Dynamic Modeling of Human Movement During Activities Involving Impact

Abstract

Modeling the behavior of the human body during weight bearing movements involving impact allows us to simulate impact conditions under hypothetical conditions. We propose a model that is simple enough to advance our understanding of body motion and interaction forces during movements involving impact and is detailed enough to account for the subject specific control of the musculoskeletal behavior during contact. The model consists of two rigid subsystems and assumes that flexibility and energy dissipation is provided by impedance type control. The model reflects the control implemented prior to touchdown that determines the interaction force during impact and the trajectory of the center of gravity during the post impact phase. This design allows the model to account for differences in control observed between tasks, landing phases, and individuals.The equations of the impact and post-impact motion and their relation to the flight phase are derived in terms of parameters critical to the performance of the task at hand. The equations also allow stability analysis, thus permitting obtaining conditions system's stability conditions in terms of the important parameters of the system. Simulation study that uses experimentally collected data was used to demonstrate the validity of the proposed approach and verified its accuracy. The ability of the model to facilitate sensitivity analysis to various system parameters was also demonstrated.