Modelling the Car Seated Human Body using Composite Ellipsoidal Bodies and Evaluation of Size and Shape Specific Stiffness Data for Various Human Segments

Automobile is one of the primary modes of worldwide transport system, which must offer highest level of health, safety and comfort levels for the occupants inside. Health, safety and comfort of any moving vehicle and its human occupants are mainly characterized by the level of the vibration generated inside the human body. With the development of modern computer based technologies, over last few decades computerized simulations have been gaining huge importance to anticipate the level of vibration generated inside the automotive seated human body. Many simulation based research works had been conducted in past to predict the effect of vibration inside automotive-human assembly, though one of the key parameters to define the simulation set up, namely stiffness values of different human segments; had been collected from past relevant research studies or available testing data resources, which overlooked the real shapes and sizes of the human portions, hence, lacking the practical feasibility. In this research paper, a simplified car seated human made of ellipsoidal segments has been proposed. The segmental dimensions and masses have been extracted from anthropometric database and later, the formulations for composite fibre-matrix configuration have been implemented. A systematic approach has been outlined to evaluate the three-dimensional stiffness values for all the human portions. The obtained stiffness values have been validated by comparing to the data obtained from similar kind of investigations and test results

Studies on Product Design using Ergonomic Considerations

Embedding ergonomic consideration into product/machine/equipment/component design as well as work environment taking into account both psychological and physical needs of user helps to enhance user efficiency, satisfaction and productivity. It is vital to find best design elements to visualize the product which possesses the characteristics not only to satisfy the users but also reduces fatigue and injury during prolonged use. Although subjective and objective product characteristics are important during product design, user comfort becomes a vital factor that can be quantified by the analysis on continuous physical interaction between product and user. Beside above influential factors, ergonomic design of product also considers cognitive and behavioral information during the design stage with a view to improve the comfort level of the user and aesthetic look of the product. To address above issues, an integrated approach using statistical and artificial intelligence techniques has been proposed in this thesis to effectively handle subjective and objectives characteristics during design phase. The statistical method is used to assess various user requirements and their significance whereas artificial intelligence method determines the relationship between user requirements and product characteristics. Since most of the psychological needs of users are difficult to express quantitatively, combined approach of statistical and artificial intelligence method can handle the subjectivity and uncertainty in an effective manner. The approach has been demonstrated with the help of design of office chair. Keeping view with the physical interaction between human soft tissue and product as a measuring factor of comfort sensation in an office environment, a numerical analysis of human soft tissue-chair seat model has been introduced into current work. In order to evaluate superior ergonomically designed product (office chair), suitable multi-attribute decision making (MADM) approach based on few important features has been chosen to address the usability of product improving satisfaction level of customer. The study also analyses a kinematic model of human upper arm extremity to diagnose comfort arm posture that allows the operator to have a comfort work zone within which possible postures can be accepted