Design and Control of an Underactuated Hip Exoskeleton for Hybrid Active-Passive Walking Assistance

Abstract

Exoskeletons have great potential to enhance the daily activities of individuals needing robotic assistance. This article presents a design for an underactuated hip exoskeleton providing both active and passive walking assistance. The system integrates a driving reversal device (DRD) and a hip energy storage walking device (HESWD) to improve performance. The DRD allows a single motor to drive both hips during the movement phase, while the HESWD stores negative work generated by the human hip joint and uses it as positive work during the “blank” phase of underactuated walking. Specialized motor trajectory planning and optimization are used to meet the active assistance phase requirements. A radial basis function (RBF) neural network-based trajectory tracking control method adapts to changes in human gait. Treadmill experiments demonstrate that the tracking error is below 0.4146<sup xmlns:mml="http://www.w3.org/1998/Math/MathML" xmlns:xlink="http://www.w3.org/1999/xlink">∘</sup>. The results show the effectiveness of the proposed control method and the exoskeleton’s ability to adapt to slight gait variations.