A novel modulation strategy to increase stimulation duration in neuromuscular electrical stimulation

Downey, Ryan J.; Bellman, Matthew J.; Sharma, Nitin; Wang, Qiang; Gregory, PT Chris M.; Dixon, Warren E.

doi:10.1002/mus.22058

Cited by 26 publications

(25 citation statements)

References 28 publications

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“…Research efforts have been directed to analyze pulse and train configurations to achieve a more physiological stimulation, thus generating more muscle force per pulse train and delaying the appearance of muscle fatigue [8,29-31]. However, muscle fatigue would eventually develop, and in our opinion very little attention has been paid to investigate strategies that may manage muscle fatigue during repetitive functional tasks.…”

Section: Methodsmentioning

confidence: 99%

Hybrid FES-robot cooperative control of ambulatory gait rehabilitation exoskeleton

del-Ama

Gil-Agudo

Pons

et al. 2014

J NeuroEngineering Rehabil

149

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Robotic and functional electrical stimulation (FES) approaches are used for rehabilitation of walking impairment of spinal cord injured individuals. Although devices are commercially available, there are still issues that remain to be solved. Control of hybrid exoskeletons aims at blending robotic exoskeletons and electrical stimulation to overcome the drawbacks of each approach while preserving their advantages. Hybrid actuation and control have a considerable potential for walking rehabilitation but there is a need of novel control strategies of hybrid systems that adequately manage the balance between FES and robotic controllers. Combination of FES and robotic control is a challenging issue, due to the non-linear behavior of muscle under stimulation and the lack of developments in the field of hybrid control. In this article, a cooperative control strategy of a hybrid exoskeleton is presented. This strategy is designed to overcome the main disadvantages of muscular stimulation: electromechanical delay and change in muscle performance over time, and to balance muscular and robotic actuation during walking.Experimental results in healthy subjects show the ability of the hybrid FES-robot cooperative control to balance power contribution between exoskeleton and muscle stimulation. The robotic exoskeleton decreases assistance while adequate knee kinematics are guaranteed. A new technique to monitor muscle performance is employed, which allows to estimate muscle fatigue and implement muscle fatigue management strategies. Kinesis is therefore the first ambulatory hybrid exoskeleton that can effectively balance robotic and FES actuation during walking. This represents a new opportunity to implement new rehabilitation interventions to induce locomotor activity in patients with paraplegia.Acronym list: 10mWT: ten meters walking test; 6MWT: six minutes walking test; FSM: finite-state machine; t-FSM: time-domain FSM; c-FSM: cycle-domain FSM; FES: functional electrical stimulation; HKAFO: hip-knee-ankle-foot orthosis; ILC: iterative error-based learning control; MFE: muscle fatigue estimator; NILC: Normalized stimulation output from ILC controller; PID: Proportional-Integral-derivative Control; PW: Stimulation pulse width; QUEST: Quebec User Evaluation of Satisfaction with assistive Technology; SCI: Spinal cord injury; TTI: torque-time integral; VAS: Visual Analog Scale.

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Section: Methodsmentioning

confidence: 99%

Hybrid FES-robot cooperative control of ambulatory gait rehabilitation exoskeleton

del-Ama

Gil-Agudo

Pons

et al. 2014

J NeuroEngineering Rehabil

149

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“…After multiplying (9) by , and utilizing (2) and (6)- (8), the open-loop dynamics during stimulation of up to two subsystems can be written as (10) where denotes an auxiliary term defined as After utilizing (3)-(5), the open-loop dynamics in (10) can be expressed as (11) where denotes the voltage applied by the th stimulation channel, and denotes an unknown positive auxiliary function of the leg angle and velocity that varies with time and relates the voltage applied by the th channel to the torque produced by the activated motor neurons, defined based on [40] as (12) Assumption 1: The moment arm is assumed to be a nonzero, positive, and bounded function [41] where the first two partial derivatives of with respect to exist and are bounded for a bounded argument. Likewise, the function is assumed to be a nonzero, positive, and bounded function [42] provided the muscle is not fully stretched or contracting concentrically at its maximum shortening velocity [43], where the first two partial derivatives of with respect to and exist and are bounded for a bounded argument.…”

Section: Control Developmentmentioning

confidence: 99%

Closed-Loop Asynchronous Neuromuscular Electrical Stimulation Prolongs Functional Movements in the Lower Body

Downey

Cheng

Bellman

et al. 2015

IEEE Trans. Neural Syst. Rehabil. Eng.

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Neuromuscular electrical stimulation (NMES) is commonly used in rehabilitative settings and is also used for assistive purposes to create functional movements, where it is termed functional electrical stimulation (FES). One limitation of NMES/FES is early onset of muscle fatigue. NMES-induced fatigue can be reduced by switching between multiple stimulation channels that target different motor units or synergistic muscles (i.e., asynchronous stimulation). However, switching stimulation channels introduces additional complexity due to the need to consider the switching dynamics and differing muscle response to stimulation. The objective of this study was to develop and test a closed-loop controller for asynchronous stimulation. The developed closed-loop controller yields asymptotic tracking of a desired trajectory for a person's knee-shank complex despite switching between stimulation channels. The developed controller was implemented on four able-bodied individuals with four-channel asynchronous stimulation as well as single-channel conventional stimulation. The results indicate that asynchronous stimulation extends the duration that functional movements can be performed during feedback control. This result is promising for the implementation of asynchronous stimulation in closed-loop rehabilitative procedures and in assistive devices as a method to reduce muscle fatigue while maintaining a person's ability to track a desired limb trajectory.

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“…Factors such as the stimulation method, muscle fiber composition, state of training of the muscle, and the duration and task to be performed have been noticed to affect fatigue during NMES. Given the impact of fatigue during NMES, researchers have proposed different stimulation strategies Maladen et al, 2007;Downey et al, 2011Downey et al, , 2015 to delay the onset of fatigue such as choosing different stimulation patterns and parameters, improving fatigue resistance through muscle retraining, sequential stimulation, and size order recruitment.…”

Section: Introductionmentioning

confidence: 99%

A Non-Linear Control Method to Compensate for Muscle Fatigue during Neuromuscular Electrical Stimulation

et al. 2017

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Neuromuscular electrical stimulation (NMES) is a promising technique to artificially activate muscles as a means to potentially restore the capability to perform functional tasks in persons with neurological disorders. A pervasive problem with NMES is that overstimulation of the muscle (among other factors) leads to rapid muscle fatigue, which limits the use of clinical and commercial NMES systems. The objective of this article is to develop an NMES controller that incorporates the effects of muscle fatigue during NMES-induced non-isometric contraction of the human quadriceps femoris muscle. Our previous work that used the RISE class of non-linear controllers cannot accommodate fatigue and muscle activation dynamics. A totally new control design approach and associated stability proof is required to derive a new class of NMES control design that accounts for muscle fatigue dynamics and a first-order activation dynamics, in addition to the second-order musculoskeletal dynamics. Motivated from a control method for robotic systems in a strict-feedback form, a backstepping based-non-linear NMES controller was designed to accommodate for the additional muscle activation dynamics. Further, experimentally identified estimates of the fatigue and activation dynamics were incorporated in the control design. The developed controller uses a neural networkbased estimate of the musculoskeletal dynamics and error due to fatigue estimation. A globally uniformly ultimately bounded stability is proven the new controller that accounts for an uncertain non-linear muscle model and bounded non-linear disturbances (e.g., spasticity and changing load dynamics). The developed controller was validated through experiments on the left and right legs of 3 able-bodied subjects and was compared with a proportional-derivative (PD) controller and a PD augmented with a neural network. The statistical analysis showed improved control performance compared with the PD controller.

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A novel modulation strategy to increase stimulation duration in neuromuscular electrical stimulation

Cited by 26 publications

References 28 publications

Hybrid FES-robot cooperative control of ambulatory gait rehabilitation exoskeleton

Hybrid FES-robot cooperative control of ambulatory gait rehabilitation exoskeleton

Closed-Loop Asynchronous Neuromuscular Electrical Stimulation Prolongs Functional Movements in the Lower Body

A Non-Linear Control Method to Compensate for Muscle Fatigue during Neuromuscular Electrical Stimulation

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