Intelligent Control of Prosthetic Leg for Gait Symmetry

Transfemoral, i.e., above-knee amputation, has a lasting adverse impact on an individual's mobility. While substantial progress has been made in the design and control of prosthetic legs, they still provide only limited mobility to the user and cannot adapt to different gait needs. This limitation causes dissimilar walking patterns in the prosthetic and intact limbs, and can result in health complications arising from increased loading on the intact limb. In this study, we first investigate the effect of transfemoral amputation on muscle activity and gait of intact and amputated legs of an individual. The gait parameters are then used to design a neuro-dynamic programming (NDP) based controller that can determine the user's gait and generate a control input that will reduce the asymmetry in gait of the intact and prosthetic leg. The controller learns and compensates for the unknown dynamics of the prosthetic-human system for varying gait patterns, thus leading to near-natural gait. The proposed control strategy holds promise in improving the long-term health outcomes for individuals with transfemoral amputation.