A study of sitting posture and belt position in a travelling car: How do passengers sit in a travelling car?

Examensarbete för masterexamen
Master Thesis
Automotive engineering (MPAUT), MSc
Hansson, Annika
Lysén, Emma Nilsson
To improve the future design of restraint systems, it is important to know how passengers’ sitting postures change over time and how the passengers interact with the restraint systems. This master thesis at Chalmers University of Technology, focuses on pelvis rotation, slouching and belt position while travelling in a front seat of a car on regular roads. The information was collected during normal drive in the passenger seat of a regular car, while the volunteers perform activities such as; resting, e-socializing and conversing. Twenty volunteers, ten male and ten female, participated in the study. Volunteers were seated in the front row passenger seat, because this sitting posture is probably similar to how passengers will sit in future autonomous cars. The inertial motion measurement system MTw Awinda from Xsens, in total eight sensors, were used in the study. They were placed on the volunteer’s sacrum, sternum, C7, T3, L5, forehead and car. The data from the sacrum sensor, that corresponds with pelvis rotation are mainly presented and discussed in this report. In addition, a surface pressure sensing array (Tekscan mat) was placed on the car seat cushion. The data from selected volunteers was analyzed with the TEMA to determine degree of slouching. Photo analysis was carried out to assess belt positions before and after the test. Additionally, the rotation of pelvis and sternum when changing seat back angle in intervals of 5° between 23° and 48° were also investigated. The results show that pelvis rearward rotation increases by average 10° when riding in the car for about 45 minutes. Comparing the activities, the volunteers had similar average pelvis rotation. Slouching could be measured only for three volunteers out of 20 and it seemed to increase on average 3 cm during the ride. The belt position of initial and final sitting posture indicates that the diagonal belt moved less than the lap belt. To investigate the dynamic belt position, future video analysis is needed. Increasing seat back angle appeared to have a correlation with increasing sacrum and sternum pitch.
Transport , Teknisk mekanik , Transport , Applied Mechanics
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