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Firefighter fitness, movement qualities, occupational low-back loading demands and injury potentialBeach, Tyson A.C. 21 February 2012 (has links)
BACKGROUND and OBJECTIVES:
Low-back overexertion injuries represent a large proportion of fireground “strains, sprains and muscular pains” and are a leading cause of disability and early retirement in firefighters. Given the inherently hazardous and unpredictable nature of many fireground activities, it is often infeasible to implement “task-focused” ergonomic controls and there are limited options to accommodate injured firefighters. Accordingly, effective and practical “worker-focused” injury prevention approaches are needed. Toward this end, four studies were conducted to address the following global thesis objectives:
1) Examine the possible role that firefighters’ personal movement strategies could have on their occupational low-back loading demands and injury potential; and
2) Compare the effects of two different exercise approaches on firefighters’ occupational low-back loading demands and injury potential.
STUDY 1: Low-Back Loading Demands during Simulated Firefighting Tasks – Inter-Subject Variation and the Impact of Fatigue and Gender.
Background: Non-modifiable fireground duties are considered hazardous for low-back health, but personal movement strategies could modulate low-back loading demands and injury potential. Study objectives were to quantify low-back loading demands during simulated firefighting tasks and to examine the impact of fatigue and gender on the peak loading response.
Methods: Ten men and 10 women performed a battery of laboratory-simulated firefighting tasks before and following repeated bouts of a fatiguing stair-climbing protocol. An EMG-assisted three-dimensional dynamic biomechanical model was used to compute peak L4/L5 joint forces during task performance.
Results: Peak low-back loading demands varied considerably between subjects and tasks, but 70% of all loading variables examined were of greater magnitudes in male subjects and 40% of all loading variables were of lower magnitudes in both males and females after stair-climbing. Some inter-subject variation in low-back loading was attributed to body size differences, but between- and within-subject differences in movement strategies also contributed to low-back loading variability between subjects and over time.
Conclusions: Results of this study suggest that characteristics of individuals, tasks performed, and physical fatigue may influence peak low-back loading demands and injury potential in firefighters. Despite considerable inter-subject variation in the internal low-back loading response to fixed external task and environmental constraints, opportunities to attenuate low-back loading demands through movement behaviour adaptations alone may be limited to only a subset of fireground activities.
STUDY 2: Ankle Immobilization alters Lifting Kinematics and Kinetics – Occupational Low-Back Loading Demands and Potential for Injury.
Background: Firefighters with lingering lower extremity functional impairments could be forced to move in ways that increase their potential for sustaining occupational low-back lifting injuries. The study objective was to examine the impact of unilateral ankle immobilization on lifting kinematics and kinetics.
Methods: With and without their right ankle immobilized, 10 male volunteers performed laboratory-simulated occupational lifting tasks. Together with force platform data, three-dimensional kinematics of the lumbar spine, pelvis, and lower extremities were collected, and a three-dimensional dynamic biomechanical model was used to calculate peak low-back compression and shear loading demands.
Results: In comparison to the unaffected conditions, ankle immobilization resulted in less knee (p-values between 0.0004 and 0.0697) and greater lumbar spine (p-values between 0.0006 and 0.3491) sagittal motion when lifting. Associated with this compensatory movement strategy were greater L4/L5 anterior/posterior reaction shear forces (p-values between 0.0009 and 0.2450). However, in a few cases where individual compensatory movement strategies differed from the “group” response (i.e., subjects increased their sagittal knee and hip motion on the affected side), peak L4/L5 joint compressive loads increased while the peak L4/L5 anterior-posterior shear did not change.
Conclusions: Distal lower extremity joint dysfunction can alter the way in which individuals move and load their low-backs when lifting. The specific ways in which individuals compensate for personal movement constraints could alter the potential site and mechanism of occupational low-back injury.
STUDY 3: FMS™ Scores and Occupational Low-Back Loading Demands – Whole-Body Movement Screening as an Ergonomic Tool?
Background: Results of Study 1 suggested that a whole-body movement screen could be used to identify personal characteristics that constrain movement behaviour in ways that impact occupational low-back loading demands and injury potential. The purpose of this study was to examine if Functional Movement Screen™ (FMS) scores could be used to project the low-back loading response to lifting.
Methods: Sagittally symmetric and asymmetric laboratory-based lifting tasks were performed by 15 firefighters who scored greater than 14 on the FMS (high-scorers) and 15 size-matched low-scorers (FMS < 14). A three-dimensional dynamic biomechanical model was used to calculate low-back loading demands, and lumbar spine posture was recorded when peak low-back compression was imposed.
Results: Regardless of the task performed, there were no differences in peak L4/L5 joint compression (p ≥ 0.4157), anterior/posterior reaction shear (p ≥ 0.5645), or medial/lateral reaction shear (p ≥ 0.2581) loading demands between high- and low-scorers. At the instant when peak compression force was detected, lumbar spine deviation was not different between high- and low-scorers about the lateral bend (p ≥ 0.4215), axial twist (p ≥ 0.2734), or flexion/extension (p ≥ 0.1354) axes.
Conclusions: Using the previously established musculoskeletal injury prediction threshold value of 14, the composite FMS score did not project the low-back loading response to lifting. Future attempts to modify or reinterpret FMS scoring are warranted given that several previous studies have revealed links between composite FMS scores and musculoskeletal complaints.
STUDY 4: Movement- vs. Fitness-Centric Exercise – Firefighter Fitness, Whole-Body Movement Qualities, and Occupational Low-Back Loading Outcomes.
Background: The impact of exercise on firefighter job performance and cardiorespiratory fitness has been studied extensively, but its effect on musculoskeletal loading remains less understood. The aim of this study was to compare various physical fitness, general movement quality, and low-back loading outcomes between groups of firefighters who completed fitness- or movement-centric exercise.
Methods: Fifty-four firefighters participated and were assigned to a control (CON), fitness-centric exercise (FIT), or movement-centric exercise (MOV) group. Before and after 12 weeks of exercise, subjects performed a physical fitness test battery, the Functional Movement Screen™ (FMS), and laboratory-simulated firefighting tasks during which low-back loading demands were quantified.
Results: FIT and MOV subjects exhibited statistically significant improvements in nearly all measures of physical fitness (i.e., body composition, cardiorespiratory capacity, muscular strength, power, endurance, and flexibility), but FMS scores and occupational low-back loading demands were not impacted in a consistent way across individuals.
Conclusions: Improving physical fitness can enhance job performance and prevent cardiac events in firefighters, but it was not clear that 12 weeks of exercise would alter their occupational low-back loading demands. Given variability in individual responses, the short study duration, and limited number and nature of tasks examined, more research incorporating alternative biomechanical and statistical analyses is needed to better understand how individuals adapt to chronic exercise and what impact these adaptations have on occupational movement behaviours, low-back loading demands, and low-back loading capacity.
SUMMARY and CONCLUSIONS:
Results confirmed that fireground activities are potentially hazardous for low-back health, as simulated occupational low-back loading demands routinely exceeded recommended exposure limits in the studies performed. However, results also indicated that personal movement strategies – possibly influenced by body size, preference, gender, physical fatigue, or distal lower extremity joint dysfunction – could alter occupational low-back loading demands and injury potential. It could not be concluded that occupational low-back loading demands and injury potential would be consistently affected by short-term improvements in physical fitness, nor could the low-back loading response to lifting be projected by scoring above or below 14 on the Functional Movement Screen™. Future research is warranted to examine the low-back loading demands associated with performing non-fireground duties, as opportunities may exist to implement ergonomic strategies to control cumulative low-back loading exposures. Particular attention should be paid to the exercise and training practices of firefighters, as musculoskeletal injuries sustained during these activities are potentially avoidable and could reduce the capacity of the musculoskeletal system to withstand demands imposed during non-modifiable fireground operations.
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Integration of Sensory Feedback When Adapting to Novel Visuomotor EnvironmentsHinder, Mark Unknown Date (has links)
The aim of the research described in this thesis is to improve our understanding of how the central nervous system (CNS) integrates feedback information from different sensory modalities to permit skill acquisition, and the subsequent consolidation of that skill, when exposed to a novel visuomotor environment. Indeed, such adaptation must be consolidated and recalled when appropriate such that we do not have to continually relearn skills we once possessed. By manipulating the sensory feedback available from the visual and proprioceptive systems during learning, it is possible to determine those facets of the sensory feedback that are essential for adaptation to occur. The thesis consists of seven chapters. The first and last provide a conceptual basis for, and an overall discussion of, the research. Chapter 2 reviews current visuomotor adaptation research, with particular focus on the manner in which information about novel tasks is stored within the CNS as we adapt, and the sensory information that is necessary to allow this adaptation to occur. Furthermore, this chapter serves to introduce many of the experimental techniques that are used to investigate motor learning in humans. Chapter 3 is a report of an investigation of the issues of interference and consolidation in an isometric target acquisition task. Exposure to a 30° counter-clockwise (CCW) rotation was followed by a period of rest, trials with no rotation, or trials with a 60° clockwise (CW) rotation. Retention of the initial adaptation was assessed 5 hours later. Full interference was manifested in circumstances in which either counter-rotated or non-rotated trials were encountered following the initial learning period. These results are consistent with the view that the observed interference is anterograde in nature, and highlight differences in the mechanisms employed by the CNS when compensating for novel kinematics (e.g. visuomotor rotations) compared with adapting to novel dynamics (e.g. external forces). Chapter 4 is a report of an investigation of the role of visual feedback in adapting to novel visuomotor environments in an isometric target acquisition task. Following trials with no rotation, participants adapted to a 60° CCW visuomotor rotation before returning to the non-rotated condition. Separate groups received either continuous visual feedback (CF) of cursor position during task execution or post-trial visual feedback (PF), both indicating task performance. One CF group were instructed to make any (feedback) modifications necessary during the task to reduce errors and acquire the target, while another CF group were instructed to make uncorrected, ballistic movements. Colour cues permitted the identification of the task environment (nonrotated/ rotated) on every trial. The results indicate that an automatic recalibration of the visuomotor mapping occurs when CF is provided, and suggest that performance improvements with PF may occur via the adoption of a cognitively mediated strategy. Furthermore, execution of feedback motor commands to correct errors did not enhance the adaptation that occurred when CF was provided, indicating that the perception of sensory errors (and not feedback commands that may be applied to reduce those errors) drives feedforward visuomotor adaptation. To investigate whether additional proprioceptive feedback associated with movement altered the adaptation patterns observed in chapter 4, a study similar to that reported in chapter 4 was undertaken, and is reported in chapter 5. In this instance a discrete, goaldirected, movement task replaced the isometric task. Subjects were deprived of vision of their arm, but were provided with PF or CF indicating task performance. The patterns of adaptation noted in the isometric task were also exhibited in this dynamic task, indicating that the timing of the visual feedback of task performance has a profound effect on how performance improvements in a novel visuomotor rotation occur. The experiment reported in Chapter 6 assessed the ability to adapt to two conflicting visuomotor rotations interleaved within the same training period, when each task variant (rotation) could be identified by contextual (colour) cues. While full dual adaptation was not observed, the results suggest that the colour cues may have been utilised to explicitly select distinct motor commands for each task rotation.
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Integration of Sensory Feedback When Adapting to Novel Visuomotor EnvironmentsHinder, Mark Unknown Date (has links)
The aim of the research described in this thesis is to improve our understanding of how the central nervous system (CNS) integrates feedback information from different sensory modalities to permit skill acquisition, and the subsequent consolidation of that skill, when exposed to a novel visuomotor environment. Indeed, such adaptation must be consolidated and recalled when appropriate such that we do not have to continually relearn skills we once possessed. By manipulating the sensory feedback available from the visual and proprioceptive systems during learning, it is possible to determine those facets of the sensory feedback that are essential for adaptation to occur. The thesis consists of seven chapters. The first and last provide a conceptual basis for, and an overall discussion of, the research. Chapter 2 reviews current visuomotor adaptation research, with particular focus on the manner in which information about novel tasks is stored within the CNS as we adapt, and the sensory information that is necessary to allow this adaptation to occur. Furthermore, this chapter serves to introduce many of the experimental techniques that are used to investigate motor learning in humans. Chapter 3 is a report of an investigation of the issues of interference and consolidation in an isometric target acquisition task. Exposure to a 30° counter-clockwise (CCW) rotation was followed by a period of rest, trials with no rotation, or trials with a 60° clockwise (CW) rotation. Retention of the initial adaptation was assessed 5 hours later. Full interference was manifested in circumstances in which either counter-rotated or non-rotated trials were encountered following the initial learning period. These results are consistent with the view that the observed interference is anterograde in nature, and highlight differences in the mechanisms employed by the CNS when compensating for novel kinematics (e.g. visuomotor rotations) compared with adapting to novel dynamics (e.g. external forces). Chapter 4 is a report of an investigation of the role of visual feedback in adapting to novel visuomotor environments in an isometric target acquisition task. Following trials with no rotation, participants adapted to a 60° CCW visuomotor rotation before returning to the non-rotated condition. Separate groups received either continuous visual feedback (CF) of cursor position during task execution or post-trial visual feedback (PF), both indicating task performance. One CF group were instructed to make any (feedback) modifications necessary during the task to reduce errors and acquire the target, while another CF group were instructed to make uncorrected, ballistic movements. Colour cues permitted the identification of the task environment (nonrotated/ rotated) on every trial. The results indicate that an automatic recalibration of the visuomotor mapping occurs when CF is provided, and suggest that performance improvements with PF may occur via the adoption of a cognitively mediated strategy. Furthermore, execution of feedback motor commands to correct errors did not enhance the adaptation that occurred when CF was provided, indicating that the perception of sensory errors (and not feedback commands that may be applied to reduce those errors) drives feedforward visuomotor adaptation. To investigate whether additional proprioceptive feedback associated with movement altered the adaptation patterns observed in chapter 4, a study similar to that reported in chapter 4 was undertaken, and is reported in chapter 5. In this instance a discrete, goaldirected, movement task replaced the isometric task. Subjects were deprived of vision of their arm, but were provided with PF or CF indicating task performance. The patterns of adaptation noted in the isometric task were also exhibited in this dynamic task, indicating that the timing of the visual feedback of task performance has a profound effect on how performance improvements in a novel visuomotor rotation occur. The experiment reported in Chapter 6 assessed the ability to adapt to two conflicting visuomotor rotations interleaved within the same training period, when each task variant (rotation) could be identified by contextual (colour) cues. While full dual adaptation was not observed, the results suggest that the colour cues may have been utilised to explicitly select distinct motor commands for each task rotation.
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Optimal Experience in Physical Activity: Examining the Multidimensionality of Flow Across CulturesKawabata, Masato Unknown Date (has links)
Applying the lens of experience, a good life is deemed to be characterized by full absorption in what one does (Nakamura & Csikszentmihalyi, 2002). In addition, experiencing flow is linked with personal growth (Seligman & Csikszentmihalyi, 2000). Therefore, it is not surprising that understanding the optimal experience of flow is considered important. Nonetheless, it is never easy to clearly explain this complex but positive subjective experience. Thus, the present investigation was conducted to provide a clearer conceptualization of flow based on theoretical and empirical grounds to foster understanding of this optimal experience. In order to pursue this primary purpose, the following 3 studies were conducted. The purpose of Study 1 was to develop multidimensional measurement instruments for use with Japanese adults to assess flow experience in physical activity. To this end, the Flow State Scale-2 and Dispositional Flow Scale-2 (FSS-2 and DFS-2) were adapted (translated) from English to Japanese, following the guidelines for test adaptation proposed by Duda and Hayashi (1998) and Tanzer and Sim (1999). Employing a 9-factor 1st-order model, the factorial validity of the Japanese versions of the FSS-2 and DFS-2 (JFSS-2 and JDFS-2) was tested and cross-validated with confirmatory factor analysis (CFA). Through a multi-staged approach, a series of CFAs were conducted on data from large Japanese samples (preliminary samples: n = 578; calibration samples: n = 975; validation samples: n = 970). In addition to internal consistency reliability for both scales, stability was assessed over a 4- week time period for the JDFS-2. Furthermore, measurement equivalence was examined across Japanese independent samples as well as 2 cultural samples. The findings from this study provided strong support for the validity and reliability of the JFSS-2 and JDFS-2 in assessing flow experiences in physical activity for Japanese adults, and indicated that the Japanese versions of the flow scales are useful instruments for cross-cultural research. The purpose of Study 2 was to examine the internal structure of flow as part of an ongoing process of construct validation of flow responses. A total of 4,175 respondents (Japanese: n = 2,041; English-speaking: n = 2,134) completed one of the Japanese and English versions of the FSS-2 or DFS-2. For the Japanese respondents, data from calibration and validation samples in Study 1 were used. Alternative representations of flow responses were cross-culturally examined by testing 11 alternative 1st- and higher-order CFA models. The CFA findings cross-culturally supported and extended Marsh and Jackson’s (1999) argument that the situational and dispositional flow responses were best represented by the multidimensional 1st-order representation rather than the higher-order representation. Confirming clear support for the 1st-order representation of flow, structural equation models (i.e., a priori and post hoc models) were tested to examine the hypothesis that flow experience is an attentional process of absorption in the task at hand, which generates intrinsically rewarding feelings. Results of both models clearly supported the hypothesis across the 2 large cultural samples. The purposes of Study 3 were to examine the utility of multi-group comparisons with the JFSS-2 and JDFS-2 and to further examine the construct validity of the Japanese flow responses. Data used in Study 3 were identical to the Japanese samples in Study 2 (N = 2,041). Factorial invariance in a 9-factor measurement model was tested for both flow scales for 5 key variables: the quality of physical activity experience, participation level, types of physical activity, gender, and age. Given an adequate level of measurement invariance, factor means were compared across groups for each variable. Furthermore, correlations between a continuous measure of the complexity of flow and the JFSS-2 factors were examined. Invariance of factor loadings and intercepts was achieved for all the key variables. Through factor mean comparisons for the quality of physical activity experience and participation level, the flow group consistently showed higher scores on most situational factors compared with the other groups (i.e., non-flow conditions), and the competitive groups had higher scores on most factors than the recreational groups for both the JFSS-2 and JDFS-2. Moreover, the continuous flow measure was most highly correlated with the situational Challenge-Skill Balance factor, and the pattern of the size of correlations between this continuous flow measure and other situational factors were similar to those between the Challenge-Skill Balance and other JFSS-2 factors. The findings from this study provided evidence that meaningful multi-group comparisons can be made for the key variables examined with the Japanese flow scales, and also further support for the construct validity of the Japanese flow responses. In conclusion, the general conceptualization of flow as an attentional process of absorption in the task at hand, which generates intrinsically rewarding feelings, fosters further understanding of flow experience in physical activity. Furthermore, systematic cross-cultural studies with different adapted versions of the flow scales aid understanding of cultural similarities and differences in flow experience and contribute to further development of flow theory and its application.
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Smart Localized Heating Control System With Human Movement TrackingChoi, Sung In January 2016 (has links)
According to the U.S. energy consumption survey in 2012, about 25% of the commercial and 42% of the residential building energy were used for heating. Despite the development of new and more efficient Heating, Ventilation, and Air Conditioning (HVAC) systems over the years, the high energy consumption in heating is still one of the major energy efficiency issues. Studies showed that decreasing HVAC operating temperature set points by 4°F will result in energy savings of 15% or more. Thus, the smart localized heating control (SLHC) system was designed and prototyped to provide localized heat directly to a person so that HVAC can run at a lower temperature set point. SLHC detects human movement and delivers the heat based on the result of the target location estimation and temperature measurement feedback. To detect the human movement, image processing techniques were used; image segmentation, mass center detection, background subtraction using the Mixture of Gaussian model, and human feature detection. In SLHC, a near-infrared heater and a tracking function were used to provide an instant and a direct heat to the person in order to minimize wasting energy. The SLHC system is divided into the sensing and processing (SP) and the heating and regulating (HR) subsystem. The SP’s primary function is to process captured video images and measured temperature data. SP also generates and sends the heater operating signal to HR. HR purposes to control the heater’s direction and power based on the signal. The communication between SP and HR was established through Wi-Fi enabled development platform. The SLHC prototype successfully processed the sensing data and transmitted the control signal. The result shows that it detected human movement and estimated the person’s location in 3D space within 10% margin of error. Also, it delivered the focused heat to the surface of the human body and increased the temperature by 10.0°F in 3 minutes at the distance of 1.5m away from the heater. This cost-effective, wireless, and localized heating system demonstrates the potential to improve energy efficiency in buildings. / Electrical and Computer Engineering
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O movimento na educa??o infantil: concep??es de pedagogos e professores de Educa??o F?sica sobre a cultura corporal de movimento e suas manifesta??esTaveira, Ricardo Alves 17 December 2015 (has links)
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Previous issue date: 2015-12-17 / This work addresses the initial training of Educators teachers and physical education teachers, with an emphasis on children movement body culture of early childhood education, aged between three and five years what the design on this body manifestation that such teachers They have and how they work with their students. It is a qualitative research, based on the cultural-historical theory of Vygotsky and authors linked to the culture of body movement and training of teachers (Children's Education and Physical Education). Used as instruments to build the empirical material research, participant observation and semi-structured interviews in two schools that have early childhood education in the city Espirito Santo do Pinhal/ SP. The choice of body culture movement is justified by the understanding that human movement is not restricted to a mechanical and insulation displacement, but in a form of body language we express and embed feelings, emotions, cultural influences, among others, contributing to overall development of children. The analysis of the material found in search field understand the investigated problems, which refers to the understanding of human movement as a necessary element and a member of the educational practice in early childhood education as a component that is linked in a timely manner in the relationship between teachers working in this cycle and the relationship between the students themselves, considering the historical and social context and promoting the use of the different aspects that interfere in Early Childhood Education (social, emotional, motor, cognitive) and also contributing in the areas of teacher training . These results indicate the need to structure the interdisciplinary work in this school stage in understanding the meanings that the body carries as a living collection of historical, social, cultural factors contributing to the development of children and the preparation of these professionals from their initial training. / Este trabalho aborda a forma??o inicial dos professores Pedagogos e dos professores de Educa??o F?sica, com ?nfase na cultura corporal de movimento de crian?as da Educa??o Infantil, com idades entre tr?s e cinco anos, ou seja, qual a concep??o sobre essa manifesta??o corporal que tais professores possuem e como trabalham com seus alunos. ? uma pesquisa qualitativa, fundamentada na teoria hist?rico-cultural de Vygotsky e em autores ligados ? cultura corporal de movimento e ? forma??o de professores (Educa??o Infantil e Educa??o F?sica). Utilizamos como procedimentos metodol?gicos para constru??o do material emp?rico da pesquisa, a observa??o participante e a entrevista semiestruturada em duas escolas que possuem a Educa??o Infantil na cidade Esp?rito Santo do Pinhal/ SP. A escolha pela cultura corporal de movimento se justifica pelo entendimento de que o movimento humano n?o se restringe apenas a um deslocamento mec?nico e isolado, mas numa forma de linguagem corporal em que expressamos e embutimos sentimentos, emo??es, influ?ncias culturais, dentre outros, contribuindo ao desenvolvimento global das crian?as. A an?lise do material encontrado em campo busca compreender a problem?tica investigada, que se refere ? compreens?o do movimento humano enquanto elemento imprescind?vel e integrante da pr?tica educativa na Educa??o Infantil, como um componente que se articula de forma pontual na rela??o entre os professores que atuam nesse ciclo, al?m das rela??es entre os pr?prios alunos, considerando-se o contexto hist?rico-social e favorecendo o aproveitamento dos diferentes aspectos que interferem na Educa??o Infantil (social, afetivo, motor, cognitivo) e, ainda, contribuindo nas ?reas de forma??o de professores. Os resultados desta pesquisa indicam a necessidade de se estruturar o trabalho interdisciplinar nesta etapa escolar, no entendimento dos significados que o corpo traz consigo, enquanto um acervo vivo de fatores hist?ricos, sociais, culturais, contribuindo com o desenvolvimento das crian?as e o preparo desses profissionais, desde suas forma??es iniciais.
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An intuitive motion-based input model for mobile devicesRichards, Mark Andrew January 2006 (has links)
Traditional methods of input on mobile devices are cumbersome and difficult to use. Devices have become smaller, while their operating systems have become more complex, to the extent that they are approaching the level of functionality found on desktop computer operating systems. The buttons and toggle-sticks currently employed by mobile devices are a relatively poor replacement for the keyboard and mouse style user interfaces used on their desktop computer counterparts. For example, when looking at a screen image on a device, we should be able to move the device to the left to indicate we wish the image to be panned in the same direction.
This research investigates a new input model based on the natural hand motions and reactions of users. The model developed by this work uses the generic embedded video cameras available on almost all current-generation mobile devices to determine how the device is being moved and maps this movement to an appropriate action.
Surveys using mobile devices were undertaken to determine both the appropriateness and efficacy of such a model as well as to collect the foundational data with which to build the model. Direct mappings between motions and inputs were achieved by analysing users' motions and reactions in response to different tasks.
Upon the framework being completed, a proof of concept was created upon the Windows Mobile Platform. This proof of concept leverages both DirectShow and Direct3D to track objects in the video stream, maps these objects to a three-dimensional plane, and determines device movements from this data.
This input model holds the promise of being a simpler and more intuitive method for users to interact with their mobile devices, and has the added advantage that no hardware additions or modifications are required the existing mobile devices.
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Influence des contraintes culturelles dans l'organisation de la motricité humaine : proposition d'un cadre théorique et mise en évidence expérimentale à travers l'exemple du tournage de poterie (France / Inde Prajapati / Inde Multani Khumar) / Influence of cultural constraints in the organization of the human movementGandon, Enora 10 November 2011 (has links)
L’objectif principal de ce travail était de montrer empiriquement l’influence des contraintes culturelles sur la motricité humaine grâce à la mise en œuvre d’une expérience standardisée dans différents contextes culturels. L’exemple choisi est le tournage de poterie. Il s’agit d’une habileté artisanale ancienne qui est encore pratiquée dans différentes sociétés. En nous appuyant sur le cadre théorique de la psychologie écologique, nous avons étudié comment, à partir d’environnements culturels distincts —en France et dans deux communautés différentes en Inde— une même tâche (le tournage) est réalisée. La tâche expérimentale consistait à reproduire quatre formes dans deux masses. Deux expériences d’interversion ont également permis d’approfondir les résultats. En étudiant les stratégies d’action et le résultat final à partir des productions, on a pu mettre en évidence un ensemble de traits invariants dans les différents groupes. Ces invariants peuvent être interprétés comme une réponse aux contraintes de la tâche. Ainsi, quel que soit l’environnement culturel dans lequel le potier a appris le tournage, ce sont les principes du tournage qui ont été appris, indépendamment des conditions spécifiques d’exécution. En même temps, les résultats ont aussi montré des modulations culturelles dans la géométrie des productions et dans l’organisation temporelle de l’action. Il est possible d’interpréter ces variations comme des adaptations aux contraintes culturelles (matérielles et sociales) spécifiques à chaque groupe. En outre, nous avons observé que l’influence des contraintes sociales était aussi prégnante que celle des contraintes matérielles. Cette dernière observation nous a amené à proposer un projet de recherche postdoctorale ayant pour but d’analyser l’influence des modèles d’action (véhiculés par l’environnement social lors de l’apprentissage) sur les stratégies d’action du potier. / The main goal of our study was to provide an empirical demonstration of the influence of cultural constraints on motor performance. We focused on wheel throwing, an ancient craft skill that is still practiced in many societies. Inspired by the theoretical framework of the ecological approach to perception and action, we studied how a same task (throwing ceramic vessels on a wheel) was realised in different cultural environments in France and in two distinct communities in India. This study was made possible by the application of a standardised experimental approach within the different cultural contexts. The task consisted in reproducing four forms in two masses. The results were further developed by crossing experimental conditions between the two Indian populations. By analysing the action strategies and the vessels produced we were able to highlight a set of invariant characteristics. These invariants are interpreted as potters’ responses to the task constraints related of throwing a vessel. We suggest that all potters studied have acquired the principles underlying wheel throwing, independent of the (cultural) specifics of the conditions in which they evolve. At the same time, our results also revealed cultural modulations in the geometry of the vessels thrown and in the temporal organisation of the throwing activity. Such variations are interpreted as adaptations to the operative (material and social) cultural constraints specific to each group. Interestingly, social constraints were found to be as influential as material constraints (such as the type of wheel used). This latter observation led us to propose a post-doctoral research programme designed to analyse the influence of social action models (promulgated by the social environment during learning) on potter’s action strategies.
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Detecção da direcionalidade do movimento humano utilizando perturbações do sinal eletromagnético de interfaces IEEE 802.11 / Sensing human movement activities using IEEE 802.11 interfacesSilva, Bruno Soares da 08 October 2018 (has links)
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Previous issue date: 2018-10-08 / Coordenação de Aperfeiçoamento de Pessoal de Nível Superior - CAPES / The movement flow detection in indoor environments requires the aquisition and implantation of specialized devices. The perturbations that can affect the electromagnetic signals used by 802.11 interfaces make this type of device a low-cost and widely available movement sensor. Most indoor environments have a 802.11 interface, which makes the use of this type of devices a good option as it doesn't requires any new device. In this work, we propose the WiDMove, a proposal to detect the movement flows in an indoor environment using the channel quality measurements (known as Channel State Information - CSI) offered
by the IEEE 802.11n standard. Our proposal is based on signal processing and pattern recognition techniques, which allow us to extract and classify event signatures using the CSI. In lab tests with off-the-shelf 802.11 interfaces, we collected CSI samples that were affected by 8 different people. From this collected data we extracted the signature of the entry and exit events using some techniques such as Principal Component Analysis (PCA), Short-Time Fourier Transform (STFT) and Continuous Wavelet Transform (CWT). We trained two model types, the first based on a Support Vector Machine (SVM) classifier and the second based on a Multi Layer Perceptral (MLP) neural network. We validated this models with average accuracy experiments and with the cross-validation, including the K-Fold and Leave-One-Out
techniques. WiDMove presented that can reach an average accuracy above 93% and that we can train neural networks that can reach an accuracy above 97%. / A detecção de fluxos de movimento em ambientes fechados demanda a aquisição e
implantação de sensores especializados. As perturbações que podem afetar o sinal
eletromagnético utilizado por interfaces de rede 802.11 tornam esse tipo de dispositivo um
sensor de fluxos de movimento de baixo custo e amplamente disponível. Grande parte dos
ambientes possuem interfaces 802.11 implantadas, tornando o uso desse tipo de dispositivo
como sensor de fluxo de movimento bastante viável por não demandar a aquisição de
nenhum novo equipamento. Neste trabalho, apresentamos o WiDMove, uma proposta que visa
detectar fluxos de movimento em ambientes fechados utilizando as medidas de qualidade do
canal oferecidas pelo padrão IEEE 802.11n, conhecidas como Channel State Information (CSI).
Nossa proposta é baseada em técnicas de processamento de sinais e de reconhecimento de
padrões, as quais nos permitem extrair e classificar assinaturas de fluxos de movimento
usando as medidas CSI. Em testes de laboratório com interfaces 802.11 convencionais,
coletamos medidas CSI influenciadas por 8 indivíduos distintos e extraímos as assinaturas de
entrada e saída utilizando, dentre outras técnicas, Principal Component Analysis (PCA), Short-
Time Fourier Transform (STFT) e Continuous Wavelet Transform (CWT). Treinamos dois tipos de
modelos, um baseado em um classificador do tipo Support Vector Machine (SVM) e outro
baseado em redes neurais do tipo Multi Layer Perceptral (MLP). Validamos esses modelos
através de testes de acurácia média e de técnicas de validação cruzada, incluindo as técnicas
K-Fold e Leave-One-Out. Os testes demonstraram que o WiDMove pode atingir uma acurácia
média superior a 93% e que é possível treinar uma rede neural com acurácia de cerca de 97%.
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La reconstruction du mouvement du squelette : l'enjeu de l'artefact des tissus mous / The reconstruction of skeletal movement : the soft tissue artefact issueBonci, Tecla 08 May 2015 (has links)
Lors de l'analyse 3D du mouvement humain basée sur des marqueurs cutanés, la position des os ne peut être qu'indirectement estimée. Au cours d'une tâche, les déformations des tissus mous génèrent des déplacements des marqueurs par rapport à l'os : les artefacts de tissus mous (STA), entraînant des effets dévastateurs sur l'estimation de la position. La compensation des STA demeure une question ouverte. L'objectif de cette thèse est de contribuer à la solution de cette question cruciale. La modélisation des STA en utilisant des variables spécifiques mesurables est une condition préalable à son élimination. Un modèle corrigeant les trajectoires individuelles de marqueurs de la cuisse, calibré par des mesures directes des STA, est d'abord présenté. Les STA sont modélisés comme une combinaison linéaire des angles articulaires impliqués. Trois représentations des STA par une série de modes sont proposées : déplacements de marqueurs individuels, transformations géométriques de clusters de marqueurs (MCGT), et variations de forme de l'enveloppe de peau. Le MCGT permet de dissocier les composantes rigides et non rigides. Il a été démontré que seule la composante rigide affecte la cinématique articulaire. Un modèle de cette composante est alors défini pour les clusters cuisse et jambe. Un compromis acceptable entre la correction des STA et le nombre de paramètres a ainsi été obtenu. Les principales applications sont de générer une simulation réaliste des STA ; et surtout, en se concentrant sur la composante rigide, le modèle permet une reconstruction satisfaisante des STA avec moins de paramètres, ce qui facilite son incorporation dans un algorithme d'estimation de la position osseuse / In 3D human movement analysis performed using stereophotogrammetry and skin markers, bone pose can be only indirectly estimated. During a task, soft tissue deformations make the markers move with respect to the underlying bone generating soft tissue artefacts (STA), causing devastating effects on pose estimation and its compensation remains an open issue. The thesis’ aim was to contribute to the solution of this crucial issue. Modelling STA using measurable trial-specific variables is a prerequisite for its removal from marker trajectories. Two STA model architectures are proposed. A thigh marker-level model is first presented. STA was modeled as a linear combination of joint angles involved in the task. The model was calibrated with direct STA measures. The considerable number of model parameters led to defining STA approximations. Three definitions were proposed to represent STA as series of modes : individual marker displacements, marker-cluster geometrical transformations (MCGT), and skin envelope shape variations. Modes were selected using two criteria : modal energy and selecting them a priori. The MCGT allows to select either rigid or non-rigid components. It was also demonstrated that only the rigid component affects joint kinematics. A model of thigh and shank rigid component at cluster-level was then defined. An acceptable trade-off between STA compensation and number of parameters was obtained. These results lead to two main potential applications : generate realistic STAs for simulation
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