A body weight support system extension to control lateral forces: Realization and validation

Wyss, Dario; Bartenbach, Volker; Pennycott, Andrew; Riener, Robert

doi:10.1109/icra.2014.6906630

Cited by 13 publications

(10 citation statements)

References 11 publications

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“…The magnitude of the lateral restoring forces we observed with BWS were fairly small, ranging from 0.36 to 1.25% body weight. While these values were similar in magnitude to those reported previously (Wyss et al, 2014), lateral restoring forces less than 0.5% body weight may not be sufficient to noticeably decrease the mechanical demands of lateral stabilization. One limitation of this study is that we calculated the restoring forces based on an assumed rather than measured constant support force provided by the BWS system, although errors in force have been previously found to be less than 1 kg during human walking (Hidler et al, 2011).…”

Section: Discussionsupporting

confidence: 85%

“…If the goal of gait training is to improve control of frontal plane stability, it is important to realize that BWS may provide lateral restoring forces and supplemental sensory information that make it easier for individuals to control lateral stability. If stability is to be challenged, obtaining a BWS system that eliminates these lateral restoring forces could be beneficial (Vallery et al, 2013; Wyss et al, 2014). However, clinical populations often receive other direct methods of stabilization (e.g.…”

Section: Discussionmentioning

confidence: 99%

“…These lateral restoring forces may act as external stabilizers, reducing the requirements of the user to actively stabilize in the frontal plane. The lateral restoring forces provided by BWS has been estimated to be as high as 8.5 N when walking with 50% BWS (Wyss et al, 2014). Previous studies showing that people take narrower steps (Pennycott et al, 2011) and increase frontal plane trunk acceleration regularity (Aaslund and Moe-Nilssen, 2008) suggesting that BWS provides external lateral stabilization.…”

Section: Introductionmentioning

confidence: 99%

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Body weight support impacts lateral stability during treadmill walking

Dragunas

Gordon

2016

Journal of Biomechanics

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Body weight support (BWS) systems are a common tool used in gait rehabilitation. BWS systems may alter the requirements for an individual to actively stabilize by 1) providing lateral restoring forces that reduce the requirements for the nervous system to actively stabilize and 2) decreasing the stabilizing gravitational moment in the frontal plane, which could increase the requirements to actively stabilize. The goal of the current study was to quantify the interaction between BWS and lateral stability. We hypothesized that when able-bodied people walk with BWS: 1) the lateral restoring forces provided by BWS would reduce the requirements to stabilize in the frontal plane when comparing dynamically similar gaits, and 2) increasing BWS would decrease the stabilizing gravitational moment in the frontal plane and increase the requirements to stabilize when speed is constrained. Our findings partly support these hypotheses, but indicate a complex interaction between BWS and lateral stability. With BWS, subjects significantly decreased step width variability and significantly increased step width (p < 0.05) for both the dynamically similar and speed-matched conditions. The decrease in step width variability may be attributable to a combination of lateral restoring forces decreasing the mechanical requirements to stabilize and an enhanced sense of position that could have improved locomotor control. Increases in step width when walking with high levels of BWS could have been due to decreases in the gravitational moment about the stance limb, which may challenge the control of stability in multiple planes.

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Section: Discussionsupporting

confidence: 85%

Section: Discussionmentioning

confidence: 99%

Section: Introductionmentioning

confidence: 99%

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Body weight support impacts lateral stability during treadmill walking

Dragunas

Gordon

2016

Journal of Biomechanics

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“…Therefore, the system's harness was designed such that it can be used directly for this purpose. Vertical unloading with a conventional BWS can interfere with the dynamic balancing task [48], and so to avoid any such undesired stabilizing effects, a system able to translate laterally with the user is preferred [49].…”

Section: Discussionmentioning

confidence: 99%

A MUltidimensional Compliant Decoupled Actuator (MUCDA) for Pelvic Support During Gait

Wyss

Pennycott

Bartenbach

et al. 2019

IEEE/ASME Trans. Mechatron.

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Series Elastic Actuation decouples actuator inertia from the interaction ports and is thus advantageous for forcecontrolled devices. Parallel or even passive compliance can fulfill a complementary role by compensating for gravitational or periodic inertial forces or by providing passive guidance. Here, these concepts are combined in an underactuated six degree of freedom (DoF) compliant manipulator with one actuated DoF. The mechanism comprises a spring assembly in which each spring serves as an actuation element and simultaneously provides passive compliance in the unactuated DoF. The device is designed to assist weight shifting via controlled lateral forces on a human pelvis during treadmill walking and its eigenfrequencies are tuned to align with normal gait. Six-DoF force and torque sensing are realized via a model of the spring deformation characteristics in combination with low-cost inertial and optical sensors. Experimental evaluation demonstrates that the system can effectively follow physiological lateral pelvis movement with low interaction forces and also has little impact on remaining pelvis motions.

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“…When patients deviate too far from the midline, these forces move the BWS endeffector back into a position directly under the rail. While walking, patients can adapt their step width and cadence to use these forces for passive stabilization in the frontal plane [36][37][38][39]. Pendulum forces, however, cannot be adjusted to patients' capacities or removed when patients become self-reliant with time.…”

Section: Introductionmentioning

confidence: 99%

Mediolateral damping of an overhead body weight support system assists stability during treadmill walking

Bannwart

Bayer

Ignasiak

et al. 2020

J NeuroEngineering Rehabil

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Background: Body weight support systems with three or more degrees of freedom (3-DoF) are permissive and safe environments that provide unloading and allow unrestricted movement in any direction. This enables training of walking and balance control at an early stage in rehabilitation. Transparent systems generate a support force vector that is near vertical at all positions in the workspace to only minimally interfere with natural movement patterns. Patients with impaired balance, however, may benefit from additional mediolateral support that can be adjusted according to their capacity. An elegant solution for providing balance support might be by rendering viscous damping along the mediolateral axis via the software controller. Before use with patients, we evaluated if controlrendered mediolateral damping evokes the desired stability enhancement in able-bodied individuals. Methods: A transparent, cable-driven robotic body weight support system (FLOAT) was used to provide transparent body weight support with and without mediolateral damping to 21 able-bodied volunteers while walking at preferred gait velocity on a treadmill. Stability metrics reflecting resistance to small and large perturbations were derived from walking kinematics and compared between conditions and to free walking. Results: Compared to free walking, the application of body weight support per-se resulted in gait alterations typically associated with body weight support, namely increased step length and swing phase. Frontal plane dynamic stability, measured by kinematic variability and nonlinear dynamics of the center of mass, was increased under body weight support, indicating reduced balance requirements in both damped and undamped support conditions. Adding damping to the body weight support resulted in a greater increase of frontal plane stability. Conclusion: Adding mediolateral damping to 3-DoF body weight support systems is an effective method of increasing frontal plane stability during walking in able-bodied participants. Building on these results, adjustable mediolateral damping could enable therapists to select combinations of unloading and stability specifically for each patient and to adapt this in a task specific manner. This could extend the impact of transparent 3-DoF body weight support systems, enabling training of gait and active balance from an early time point onwards in the rehabilitation process for a wide range of mobility activities of daily life.

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A body weight support system extension to control lateral forces: Realization and validation

Cited by 13 publications

References 11 publications

Body weight support impacts lateral stability during treadmill walking

Body weight support impacts lateral stability during treadmill walking

A MUltidimensional Compliant Decoupled Actuator (MUCDA) for Pelvic Support During Gait

Mediolateral damping of an overhead body weight support system assists stability during treadmill walking

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