Biomechanical Model with Joint Resistance for Impact Simulation

Based on a general methodology using natural co-ordinates, a three-dimensional whole body response model for the articulated human body is presented in this paper. The joints between biomechanical segments are defined by forcing adjacent bodies to share common points and vectors that are used in their definition. A realistic relative range of motion for the body segments is obtained introducing a set of penalty forces in the model rather than setting up new unilateral constraints between the system components. These forces, representing the reaction moments between segments of the human body model when the biomechanical joints reach the limit of their range of motion, prevent the biomechanical model from achieving physically unacceptable positions. Improved efficiency in the integration process of the equations of motion is obtained using the augmented Lagrange formulation. The biomechanical model is finally applied in different situations of passive human motion such as that observed in vehicle occupants during a crash or in an athlete during impact.