Validity and Consistency of Concurrent Extraction of Gait Features Using Inertial Measurement Units and Motion Capture System

Conditions causing gait abnormalities are very common and their treatment requires the detailed assessment of gait. Currently such assessments are carried out in gait laboratories and require the use of complex and expensive equipment. To increase availability and use at home and clinics, we design and develop an affordable, user friendly, wireless, portable automatic system to extract spatiotemporal features of gait that can be used indoors and outdoors. This study determines the concurrent validity of extracted gait features from Inertial Measurement Units (IMUs) against ‘gold standard’ Motion Capture System (MoCap) using a hybrid gait features extraction method. The analysis of the proposed method is based on minimum prominence and abrupt transition points in the IMU signals. We also compare the degree of agreement for mean spatiotemporal gait features. The concurrent data from synchronized IMUs and MoCap are collected from 18 subjects. We validate our proposed system using two experiments; 1) IMU and MoCap with self-selected (free) walking and 2) IMU and MoCap at various walking speeds. Interclass correlations, Lin’s concordance correlation coefficients and Pearson’s correlation coefficients (r) are applied to determine the correlation between extracted gait features from IMU and MoCap measurements. Bland-Altman plots are also generated to evaluate any unknown bias between the mean extracted features. The experiments show that spatiotemporal features of gait extracted from IMUs are highly valid. Our methods facilitate gait assessment in clinics and at home including the possibility of self-assessment

Free vibration of symmetric angly-plane layered truncated conical shells under classical theory

Truncated conical shell finds wide ranging of engineering applications. They are used in space crafts, robots, shelters, domes, tanks, nozzles and in machinery devices. Thus, the study of their vibrational characteristics has long been of interest for the designers. The use of the lamination for the structures leads to design with the maximum reliability and minimum weight. Moreover, the study of free vibration of laminated conical shells has been treated by a number of researchers. Irie et al. (1982) studied free vibration of conical shells with variable thickness using Rayleigh-Ritz method of solution. Wu and Wu (2000) provided 3D elasticity solutions for the free vibration analysis of laminated conical shells by an asymptotic approach. Wu and Lee (2001) studied the natural frequencies of laminated conical shells with variable stiffness using the differential quadrature method under first-order shear deformation theory (FSDT). Tripathi et al. (2007) studied the free vibration of composite conical shells with random material properties of the finite element method. Civalek (2007) used the Discrete Singular Convolution (DSC) to investigate the frequency response of orthotropic conical and cylindrical shells. Sofiyez et al. (2009) studied the vibrations of orthotropic non-homogeneous conical shells with free boundary conditions. Ghasemi et al. (2012) presented their study of free vibration of composite conical shells which was investigated under various boundary conditions using the solution of beam function and Galerkin method. Viswanathan et al. (2007, 2011) studied free vibration of laminated cross-ply plates, including shear deformation, symmetric angle-ply laminated cylindrical shells of variable thickness with shear deformation theory using the spline collocation method. In the present work, free vibration of symmetric angle-ply laminated truncated conical shells is analyzed and displacement functions are approximated using cubic and quantic spline and collocation procedure is applied to obtain a set of field equations. The field equations along with the equations of boundary conditions yield a system of homogeneous simultaneous algebraic equations on the assumed spline coefficients which resulting to the generalized eigenvalue problem. This eigenvalue problem is solved using eigensolution technique to get as many eigenfrequencies as required. The effect of circumferential mode number, length ratio, cone angle, ply angles and number of layers under two boundary conditions on the frequency parameter is studied for three- and five- layered conical shells consisting of two types of layered materials

Integrated navigation system for pedestrians using inertial sensors and GPS of mobile devices

Orientador: Leonardo de Souza MendesDissertação (mestrado) - Universidade Estadual de Campinas, Faculdade de Engenharia Elétrica e de ComputaçãoResumo: Normalmente as pessoas usam o sistema de posicionamento global (GPS) para localização precisa, não obstante edifícios altos e outras construções podem gerar interrupções do sinal em áreas urbanas. Além disso, a precisão do GPS é afetada por erros provenientes dos satélites, originados no receptor ou devidos à propagação do sinal. Os sistemas de navegação inercial proporcionam posicionamento do usuário de forma contínua, não obstante o erro induzido por dispositivos inerciais se acumula ao longo do tempo afetando a precisão de navegação no longo prazo. Este estudo visa integrar o GPS com sistemas inerciais para fornecer uma solução de navegação para pedestres com melhor desempenho. Considerando a proliferação de telefones móveis equipados com GPS, acelerômetros e magnetômetros, este trabalho captura os dados de mobilidade humana através de smartphones. As medições de aceleração e campo magnético terrestre são empregadas para construir um sistema de coordenadas local, e as medições de latitude e longitude são empregadas para construir um sistema de coordenadas global, logo as posições globais são ajustadas à estrutura medida localmente para obter um posicionamento refinado mais propenso de extrair o terreno real. O algoritmo de navegação integrada proposto foi testado no seguimento de trajetórias de pedestres em áreas exteriores a fim de avaliar sua precisão e desempenhoAbstract: People usually use the Global Positioning System (GPS) for accurate location, however tall buildings and other constructions can generate signal interruptions in urban areas. Also, GPS accuracy is affected by errors originated in the satellites, in the receiver or by the signal propagation. Inertial navigation systems provide continuous user positioning, nevertheless the error induced by inertial devices accumulates over time, affecting the navigation accuracy in the long term. This study aims to integrate GPS with inertial systems to provide a pedestrian navigation solution with better performance. Considering the proliferation of mobile phones equipped with GPS, accelerometers and magnetometers, this work captures the data of human mobility through smartphones. Acceleration and magnetic field measurements are used to construct a local coordinate system, and latitude and longitude measurements are used to construct a global coordinate system, next the global positions are adjusted to the locally measured structure to obtain a refined positioning more faithful to the ground truth. The proposed integrated navigation algorithm was tested following pedestrian trajectories in outdoor areas in order to evaluate its accuracy and performanceMestradoTelecomunicações e TelemáticaMestra em Engenharia ElétricaCAPE

Realidade aumentada móvel aplicada na navegação indoor para cadeirantes

Physical deficiency is an obstacle to the afflicted individual, as they are deprived from realizing routine activities, without the help of others. For many, the use of wheelchairs is fundamental to providing mobility and social inclusion. However, these individuals still come up against a series of challenges in order to improve their life quality. Among the many difficulties, one in particular is highlighted: navigation in indoor environments buildings, such as localizing the shortest and best route for arriving at a desired destination. In the context of the Information Society, the use of pervasive computation and intelligent environments have application potential in supporting navigation assisted by mobile devices. In this scenario, it is noted that there exist a sparse quantity of applications capable of attending to the special needs of wheelchair users. Therefore, this study considers the hypothesis that other technologies, such as Mobile Augmented Reality (AR), possess the potential to facilitate the navigation of wheelchair users in indoor environments. In light of the above, the main motive behind this research study is to investigate computational techniques that support the use of indoor navigation based on Mobile AR, especially those which possess total control over their upper limbs. In order to achieve such, this work study proposes an architecture to support the development of these applications. Experiments were performed with wheelchair user volunteers. These interacted with an application via touch or voice commands in order to navigate within a test environment. This environment proposes the use of navigation arrows through use of AR. The features implemented onto the proposed architecture were capable of providing significant benefits for indoor navigation. Especially, when compared to traditional techniques.Tese (Doutorado)A deficiência física é um obstáculo aos portadores, uma vez que os mesmos são privados de realizar atividades rotineiras, sem auxílio de outros. Para muitos, o uso de cadeiras de rodas é fundamental para proporcionar mobilidade e inclusão social. No entanto, cadeirantes ainda enfrentam uma série de desafios para melhorar sua qualidade de vida. Entre as muitas dificuldades, uma em especial se destaca: a navegação em ambientes internos (indoor) de edificações, tais como a localização do menor e melhor caminho para chegar ao seu destino final. No contexto da Sociedade da Informação, o uso de computação pervasiva e de ambientes inteligentes tem potencial de aplicação no apoio à navegação suportada por dispositivos móveis. Neste cenário, observa-se parca quantidade de aplicações capazes de atender as necessidades especiais de cadeirantes. Portanto, este trabalho considera a hipótese de que outras tecnologias como a Realidade Aumentada (RA) Móvel, possui potencial para facilitar a navegação de cadeirantes em ambientes fechados. Diante disso, a motivação principal desta pesquisa é investigar técnicas computacionais que suportem o uso da navegação indoor de cadeirantes, baseada na RA Móvel, especialmente os que possuem total controle dos membros superiores. Para tanto, este trabalho propõe uma arquitetura para suportar o desenvolvimento destas aplicações. Experimentos foram realizados com voluntários cadeirantes. Estes interagiram com a aplicação por meio de comandos de toque ou de voz, para navegar dentro de um ambiente de teste. Este ambiente propõe o uso de setas de navegação com o uso de RA. As características implementadas na arquitetura proposta foram capazes de proporcionar benefícios significativos para navegação indoor de cadeirantes. Principalmente, quando comparado com técnicas tradicionais. Palavras-chave: realidade aumentada móvel, navegação indoor, cadeirantes

Internet of Things data contextualisation for scalable information processing, security, and privacy

The Internet of Things (IoT) interconnects billions of sensors and other devices (i.e., things) via the internet, enabling novel services and products that are becoming increasingly important for industry, government, education and society in general. It is estimated that by 2025, the number of IoT devices will exceed 50 billion, which is seven times the estimated human population at that time. With such a tremendous increase in the number of IoT devices, the data they generate is also increasing exponentially and needs to be analysed and secured more efficiently. This gives rise to what is appearing to be the most significant challenge for the IoT: Novel, scalable solutions are required to analyse and secure the extraordinary amount of data generated by tens of billions of IoT devices. Currently, no solutions exist in the literature that provide scalable and secure IoT scale data processing. In this thesis, a novel scalable approach is proposed for processing and securing IoT scale data, which we refer to as contextualisation. The contextualisation solution aims to exclude irrelevant IoT data from processing and address data analysis and security considerations via the use of contextual information. More specifically, contextualisation can effectively reduce the volume, velocity and variety of data that needs to be processed and secured in IoT applications. This contextualisation-based data reduction can subsequently provide IoT applications with the scalability needed for IoT scale knowledge extraction and information security. IoT scale applications, such as smart parking or smart healthcare systems, can benefit from the proposed method, which  improves the scalability of data processing as well as the security and privacy of data.   The main contributions of this thesis are: 1) An introduction to context and contextualisation for IoT applications; 2) a contextualisation methodology for IoT-based applications that is modelled around observation, orientation, decision and action loops; 3) a collection of contextualisation techniques and a corresponding software platform for IoT data processing (referred to as contextualisation-as-a-service or ConTaaS) that enables highly scalable data analysis, security and privacy solutions; and 4) an evaluation of ConTaaS in several IoT applications to demonstrate that our contextualisation techniques permit data analysis, security and privacy solutions to remain linear, even in situations where the number of IoT data points increases exponentially

An automatic wearable multi-sensor based gait analysis system for older adults.

Gait abnormalities in older adults are very common in clinical practice. They lead to serious adverse consequences such as falls and injury resulting in increased care cost. There is therefore a national imperative to address this challenge. Currently gait assessment is done using standardized clinical tools dependent on subjective evaluation. More objective gold standard methods (motion capture systems such as Qualisys and Vicon) to analyse gait rely on access to expensive complex equipment based in gait laboratories. These are not widely available for several reasons including a scarcity of equipment, need for technical staff, need for patients to attend in person, complicated time consuming procedures and overall expense. To broaden the use of accurate quantitative gait monitoring and assessment, the major goal of this thesis is to develop an affordable automatic gait analysis system that will provide comprehensive gait information and allow use in clinic or at home. It will also be able to quantify and visualize gait parameters, identify gait variables and changes, monitor abnormal gait patterns of older people in order to reduce the potential for falling and support falls risk management. A research program based on conducting experiments on volunteers is developed in collaboration with other researchers in Bournemouth University, The Royal Bournemouth Hospital and care homes. This thesis consists of five different studies toward addressing our major goal. Firstly, a study on the effects on sensor output from an Inertial Measurement Unit (IMU) attached to different anatomical foot locations. Placing an IMU over the bony prominence of the first cuboid bone is the best place as it delivers the most accurate data. Secondly, an automatic gait feature extraction method for analysing spatiotemporal gait features which shows that it is possible to extract gait features automatically outside of a gait laboratory. Thirdly, user friendly and easy to interpret visualization approaches are proposed to demonstrate real time spatiotemporal gait information. Four proposed approaches have the potential of helping professionals detect and interpret gait asymmetry. Fourthly, a validation study of spatiotemporal IMU extracted features compared with gold standard Motion Capture System and Treadmill measurements in young and older adults is conducted. The results obtained from three experimental conditions demonstrate that our IMU gait extracted features are highly valid for spatiotemporal gait variables in young and older adults. In the last study, an evaluation system using Procrustes and Euclidean distance matrix analysis is proposed to provide a comprehensive interpretation of shape and form differences between individual gaits. The results show that older gaits are distinguishable from young gaits. A pictorial and numerical system is proposed which indicates whether the assessed gait is normal or abnormal depending on their total feature values. This offers several advantages: 1) it is user friendly and is easy to set up and implement; 2) it does not require complex equipment with segmentation of body parts; 3) it is relatively inexpensive and therefore increases its affordability decreasing health inequality; and 4) its versatility increases its usability at home supporting inclusivity of patients who are home bound. A digital transformation strategy framework is proposed where stakeholders such as patients, health care professionals and industry partners can collaborate through development of new technologies, value creation, structural change, affordability and sustainability to improve the diagnosis and treatment of gait abnormalities