An assistance approach for a powered knee exoskeleton during level walking and the effects on metabolic cost

In this paper, we propose a walking assistance method based on intrinsic gait events for level walking in a powered knee exoskeleton. The proposed method utilizes three gait events in order to determine the timing of initiation and termination for assistance torque profiles. This method plans uni-directional torque profiles for each flexion and extension movement for the next step and executes them in a feedfor-ward manner. It has the advantages of easy to adjust the assistance timing, intensity, and duration according to wearer's preference. In experiments, we investigated that the increase of metabolic cost was close to zero when worn and walked with our portable powered knee exoskeleton by the proposed assistance method compared with walking without wearing it on the treadmill.