Analysis and Evaluation of a Quasi-Passive Lower Limb Exoskeleton for Gait Rehabilitation

Abstract

Using lower limb exoskeletons in healthcare sector like for rehabilitation is an important application. Lower limb exoskeletons can help in performing specific functions like gait assistance, and physical therapy support for patients who are lost their ability to walk again. Since active lower limb exoskeletons require more complicated control instrumentation and according to the limitations of the power/weight ratio that arises in such exoskeletons, many quasi-passive systems have developed and employed. This paper presents the design and testing of lightweight and adjustable two degree of freedom quasi-passive lower limb exoskeleton for improving gait rehabilitation. The exoskeleton consists of a high torque DC motor mounted on a metal plate above the hip joint, and a link that transmit assistance torque from the motor to the thigh. The knee joint is passively actuated with spring. The action of the passive component (spring) is combined with mechanical output of the motor to provide a good control on the designed exoskeleton during walking. The results show that muscles' efforts on both the front and the back sides of the user's leg were decreased when walking using the exoskeleton with the motor and spring.

Designing a Fuzzy Sliding Mode Controller for 2-DOF Lower Limb Exoskeleton Rehabilitation Robot

“…One of the main classes of rehab robots are lower limb rehabilitation exoskeleton robots, which can manage all joints during exercise by integrating wearable with human anatomy. The 1960s marked the beginning of studies on exoskeleton robots for lower-extremity rehabilitation [3].…”

Evaluation of a machine-learning-driven active–passive upper-limb exoskeleton robot: Experimental human-in-the-loop study

“…As a result, active (powered) exoskeletons are big, heavy, fixed in place, expensive, and have a low power-to-weight ratio (Bogue, 2018). Some technologies combine active and passive power transmissions to reduce the drawbacks of fully active and fully passive exoskeletons (Naito et al, 2007;Matthew et al, 2015;Otten et al, 2018;Al-Hayali et al, 2021aMiakovic et al, 2022). Passive mechanisms serve to minimize the size, weight, and necessary active torque, which in turn improves portability (Smith et al, 2013;Blanchet et al, 2020;Miakovic et al, 2022).…”

“…Passive mechanisms serve to minimize the size, weight, and necessary active torque, which in turn improves portability (Smith et al, 2013 ; Blanchet et al, 2020 ; Miakovic et al, 2022 ). Recently, the semi-active, semi-passive, and quasi-passive nature of this combined transmission system has been conceptually investigated on lower limbs (Lambrecht and Kazerooni, 2009 ; Hassan and Sadik, 2018 ; Di Natali et al, 2020 ; Pillai et al, 2020 ; Al-Hayali et al, 2021a , 2021b ; Ren et al, 2021 ; Wang et al, 2021 ), upper limbs (Naito et al, 2007 ; Smith et al, 2013 ; Zahedi et al, 2021 ; Bai et al, 2022 ; Winter et al, 2022 ), and spines (Jamsek et al, 2020 ). However, from a practical point of view, it is necessary to consider the HRI, as well as control delays in regulating the active component of this integrated system.…”

Experimental Study of Fully Passive, Fully Active, and Active–Passive Upper-Limb Exoskeleton Efficiency: An Assessment of Lifting Tasks

“…For example, Hodson [ 9 ], Kim et al [ 10 ] and Alemi et al [ 11 ] have used maximum voluntary isometric contractions (MVICs) [ 12 ] for exoskeleton evaluation. The other evidence-based metrics are muscle activity measured through surface electromyography (sEMG) [ 13 , 14 , 15 , 16 ], fatigue/endurance using mean power frequency [ 16 , 17 , 18 , 19 ], muscle metabolic energy expenditure (MMEE) [ 11 ], task completion or time [ 10 , 20 ], subjective feedback [ 10 , 20 ], or discomfort feedback [ 11 , 20 , 21 ]. However, to the best of our knowledge, there have been limited efforts to employ an inverse dynamic skeletal model integrated with machine learning-based muscle models that exhibit kinematic closed-loop interactions with exoskeletons.…”