Development of MEMS - based IMU for position estimation: comparison of sensor fusion solutions

With the surge of inexpensive, widely accessible, and precise Micro-Electro Mechanical Systems (MEMS) in recent years, inertial systems tracking move ment have become ubiquitous nowadays. Contrary to Global Positioning Sys tem (GPS)-based positioning, Inertial Navigation System (INS) are intrinsically unaffected by signal jamming, blockage susceptibilities, and spoofing. Measure ments from inertial sensors are also acquired at elevated sampling rates and may be numerically integrated to estimate position and orientation knowledge. These measurements are precise on a small-time scale but gradually accumulate errors over extended periods. Combining multiple inertial sensors in a method known as sensor fusion makes it possible to produce a more consistent and dependable un derstanding of the system, decreasing accumulative errors. Several sensor fusion algorithms occur in literature aimed at estimating the Attitude and Heading Reference System (AHRS) of a rigid body with respect to a reference frame. This work describes the development and implementation of a low-cost, multi purpose INS for position and orientation estimation. Additionally, it presents an experimental comparison of a series of sensor fusion solutions and benchmarking their performance on estimating the position of a moving object. Results show a correlation between what sensors are trusted by the algorithm and how well it performed at estimating position. Mahony, SAAM and Tilt algorithms had best general position estimate performance.Com o recente surgimento de sistemas micro-eletromecânico amplamente acessíveis e precisos nos últimos anos, o rastreio de movimento através de sistemas de in erciais tornou-se omnipresente nos dias de hoje. Contrariamente à localização baseada no Sistema de Posicionamento Global (GPS), os Sistemas de Naveg ação Inercial (SNI) não são afetados intrinsecamente pela interferência de sinal, suscetibilidades de bloqueio e falsificação. As medições dos sensores inerciais também são adquiridas a elevadas taxas de amostragem e podem ser integradas numericamente para estimar os conhecimentos de posição e orientação. Estas medições são precisas numa escala de pequena dimensão, mas acumulam grad ualmente erros durante longos períodos. Combinar múltiplos sensores inerci ais num método conhecido como fusão de sensores permite produzir uma mais consistente e confiável compreensão do sistema, diminuindo erros acumulativos. Vários algoritmos de fusão de sensores ocorrem na literatura com o objetivo de estimar os Sistemas de Referência de Atitude e Rumo (SRAR) de um corpo rígido no que diz respeito a uma estrutura de referência. Este trabalho descreve o desenvolvimento e implementação de um sistema multiusos de baixo custo para estimativa de posição e orientação. Além disso, apresenta uma comparação experimental de uma série de soluções de fusão de sensores e compara o seu de sempenho na estimativa da posição de um objeto em movimento. Os resultados mostram uma correlação entre os sensores que são confiados pelo algoritmo e o quão bem ele desempenhou na posição estimada. Os algoritmos Mahony, SAAM e Tilt tiveram o melhor desempenho da estimativa da posição geral

Development of a user-centred design methodology to accommodate changing hardware and software user requirements in the sports domain

The research presented in this thesis focuses on the development of wireless, real time performance monitoring technology within the resistance training domain. The functionality of current performance monitoring technology and differences in monitoring ability is investigated through comparative force platform, video and accelerometer testing and analysis. Determining the complexity of resistance training exercises and whether performance variable profiles such as acceleration, velocity and power can be used to characterise lifts is also investigated. A structured user-centred design process suitable for the sporting domain is proposed and followed throughout the research to consider the collection, analysis and communication of performance data. Identifying the user requirements and developing both hardware and software to meet the requirements also forms a major part of the research. The results indicate that as the exercise complexity increases, the requirement for sophisticated technology increases. A simple tri-axial accelerometer can be used to monitor simple linear exercises at the recreational level. Gyroscope technology is required to monitor complex exercises in which rotation of the bar occurs. Force platform technology is required at the elite level to monitor the distribution of force and resultant balance throughout a lift (bilateral difference). An integrated system consisting of an Inertial Measurement Unit (both accelerometer and gyroscope technology) and a double plate force platform is required to accurately monitor performance in the resistance training domain at the elite level

Wearables for Movement Analysis in Healthcare

Quantitative movement analysis is widely used in clinical practice and research to investigate movement disorders objectively and in a complete way. Conventionally, body segment kinematic and kinetic parameters are measured in gait laboratories using marker-based optoelectronic systems, force plates, and electromyographic systems. Although movement analyses are considered accurate, the availability of specific laboratories, high costs, and dependency on trained users sometimes limit its use in clinical practice. A variety of compact wearable sensors are available today and have allowed researchers and clinicians to pursue applications in which individuals are monitored in their homes and in community settings within different fields of study, such movement analysis. Wearable sensors may thus contribute to the implementation of quantitative movement analyses even during out-patient use to reduce evaluation times and to provide objective, quantifiable data on the patients’ capabilities, unobtrusively and continuously, for clinical purposes

Body sensor networks: smart monitoring solutions after reconstructive surgery

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

Analysis of the backpack loading efects on the human gait

Gait is a simple activity of daily life and one of the main abilities of the human being. Often during leisure, labour and sports activities, loads are carried over (e.g. backpack) during gait. These circumstantial loads can generate instability and increase biomechanicalstress over the human tissues and systems, especially on the locomotor, balance and postural regulation systems. According to Wearing (2006), subjects that carry a transitory or intermittent load will be able to find relatively efficient solutions to compensate its effects.info:eu-repo/semantics/publishedVersio

Research, design and testing of a multi-function modular exercise system

The aim of this research was to develop a novel multi-function exercise system for use in a broad range of applications. Market research indicates that the demand for aerobic and anaerobic exercise devices will continue to grow with the introduction of government physical activity guidelines and increased social pressure regarding health related issues. A detailed investigation of the basic exercise science fundamentals and training methodologies was conducted in order to develop a system which would provide efficient and effective training related stimuli for improving fitness. The generation, storage and utilisation of actual and virtual load and velocity profiles for use in the development of original training modes was identified as an important area of the research. The proposed solution utilises an electromechanical programmable motion control system which provides all of the necessary exercise modalities defined in the system specification. This system combines existing industrial servo drive technology with proprietary software and database facilities to provide a step change in functionality, ease of use and safety for all users. Development of these hardware and software elements was supported by the creation of a series of system models at the initial stages of the research using the computer integrated manufacturing open systems architecture (CIMOSA) modelling approach. These diagrams were an invaluable resource during the concept generation and refinement processes and have clearly demonstrated the cross-discipline applications of such formalised modelling techniques. Validation and reliability data collected during prototype testing indicated that the exercise motion generation capabilities and performance measurement facilities were comparable to existing isokinetic dynamometer equipment. Additional subject testing produced results with peak output values and parameter trends which correlated closely to those determined during clinical and academic research. These experimental results suggest that the modular exercise system could be a valuable tool for the collection of research data to be used in support of current and future training theories.EThOS - Electronic Theses Online ServiceGBUnited Kingdo

Exploring the use of wearables in the management of mild traumatic brain injury

a) Why is the subject of your thesis important? Every year more than 1 million people attend Accident and Emergency with mild traumatic brain injuries (mTBI), many of which arise from Sports Related Concussion (SRC). Despite the high incidence of such injuries, there is still no gold standard method to monitor the wide variety of impairments (cognitive, visual, motor symptom) accompanying mTBI. Accordingly, there is concern about the long-term effects of mTBI if diagnosis is delayed or missed entirely. Current reliance on subjective techniques such as symptoms are non-specific and an unreliable indicator of recovery, making it difficult to know when it is safe for players to return to play (RTP). This highlights the need for testing and validating the accuracy and applicability of objective tools to aid diagnosis, monitoring, and RTP protocols for individuals exposed to mTBI and SRC. b) How have you undertaken the research? I have taken a systematic approach to this problem-based research, starting by understanding the clinical challenges of mTBI from SRC where amateur rugby union is used as an exemplar for investigation throughout the thesis. Both mTBI and SRC is an under-researched area confounded by insufficient medical staff available to recognise SRC and monitor players within low resource (community) based settings. This may place these individuals at an increased risk of having a delayed diagnosis or it being missed entirely. My hypothesis tests if the use of digital technologies may enable affordable mTBI management, ensuring continuity and objective personalised assessment to support traditional approaches. Accordingly, my thesis broadly comprises of a literature examination and preliminary validation and testing, progressing to an in-depth exploration involving larger datasets and concluding with recommendations for clinical practice. c) What are your main research findings? My multidisciplinary approach reveals that focusing on one impairment in mTBI is unlikely to reveal meaningful insight to mTBI/SRC and RTP. Instead, multimodal digital technologies could enable affordable management, ensuring consistency and continuity (e.g., between assessors) while offering objective personalised data to better support traditional approaches. My results provide insight and identify the usefulness of instrumented walking (gait) as a digital (bio) marker for mTBI management. Based on receiver operating characteristics (ROC) and area under the curve (AUC) analyisis free-living step velocity (i.e., walking speed) was the most sensitive (>0.72) at distinguishing healthy from acute SRC and may be useful for continuous monitoring and therefore informing SRC RTP. In a purely computing science context, my findings have uncovered challenges and opportunities for further refinement. For example, there is still room for more ‘no code’ solutions in gait and algorithm analysis. Few clinicians would have the technical skillsets for completing free-living gait analysis. Therefore, validated algorithms within a "drag and drop", click and collect approach is needed to meet the recommend approach of remote, free-living monitoring of habitual behaviours. That is an important next step for the translation of academic research grade devices for broader deployment in clinical practice. d) Why do your research findings matter This thesis generally supports the suggested use of digital technologies as an affordable and objective method to support traditional approaches of assessment in mTBI/SRC. Passive and continuous monitoring solutions such as wearables are becoming ubiquitous in daily life. Moreover, the use of instrumented (lab) and free-living gait may fit that context with evidence of its use as a diagnostic tool. More work is needed to strengthen that claim as well as further investigate its use as a responsive tool. Identifying useful digital biomarkers in pathological cohorts such as mTBI may improve the detection of injuries and better inform safe (personalised) RTP guidelines. Identifying critical stages of recovery more accurately will also reduce the likelihood of premature return to play before full recovery, which is a necessary threshold in offering personalised care and rehabilitation. That is an important next step for the translation of academic research grade devices for broader deployment in clinical practice