Can We Use the Oculus Quest VR Headset and Controllers to Reliably Assess Balance Stability?

Balance is the foundation upon which all other motor skills are built. Indeed, many neurological diseases and injuries often present clinically with deficits in balance control. With recent advances in virtual reality (VR) hardware bringing low-cost headsets into the mainstream market, the question remains as to whether this technology could be used in a clinical context to assess balance. We compared the head tracking performance of a low-cost VR headset (Oculus Quest) with a gold standard motion tracking system (Qualisys). We then compared the recorded head sway with the center of pressure (COP) measures collected from a force platform in different stances and different visual field manipulations. Firstly, our analysis showed that there was an excellent correspondence between the two different head movement signals (ICCs > 0.99) with minimal differences in terms of accuracy (<5 mm error). Secondly, we found that head sway mapped onto COP measures more strongly when the participant adopted a Tandem stance during balance assessment. Finally, using the power of virtual reality to manipulate the visual input to the brain, we showed how the Oculus Quest can reliably detect changes in postural control as a result of different types of visual field manipulations. Given the high levels of accuracy of the motion tracking of the Oculus Quest headset, along with the strong relationship with the COP and ability to manipulate the visual field, the Oculus Quest makes an exciting alternative to traditional lab-based balance assessments

Correction of joint angles from kinect for balance exercising and assessment

[EN] The new generation of videogame interfaces such as Microsoft's Kinect opens the possibility of implementing exercise programs for physical training, and of evaluating and reducing the risks of elderly people falling. However, applications such as these might require measurements of joint kinematics that are more robust and accurate than the standard output given by the available middleware. This article presents a method based on particle filters for calculating joint angles from the positions of the anatomical points detected by PrimeSense's NITE software. The application of this method to the measurement of lower limb kinematics reduced the error by one order of magnitude, to less than 10 degrees, except for hip axial rotation, and it was advantageous over inverse kinematic analysis, in ensuring a robust and smooth solution without singularities, when the limbs are out-stretched and anatomical landmarks are aligned.This work has been undertaken within the framework of the iStoppFalls project, which has received funding from the European Community (grant agreement FP7-ICT-2011-7-287361) and the Australian Government.De Rosario Martínez, H.; Belda Lois, JM.; Fos Ros, F.; Medina Ripoll, E.; Poveda Puente, R.; Kroll, M. (2014). Correction of joint angles from kinect for balance exercising and assessment. Journal of Applied Biomechanics. 30(2):294-299. https://doi.org/10.1123/jab.2013-0062S29429930

Effects of Sensorimotor Perturbations on Balance Performance and Electrocortical Dynamics

Humans must frequently adapt their posture to prevent loss of balance. Such balance control requires complex, precisely-timed coordination among sensory input, neural processing, and motor output. Despite its importance, our current understanding of cortical involvement during balance control remains limited by traditional neuroimaging methods, which are stationary and have poor time resolution. High-density electroencephalography (EEG), combined with independent component analysis, has become a promising tool for recording cortical dynamics during balance perturbations due to its portability and high temporal resolution. Additionally, recent improvements in immersive virtual reality headsets may provide new rehabilitative paradigms, but the effects of virtual reality on balance and cortical function remain poorly understood. In my first study, I recorded high-density EEG from healthy, young adult subjects as they walked along a beam with and without virtual reality high heights exposure. While virtual high heights did induce stress, the use of virtual reality during the task increased performance errors and EEG measures of cognitive loading compared to real-world viewing without a headset. In my second study, I collected high-density EEG from healthy young adults as they walked along a treadmill-mounted balance beam to determine the effect of a transient visual perturbation on training in virtual reality. Subjects in the perturbations group improved comparably to those that trained without virtual reality, indicating that the perturbation helped subjects overcome the negative effects of virtual reality on motor learning. The perturbation primarily elicited a cognitive change. In my third study, healthy, young adult EEG was recorded during physical pull and visual rotation perturbations to tandem walking and tandem standing. I found similar electrocortical patterns for both perturbation types, but different cortical areas were involved for each. In my fourth study, I used a phantom head to validate EEG connectivity methods based on Granger causality in a real-world environment. In general, connectivity measures could determine the underlying connections, but many were susceptible to high-frequency false positives. Using data from my third study, my fifth study analyzed corticomuscular connectivity patterns following sensorimotor balance perturbations. I found strong occipito-parietal connections regardless of perturbation type, along with evidence of direct muscular control from the supplementary motor area during the standing perturbation response. Taken together, the work presented in this dissertation greatly expands upon the current knowledge of cortical processing during sensorimotor balance perturbations and the effect of such perturbations on short-term motor learning, providing multiple avenues for future exploration.PHDBiomedical EngineeringUniversity of Michigan, Horace H. Rackham School of Graduate Studieshttps://deepblue.lib.umich.edu/bitstream/2027.42/147615/1/stepeter_1.pd

Effects of Random Oscillations on Balance Control in Healthy Young Adults

In human walking, balance control is managed through proactive changes in spatio-temporal parameters of stepping [1]. It has been suggested that continuous disruptions to healthy young adult balance cause greater changes to overall variability of these parameters than a shift in the mean stepping parameters [2]. This suggests that walking may be occurring in a more reactive manner, modulating to maintain balance without increasing the mean significantly. Work using continuous oscillations to treadmill walking suggest there is an interplay between the predictability of a signal used to disrupt subject balance and the degree to which compensation occurs [3]. To determine how balance compensation occurs during continuous, unpredictable oscillations this work investigated the effects of unpredictable oscillations on human walking. A 6 Degree of Freedom Motion base was used to oscillate 12 subjects walking on a treadmill for seven different balance conditions: (1) Normal Walking (2) Pitch Amplitude Oscillations, (3) Pitch Frequency Oscillations, (4) Roll Amplitude Oscillations, (5) Roll Frequency Oscillations, (6) Medial-Lateral Amplitude Oscillations, and (7) Medial-Lateral Frequency Oscillations. Amplitude perturbations used a probabilistic multiplier to change the amplitude of an applied sine wave each period, maintaining timing, while frequency perturbations used the same multiplier to vary the timing of sine waves for each period. Amplitude oscillations caused a greater degree of proactive control characterized by changes in temporal stepping parameters. Frequency oscillations resulted in a greater change in reactive control, demonstrating variability in stepping parameters immediately preceding and following peaks in accelerations peaks which exceed 0.5 m/s2. These observations suggest that healthy young adults shift to a reactive strategy of balance compensation when subject to more difficult, higher acceleration oscillations of support surface while maintaining a proactive rate of level walking at low accelerations

Performance of the Intrac Wireless Activity Tracking System for the Afari Assistive Device

Afari is a mobility device that was designed to be more recreational, aesthetic, and functional outside than the typical mobility devices commonly used today such as walkers, crutches, and rollators. The Afari transfers weight from a user through the arm rests and enforces an upright posture while walking with correct adjustments to the arm rest height. In addition to assisting with walking or running, a sensor system fitted to the Afari device has been designed to analyze different aspects of activity tracking such as the dynamic loading applied to the arm rests, spatial-temporal gait parameters, speed, and distance. This includes various sensors, namely, load cells for each arm rest, an inertial measurement unit, and a speed and distance sensor that wirelessly transmit data via Bluetooth Low Energy (BLE) to either a smartphone or computer. The total distance, pitch angle, right and left loading on each armrest can be viewed in real time by the user. An algorithm was created in MATLAB to process all the raw data and compute cadence, stride length, average toe-off and heel strike angle, swing and stance time, and speed over the duration of active use. An Afari user can monitor these different aspects of their activity and adjust accordingly to potentially improve their balance or gait

DEVELOPMENT OF CONFOCAL IMAGING TECHNIQUES FOR PROBING INTERFACIAL DYNAMICS IN MICROSCALE, GAS-LIQUID, TWO-PHASE FLOW

Micro-scale, two-phase flow is found in a variety of devices such as Lab-on-a-chip, bio-chips, micro-heat exchangers, and fuel cells. Knowledge of the fluid behavior near the dynamic gas-liquid interface is required for developing accurate predictive models. Light is distorted near a curved gas-liquid interface preventing accurate measurement of interfacial shape and internal liquid velocities. This research focused on the development of experimental methods designed to isolate and probe dynamic liquid films and measure velocity fields near a moving gas-liquid interface. A high-speed, reflectance, swept-field confocal (RSFC) imaging system was developed for imaging near curved surfaces. Experimental studies of dynamic gas-liquid interface of micro-scale, two-phase flow were conducted in three phases. Dynamic liquid film thicknesses of segmented, two-phase flow were measured using the RSFC and compared to a classic film thickness deposition model. Flow fields near a steadily moving meniscus were measured using RSFC and particle tracking velocimetry. The RSFC provided high speed imaging near the menisci without distortion caused the gas-liquid interface. Finally, interfacial morphology for internal two-phase flow and droplet evaporation were measured using interferograms produced by the RSFC imaging technique. Each technique can be used independently or simultaneously when

Personalised Procedures for Thoracic Radiotherapy

This thesis presents the investigation, development, and estimation of two personalised procedures for thoracic cancer therapy in Shenzhen, China and two projects were carried out: (1) respiratory motion management of a lung tumour, and (2) the application of a three-dimensional (3D) printing technique for postmastectomy irradiation. For the first project, all subjects attended sessions of free-breathing (FB) and personalised vocal coaching (VC) for respiratory regulation. Thoracic and abdominal breathing signals were extracted from the subjects’ surface area then estimated as kernel density estimation (KDE) for motion visualisation. The mutual information (MI) and correlation coefficient (CC) calculated from KDEs indicate the variation in the relationship between the two signals. From the 1D signal, through VC, the variation of cycle time and the signal value of end-of-exhale/inhale increased in the patient group but decreased in volunteers. Mixed results were presented on KDE and MI. Compared with FB, VC improves movement consistency between the two signals in eight of eleven subjects by increasing MI. The fixed instruction method showed no improvement for day-to-day variation, while the daily generated instruction enhanced the respiratory regularity in three of five volunteers. VC addresses the variation of the single signal, while the outcome of the two signals, thoracic and abdominal signals, requires further interpretation. The second project aims to address both the enhancement of the skin dose and avoidance of hotspots of critical organs, focusing on improving irradiative treatment for post-mastectomy patients. A 3D-printed bolus was presented as a solution for the air gap between the bolus and skin. The results showed no evidence of significant skin dose enhancement with the printed bolus. Additionally, an air gap larger than 5 mm was evident in all patients. Until a solution for complete bolus adhesion is found, this customised bolus is not suitable for clinical use

A look at aging : balance ability and fall prevention interventions

xiii, 91 leaves : ill. ; 29 cm. --The main objective of this work is to address the growing concern of balance loss and falls in the aging population. The initial aspect looks at balance control in a dynamic environment. Observation of age and gender influence on motor control will be made related to a new dynamic balance testing platform (DBTP). The topic of focus in the second portion relates to reaction time in an unstable environment. Research has found that balance improves when physical activity is a part of daily life for seniors. Physical activity influence on reaction time will be investigated with a new approach to exercise classes for seniors. Finally, an understanding of motor control and balance may be acquired and physical activity incorporated into the life of an elderly individual, however this will never fully prevent falls from taking place. A novel approach to injury prevention due to falls is explored in the final portion of this thesis. Study One - Using a newly constructed dynamic balance testing platform (DBTP), balance ability of three age groups was observed in two visual conditions and in relation to gender. Center of Gravity excursion (COGex) was observed to determine the differences between age groups and gender. Platform response patterns were also observed to asses the functionality of the DBTP as a new tool for balance testing. Three things were found: 1) Age differencesrelated to platform movement suggested that balance decreased with age in both visual conditions. 2) Gender differences between COGex found that males covered the most distance in both visual conditions when compared to females. 3) Gender differences between platform characteristics showed that females balanced longer and had lower platform movement rate than males, in both visual conditions. In order to consider the DBTP as a new tool for determination of balance ability, more refined tests are necessary. Study Two - Using pre- and post-training tests, the effects of a Fitball® exercise program on performance in eight subjects was documented. The exercise program focused on improving dynamic balance and postural stability of seniors. To evaluate progress-related changes, pre and post-tests in a dynamic environment were applied. Center of gravity (COG) excursion, catch success rate, and balance success rate were quantified, and synchronized data collection of 3D motion capture (VICON v8i) and ground reaction force (2 KISTLER platforms) was analyzed. During pre- and post-tests, participants stood in a walk-like stance and were asked to catch a weighted ball, which dropped unexpectedly. Results showed no significant changes in balance success rate. Significant improvements were found, however, in both COG control and catch success rate following training (p 0.05). Study Three - Falls in the elderly are inevitable so it is necessary to take precautions. This study looks at falls in relation to velocity characteristics of various locations on the trunk, and contrasts them to activities of daily living (ADL) in 13 individuals. A threshold level was established to be 2.0m/s, a value that exceeded all maximum resultant velocities for ADL, but was superseded by all fall activity resultant velocities. This suggests that a life vest, which responds similar to a vehicle airbag, may be created and worn that will deploy past a threshold of 2.0m/s with the incidence of a fall

Quantitative Gait and Balance Outcomes for Ataxia Trials: Consensus Recommendations by the Ataxia Global Initiative Working Group on Digital-Motor Biomarkers

\ua9 2023, The Author(s).With disease-modifying drugs on the horizon for degenerative ataxias, ecologically valid, finely granulated, digital health measures are highly warranted to augment clinical and patient-reported outcome measures. Gait and balance disturbances most often present as the first signs of degenerative cerebellar ataxia and are the most reported disabling features in disease progression. Thus, digital gait and balance measures constitute promising and relevant performance outcomes for clinical trials. This narrative review with embedded consensus will describe evidence for the sensitivity of digital gait and balance measures for evaluating ataxia severity and progression, propose a consensus protocol for establishing gait and balance metrics in natural history studies and clinical trials, and discuss relevant issues for their use as performance outcomes