Evaluation of slouched sitting postures of rear seated car passengers

Abstract

To evaluate passenger safety in cars, crash tests and simulations are often conducted. When doing these tests or simulations, the dummies are placed in standardised po sitions, called the nominal sitting postures. However, these sitting postures usually do not represent how real people sit in cars. Occupants often change their sitting posture from time to time to achieve better comfort. One possible sitting posture is called slouching, where the hips usually moves forward, the pelvis is angled and the upper body slides down. This cause the belt not to function in the way it is intended to do and could thereby lead to implications during a crash. This study’s main purpose is to identify and evaluate different parameters that con tribute to slouching as well as studying how the comfort experience is affected. To achieve this, the study was split into three different stages, being pre-study, param eter evaluation and parameter evaluation over time. The pre-study aimed to find parameters through benchmarking, literature studies and conducting smaller tests. It provided information on which parameters could be worth testing to evaluate the influence of slouching. In the first study, the parameter evaluation, the results of the pre- study were used to decide which parameters to test further. Ten persons were selected to sit in five different seats that were modified to test different parameters. The results showed that the wool mix upholstery had the highest tendency to slouch while the lower sitting height had the worst comfort scores among the parameters tested. Based on the results of the first study, the second study examined slouching over time. Since slouching is connected to the sitting discomfort of the passenger over time, the lowered sitting height was selected to be further studied. The test was con ducted over 30 minutes with 5 test persons. The subjective methods for parameter evaluation over time were a comfort evaluation form and interviews. The objective measurements were the ASIS measurement and photo analysis. Based on the learning’s from the user studies and the pre-study, a number of con cepts were developed as inspiration for future product development. These solutions aimed to both improve the comfort as well as the safety of the passengers.