfortable seat, it would allow for better informed decisions to-be made about chair design factors that may in turn impact on innovation and ultimately user health. In terms of possible objective measures that warranted further investigation, in-chair movement (or lack thereof), temperature and humidity appeared to show most potential due to their roles within the current models of comfort and discomfort. For example, in-chair movements are understood to be a subconscious action performed to prevent or minimize the perception of discomfort. A lack of in- chair movements in a healthy unrestrained person may therefore be consistent with the existence of comfort. The studies presented in Chapters 2, 3, 4 focuses on the effects of specific chair design factors (legroom, cushion firmness, cushion contour) on in-chair movement and the subjective appreciation of comfort and discomfort. A high temperature or humidity at the user seat interface may result in the softening of the tissues in contact with the seat with the potential for macerative damage, skin or deeper tissue nociceptor stimulation and discomfort. In order to study the possible relationships between such physical modalities and the subjective domains of comfort and discomfort, it is therefore important to determine the number of sensors needed and the location for their placement in order to accurately measure these variables at the user-seat interface. The studies presented in Chapters 5 and 6 focus on the minimum number of sensors required and their placement, in orderto accurately assess temperature and humidity at the user-seat interface.EThOS - Electronic Theses Online ServiceGBUnited Kingdo