An automatic procedure for identifying alternative automobile ingress movements in young and elderly populations with or without prostheses

This paper presents an automatic numerical procedure for classifying the automobile ingress movements in young and elderly populations with or without prostheses. This procedure proceeds in two stages. The first stage works to identify the main movement strategies by classifying the subjects according to new indices, called 3BJCV (3 Bases Joint Contribution Vector). These indices make it possible to take the complexity of the automobile ingress movement into account. They quantify the contribution of the lower limbs chains angles' and those of the chain gathering the trunk and head in the final positioning of the midpoint between the two hips (MPH). The second stage specifies the main movement strategies obtained in stage 1 by classifying the subjects according to the relevant articular variables of the ingress movement.This two-stage procedure was applied to the ingress movements extracted from the national HANDIMAN (RNTS, 2004) project, measured in experiments carried out with a small vehicle and a large vehicle (i.e., a minivan). The two main ingress movement strategies were identified: a one-foot ingress strategy and a two-foot ingress strategy. In all, 6 ingress sub-strategies were highlighted automatically, without requiring any special expertise. Five of these sub-strategies had already been observed, based on the same experiments, in the past. The 6th sub-strategy was used by subjects who were divided into 2 other sub-strategy groups while of the observation.Relevance to industryThe procedure proposed in this study can help ergonomists and car manufacturers to quantify and classify the automobile ingress movements without requiring any a priori expertise on the movement. It also helps to improve any given numerical simulation by providing numerical data characterizing the different ingress movement profiles.