Dynamic Locomotion Synchronization and Fuzzy Control of a Lower Limb Exoskeleton With Body Weight Support for Active Following Human Operator

Abstract

Despite remarkable progress in robotic exoskeletons, exoskeletons are still far from matching human-level guidance and locomotion performance in gait training or movement enhancement. A desirable exoskeleton would first provide a standard gait profile by learning from human operators while requiring body weight support with active human-following to govern dynamic locomotion synchronization. To address these issues, in this article, we propose a human operator-involved dynamic locomotion synchronization control framework for the lower limb exoskeleton actively following gait training with gravity-supporting. First, we designed a human motion capture system based on a five-link model for the locomotion of a human operator. To reproduce human-level motor skills, we use whole-body teleoperation to leverage human control intelligence to command the locomotion of a robotic exoskeleton system. Specifically, using the linear inverted pendulum (LIP) model, the human operator’s divergent component of motion (DCM) is obtained by the human motion capture system. The dynamic similarity is used to generate a reference DCM for the robotic exoskeleton to synchronize the human operator’s movement. Finally, a fuzzy-based adaptive controller is designed to track the synchronous trajectory for the exoskeleton in the presence of robotic dynamics uncertainties with input saturation. Experiments on the human subject are carried out to demonstrate the effectiveness of the proposed method.