Generalization of a muscle-reflex control model to 3D walking.

The neural controller that generates human locomotion can currently not be measured directly, and researchers often resort to forward dynamic simulations of the human neuromuscular system to propose and test different controller architectures. However, most of these models are restricted to locomotion in the sagittal plane, which limits the ability to study and compare proposed neural controls for 3D-related motions. Here we generalize a previously identified reflex control model for sagittal plane walking to 3D locomotion. The generalization includes additional degrees of freedom at the hips in the lateral plane, their actuation and control by hip abductor and adductor muscles, and 3D compliant ground contact dynamics. The resulting 3D model of human locomotion generates normal walking while producing human-like ground reaction forces and moments, indicating that the proposed neural controller based on muscle reflexes generalizes well to 3D locomotion.