A comprehensive model for human motion simulation and its application to the take-off phase of the long jump.

Abstract A mathematical model is presented which makes it possible to simulate complex motions of a 17-segment hominoid. The dynamical equations are given in compact form and the treatment of external constraints and impact situations, such as occur at heel strike in locomotion, is discussed in depth. The practical implementation of the model is outlined and demonstrated by simulating the long-jump take-off phase of a given athlete. In contrast to other similar models, the present one not only fully accounts for the dynamics of the executor (skeletal) subsystem but also simulates in detail the intricately controlled internal excitation and contraction dynamics of the myoactuator (muscular) sybsystem. The controls in the model are the actual neural controls motor unit recruitment and stimulation rate, for each of the 46 muscles of the model. For a given set of subject-specific input parameters, a given initial state, and given neural control functions, the computer program executing the model computes the state trajectory (i.e. the resulting motion), the histories of all constraint forces, the trajectory of the centre of mass, and the histories of the components of the velocity of the centre of mass, of the total angular momentum, of all muscle and joint reaction forces, and of the energies of all 17 model segments. Finally, the optimization problem of the long jump and the corresponding objective function are formulated and briefly discussed.