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Discomfort models play a significant role in ergonomic simulation. More detailed and specific discomfort models are required for older drivers who represent the fastest-growing segment of the driving population. Owing to the physical degradation, various biomechanical discomfort factors should be incorporated into the model to properly evaluate discomfort for the older population group. In this experimental study we attempted to identify and quantify biomechanical factors that affect the older drivers' discomfort ratings. Different egress motion strategies (e.g., with and without using assist devices) were designed to induce various physical activities. The corresponding discomfort ratings were then produced. From the kinematic analysis using a digital human body model with reconstructed egress motion, the hip abduction was found to have the most statistically significant effect on the discomfort rating.

This paper focuses on full body dynamical analysis of car ingress/egress motion. It aims at proposing an experimental protocol adapted for analysing joint loads using inverse dynamics. Two preliminary studies were first performed in order to 1/ define the main driver/car interactions so as to allow measuring the contact forces at all possible contact zones and 2/ identify the design parameters that mainly influence the discomfort. In order to verify the feasibility of the protocol, a laboratory study was carried out, during which two subjects tested two car configurations. The experimental equipment was composed of a variable car mock-up, an optoelectronic motion tracking system, two 6D-force plates installed on the ground next to the doorframe and on the car floor, a 6D-Force sensor between the steering wheel and the steering column, and two pressure maps on the seat. Motions were reconstructed from measured surface markers trajectories using inverse kinematics.

This paper investigates the feasibility of calculating joint forces and moments during a whole body truck cabin ingress/egress motion. For such a task, it is difficult to evaluate a future truck instep as the influences of the architecture parameters are complex over the motion and the discomfort feeling. In order to evaluate the future product at an early stage of the design process, Digital Human Models (DHMs) are interesting tools. However, most existing DHM simulation packages can only efficiently evaluate the kinematics of postures where the dynamics of the whole motion is necessary for such a task. The enhancement of DHMs towards a dynamic analysis and modeling is therefore necessary. In this study, the motions of subjects entering and exiting an adjustable truck cabin were measured by mean of an opto-electronic motion capture system and six load sensors. The joint angles were then calculated using an inverse kinematics method.