Biology subjects

Schonhaut, E. B.

Publications and source records attributed to Schonhaut, E. B..

2 recordsLinked to original sources

bioRxiv2025

Frequency-dependent effects of hip abductor vibration and surface translation on mediolateral sway

The control of mediolateral standing balance is altered in many clinical populations, due in part to disrupted sensorimotor processing. Sensory perturbations, as evoked by musculotendon vibration, can provide insight into the contributions of individual sources of sensory feedback to this control. The purpose of this study was to investigate whether hip abductor vibration can elicit mediolateral sway at frequencies <1 Hz, which dominate standing posture. Secondarily, we quantified the effects of mediolateral surface translations in this frequency range. Participants (n=12) without neurological or orthopedic conditions completed a series of standing trials in which we quantified center of pressure motion. In a subset of trials, time-varying hip abductor vibration was delivered, with vibration intensity following sum-of-sine trajectories with frequency content from 0.1-0.9 Hz. In other trials, the standing surface translated mediolaterally following similar trajectories. Participants were not provided instructions regarding how to respond to the stimuli. Vibration significantly increased mediolateral sway for frequencies greater than 0.5 Hz, while surface translation caused substantial sway increases throughout the investigated frequency range. The effects of vibration were observed in the frequency range typically interpreted as reflecting feedback-driven corrective responses, suggesting the potential of this approach to influence balance performance through sensory augmentation.

bioengineering↗

bioRxiv2025

Optimized Mappings from Biological Hip Moment Estimates to Exoskeleton Torque can Personalize Assistance Across Users and Generalize Across Tasks

Recent advancements in data-driven methods have enabled real-time estimation of biomechanical states for exoskeleton control. While biological joint moments can be directly used to scale exoskeleton assistance, this approach is often suboptimal. An optimized mapping between biological joint moments and exoskeleton assistance could enhance end-to-end controllers based on the users physiological state. We introduce a flexible parametrization of biological moment-based control using delay, scaling, and shaping terms to transform joint moment estimates into commanded torque. We performed human-in-the-loop optimization, using metabolic cost to evaluate each iterations controller parameters, for 9 subjects across three ambulation modes: level walking at 1.1 m/s, 1.5 m/s, and 5{degrees} inclined walking. We evaluated three methods of exoskeleton control: 1. Personalized/Task Dependent, 2. Task Dependent/Non-personalized, and 3. Task Agnostic/Non-personalized. On average, our personalized approach provided the greatest benefit of 18.3% reduction in metabolic cost compared to walking without the exoskeleton, with the task dependent and task agnostic controllers producing similar reductions of 8.6% and 8.4%, respectively. Our results show that while generalizable, task agnostic control parameters can improve user energetics across cyclic tasks, fully personalized exoskeleton control parameters yield larger metabolic reductions, highlighting the value of personalizing exoskeleton assistance to users across many diverse tasks.

bioengineering↗