There has been a rapid growth in the vehicle industry market, companies are expected to provide comfortable and safer products, improving with every new model. Hence, the interest on developing Digital Human Modelling (DHM) tools that are focused on their needs. The aim of this project is to suggest a standard seating posture that could be used with ergonomic software like IMMA, to address the research an initial literature study was performed to understand existing methods used in the industry and previous posture studies. In order to visualize the extent of the topic, it was required to acquire information from the vehicle industries and make an investigation on preferred postures by real drivers. Comparisons are made between the different categories of observed vehicles, and literature found for ideal postures. The results were also used to implement suggestions for the ergonomic IMMA software development / Virtual Driver Research

For many years seat cushions have been investigated for their ability to reduce seating discomfort. The objective of this thesis is to examine air-inflated seat cushions to determine how seating comfort (determined by pressure change rate) is affected by changing various parameters of the cushion. To this end, a mathematical model was built using MatLab and SimuLINK to accurately represent the cushion and its response. Different aspects of the cushion, such as seating area, outlet size, cell height, and material elasticity are varied to determine how they each affect seating comfort. For each parameter three different weights are tested to see how the trends observed per parameter are affected by a person's weight. The results of this study indicate that by changing the base radius, the cell height, the outlet diameter, and the material elasticity of each cell, it is possible to improve seating comfort, as determined by pressure change rate. The study confirms that comfort levels increase with increasing seated area. The study also shows that although increasing the weight of a person decreases the comfort performance of the cushion, not all the trends observed when the cushion parameters are varied remain the same as the person's weight is changed. The trends observed when the cell height and outlet diameter are varied are not affected by the subject weight but all the other trends changed as the subject weight was changed. / Master of Science

During the last couple of years several studies have been conducted to investigate how children move and position during car rides. This in order to map when, and for how long children sit in positions that are not safe as well as to identify the reason for these movements. One of the conclusions is that children do not always sit comfortable in today’s belt-positioning boosters and thereby they chose positions that are unwanted for safety reasons. The aim for the master thesis has thereby been to improve seating comfort for children while traveling safely in the rear seat of a car. The target group has been children in ages 5-11 years old with body height 110-145 cm, a Swedish population 50 percentile has been used for the extreme dimensions. The master thesis process is divided in three phases; Discovery, Development and Testing and Evaluation. In the Discovery phase information in the areas child safety, child methodology and comfort was gathered through literature study, interviews with experts, benchmarking and a focus group with parents. As a final step customer needs were formulated. In the Development phase a workshop with children was initially performed to complement the customer needs with inputs from the users. The customer needs were afterwards reformulated into a specification of requirements and five comfort hypotheses. Finally a prototype was developed, designed from the requirements with the purpose to validate the comfort hypotheses, using an anthropometric design method (Osvalder, et al., 2010). In the final phase, Testing and Evaluation, the prototype and reference belt-positioning boosters were evaluated by children in two user studies; one static study and one on road study, to evaluate comfort features and try out different seating comfort evaluation methods. The result is divided into child seating comfort characteristics and child seating comfort methodology guidelines. To assist future development of belt-positioning boosters, seven comfort features are defined to help children ride comfortable in a safe position in the car. Furthermore, 13 child methodology guidelines are formulated to help further seating comfort evaluation with children. Conclusively to make children sit comfortable and safe positioned in the car they should be seated in a belt-positioning booster with headrest, backrest, seat cushion and foot support, the supporting parts need to be perceived as soft around head, back and under the buttock and all parts need to be dimensioned for all children in the target group. The size of the belt-positioning booster and the combination of foam thickness, foam hardness and shape are the main factors for affecting the perceived seating comfort. Furthermore, children shall be included as both design partners and testers during the development of belt-positioning boosters. During the prototype development static comfort evaluation with children should be done repeatedly to verify measurements, shape and foam hardness. To evaluate comfort both static evaluation and on road evaluation should be performed since comfort varies over time. Data should be collected subjectively from children through quantitative methods, such as rating scales, and qualitative methods, such as general questions regarding comfort/discomfort experience. Video observations can identify children’s position during car rides. Different positions can be timed and together with subjective data reasons for repositioning can be identified.