Design and analysis of a novel 12-DOF self-balancing lower extremity exoskeleton for walking assistance. (January 2022)

• Record Type: Journal Article
• Authors: Liu, Jingshuai; He, Yong; Yang, Jiantao; Cao, Wujing; Wu, Xinyu
• Is Part Of: Mechanism and machine theory. Volume 167(2022)
• Publication Date: 2022-01
• Subjects: Rehabilitation exoskeleton -- Self-balancing -- Mechanism synthesis -- Workspace analysis -- Kinematic simulation; Machine theory -- Periodicals; Machinery -- Periodicals; Machines -- Périodiques; Génie mécanique -- Périodiques; Machine theory; Machinery; Periodicals; 621.81
• DOI: 10.1016/j.mechmachtheory.2021.104519
• Languages: English
• ISSNs: 0094-114X

Abstract

Highlights: Propose a hybrid serial‐parallel mechanism for the self‐balancing exoskeleton. Bio‐inspired synthesis of the 3‐DOF hip, 1‐DOF knee, 2‐DOF ankle mechanisms. Closed‐form solutions for both forward and inverse kinematic problems. Workspace equations established by a geometric method in the two walking phases. Verify kinematics model and self‐balancing ability by simulation and experiment. Abstract: Lower extremity exoskeletons are often used as walking assistance rehabilitation robots for paralyzed patients. However, due to the requirement of crutches or other devices to maintain balance, the under-actuated exoskeleton has limited applicability. This paper aims to design a novel mechanism for the self-balancing lower extremity exoskeleton, which structurally consistent with the human anatomy and fully actuated with 12 DOFs. In this study, based on the human-centered design principles, a bio-inspired exoskeleton mechanism synthesis methodology is presented. The novel serial-parallel hybrid mechanism is designed based on a 3-DOF RCM hip mechanism, 1-DOF parallelogram-linkage knee mechanism, and 2-DOF decoupled parallel ankle mechanism. To describe the forward and inverse kinematics of the mechanism, the closed-form solutions by the D-H method and geometric method are obtained, respectively. In addition, to analyze the exoskeleton workspace, the reachable workspace equations in the double foot support and single foot support phases are established. The numerical simulation and experimental results show the kinematics model validity and self-balancing walking ability, which illustrate the feasibility of the proposed exoskeleton mechanism. Graphical abstract: Image, graphical abstract