A Bond Graph Model for the Actuation Mechanism of Musculo-Skeletal Joints

Modeling the dynamics of actuation of musculoskeletal joints involves the generalized three dimensional motion of rigid bones caused by flexible muscles which cling to the skeletal structures and is a difficult issue. A bond graph model for such joints is systematically developed. Muscles have been considered as string tube models. Each of the component subsystems such as bones, muscles, rotational couplings, etc. have been modeled as Word Bond Graph Objects. These are then integrated to yield the complete bond graph model. An example of a joint, with two mating bones and actuated by a pair of muscles is considered. The bond graph model for the joint system has also been verified using simulation. The resulting model is simple yet captures the complete dynamics and provides insight into the dynamics of musculoskeletal joint actuation.