A subjective-biomechanical evaluation of comfort in automobile seats

Typescript (photocopy).This dissertation presents the results of an investigation of the relationship between posture and comfort in a suite of four automobile seats. Sixteen university students (eight males, eight females) participated in a series of simulated automobile driving sessions. During each trial, participants sat in one of three General Motors Corporation standard automobile seats (Camaro, Celebrity and L-Car) or in a prototype seat based on the Neutral Posture (ergonomic) Chair design. Dependent variables were: subjective (general comfort, body part discomfort, chair feature evaluation); biomechanical (trochanteric-acromion chord [TAC] ratio and movement factor) performance, and pressures between the buttocks-seatpan and back and backrest, respectively. Independent variables were: seat type, lower back support (via presence or absence of an airbag) and gender. Analyses of variance and correlation comparisons were performed on the data. General subjective comfort was significantly affected by the type of seat used, the presence/absence of lumbar airbags and gender. The Neutral Posture Chair received the best overall mean comfort rating. Females were, as a group, more uncomfortable than males. Performance was responsive only to gender with men achieving better mean scores than women. Both of the biomechanical independent variables, TAC ratio and movement factor, were affected by seat type. The Neutral Posture Seat achieved the best (i.e., highest) mean TAC ratios (reflecting better middle and upper back support) and movement factor evaluations (indicating better freedom of movement). Males had significantly higher TAC ratios than did women. Body part discomfort evaluations of the neck, upper middle and lower back, buttocks and thighs were responsive to the type of seat used. The Neutral Posture Chair received the better mean discomfort ratings for all body parts in contact with the seat. The General Motors seats were found deficient in lower back support. The presence of airbags significantly effected the lower back discomfort ratings of the Camaro and L-Car seats and had a near significant effect (p < 0.085) on the Celebrity seat..