Integrating efficient kinematics in biomechanics of human motions

Biomechanical modeling of human motion often is based on simple tree-type structures with elementary joint and contact situations. This is adequate for coarse evaluation of motion parameters and their effects but insufficient for detailed analysis of joint or system/environment interactions. In this lecture, an object-oriented approach for the modeling of kinematics and dynamics of musculoskeletal motion is presented which is open for integration of arbitrarily complex subsystems and their coupling to state-of-the art numerical and visualization tools. The approach is based on the concept of kinetostatic transmission element which allows one to embed intricate kinematical dependencies in easy-to-use, multilayered objects. Based on this approach, the inverse and direct dynamics problem can be formulated in a highly-efficient and implementation-independent manner, featuring different methodologies as ‘flavors’ of the generic transmission properties. This allows one to re-use methods developed for technical systems such as contact effects, multiloop transmission mechanisms, multidisciplinary mechatronic components, and efficient numerical solution schemes. The concepts have been implemented in the object-oriented 3D biomechanical simulation environment MobileBody featuring mechanism surrogates for joint motion, higher-order foot-ground contact, data fusion of MRI and motion capturing, composite numerical clinical scoring algorithms, optimization-based muscle activation identification, verification by interval analysis, and embedded 3D visualization.