Parametric modeling of optimal aircraft seat surface and seat pressure distribution

Overview & Synopsis

Pressure distribution is well accepted as the objective measure that is the most related to subjective rating of seat discomfort. However, very few studies have examined ideal seat pressure distribution for guiding seat design. In this study, to improve airplane seat comfort, the compressed seat surface which optimizes pressure distribution was studied experimentally using a newly built multi - adjustable experimental seat. One of the innovative aspects of this new experimental seat was that seat pan surface was simulated by a matrix of 52 cylinders, each with a freely rotatable circular flat head of 60 mm in diameter. Each cylinder was equipped with a tri - axial force sensor, enabling the measurement of both normal and tangential forces. The height of each cylinder was adjustable with a maximum stroke length of 40 mm, making it possible to control pressure distribution underneath the soft tissue of the buttocks and thighs. A uniform law relating normal force and displacement for each cylinder was used, permitting a pressure distribution as uniform as possible for a given maximum displacement of the cylinders. The backrest consisted of adjustable lumbar, thoracic and neck panels. Seat pan length, height and inclination were also adjustable. Thirty - six participants (18 males, 18 females) of varying weight (healthy BMI, obese BMI) and stature (small, medium and tall) were recruited. Participants were instructed to sit in 40 seat positions (each lasting approximately 1 minute) that simulated an economic airplane seat. Varying seat positions included: backrest angle (100°, 110°), seat pan angle (0°, 5°, freely adjustable), stroke height of seat pan cylinders (20mm, 40mm) and task (watching forward without neck support, relaxed sitting with neck support). A principal component (PC) analysis was first proceeded to reduce the dimensionality of the data. A linear regression was then performed in the reduced PC space so that the seat surface and corresponding contact force distribution were related to main anthropometric dimensions (stature, BMI, sitting height to stature ratio) and seat parameters (seat pan and back angles). It was observed that the profile of the ?optimal? compressed seat pan surface in the symmetric plane showed little variability between the different body sizes, while the profile in the frontal plane showed higher variability. Contact force distribution was highly dependent on the sitter's BMI. The parametric models obtained will provide quantitative guidance to the design of airplane seats (i.e. determining the ?optimal? seat pan compressed surface and pressure distribution) that would best accommodate the general population.