Fig. 2

Perturbed walking with ankle–foot exoskeleton. Twelve subjects walked with a bilateral ankle–foot exoskeleton in minimal-impedance mode and controlled with the neuromechanical model with and without additional COM velocity feedback. A External forces were applied at the pelvis after right heel strike in forward (push) or backward (pull) direction to perturb human walking. B, C The neuromuscular controller uses the encoder on the ankle joint, ground reaction forces and deviation in COM velocity from the reference trajectory as input and ankle joint moment as output. D The exoskeleton delivered 30% of the ankle joint moment computed with the neuromuscular controller. E Surface Electromyography was used to quantify muscle activity to evaluate controller performance. This figure contains data of one backward directed perturbation of a typical subject walking with the neuromuscular controller with additional feedback of COM velocity