A simplified model for a biomechanical joint with soft cartilage

The modeling of joints on human limbs involves complexities due to the presence of articular cartilage at the synovial joint interface between mating bones, and the geometries involved. In this work, a simple yet innovative model for such a joint which can still capture most of the behavior of the bone joint system is presented. The model is applied to a ball and socket joint system with soft cartilage. The functional role of the soft cartilage material is replaced by a nonlinear stiffness field, whose properties are defined with relation to the ball position with respect to any fixed reference point within the socket. Bond graph modeling and simulation are used to study the system dynamics. Simulations indicate that this simple but significant model holds promise for applications in simulation, control of biomechanical, robotic and virtual reality based devices