Estimation of Knee Assistive Moment in a Gait Cycle Using Knee Angle and Knee Angular Velocity through Machine Learning and Artificial Stiffness Control Strategy (MLASCS)

Pornpipatsakul, Khemwutta; Ajavakom, Nopdanai

doi:10.3390/robotics12020044

Cited by 5 publications

(2 citation statements)

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“…In this study, the gait characteristics of walkers with an inflatable socket were evaluated using optical motion analysis equipment (Vicon Motion System Ltd., Oxford, UK) [ 21 , 22 ]. Several markers were attached to the hip, knee, ankle, and foot, as shown in Figure 9 a.…”

Section: Resultsmentioning

confidence: 99%

A Pneumatically Controlled Prosthetic Socket for Transfemoral Amputees

Lee,

Heo,

Kim

et al. 2023

Sensors

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Amputees typically experience changes in residual limb volume in their daily lives. It causes an uncomfortable fit of the socket by applying high pressure on the sensitive area of the residual limb or by loosening the socket. In this study, we developed a transfemoral prosthetic socket for above-the-knee amputees that ensures a good socket fit by maintaining uniform and constant contact pressure despite volume changes in the residual limb. The socket has two air bladders in the posterior femoral region, and the pneumatic controller is located on the tibia of the prosthesis. The pneumatic system aims to minimize unstable fitting of the socket and improve walking performance by inflating or deflating the air bladder. The developed socket autonomously maintains the air pressure inside the prosthetic socket at a steady-state error of 3 mmHg or less by adjusting the amount of air in the air bladder via closed-loop control. In the clinical trial, amputee participants walked on flat and inclined surfaces. The displacement between the residual limb and socket during the gait cycle was reduced by up to 33.4% after air injection into the socket. The inflatable bladder increased the knee flexion angle on the affected side, resulting in increased stride length and gait velocity. The pneumatic socket provides a stable and comfortable walking experience not only when walking on flat ground but also on slopes.

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Section: Resultsmentioning

confidence: 99%

A Pneumatically Controlled Prosthetic Socket for Transfemoral Amputees

Lee,

Heo,

Kim

et al. 2023

Sensors

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“…Another study presented impedance modulation using an electromagnetic brake [9]. Several other methods have been used for human-exoskeleton force estimation, and some for rehabilitation of patients [10][11][12][13].…”

Section: Introductionmentioning

confidence: 99%

Sensorless Estimation of Human Joint Torque for Robust Tracking Control of Lower-Limb Exoskeleton Assistive Gait Rehabilitation

Abdullahi

Chaichaowarat

2023

JSAN

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Patients suffering from motor disorders or weakness resulting from either serious spinal cord injury or stroke often require rehabilitation therapy to regain their mobility. In the lower limbs, exoskeletons have two motors aligned with the patients’ hip and knee to assist in rehabilitation exercises by supporting the patient’s body structure to increase the torques at the hip and knee joints. Assistive rehabilitation is, however, challenging, as the human torque is unknown and varies from patient to patient. This poses difficulties in determining the level of assistance required for a particular patient. In this paper, therefore, a modified extended state observer (ESO)-based integral sliding mode (ISM) controller (MESOISMC) for lower-limb exoskeleton assistive gait rehabilitation is proposed. The ESO is used to estimate the unknown human torque without application of a torque sensor while the ISMC is used to achieve robust tracking of preset hip and knee joint angles by considering the estimated human torque as a disturbance. The performance of the proposed MESOISMC was assessed using the mean absolute error (MAE). The obtained results show an 85.02% and 87.38% reduction in the MAE for the hip and joint angles, respectively, when the proposed MESOISMC is compared with ISMC with both controllers tuned via LMI optimization. The results also indicate that the proposed MESOISMC method is effective and efficient for user comfort and safety during gait rehabilitation training.

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