14 research outputs found

    PhysioAR: smart sensing and augmented reality for physical rehabilitation

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    The continuous evolution of technology allows for a better analysis of the human being. In certain medical areas such as physiotherapy is required a correct analysis of the patient's evolution. The development of Information and Communication Technologies and recent innovations in the Internet of Things opens new possibilities in the medical field as systems of remote monitoring of patients with new sensors that allow the correct analysis of the health data of patients. In physiotherapy one of the most common problems in the application of treatments is the patient demotivation, something that today can be reduced with the introduction of Augmented Reality that provides a new experience to the patient. For this purpose, a system was developed that combines intelligent sensors with Augmented Reality application that will help monitor patient performance. This system is capable of monitoring lower limb movements acceleration, knee joint angle, patient equilibrium, muscular activity and cardiac activity using electromyography and electrocardiography with a wearable set of tools for easy utilization.A evolução continua da tecnologia permite cada vez mais uma melhor análise do ser humano. Em certas áreas médicas, como a fisioterapia, é necessária uma correta análise da evolução do paciente. O desenvolvimento das Tecnologias de Informação e Comunicação, e as inovações no domínio de Internet das Coisas novas possibilidades no ramo da medicina, como sistemas de monitorização remota de pacientes com novos sensores que permitem a correta análise dos dados de saúde dos pacientes. Na fisioterapia um dos problemas mais comuns na aplicação dos tratamentos é a desmotivação do paciente, algo que hoje pode ser reduzido com introdução da aplicação da Realidade Aumentada que proporciona uma nova experiência ao paciente. Para isso nesta dissertação foi desenvolvido um sistema que combina sensores inteligentes com Realidade Aumentada que vai ajudar o paciente monitorizando o seu desempenho. Este sistema é capaz de monitorizar o ângulo do joelho, captar acelaração de movimentos dos membros inferiores, equilíbrio do paciente, atividade muscular e atividade cárdica usando electromiografia e electrocardiografia num conjunto wearable de fácil utilização

    Body sensor networks: smart monitoring solutions after reconstructive surgery

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    Advances in reconstructive surgery are providing treatment options in the face of major trauma and cancer. Body Sensor Networks (BSN) have the potential to offer smart solutions to a range of clinical challenges. The aim of this thesis was to review the current state of the art devices, then develop and apply bespoke technologies developed by the Hamlyn Centre BSN engineering team supported by the EPSRC ESPRIT programme to deliver post-operative monitoring options for patients undergoing reconstructive surgery. A wireless optical sensor was developed to provide a continuous monitoring solution for free tissue transplants (free flaps). By recording backscattered light from 2 different source wavelengths, we were able to estimate the oxygenation of the superficial microvasculature. In a custom-made upper limb pressure cuff model, forearm deoxygenation measured by our sensor and gold standard equipment showed strong correlations, with incremental reductions in response to increased cuff inflation durations. Such a device might allow early detection of flap failure, optimising the likelihood of flap salvage. An ear-worn activity recognition sensor was utilised to provide a platform capable of facilitating objective assessment of functional mobility. This work evolved from an initial feasibility study in a knee replacement cohort, to a larger clinical trial designed to establish a novel mobility score in patients recovering from open tibial fractures (OTF). The Hamlyn Mobility Score (HMS) assesses mobility over 3 activities of daily living: walking, stair climbing, and standing from a chair. Sensor-derived parameters including variation in both temporal and force aspects of gait were validated to measure differences in performance in line with fracture severity, which also matched questionnaire-based assessments. Monitoring the OTF cohort over 12 months with the HMS allowed functional recovery to be profiled in great detail. Further, a novel finding of continued improvements in walking quality after a plateau in walking quantity was demonstrated objectively. The methods described in this thesis provide an opportunity to revamp the recovery paradigm through continuous, objective patient monitoring along with self-directed, personalised rehabilitation strategies, which has the potential to improve both the quality and cost-effectiveness of reconstructive surgery services.Open Acces

    Dynamic estimation of human energy expenditure with wearable sensors

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    &nbsp;This study investigated energy expenditure estimation using inertial measurement units, electromyography and O2 Gas Mask sensors whilst undergoing motion. Further investigations included the precision measurement of IMUs in order to achieve extremely accurate energy estimation calculations using an experimental Dual-Kalman Filter and limb length estimation using entropy based methods .<br /

    An enhanced sensor-based approach for evaluation of a geriatric fall risk in non-ambulatory environments

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    Jedes Jahr stürzt rund ein Drittel der über 65 Jährigen. Stürze sind die Hauptursache für mittlere bis schwere Verletzungen und damit eine enorme Belastung für das Gesundheitssystem. Eine zeitlich akkurate Sturzrisikobewertung in einer breit akzeptierten und nicht-stigmatisierenden Art und Weise kann zu signifikanten Veränderungen in der Strategie der Sturzprävention führen und damit dazu beitragen, die Anzahl der stürzenden Personen, sowie die Sturzrate zu reduzieren. Die gegenwärtige klinische Evaluierung des Sturzrisikos ist zeitaufwendig und subjektiv. Folglich sind Bewertungen in stationärem Umfeld obstruktiv, oder fokussieren sich ausschließlich auf einmalige, periodische Merkmale der menschlichen Bewegung. Der Fokus dieser Arbeit liegt in der Erforschung und Definition neuer Konzepte zur Beurteilung der Koordination der Extremitäten, der Art des Gehens und der Aufstehvorgänge anhand von Signalen von am Handgelenk getragener Inertial- und Umgebungssensorik. Merkmale im Zeit- und Frequenzraum wurden händisch entwickelt, um daraus Support Vector Maschine -Modelle abzuleiten. Die Modelle beschreiben die physikalische Leistungsfähigkeit einer Person in Form einer objektiven (quantitativen) Sturzrisikobewertung in einem störungsanfälligen häuslichen Umfeld. Für erste Untersuchungszwecke wurde eine Forschungsstudie mit 28 älteren Teilnehmern in einem kontrollierten Umfeld durchgeführt. Darauf aufsetzend wurde eine große Querschnittsstudie mit einer Kohorte von 180 Probanden durchgeführt. Eine sich der Messwoche anschließende sechsmonatige Nachverfolgungsphase wurde zur Validierung der Modelle in die Studie inkludiert. Die Ergebnisse haben einen neuen Prädiktor für akutes Sturzrisiko hervorgebracht. Zusätzlich konnte aufgezeigt werden, dass die Kenntnis der Umgebungsbedingungen relevant sind, um die menschlichen Bewegungen richtig bewerten zu können. Ein innovativer Echtzeitalgorithmus wurde entwickelt, in dem Multi-Sensor-Ansätze fusioniert, sowie auf Bewegung basierende Filter integriert sind. Die Einflüsse der Hand-Abhängigkeit auf die Leistungsfähigkeit des Algorithmus konnten im Rahmen dieser Arbeit untersucht werden. Die Validierung der entwickelten Modelle in allen drei Domänen gegen die Grundwahrheit zeigt eine klinisch relevante Genauigkeit oder zumindest teilweise bessere Ergebnisse gegenüber dem Stand der Technik. Die Studie zeigt die Möglichkeit auf, Einschränkungen klinischer Tests zu bewältigen, sowie in Armbändern integrierte Sensorik sowohl für eine akute, wie auch eine konventionelle Sechsmontasbewertung des Sturzrisikos verlässlich anzuwenden

    Body Motion Capture Using Multiple Inertial Sensors

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    Near-fall detection is important for medical research since it can help doctors diagnose fall-related diseases and also help alert both doctors and patients of possible falls. However, in people’s daily life, there are lots of similarities between near-falls and other Activities of Daily Living (ADLs), which makes near-falls particularly difficult to detect. In order to find the subtle difference between ADLs and near-fall and accurately identify the latter, the movement of whole human body needs to be captured and displayed by a computer generated avatar. In this thesis, a wireless inertial motion capture system consisting of a central control host and ten sensor nodes is used to capture human body movements. Each of the ten sensor nodes in the system has a tri-axis accelerometer and a tri-axis gyroscope. They are attached to separate locations of a human body to record both angular and acceleration data with which body movements can be captured by applying Euler angle based algorithms, specifically, single rotation order algorithm and the optimal rotation order algorithm. According to the experiment results of capturing ten ADLs, both the single rotation order algorithm and the optimal rotation order algorithm can track normal human body movements without significantly distortion and the latter shows higher accuracy and lower data shifting. Compared to previous inertial systems with magnetometers, this system reduces hardware complexity and software computation while ensures a reasonable accuracy in capturing human body movements

    Validation, optimization and exploitation of orientation measurements issued from inertial systems for clinical biomechanics

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    Les centrales inertielles (triade de capteurs inertiels dont la fusion des données permet l’estimation de l’orientation d’un corps rigide) sont de plus en plus populaires en biomécanique. Toutefois, les qualités métrologiques des centrales inertielles (CI) sont peu documentées et leur capacité à identifier des incapacités liées à la mobilité, sous-évaluée. Objectifs : (i) Caractériser la validité de la mesure d’orientation issue de CI ; (ii) Optimiser la justesse et la fidélité de ces mesures; et (iii) Proposer des métriques de mobilité basées sur les mesures d’orientation issues de CI. Méthodologie et résultats : La validité de la mesure d’orientation de différents types de CI a d’abord été évaluée en conditions contrôlées, à l’aide d’une table motorisée et d’une mesure étalon. Il a ainsi été démontré que les mesures d’orientation issues de CI ont une justesse acceptable lors de mouvements lents (justesse moyenne ≤ 3.1º), mais que cette justesse se dégrade avec l’augmentation de la vitesse de rotation. Afin d’évaluer l’impact de ces constatations en contexte clinique d’évaluation de la mobilité, 20 participants ont porté un vêtement incorporant 17 CI lors de la réalisation de diverses tâches de mobilité (transferts assis-debout, marche, retournements). La comparaison des mesures des CI avec celles d’un système étalon a permis de dresser un portrait descriptif des variations de justesse selon la tâche exécutée et le segment/l’articulation mesuré. À partir de ces constats, l’optimisation de la mesure d’orientation issue de CI est abordée d’un point de vue utilisateur, démontrant le potentiel d’un réseau de neurones artificiel comme outil de rétroaction autonome de la qualité de la mesure d’orientation (sensibilité et spécificité ≥ 83%). Afin d’améliorer la robustesse des mesures de cinématique articulaire aux variations environnementales, l’ajout d’une photo et d’un algorithme d’estimation de pose tridimensionnelle est proposé. Lors d’essais de marche (n=60), la justesse moyenne de l’orientation à la cheville a ainsi été améliorée de 6.7° à 2.8º. Finalement, la caractérisation de la signature de la cinématique tête-tronc pendant une tâche de retournement (variables : angle maximal tête-tronc, amplitude des commandes neuromusculaires) a démontré un bon pouvoir discriminant auprès de participants âgés sains (n=15) et de patients atteints de Parkinson (PD, n=15). Ces métriques ont également démontré une bonne sensibilité au changement, permettant l’identification des différents états de médication des participants PD. Conclusion : Les mesures d’orientation issues de CI ont leur place pour l’évaluation de la mobilité. Toutefois, la portée clinique réelle de ce type de système ne sera atteinte que lorsqu’il sera intégré et validé à même un outil de mesure clinique.Abstract : Inertial measurement of motion is emerging as an alternative to 3D motion capture systems in biomechanics. Inertial measurement units (IMUs) are composed of accelerometers, gyroscopes and magnetometers which data are fed into a fusion algorithm to determine the orientation of a rigid body in a global reference frame. Although IMUs offer advantages over traditional methods of motion capture, the value of their orientation measurement for biomechanics is not well documented. Objectives: (i) To characterize the validity of the orientation measurement issued from IMUs; (ii) To optimize the validity and the reliability of these measurements; and (iii) To propose mobility metrics based on the orientation measurement obtained from IMUs. Methods and results: The criterion of validity of multiple types of IMUs was characterized using a controlled bench test and a gold standard. Accuracy of orientation measurement was shown to be acceptable under slow conditions of motion (mean accuracy ≤ 3.1º), but it was also demonstrated that an increase in velocity worsens accuracy. The impact of those findings on clinical mobility evaluation was then assessed in the lab, with 20 participants wearing an inertial suit while performing typical mobility tasks (standing-up, walking, turning). Comparison of the assessed IMUs orientation measurements with those from an optical gold standard allowed to capture a portrait of the variation in accuracy across tasks, segments and joints. The optimization process was then approached from a user perspective, first demonstrating the capability of an artificial neural network to autonomously assess the quality of orientation data sequences (sensitivity and specificity ≥ 83%). The issue of joint orientation accuracy in magnetically perturbed environment was also specifically addressed, demonstrating the ability of a 2D photograph coupled with a 3D pose estimation algorithm to improve mean ankle orientation accuracy from 6.7° to 2.8º when walking (n=60 trials). Finally, characterization of the turn cranio-caudal kinematics signature (variables: maximum head to trunk angle and neuromuscular commands amplitude) has demonstrated a good ability to discriminate between healthy older adults (n=15) and early stages of Parkinson’s disease patients (PD, n=15). Metrics have also shown a good sensitivity to change, enabling to detect changes in PD medication states. Conclusion: IMUs offer a complementary solution for mobility assessment in clinical biomechanics. However, the full potential of this technology will only be reached when IMUs will be integrated and validated within a clinical tool

    Classification of Frailty among Community Dwelling Older Adults Using Parameters of Physical Activity Obtained Independently and Unsupervised

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    The global population is ageing at an unprecedented rate, with the percentage of those aged over 65 years expected to double and those aged over 80 years expected to treble by the year 2050. With ageing comes biological and physiological changes that affect functional capacity. Frailty is a potentially avoidable, reversible biopsychosocial condition associated with biological but not chronological age, affecting a quarter of all community-dwelling older adults. Frailty results in disability, increased dependency and institutionalisation. Screening for frailty could help reduce its prevalence and mitigate the adverse outcomes however, traditional screening tools are time-consuming to perform, require clinician input and by their subjective nature are flawed. The use of wearable sensors has been proposed as a means of screening for frailty and parameters of mobility and physical activity have been identified as being associated with frailty. The goal of this thesis was to examine if community-dwelling older adults could capture parameters of mobility and physical activity independently in their own home and if these parameters could discriminate between frail and non-frail status. This work provides evidence that a single parameter of mobility and physical activity obtained from a single body-worn sensor correlates with frailty. It also provides evidence that community-dwelling older adults can independently capture parameters of mobility and physical activity, unsupervised in their own home using a consumer-grade wearable device, and that these data can predict pre-frailty and frailty with acceptable accuracy. Thresholds for parameters of physical activity predictive of frailty have been identified. The results of this thesis will guide future work to focus community-dwelling older adults on the importance of frailty screening and guide the development of a user-friendly device or sensor system suitable for use by older adults for continuous data collection relevant to frailty

    Detection and Prediction of Freezing of Gait in Parkinson’s Disease using Wearable Sensors and Machine Learning

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    Freezing of gait (FOG), is a brief episodic absence of forward body progression despite the intention to walk. Appearing mostly in mid-late stage Parkinson’s disease (PD), freezing manifests as a sudden loss of lower-limb function, and is closely linked to falling, decreased functional mobility, and loss of independence. Wearable-sensor based devices can detect freezes already in progress, and intervene by delivering auditory, visual, or tactile stimuli called cues. Cueing has been shown to reduce FOG duration and allow walking to continue. However, FOG detection and cueing systems require data from the freeze episode itself and are thus unable to prevent freezing. Anticipating the FOG episode before onset and supplying a timely cue could prevent the freeze from occurring altogether. FOG has been predicted in offline analyses by training machine learning models to identify wearable-sensor signal patterns known to precede FOG. The most commonly used sensors for FOG detection and prediction are inertial measurement units (IMU) that include an accelerometer, gyroscope and sometimes magnetometer. Currently, the best FOG prediction systems use data collected from multiple sensors on various body locations to develop person-specific models. Multi-sensor systems are more complex and may be challenging to integrate into real-life assistive devices. The ultimate goal of FOG prediction systems is a user-friendly assistive device that can be used by anyone experiencing FOG. To achieve this goal, person-independent models with high FOG prediction performance and a minimal number of conveniently located sensors are needed. The objectives of this thesis were: to develop and evaluate FOG detection and prediction models using IMU and plantar pressure data; determine if event-based or period of gait disruption FOG definitions have better classification performance for FOG detection and prediction; and evaluate FOG prediction models that use a single unilateral plantar pressure insole sensor or bilateral sensors. In this thesis, IMU (accelerometer and gyroscope) and plantar pressure insole sensors were used to collect data from 11 people with FOG while they walked a freeze provoking path. A custom-made synchronization and labeling program was used synchronize the IMU and plantar pressure data and annotate FOG episodes. Data were divided into overlapping 1 s windows with 0.2 s shift between consecutive windows. Time domain, Fourier transform based, and wavelet transform based features were extracted from the data. A total of 861 features were extracted from each of the 71,000 data windows. To evaluate the effectiveness of FOG detection and prediction models using plantar pressure and IMU data features, three feature sets were compared: plantar pressure, IMU, and both plantar pressure and IMU features. Minimum-redundancy maximum-relevance (mRMR) and Relief-F feature selection were performed prior to training boosted ensembles of decision trees. The binary classification models identified Total-FOG or Non-FOG states, wherein the Total-FOG class included windows with data from 2 s before the FOG onset until the end of the FOG episode. The plantar-pressure-only model had the greatest sensitivity, and the IMU-only model had the greatest specificity. The best overall model used the combination of plantar pressure and IMU features, achieving 76.4% sensitivity and 86.2% specificity. Next, the Total-FOG class components were evaluated individually (i.e., Pre-FOG windows, freeze windows, and transition windows between Pre-FOG and FOG). The best model, which used plantar pressure and IMU features, detected windows that contained both Pre-FOG and FOG data with 85.2% sensitivity, which is equivalent to detecting FOG less than 1 s after the freeze began. Models using both plantar pressure and IMU features performed better than models that used either sensor type alone. Datasets used to train machine learning models often generate ground truth FOG labels based on visual observation of specific lower limb movements (event-based definition) or an overall inability to walk effectively (period of gait disruption based definition). FOG definition ambiguity may affect FOG detection and prediction model performance, especially with respect to multiple FOG in rapid succession. This research examined the effects of defining FOG either as a period of gait disruption (merging successive FOG), or based on an event (no merging), on FOG detection and prediction. Plantar pressure and lower limb acceleration data were used to extract a set of features and train decision tree ensembles. FOG was labeled using an event-based definition. Additional datasets were then produced by merging FOG that occurred in rapid succession. A merging threshold was introduced where FOG that were separated by less than the merging threshold were merged into one episode. FOG detection and prediction models were trained for merging thresholds of 0, 1, 2, and 3 s. Merging had little effect on FOG detection model performance; however, for the prediction model, merging resulted in slightly later FOG identification and lower precision. FOG prediction models may benefit from using event-based FOG definitions and avoiding merging multiple FOG in rapid succession. Despite the known asymmetry of PD motor symptom manifestation, the difference between the more severely affected side (MSS) and less severely affected side (LSS) is rarely considered in FOG detection and prediction studies. The additional information provided by the MSS or LSS, if any, may be beneficial to FOG prediction models, especially if using a single sensor. To examine the effect of using data from the MSS, LSS, or both limbs, multiple FOG prediction models were trained and compared. Three datasets were created using plantar pressure data from the MSS, LSS, and both sides together. Feature selection was performed, and FOG prediction models were trained using the top 5, 10, 15, 20, 25 or 30 features for each dataset. The best models were the MSS model with 15 features, and the LSS and bilateral features with 5 features. The LSS model reached the highest sensitivity (79.5%) and identified the highest percentage of FOG episodes (94.9%). The MSS model achieved the highest specificity (84.9%) and the lowest false positive (FP) rate (2 FP/walking trial). Overall, the bilateral model was best. The bilateral model had 77.3% sensitivity, 82.9% specificity, and identified 94.3% of FOG episodes an average of 1.1 s before FOG onset. Compared to the bilateral model, the LSS model had a higher false positive rate; however, the bilateral and LSS models were similar in all other evaluation metrics. Therefore, using the LSS model instead of the bilateral model would produce similar FOG prediction performance at the cost of slightly more false positives. Given the advantages of single sensor systems, the increased FP rate may be acceptable. Therefore, a single plantar pressure sensor placed on the LSS could be used to develop a FOG prediction system and produce performance similar to a bilateral system

    Smart Sensors for Healthcare and Medical Applications

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    This book focuses on new sensing technologies, measurement techniques, and their applications in medicine and healthcare. Specifically, the book briefly describes the potential of smart sensors in the aforementioned applications, collecting 24 articles selected and published in the Special Issue “Smart Sensors for Healthcare and Medical Applications”. We proposed this topic, being aware of the pivotal role that smart sensors can play in the improvement of healthcare services in both acute and chronic conditions as well as in prevention for a healthy life and active aging. The articles selected in this book cover a variety of topics related to the design, validation, and application of smart sensors to healthcare
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