Down regulation of vestibular balance stabilizing mechanisms to enable transition between motor states.

The neural control of transition between posture and movement encompasses the regulation of reflex-stabilizing mechanisms to enable motion. Optimal feedback theory suggests that such transitions require the disengagement of one motor control policy before the implementation of another. To test this possibility, we investigated the continuity of the vestibular control of balance during transitions between quiet standing and locomotion and between two standing postures.

Transformation of Vestibular Signals for the Control of Standing in Humans.

Unlabelled: During standing balance, vestibular signals encode head movement and are transformed into coordinates that are relevant to maintaining upright posture of the whole body. This transformation must account for head-on-body orientation as well as the muscle actions generating the postural response. Here, we investigate whether this transformation is dependent upon a muscle's ability to stabilize the body along the direction of a vestibular disturbance.

Shifting the balance of human standing: Inter-limb coordination for the control of a robotic balance simulation.

Learning to maintain standing balance in the presence of a paretic limb is an important recovery process for many stroke survivors. In this study, we used a robotic balance simulator to investigate whether manipulating medial-lateral or anterior-posterior torque contributions (i.e.

A wearable vibrotactile device for upper-limb bilateral motion training in stroke rehabilitation: A case study.

Real-time feedback is essential for motor learning. Automated feedback is especially valuable for at-home stroke rehabilitation in the absence of therapist supervision. This study examined the effect of real-time corrective vibrotactile feedback for training bilateral reaching motions.

Exploring the role of haptic feedback in enabling implicit HCI-based bookmarking.

We examine how haptic feedback could enable an implicit human-computer interaction, in the context of an audio stream listening use case where a device monitors a user's electrodermal activity for orienting responses to external interruptions. When such a response is detected, our previously developed system automatically places a bookmark in the audio stream for later resumption of listening. Here, we investigate two uses of haptic feedback to support this implicit interaction and mitigate effects of noisy (false-positive) bookmarking: (a) low-attention notification when a bookmark is placed, and (b) focused-attention display of bookmarks during resumptive navigation.

Experimental performance evaluation of human balance control models.

Two factors commonly differentiate proposed balance control models for quiet human standing: 1) intermittent muscle activation and 2) prediction that overcomes sensorimotor time delays. In this experiment we assessed the viability and performance of intermittent activation and prediction in a balance control loop that included the neuromuscular dynamics of human calf muscles. Muscles were driven by functional electrical stimulation (FES).

Comparison of seat, waist, and arm sit-to-stand assistance modalities in elderly population.

The ability to perform a sit-to-stand (STS) motion is important for ambulatory adults to function independently and maintain daily activities. Roughly 6% of community-dwelling older adults experience significant difficulties with STS, a major risk factor for institutionalization. While mechanical STS assistance can help address this problem, full dependence on STS assistance provided by devices such as lift chairs can lead to atrophy of the leg muscles.

Independent ankle motion control improves robotic balance simulator.

We present a validation study for the effectiveness of an additional ankle-tilt platform to enhance somatosensory ankle feedback available to subjects actuating a 6-axis robotic balance simulator platform. To address this need, we have developed and integrated a device to permit independent manipulation of ankle rotation while the whole-body is actuated by the balance simulator. The addition of ankle rotation is shown to provide both quantitative and qualitative improvements to the balance simulation experience compared to when the ankle joint is referenced to the motion of the balance simulator.

Human standing is modified by an unconscious integration of congruent sensory and motor signals.

We investigate whether the muscle response evoked by an electrically induced vestibular perturbation during standing is related to congruent sensory and motor signals. A robotic platform that simulated the mechanics of a standing person was used to manipulate the relationship between the action of the calf muscles and the movement of the body. Subjects braced on top of the platform with the ankles sway referenced to its motion were required to balance its simulated body-like load by modulating ankle plantar-flexor torque.

Validation of a robotic balance system for investigations in the control of human standing balance.

Previous studies have shown that human body sway during standing approximates the mechanics of an inverted pendulum pivoted at the ankle joints. In this study, a robotic balance system incorporating a Stewart platform base was developed to provide a new technique to investigate the neural mechanisms involved in standing balance. The robotic system, programmed with the mechanics of an inverted pendulum, controlled the motion of the body in response to a change in applied ankle torque.