Toward Improving Actuation Transparency and Safety of a Hip Exoskeleton With a Novel Nonlinear Series Elastic Actuator

Qian, Yuepeng; Han, Shuaishuai; Wang, Yining; Huang, Yu; Fu, Chenglong

doi:10.1109/tmech.2022.3201255

Cited by 27 publications

(6 citation statements)

References 35 publications

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“…where m is the number of spring pairs, k s is the spring stiffness, l 0 is the rest length of spring. More details about the design and modeling of the reconfigurable RSEE can be found in our previous works [23], [24].…”

Section: Hip Exoskeleton Designmentioning

confidence: 99%

“…Mechanical drawbacks, such as friction and backlash, are neglected here. Different from conventional cascade PI controller that adopts a torque loop as the outer loop [29], [30], the cascade PI controller used in this work adopts a position loop as the outer loop while the inner loop is still a velocity loop, which can achieve a more accurate and stable torque control for the nSEA [24]. The desired deflection angle is online computed according to the desired torque utilizing Newton-Raphson method.…”

Section: B Inner-loop Controlmentioning

confidence: 99%

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Adaptive Oscillator-Based Assistive Torque Control for Gait Asymmetry Correction With a nSEA-Driven Hip Exoskeleton

Qian

Huang

2022

IEEE Trans. Neural Syst. Rehabil. Eng.

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Gait asymmetry is an important clinical characteristic of the hemiplegic gait most stroke survivors suffered, leading to restricted functional mobility and long-term negative impact on their quality of life. In recent years, robot assistance has been proven able to improve stroke patients' functional walking, but few studies have been conducted to specifically correct gait asymmetry of stroke patients during the whole gait cycle. In this work, an adaptive oscillator-based assistive torque control was developed and implemented on a unilateral hip exoskeleton driven by a novel nonlinear series elastic actuator (nSEA), aiming at correcting gait asymmetry at hip joints during the whole gait cycle. The adaptive oscillator-based gait asymmetry detection method extracted continuous gait phase and gait asymmetry seamlessly, and then the proposed assistive control attempted to correct gait asymmetry by delivering precise assistive torques synchronized with the continuous gait phase of the patients' gait. An initial experimental study was conducted to evaluate the proposed assistive control on seven healthy subjects with artificial impairment. The participants walked on a treadmill with assistance from the hip exoskeleton, while artificial impairment was added to mimic the hemiplegic gait with both spacial and temporal asymmetry (such as reduced hip flexion in the impaired side and reduced hip extension in the healthy side). Experimental results suggested the effectiveness of the proposed assistive control in restoring gait symmetry to levels comparable to a normal gait of the participants (p < 0.05).

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Section: Hip Exoskeleton Designmentioning

confidence: 99%

Section: B Inner-loop Controlmentioning

confidence: 99%

Adaptive Oscillator-Based Assistive Torque Control for Gait Asymmetry Correction With a nSEA-Driven Hip Exoskeleton

Qian

Huang

2022

IEEE Trans. Neural Syst. Rehabil. Eng.

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“…Recent advancements in portable walking-assist exoskeletons demonstrate considerable potential in improving the wearers' mobility, for instance, by reducing metabolic costs [5][6][7][8] or muscular activity [9,10]. Simultaneously, mechanical adaptations, e.g., serial elastic actuator [11] and quasi-direct driver [12], along with cognitive adaptations, such as admittance control [13], have been extensively researched to foster improved human-exoskeleton interactions. Despite the innovations, determining the exertion of forces and torques on the human body and understanding and predicting individual adaptation or response remain 2 of 16 unresolved challenges [14,15].…”

Section: Introductionmentioning

confidence: 99%

Optimizing Exoskeleton Assistance: Muscle Synergy-Based Actuation for Personalized Hip Exoskeleton Control

Ma,

Liu,

Yan

et al. 2024

Actuators

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Exoskeleton robots hold promising prospects for rehabilitation training in individuals with weakened muscular conditions. However, achieving improved human–machine interaction and delivering customized assistance remains a challenging task. This paper introduces a muscle synergy-based human-in-the-loop (HIL) optimization framework for hip exoskeletons to offer more personalized torque assistance. Initially, we propose a muscle synergy similarity index to quantify the similarity of synergy while walking with and without the assistance of an exoskeleton. By integrating surface electromyography (sEMG) signals to calculate metrics evaluating muscle synergy and iteratively optimizing assistance parameters in real time, a muscle synergy-based HIL optimized torque configuration is presented and tested on a portable hip exoskeleton. Iterative optimization explores the optimal and suboptimal assistance torque profiles for six healthy volunteers, simultaneously testing zero torque and predefined assistance configurations, and verified the corresponding muscle synergy similarity indices through experimental testing. In our validation experiments, the assistance parameters generated through HIL optimization significantly enhance muscle synergy similarity during walking with exoskeletal assistance, with an optimal average of 0.80 ± 0.04 (mean ± std), marking a 6.3% improvement over prior assistive studies and achieving 96.4% similarity compared with free walking. This demonstrates that the proposed muscle synergy-based HIL optimization can ensure robotic exoskeleton-assisted walking as “natural” as possible.

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“…However, more powered robotic joints in wearable exoskeletons mean additional mass on the user's body and higher system complexity. Therefore, reported portable devices for post-stroke gait rehabilitation mainly focus on assisting single human joint, such as assist-on the hip joint [22], [23], ankle joint [7], [17], [24], [25], and knee joint [26], [27]. Devices with multi-active joints usually adopted entire rigid structures to transfer the system weight to the ground [2], leading to compromised wearability.…”

Section: Introductionmentioning

confidence: 99%

A Cable-Driven Exoskeleton With Personalized Assistance Improves the Gait Metrics of People in Subacute Stroke

Zhong

Shen

Liu

et al. 2023

IEEE Trans. Neural Syst. Rehabil. Eng.

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Most stroke survivors have mobility deficits and show a pathological gait pattern. Seeking to enhance the gait performance among this population, we have developed a hybrid cable-driven lower limb exoskeleton (called SEAExo). This study aimed to determine the effects of SEAExo with personalized assistance on immediate changes in gait performance of people after stroke. Gait metrics (i.e., the foot contact angle, knee flexion peak, temporal gait symmetry indices) and muscle activities were the primary outcomes to evaluate the assistive performance. Seven subacute stroke survivors participated and completed the experiment with three comparison sessions,

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Toward Improving Actuation Transparency and Safety of a Hip Exoskeleton With a Novel Nonlinear Series Elastic Actuator

Cited by 27 publications

References 35 publications

Adaptive Oscillator-Based Assistive Torque Control for Gait Asymmetry Correction With a nSEA-Driven Hip Exoskeleton

Adaptive Oscillator-Based Assistive Torque Control for Gait Asymmetry Correction With a nSEA-Driven Hip Exoskeleton

Optimizing Exoskeleton Assistance: Muscle Synergy-Based Actuation for Personalized Hip Exoskeleton Control

A Cable-Driven Exoskeleton With Personalized Assistance Improves the Gait Metrics of People in Subacute Stroke

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