Application of Inertial Measurement Units to Assess Vehicle Ingress and Egress Characteristics. (September 2016)

• Record Type: Journal Article
• Authors: Schall, Mark; Huangfu, Rong; Gallagher, Sean; Davis, Jerry; Sesek, Richard; Escobar, Claudia
• Is Part Of: Proceedings of the Human Factors and Ergonomics Society ... Annual Meeting. Volume 60:Part 1(2016)
• Page Start: 855
• Page End: 855
• Publication Date: 2016-09
• Subjects: Human engineering -- Congresses; 620.8205
• DOI: 10.1177/1541931213601195
• Languages: English
• ISSNs: 1541-9312

Abstract

The increasing number of elderly and overweight drivers in the United States has necessitated that vehicle manufacturers develop automobiles that accommodate these changing demographics. While digital human models have been successfully used to simulate human vehicle interaction (Chaffin, 2005; Ozsoy et al., 2015; Yang et al., 2007), the variability in ingress and egress procedures among drivers with different physical attributes poses a unique challenge to developing accurate models. The objective of this study was to apply inertial measurement units (IMUs) to compare ingress and egress characteristics of individuals of varying age and body type. Ninety-three participants, comprising a control group (aged 21–<65 years with body mass index [BMI] <30 kg/m2), a high-BMI group (aged 21–<65 years with BMI ≥30 kg/m2), and an elderly group (aged ≥65 years), performed ingress and egress trials in three vehicles (compact, sedan, and sport utility vehicle [SUV]) while wearing a wireless IMU system (Xsens MVN BIOMECH Awinda system, Xsens Technologies BV, Enschede, Netherlands). Native protocols of the IMU system were used to estimate the joint centers and motion paths of several bilateral body joints including the ankle, knee, hip, wrist, elbow, and shoulder. The transition of each joint center across the edge of the seating area at the door sill as the subject got into and out of the vehicles was measured. The start of the ingress process was defined as the time when the first joint center passed through the door sill into the driver's seating area. The end of ingress was considered to be the time when the final joint passed back through the edge of the seating area. Two-way analyses of variance (ANOVA) examining the effects of population (control vs. elderly vs. high-BMI), gender, vehicle model, and their interactions on ingress and egress times were conducted. In general, the right ankle was the first body segment to enter each of the three vehicles followed by the right knee, right hip, right shoulder, left hip, left shoulder, left knee and the left ankle regardless of population group. Ingress time was observed to be affected by population (F2, 28 = 17.97, p < 0.001), and was characterized by a much slower ingress time among the elderly (mean = 4.33 secs), compared with controls (2.97 secs) and high-BMI participants (2.71 secs). Egress was also observed to be affected by population (F2, 28 = 8.85, p < 0.001), but in a slightly different manner. The control group (mean = 2.95 secs) was the fastest to egress the car, followed by the high-BMI group (4.42 secs) and the elderly (5.26 secs). The results indicate that IMUs may be successfully applied to characterize ingress and egress motion paths of different population groups and may be useful when designing seated applications, particularly for elderly and high-BMI populations.