Gait recovery in healthy subjects: perturbations to the knee motion with a smart knee brace

Agrawal, Sunil K.Smart Knee Brace (SKB) is designed to provide controlled perturbations to the human knee during walking. A motion capture system records the gait movement before and after these perturbations to assess the human response to the perturbations. A dynamic model of human walking is then used to evaluate the human applied joint torques to hypothesize how the human neuro-muscular system modulates the joint torques as a response to the perturbations caused on the gait. Subjects respond differently to perturbations but all healthy subjects restore their nominal gait in a few subsequent cycles. With a single perturbation to the gait, the subjects restore their nominal gait immediately while they tend to show aftereffects under sustained perturbations. The results show that the neuro-muscular response to perturbations can be reasonably well characterized by including the following features in the model: (i) nominal gait in the absence of perturbation, (ii) corrective torque at a joint in response to the error at that joint and other joints, (iii) a characteristic time shift in the response. There is intuitive justification for each of the components included in the model. Detailed parameters that characterize these components, obtained by data fitting from the response data, are specific to an individual's neuro-muscular response to perturbations in the gait. These parameters may be used to characterize subjects who are more prone to falling under gait perturbations.University of Delaware, Department of Mechanical EngineeringM.S.M.E