Design and control of a wearable lower-body exoskeleton for squatting and walking assistance in manual handling works
Document Type
Article
Publication Date
1-1-2019
Abstract
Several manual-handling works (e.g. load-lifting, carrying, carpet-laying, etc.) involve repetitive lower limb movements (RLLM) such as squatting, kneeling, or walking which are notable risk factors for work-related musculoskeletal disorders of the lower-limb and lumbar spine. Wearable exoskeletons can augment workers’ strength and minimize muscular activation in RLLM, thus enhancing efficiency and improving workers health. In this paper, we present the design and control of a wearable lower-body exoskeleton to assist RLLM. The design of the exoskeleton is anthropomorphic with six-degrees of freedom (6-DoF) on each leg: 1-active and 1-passive DoF on the hip-joint, 1-active and 1-passive DoF on the knee-joint, and 2-passive DoFs on the ankle-joint. The active DoFs are actuated by bi-directional brushless DC motors to permit sagittal movements. The exoskeleton controller is designed hierarchical with a low-level linear quadratic gaussian (LQG) torque controller, a middle-level user-input torque estimator based on dual extended Kalman filter (EKF), and a novel high-level supervisory algorithm for movement detection and synchronization of the exoskeleton with the user. Initial evaluation of the prototype is conducted on five healthy participants recruited to perform repetitive load-lifting and carrying manual-handling tasks. Electromyogram sensors are placed at the participants’ right Vastus Intermedius and right Gastrocnemius to extract muscle activity signals. Results show that the exoskeleton could provide torque assistance by amplifying participants’ input joint torques and could minimize muscular activation in the two muscles by more than 36% respectively in all movement tasks. © 2019
Keywords
Dual extended Kalman filter, Linear quadratic Gaussian, Manual handling works, Movement detection and synchronization, Repetitive movements, Wearable lower-body exoskeletons
Divisions
fac_eng
Funders
University of Malaya under RU Operation Grant ( RU016-2016 ) and Grant ( GPF023A-2018 ),Ministry of Higher Education of Malaysia for the facility and equipment support under High Impact Research Grant UM.C/625/1/HIR/MOHE/ENG/41
Publication Title
Mechatronics
Volume
63
Publisher
Elsevier