BackgroundAlthough significant progress has been achieved in developing sensory augmentation methods to improve standing balance, attempts to extend this research to locomotion have been quite limited in scope. The goal of this study was to characterize the effects of two real-time feedback displays on locomotor performance during four gait-based tasks ranging in difficulty.MethodsSeven subjects with vestibular deficits used a trunk-based vibrotactile feedback system that provided real-time feedback regarding their medial-lateral (M/L) trunk tilt when they exceeded a subject-specific predefined tilt threshold during slow and self-paced walking, walking along a narrow walkway, and walking on a foam surface. Two feedback display configurations were evaluated: the continuous display provided real-time continuous feedback of trunk tilt, and the gated display provided feedback for 200 ms during the period immediately following heel strike. The root-mean-square (RMS) trunk tilt and percentage of time below the tilt thresholds were calculated for all locomotor tasks.ResultsUse of continuous feedback resulted in significant decreases in M/L trunk tilt and increases in percentage times below the tilt thresholds during narrow and foam trials. The gated display produced generally smaller changes.ConclusionsThis preliminary study demonstrated that use of continuous vibrotactile feedback during challenging locomotor tasks allowed subjects with vestibular deficits to significantly decrease M/L RMS trunk tilt. Analysis of the results also showed that continuous feedback was superior.
BackgroundMulti-axis vibrotactile feedback has been shown to significantly reduce the root-mean-square (RMS) sway, elliptical fits to sway trajectory area, and the time spent outside of the no feedback zone in individuals with vestibular deficits during continuous multidirectional support surface perturbations. The purpose of this study was to examine the effect of multidirectional vibrotactile biofeedback on postural stability during discrete multidirectional support surface perturbations.MethodsThe vibrotactile biofeedback device mapped tilt estimates onto the torso using a 3-row by 16-column tactor array. The number of columns displayed was varied to determine the effect of spatial resolution upon subject response. Torso kinematics and center of pressure data were measured in six subjects with vestibular deficits. Transient and steady state postural responses with and without feedback were characterized in response to eight perturbation directions. Four feedback conditions in addition to the tactors off (no feedback) configuration were evaluated. Postural response data captured by both a force plate and an inertial measurement unit worn on the torso were partitioned into three distinct phases: ballistic, recovery, and steady state.ResultsThe results suggest that feedback has minimal effects during the ballistic phase (body’s outbound trajectory in response to the perturbation), and the greatest effects during the recovery (return toward baseline) and steady state (post-recovery) phases. Specifically, feedback significantly decreases the time required for the body tilt to return to baseline values and significantly increases the velocity of the body’s return to baseline values. Furthermore, feedback significantly decreases root mean square roll and pitch sway and significantly increases the amount of time spent in the no feedback zone. All four feedback conditions produced comparable performance improvements. Incidences of delayed and uncontrolled responses were significantly reduced with feedback while erroneous (sham) feedback resulted in poorer performance when compared with the no feedback condition.ConclusionsThe results show that among the displays evaluated in this study, no one tactor column configuration was optimal for standing tasks involving discrete surface perturbations. Feedback produced larger effects on body tilt versus center of pressure parameters. Furthermore, the subjects’ performance worsened when erroneous feedback was provided, suggesting that vibrotactile stimulation applied to the torso is actively processed and acted upon rather than being responsible for simply triggering a stiffening response.
This study uses frequency-domain techniques and stabilogram diffusion analysis (SDA) to investigate the effect of vibrotactile feedback during continuous multidirectional perturbations of a support platform. Eight subjects with vestibular deficits were subjected to two-axis pseudorandom surface platform motion while donning a multiaxis vibrotactile feedback device that mapped body tilt estimates onto their torsos via a 3-row by 16-column array of tactile vibrators (tactors). Four tactor display configurations with spatial resolutions ranging between 22.5 degrees and 90 degrees, in addition to the tactors off configuration, were evaluated. Power spectral density functions of body sway in the anterior-posterior (A/P) and medial-lateral (M/L) directions, and transfer functions between platform motion and body sway, were computed at frequencies ranging from 0.0178 to 3.56 Hz. Cross-spectral analysis revealed that the A/P responses were not significantly driven by M/L inputs, and vice versa, thus supporting the notion of independent A/P and M/L postural control. Vibrotactile feedback significantly decreased A/P and M/L spectral power, decreased transfer function gains up to a frequency of 1.8 and 0.6 Hz in the A/P and M/L directions, respectively, and increased phase leads above 0.3 Hz. SDA showed significantly decreased transition time for both A/P and M/L tilts, and decreased transition displacement and short-term diffusion coefficients for A/P tilt. However, the spatial resolution of the tactor displays did not affect subjects' performance, thereby supporting the use of a lower spatial resolution display in future device designs.
OKN testing may be useful as an additional, more objective means of assessing visual function in a select group of severely visually impaired patients who are being considered as candidates for new visual rehabilitative strategies.
Single-axis vibrotactile feedback of trunk tilt provided in real-time has previously been shown to significantly reduce the root-mean-square (RMS) trunk sway in subjects with vestibular loss during single-axis perturbation. This research examines the effect of multi-directional vibrotactile feedback on postural sway during continuous multi-directional surface perturbations when the subjects' eyes are closed. Eight subjects with vestibular loss donned a multi-axis feedback device that mapped body tilt estimates onto their torsos with a 3-row by 16-column array of tactile actuators (tactors). Tactor row indicated tilt magnitude and tactor column indicated tilt direction. Root-mean-square trunk tilt, elliptical fits to trunk sway trajectory areas, percentage of time spent outside a no vibrotactile feedback zone, RMS center of pressure, and anchoring index parameters indicating intersegmental coordination were used to assess the efficacy of the multi-directional vibrotactile balance aid. Four tactor display configurations in addition to the tactors off configuration were evaluated. Subjects had significantly reduced RMS trunk sway, significantly smaller elliptical fits of the trajectory area, and spent significantly less time outside of the no feedback zone in the tactors on versus the tactors off configuration. Among the displays evaluated in this study, there was not an optimal tactor column configuration for standing tasks involving continuous surface perturbations. Furthermore, subjects performed worse when erroneous information was displayed. Therefore, a spatial resolution of 90° (4 columns) seems to be as effective as a spatial resolution of 22.5° (16 columns) for control of standing.
This study uses frequency domain techniques to demonstrate the effect of vibrotactile feedback during continuous multidirectional perturbations of a support platform. Eight subjects with bilateral or unilateral vestibular loss were subjected to two-axis pseudo random surface platform motion while donning a multi-axis feedback balance aid that mapped body tilt estimates onto their trunks via a 3-row by 16-column array of tactile vibrators (tactors). Four tactor display configurations with spatial resolutions ranging between 22.5 degrees and 90 degrees , in addition to the tactors off configuration, were evaluated. Power spectral density (PSD) functions of body sway in the anterior-posterior (A/P) and medial-lateral (M/L) directions were computed at frequencies ranging from 0.0178 Hz to 3.56 Hz. Transfer functions between the platform motion and body sway were also computed. Vibrotactile feedback produced significant decreases in A/P and M/L spectral power, decreased transfer function gains up to a frequency of 1.8 Hz and 0.6 Hz in the A/P and M/L directions, respectively, and increased phase leads above 0.3 Hz. The lack of a consistent difference among tactor configurations argue in favor of the simplest 4-column configuration during multidirectional continuous surface perturbations.
This paper discusses the development of a balance device from lab to clinic/home use. An emerging practice among physical therapists in balance training and falls prevention addresses a major health problem in the United States: imbalance and its consequences. The annual cost for treating balance disorders exceeds $1 billion, not including the cost to treat falls. We aim to develop a non-invasive device worn around the waist. It detects when a person is tipping too far in any direction and vibrates on that side, signaling the wearer to stay within their limits of stability. Because this new technology gets a patient to a higher level of function in a shorter number of trials, it offers an opportunity to advance rehabilitation by enabling more effective outcomes for the same number of treatment sessions.
scite is a Brooklyn-based organization that helps researchers better discover and understand research articles through Smart Citations–citations that display the context of the citation and describe whether the article provides supporting or contrasting evidence. scite is used by students and researchers from around the world and is funded in part by the National Science Foundation and the National Institute on Drug Abuse of the National Institutes of Health.
hi@scite.ai
10624 S. Eastern Ave., Ste. A-614
Henderson, NV 89052, USA
Copyright © 2024 scite LLC. All rights reserved.
Made with 💙 for researchers
Part of the Research Solutions Family.