Improving the Standing Balance of Paraplegics through the Use of a Wearable Exoskeleton

Emmens, Amber Raphel; Asseldonk, Edwin H.F. van; Masciullo, Marcella; Arquilla, M.; Pisotta, Iolanda; Tagliamonte, Nevio Luigi; Tamburella, Federica; Molinari, Marco; Kooij, Herman van der

doi:10.1109/biorob.2018.8488066

Cited by 17 publications

(15 citation statements)

References 18 publications

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“…In addition to the experiments presented in this paper, we also used the exoskeleton to support standing balance in our SCI test pilots [25]. Using the exoskeleton in the ankle-knee configuration, we tested how various low-level controllers (PD control on center of mass and a momentum-based controller [26]) performed in assisting individuals with incomplete SCI with maintaining their balance while standing.…”

Section: Discussionmentioning

confidence: 99%

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Symbitron Exoskeleton: Design, Control, and Evaluation of a Modular Exoskeleton for Incomplete and Complete Spinal Cord Injured Individuals

Meijneke

Oort

Sluiter

et al. 2021

IEEE Trans. Neural Syst. Rehabil. Eng.

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In this paper, we present the design, control, and preliminary evaluation of the Symbitron exoskeleton, a lower limb modular exoskeleton developed for people with a spinal cord injury. The mechanical and electrical configuration and the controller can be personalized to accommodate differences in impairments among individuals with spinal cord injuries (SCI). In hardware, this personalization is accomplished by a modular approach that allows the reconfiguration of a lowerlimb exoskeleton with ultimately eight powered series actuated (SEA) joints and high fidelity torque control. For SCI individuals with an incomplete lesion and sufficient hip control, we applied a trajectory-free neuromuscular control (NMC) strategy and used the exoskeleton in the ankle-knee configuration. For complete SCI individuals, we used a combination of a NMC and an impedance based trajectory tracking strategy with the exoskeleton in the ankle-knee-hip configuration. Results of a preliminary evaluation of the developed hardware and software showed that SCI individuals with an incomplete lesion could naturally vary their walking speed and step length and walked faster compared to walking without the device. SCI individuals with a complete lesion, who could not walk without support, were able to walk with the device and with the support of crutches that included a push-button for step initiationOur results demonstrate that an exoskeleton with modular hardware and control allows SCI individuals with limited or no lower limb function to receive tailored support and regain mobility.

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Section: Discussionmentioning

confidence: 99%

“…Results were promising since all SCI test pilots improved their balance recovery after being perturbed. One of the SCI test pilots could only stand stably with help of the exoskeleton [25].…”

Section: Discussionmentioning

confidence: 99%

Symbitron Exoskeleton: Design, Control, and Evaluation of a Modular Exoskeleton for Incomplete and Complete Spinal Cord Injured Individuals

Meijneke

Oort

Sluiter

et al. 2021

IEEE Trans. Neural Syst. Rehabil. Eng.

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“…As in Emmens et al ( 2018 ), the perturbation amplitude is defined by the push/pull force multiplied by the perturbation duration. The experimenter keeps the duration of the pulses short and as constant as possible.…”

Section: Methodsmentioning

confidence: 99%

“…Several research groups work on partial assistance during stance in the goal to improve the balance of people with incomplete SCI. Most of these control strategies are using torque control (Rajasekaran et al, 2015 ; Emmens et al, 2018 ; Farkhatdinov et al, 2019 ; van Asseldonk et al, 2019 ). These studies mimic the most common postural strategies highlighted by Winter ( 1995 ): the ankle, the hip, and their combined strategies.…”

Section: Introductionmentioning

confidence: 99%

Bioinspired Postural Controllers for a Locked-Ankle Exoskeleton Targeting Complete SCI Users

et al. 2020

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Several lower-limb exoskeletons enable overcoming obstacles that would impair daily activities of wheelchair users, such as going upstairs. Still, as most of the currently commercialized exoskeletons require the use of crutches, they prevent the user from interacting efficiently with the environment. In a previous study, a bio-inspired controller was developed to allow dynamic standing balance for such exoskeletons. It was however only tested on the device without any user. This work describes and evaluates a new controller that extends this previous one with an online model compensation, and the contribution of the hip joint against strong perturbations. In addition, both controllers are tested with the exoskeleton TWIICE One, worn by a complete spinal cord injury pilot. Their performances are compared by the mean of three tasks: standing quietly, resisting external perturbations, and lifting barbells of increasing weight. The new controller exhibits a similar performance for quiet standing, longer recovery time for dynamic perturbations but better ability to sustain prolonged perturbations, and higher weightlifting capability.

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“…On the other hand, model-based predictive control could be ineffective or even unstable due to inaccurate dynamics modeling, and it typically requires a laborious task-specific parameters tuning. The momentum-based control strategies have also been applied to impose standing balancing on the exoskeleton ( Bayon et al, 2020 ; Emmens et al, 2018 ), which was first applied in humanoid robotics to impose standing and walking balance ( Lee and Goswami, 2012 ; Koolen et al, 2016 ). This method aimed to simultaneously regulate both the linear and angular component of the whole body momentum for balance maintenance with desired GRF and CoP at each support foot.…”

Section: Introductionmentioning

confidence: 99%

Reinforcement Learning and Control of a Lower Extremity Exoskeleton for Squat Assistance

et al. 2021

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A significant challenge for the control of a robotic lower extremity rehabilitation exoskeleton is to ensure stability and robustness during programmed tasks or motions, which is crucial for the safety of the mobility-impaired user. Due to various levels of the user’s disability, the human-exoskeleton interaction forces and external perturbations are unpredictable and could vary substantially and cause conventional motion controllers to behave unreliably or the robot to fall down. In this work, we propose a new, reinforcement learning-based, motion controller for a lower extremity rehabilitation exoskeleton, aiming to perform collaborative squatting exercises with efficiency, stability, and strong robustness. Unlike most existing rehabilitation exoskeletons, our exoskeleton has ankle actuation on both sagittal and front planes and is equipped with multiple foot force sensors to estimate center of pressure (CoP), an important indicator of system balance. This proposed motion controller takes advantage of the CoP information by incorporating it in the state input of the control policy network and adding it to the reward during the learning to maintain a well balanced system state during motions. In addition, we use dynamics randomization and adversary force perturbations including large human interaction forces during the training to further improve control robustness. To evaluate the effectiveness of the learning controller, we conduct numerical experiments with different settings to demonstrate its remarkable ability on controlling the exoskeleton to repetitively perform well balanced and robust squatting motions under strong perturbations and realistic human interaction forces.

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Improving the Standing Balance of Paraplegics through the Use of a Wearable Exoskeleton

Cited by 17 publications

References 18 publications

Symbitron Exoskeleton: Design, Control, and Evaluation of a Modular Exoskeleton for Incomplete and Complete Spinal Cord Injured Individuals

Symbitron Exoskeleton: Design, Control, and Evaluation of a Modular Exoskeleton for Incomplete and Complete Spinal Cord Injured Individuals

Bioinspired Postural Controllers for a Locked-Ankle Exoskeleton Targeting Complete SCI Users

Reinforcement Learning and Control of a Lower Extremity Exoskeleton for Squat Assistance

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