Development and evaluation of a new body-seat interface shape measurement system

A new system has been developed to capture the body-seat interface shape. It can repeatedly and accurately measure interface deformation. The shape sensing array system uses optical fiber technology and is noninvasive. The system can cover an interface as large as 400/spl times/480 mm and the shape is measured over a 10/spl times/12 array of sensors laminated on ribbon substrates. The accuracy and repeatability of this system were assessed. Measurement errors were evaluated by comparing the shape with a reference shape obtained by a mechanical digitizer. The root-mean-square error in the Z direction for the system was 3.79 mm. The repeatability of the system was within 0.38 mm under controlled conditions. Different interface materials noticeably affected measurements. With the development of this interface shape measurement device, the basic information gathered through its use may prove to be fundamental in the successful design of generic-shape contoured support surfaces. Furthermore, we expect that the new shape measurement device will provide a quick and effective tool for cushion evaluation and clinical guidelines for cushion prescription.

I. Introduction

Measuring the shape of a body-seat interface has been used successfully in research to study tissue loading and to fabricate custom contoured cushions. Levine et al. [1] proposed that tissue shape and deformation measurements are superior to interface pressure measurements as a characterization of the loading condition between the buttocks and a seat support surface. Yamazaki [2] studied the relationships among the body-seat contact shape, the pressure, the posture, the body build, and the sitting comfort. After qualitatively comparing contact shapes to pressures, Yamazaki concluded that pressure patterns provided data for seat evaluation, while contact shape patterns provided data for seat design. Sprigle and Schuch [3] suggested that seat contour measurements complemented other clinical measures such as seat interface pressures and general postural assessments, to form a more complete picture of the buttocks-cushion interface.