Biomechanics analysis of human lower limb during walking for exoskeleton design

Human body experiences a long natural evolution to have good movement forms and flexible driving mode, during which process, human muscles have already evolved to a sophisticated bio-actuator, usually used in the bionic design of mechanical structures. The article presents a novel idea for the bionics design of artificial limb or exoskeleton robot, considering the motion level and the driving level of human body simultaneously, i.e. the lower limb segment movement and the muscle activity. Firstly, as the support phase, the most complex process during human walking, we divided it into three sub-phases and studied each other’s variations about the angle and torque by the built motion capture system, which is important for ground reaction force control (GRF control). Secondly, the principal muscles around the knee joint were studied by biomechanical simulation, i.e. the vastus medialis muscle and the biceps femoris muscle, after the data of clinical gait by experiment was imported into the human simulation software. The result showed that the vastus medialis muscle, as Hill three elements model, was the principal muscle during knee’s extension motion, which mainly worked during the support phase and could provide a maximum force of 280 N.m. In contrast, the biceps femoris muscle, as Hill two elements model, was the principal muscle during knee’s flexion motion, which mainly worked during the swing phase and could provide a maximum force of 220 N.m