471 research outputs found
Gait sonification for rehabilitation: adjusting gait patterns by acoustic transformation of kinematic data
To enhance motor learning in both sport and rehabilitation, auditory feedback has emerged as an effective tool. Since it requires less attention than visual feedback and hardly affects the visually dominated orientation in space, it can be used safely and effectively in natural locomotion such as walking. One method for generating acoustic movement feedback is the direct mapping of kinematic data to sound (movement sonification). Using this method in orthopedic gait rehabilitation could make an important contribution to the prevention of falls and secondary diseases. This would not only reduce the individual suffering of the patients, but also medical treatment costs. To determine the possible applications of movement sonification in gait rehabilitation in the context of this work, a new gait sonification method based on inertial sensor technology was developed. Against the background of current scientific findings on sensorimotor function, feedback methods, and gait analysis, three studies published in scientific journals are presented in this thesis:
The first study shows the applicability and acceptance of the feedback method in patients undergoing inpatient rehabilitation after unilateral total hip arthroplasty. In addition, the direct effect of gait sonification during ten gait training sessions on the patientsâ gait pattern was revealed. In the second study, the immediate follow-up effect of gait sonification on the kinematics of the same patient group is examined at four measurement points after gait training. In this context, a significant influence of sonification on the gait pattern of the patients was shown, which, however, did not meet the previously expected effects. In view of this finding, the effect of the specific sound parameter loudness of gait sonification on the gait of healthy persons was analyzed in a third study. Thus, an impact of asymmetric loudness of gait sonification on the ground contact time could be detected. Considering this cause-effect relationship can be a component in improving gait sonfication in rehabilitation.
Overall, the feasibility and effectiveness of movement sonification in gait rehabilitation of patients after unilateral hip arthroplasty becomes evident. The findings thus illustrate the potential of the method to efficiently support orthopedic gait rehabilitation in the future. On the basis of the results presented, this potential can be exploited in particular by an adequate mapping of movement to sound, a systematic modification of selected sound parameters, and a target-group-specific selection of the gait sonification mode. In addition to a detailed investigation of the three factors mentioned above, an optimization and refinement of gait analysis in patients after arthroplasty using inertial sensor technology will be beneficial in the future.Akustisches Feedback kann wirkungsvoll eingesetzt werden, um das Bewegungslernen sowohl im Sport als auch in der Rehabilitation zu erleichtern. Da es weniger Aufmerksamkeit als visuelles Feedback erfordert und die visuell dominierte Orientierung im Raum kaum beeintrĂ€chtigt, kann es wĂ€hrend einer natĂŒrlichen Fortbewegung wie dem Gehen sicher und effektiv genutzt werden. Eine Methode zur Generierung akustischen Bewegungsfeedbacks ist die direkte Abbildung kinematischer Daten auf Sound (Bewegungssonifikation). Ein Einsatz dieser Methode in der orthopĂ€dischen Gangrehabilitation könnte einen wichtigen Beitrag zur PrĂ€vention von StĂŒrzen und Folgeerkrankungen leisten. Neben dem individuellen Leid der Patienten lieĂen sich so auch medizinische Behandlungskosten erheblich reduzieren.
Um im Rahmen dieser Arbeit die Einsatzmöglichkeiten der Bewegungssonifikation in der Gangrehabilitation zu bestimmen, wurde eine neue Gangsonifikationsmethodik auf Basis von Inertialsensorik entwickelt. Zu der entwickelten Methodik werden, vor dem Hintergrund aktueller wissenschaftlicher Erkenntnisse zur Sensomotorik, zu Feedbackmethoden und zur Ganganalyse, in dieser Thesis drei in Fachzeitschriften publizierte Studien vorgestellt.
Die erste Studie beschreibt die Anwendbarkeit und Akzeptanz der Feedbackmethode bei Patienten in stationĂ€rer Rehabilitation nach unilateraler HĂŒftendoprothetik. DarĂŒber hinaus wird der direkte Effekt der Gangsonifikation wĂ€hrend eines zehnmaligen Gangtrainings auf das Gangmuster der Patienten deutlich. In der zweiten Studie wird der unmittelbare Nacheffekt der Gangsonifikation auf die Kinematik der gleichen Patientengruppe zu vier Messzeitpunkten nach dem Gangtraining untersucht. In diesem Zusammenhang zeigte sich ein signifikanter Einfluss der Sonifikation auf das Gangbild der Patienten, der allerdings nicht den zuvor erwarteten Effekten entsprach. Aufgrund dieses Ergebnisses wurde in einer dritten Studie die Wirkung des spezifischen Klangparameters LautstĂ€rke der Gangsonifikation auf das Gangbild von gesunden Personen analysiert. Dabei konnte ein Einfluss von asymmetrischer LautstĂ€rke der Gangsonifikation auf die Bodenkontaktzeit nachgewiesen werden. Die BerĂŒcksichtigung dieses Ursache-Wirkungs-Zusammenhangs kann einen Baustein bei der Verbesserung der Gangsonifikation in der Rehabilitation darstellen.
Insgesamt wird die Anwendbarkeit und Wirksamkeit von Bewegungssonifikation in der Gangrehabilitation bei Patienten nach unilateraler HĂŒftendoprothetik evident. Die gewonnenen Erkenntnisse verdeutlichen das Potential der Methode, die orthopĂ€dische Gangrehabilitation zukĂŒnftig effizient zu unterstĂŒtzen. Ausschöpfen lĂ€sst sich dieses Potential auf Grundlage der vorgestellten Ergebnisse insbesondere anhand einer adĂ€quaten Zuordnung von Bewegung zu Sound, einer systematischen Modifikation ausgewĂ€hlter Soundparameter sowie einer zielgruppenspezifischen Wahl des Modus der Sonifikation. Neben einer differenzierten Untersuchung der genannten Faktoren, erscheint zukĂŒnftig eine Optimierung und Verfeinerung der Ganganalyse bei Patienten nach Endoprothetik unter Einsatz von Inertialsensorik notwendig
Mobilise-D insights to estimate real-world walking speed in multiple conditions with a wearable device
This study aimed to validate a wearable deviceâs walking speed estimation pipeline, considering complexity, speed, and walking bout duration. The goal was to provide recommendations on the use of wearable devices for real-world mobility analysis. Participants with Parkinsonâs Disease, Multiple Sclerosis, Proximal Femoral Fracture, Chronic Obstructive Pulmonary Disease, Congestive Heart Failure, and healthy older adults (nâ=â97) were monitored in the laboratory and the real-world (2.5 h), using a lower back wearable device. Two walking speed estimation pipelines were validated across 4408/1298 (2.5 h/laboratory) detected walking bouts, compared to 4620/1365 bouts detected by a multi-sensor reference system. In the laboratory, the mean absolute error (MAE) and mean relative error (MRE) for walking speed estimation ranged from 0.06 to 0.12 m/s and ââ2.1 to 14.4%, with ICCs (Intraclass correlation coefficients) between good (0.79) and excellent (0.91). Real-world MAE ranged from 0.09 to 0.13, MARE from 1.3 to 22.7%, with ICCs indicating moderate (0.57) to good (0.88) agreement. Lower errors were observed for cohorts without major gait impairments, less complex tasks, and longer walking bouts. The analytical pipelines demonstrated moderate to good accuracy in estimating walking speed. Accuracy depended on confounding factors, emphasizing the need for robust technical validation before clinical application.
Trial registration: ISRCTN â 12246987
The efficacy of virtual reality in professional soccer
Professional soccer clubs have taken an interest to virtual reality, however, only a paucity of evidence exists to support its use in the soccer training ground environment. Further, several soccer virtual reality companies have begun providing solutions to teams, claiming to test specific characteristics of players, yet supportive evidence for certain measurement properties remain absent from the literature. The aims of this thesis were to explore the efficacy of virtual reality being used in the professional football training ground environment. To do so, this thesis looked to explore the fundamental measurement properties of soccer specific virtual reality tests, along with the perceptions of professional coaches, backroom staff, and players that could use virtual reality. The first research study (Chapter 3) aimed to quantify the learning effect during familiarisation trials of a soccer-specific virtual reality task. Thirty-four professional soccer players age, stature, and body mass: mean (SD) 20 (3.4) years; 180 (7) cm; 79 (8) kg, participated in six trials of a virtual reality soccer passing task. The task required participants to receive and pass 30 virtual soccer balls into highlighted mini-goals that surrounded the participant. The number of successful passes were recorded in each trial. The one-sided Bayesian paired samples t-test indicated very strong evidence in favour of the alternative hypothesis (H1)(BF10 = 46.5, d = 0.56 [95% CI = 0.2 to 0.92]) for improvements in total goals scored between trial 1: 13.6 (3.3) and trial 2: 16 (3.3). Further, the Bayesian paired-samples equivalence t-tests indicated strong evidence in favour of H1 (BF10 = 10.2, d = 0.24 [95% CI = -0.09 to 0.57]) for equivalence between trial 4: 16.7 (3.7) and trial 5: 18.2 (4.7); extreme evidence in favour of H1 (BF10 = 132, d = -0.02 [95% CI = -0.34 to 0.30]) for equivalence between trials 5 and 6: 18.1 (3.5); and moderate evidence in favour of H1 (BF10 = 8.4, d = 0.26 [95% CI = -0.08 to 0.59]) for equivalence between trials 4 and 6. Sufficient evidence indicated that a learning effect took place between the first two trials, and that up to five trials might be necessary for performance to plateau in a specific virtual reality soccer passing task.The second research study (Chapter 4) aimed to assess the validity of a soccer passing task by comparing passing ability between virtual reality and real-world conditions. A previously validated soccer passing test was replicated into a virtual reality environment. Twenty-nine soccer players participated in the study which required them to complete as many passes as possible between two rebound boards within 45 s. Counterbalancing determined the condition order, and then for each condition, participants completed four familiarisation trials and two recorded trials, with the best score being used for analysis. Sense of presence and fidelity were also assessed via questionnaires to understand how representative the virtual environments were compared to the real-world. Results showed that between conditions a difference was observed (EMM = -3.9, 95% HDI = -5.1 to -2.7) with the number of passes being greater in the real-world (EMM = 19.7, 95% HDI = 18.6 to 20.7) than in virtual reality (EMM = 15.7, 95% HDI = 14.7 to 16.8). Further, several subjective differences for fidelity between the two conditions were reported, notably the ability to control the ball in virtual reality which was suggested to have been more difficult than in the real-world. The last research study (Chapter 5) aimed to compare and quantify the perceptions of virtual reality use in soccer, and to model behavioural intentions to use this technology. This study surveyed the perceptions of coaches, support staff, and players in relation to their knowledge, expectations, influences, and barriers of using virtual reality via an internet-based questionnaire. To model behavioural intention, modified questions and constructs from the Unified Theory of Acceptance and Use of Technology were used, and the model was analysed through partial least squares structural equation modelling. Respondents represented coaches and support staff (n = 134) and players (n = 64). All respondents generally agreed that virtual reality should be used to improve tactical awareness and cognition, with its use primarily in performance analysis and rehabilitation settings. Generally, coaches and support staff agreed that monetary cost, coach buy-in and limited evidence base were barriers towards its use. In a sub-sample of coaches and support staff without access to virtual reality (n = 123), performance expectancy was the strongest construct in explaining behavioural intention to use virtual reality, followed by facilitating conditions (i.e., barriers) construct which had a negative association with behavioural intention. This thesis aimed to explore the measurement properties of soccer specific virtual reality tests, and the perceptions of staff and players who might use the technology. The key findings from exploring the measurement properties were (1) evidence of a learning curve, suggesting the need for multiple familiarisation trials before collecting data, and (2) a lack of evidence to support the validity of a virtual reality soccer passing test as evident by a lack of agreement to a real-world equivalent. This finding raises questions on the suitability for virtual reality being used to measure passing skill related performance. The key findings from investigating the perceptions of users included, using the technology to improve cognition and tactical awareness, and using it in rehabilitation and performance analysis settings. Future intention to use was generally positive, and driven by performance related factors, yet several barriers exist that may prevent its widespread use. In Chapter 7 of the thesis, a reflective account is presented for the reader, detailing some of the interactions made with coaches, support staff and players in relation to the personal, moral, and ethical challenges faced as a practitioner-researcher, working and studying, respectively, in a professional soccer club
Analytical validation of innovative magneto-inertial outcomes: a controlled environment study.
peer reviewe
Beam scanning by liquid-crystal biasing in a modified SIW structure
A fixed-frequency beam-scanning 1D antenna based on Liquid Crystals (LCs) is designed for application in 2D scanning with lateral alignment. The 2D array environment imposes full decoupling of adjacent 1D antennas, which often conflicts with the LC requirement of DC biasing: the proposed design accommodates both. The LC medium is placed inside a Substrate Integrated Waveguide (SIW) modified to work as a Groove Gap Waveguide, with radiating slots etched on the upper broad wall, that radiates as a Leaky-Wave Antenna (LWA). This allows effective application of the DC bias voltage needed for tuning the LCs. At the same time, the RF field remains laterally confined, enabling the possibility to lay several antennas in parallel and achieve 2D beam scanning. The design is validated by simulation employing the actual properties of a commercial LC medium
Classification of Frailty among Community Dwelling Older Adults Using Parameters of Physical Activity Obtained Independently and Unsupervised
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
Evaluating EEGâEMG Fusion-Based Classification as a Method for Improving Control of Wearable Robotic Devices for Upper-Limb Rehabilitation
Musculoskeletal disorders are the biggest cause of disability worldwide, and wearable mechatronic rehabilitation devices have been proposed for treatment. However, before widespread adoption, improvements in user control and system adaptability are required. User intention should be detected intuitively, and user-induced changes in system dynamics should be unobtrusively identified and corrected. Developments often focus on model-dependent nonlinear control theory, which is challenging to implement for wearable devices.
One alternative is to incorporate bioelectrical signal-based machine learning into the system, allowing for simpler controller designs to be augmented by supplemental brain (electroencephalography/EEG) and muscle (electromyography/EMG) information. To extract user intention better, sensor fusion techniques have been proposed to combine EEG and EMG; however, further development is required to enhance the capabilities of EEGâEMG fusion beyond basic motion classification. To this end, the goals of this thesis were to investigate expanded methods of EEGâEMG fusion and to develop a novel control system based on the incorporation of EEGâEMG fusion classifiers.
A dataset of EEG and EMG signals were collected during dynamic elbow flexionâextension motions and used to develop EEGâEMG fusion models to classify task weight, as well as motion intention. A variety of fusion methods were investigated, such as a Weighted Average decision-level fusion (83.01 ± 6.04% accuracy) and Convolutional Neural Network-based input-level fusion (81.57 ± 7.11% accuracy), demonstrating that EEGâEMG fusion can classify more indirect tasks.
A novel control system, referred to as a Task Weight Selective Controller (TWSC), was implemented using a Gain Scheduling-based approach, dictated by external load estimations from an EEGâEMG fusion classifier. To improve system stability, classifier prediction debouncing was also proposed to reduce misclassifications through filtering. Performance of the TWSC was evaluated using a developed upper-limb brace simulator. Due to simulator limitations, no significant difference in error was observed between the TWSC and PID control. However, results did demonstrate the feasibility of prediction debouncing, showing it provided smoother device motion. Continued development of the TWSC, and EEGâEMG fusion techniques will ultimately result in wearable devices that are able to adapt to changing loads more effectively, serving to improve the user experience during operation
Microfluidic systems based on electroactive polymers technology
Dielectric elastomer actuators (DEAs) have been widely investigated for more than 30 years. Lately, several fabrication methods have successfully allowed the creation of very thin elastomer and electrode layers. The development of attractive applications, in which DEAs offer advantages over conventional technologies, is thus necessary for the advance of the technology. In this work, new biocompatible microfluidic devices based on DEAs are developed.
In the first part of this thesis, several prototypes of peristaltic pumps of single layer dielectric elastomer actuators are designed, manufactured and characterized. Although these prototypes were not able to produce fluid flow, novel insights into the capabilities of Electroactive Polymer technology were gained.
In the second part of this work, a pumping micromixer as a novel application of dielectric elastomer stacked actuators is manufactured. The pumping micromixer is based on peristaltic movements, which gently act as a mixer and a pump for microfluidics. Experimental data show a maximal flow rate of 21.5 ”L/min at 10 Hz. Image analysis at the outlet proves a 50/50 mixing when all actuators are functioning at the same pace and voltage.
The performance of the pumping micromixer is further studied with the Finite Element Method, using the COMSOL MultiphysicsŸ software. Simulations demonstrate the versatility of the pumping characteristics of such a microdevice, from very few ”L/min to mL/min, and from a very low pressure in the range of Pa to hundreds of kPa, by only changing the duty cycle, phase shift and actuation frequency
Complexity Science in Human Change
This reprint encompasses fourteen contributions that offer avenues towards a better understanding of complex systems in human behavior. The phenomena studied here are generally pattern formation processes that originate in social interaction and psychotherapy. Several accounts are also given of the coordination in body movements and in physiological, neuronal and linguistic processes. A common denominator of such pattern formation is that complexity and entropy of the respective systems become reduced spontaneously, which is the hallmark of self-organization. The various methodological approaches of how to model such processes are presented in some detail. Results from the various methods are systematically compared and discussed. Among these approaches are algorithms for the quantification of synchrony by cross-correlational statistics, surrogate control procedures, recurrence mapping and network models.This volume offers an informative and sophisticated resource for scholars of human change, and as well for students at advanced levels, from graduate to post-doctoral. The reprint is multidisciplinary in nature, binding together the fields of medicine, psychology, physics, and neuroscience
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Association Among Neurophysiology, Cognition And Mobility In Older Adults
Age-related structural and molecular changes in older adults have been shown to significantly affect their cognitive and motor functions (Trollor and Valenzuela, 2001). Given the growing population of older adults, it is imperative to bridge the gaps in scientific understanding of cognition and motor capabilities in healthy older adultsâ population. This study investigates five major neurochemicals and their potential correlations with gait, balance, executive function, and attention in healthy older adults. Additionally, we explore the interplay between cognition and motor performance in our participants. Furthermore, we hypothesize that the neurochemical values of interest may serve as predictive indicators for motor performance and cognition in healthy older adults
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