Modelling the human body for ergonomic CAD

A recently completed Brite-Euram (European Community) research project was concerned with life-cycle aspects of car seating with Loughborough University being responsible for driver comfort assessment. This was achieved by road and laboratory trials, with the results to be incorporated within the SAMMIE computer-aided ergonomic design system. Driver comfort is in part determined by seat pressure distributions which lead to deformation of the human flesh and the seat and result in uncertainty in the position of important design locations such as the driver's eyepoint. Accommodation of these effects requires a realistic representation of the human body using surface rather than solid representations. Hence a shadow scanning technique was used to capture human body shape which was processed into the DUCT surface modelling system and via IGES files into SAMMIE. Finite element techniques were then used to predict deformations at the seat/driver interface. Having established an anthropometrically correct representation of body shape, current research is aimed at improving the kinematic and analytic capabilities of the human model by introducing a multi-segment spine that can respond to external and internal loadings. This spine model is intended for use in the evaluation of human working postures (such as car driving) where, although the loadings might be viewed as well within human capabilities, previous studies have· shown that back pain or damage might result. The model described is based on an arch representation rather than the pin-jointed rigid link systems which are perhaps more usual, but which have been shown to be deficient in several respects.