Kinematics study of a 10 degrees-of-freedom lower extremity exoskeleton for crutch-less walking rehabilitation.

Abstract

Wearable lower extremity exoskeletons can provide walking assistance for the physical rehabilitation of paralyzed individuals. However, most of the existing exoskeletons require crutches to maintain balance, thus a self-balancing type is needed to improve applicability. The purpose of this work is to study the kinematic characteristics of a novel lower extremity exoskeleton for crutch-less walking rehabilitation, and evaluate the movement performance through practical experiments. Based on the human lower limb structure and movement characteristics, a fully actuated 10 degrees-of-freedom (DoF) lower extremity exoskeleton was proposed. The kinematic characteristics of the exoskeleton were analyzed by the D-H method and geometric method, and the model validity was verified through simulations and experiments. The closed-form solutions for both forward and inverse kinematics models were obtained. The consistent results of theoretical calculation and numerical simulation have shown the accuracy of the established models. The practical experiments regarding six trials have demonstrated the movement performance of the proposed exoskeleton, including sit, stance, leg extension/flexion, and left/right swing. The kinematic characteristics of the proposed 10-DoF lower extremity exoskeleton are similar to the human lower limb, and it could meet the motion demands of crutch-less walking rehabilitation.