On high-level control of power-augmentation lower extremity exoskeletons: Human walking intention

Abstract

Lower extremity exoskeleton is a powerful tool for power augmentation of the user. In general, three control levels can be designed for motion stabilization of human-robot interaction: high-level control represented by human walking intention, mid-level control for regulation of switching periods of walking phases, and low-level control for motion tracking and stabilization purposes. Three important points should be considered while designing the control architecture: (1) determination of the power assist rate required for empowering the user, (2) minimization of the interaction force wrench at the attachment locations, and (3) regulation of switching periods of the walking phases. To end this, the user's joint torques and/or his/her position are often required to be measured/estimated. There are different techniques used for extracting and capturing the user intention such as electromyography technique, measurement of global kinematic parameters, and the use of force/torque sensors at the physical interaction interfaces. Accordingly, this paper introduces a systematic overview of capturing user-walking intention with focus on poweraugmentation lower extremity exoskeletons.