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  • About
  • The Global ETD Search service is a free service for researchers to find electronic theses and dissertations. This service is provided by the Networked Digital Library of Theses and Dissertations.
    Our metadata is collected from universities around the world. If you manage a university/consortium/country archive and want to be added, details can be found on the NDLTD website.
1011

Design of a Pneumatic Artificial Muscle for Powered Lower Limb Prostheses

Murillo, Jaime 01 May 2013 (has links)
Ideal prostheses are defined as artificial limbs that would permit physically impaired individuals freedom of movement and independence rather than a life of disability and dependence. Current lower limb prostheses range from a single mechanical revolute joint to advanced microprocessor controlled mechanisms. Despite the advancement in technology and medicine, current lower limb prostheses are still lacking an actuation element, which prohibits patients from regaining their original mobility and improving their quality of life. This thesis aims to design and test a Pneumatic Artificial Muscle that would actuate lower limb prostheses. This would offer patients the ability to ascend and descend stairs as well as standing up from a sitting position. A comprehensive study of knee biomechanics is first accomplished to characterize the actuation requirement, and subsequently a Pneumatic Artificial Muscle design is proposed. A novel design of muscle end fixtures is presented which would allow the muscle to operate at a gage pressure surpassing 2.76 MPa (i.e. 400 psi) and yield a muscle force that is at least 3 times greater than that produced by any existing equivalent Pneumatic Artificial Muscle. Finally, the proposed Pneumatic Artificial Muscle is tested and validated to verify that it meets the size, weight, kinetic and kinematic requirements of human knee articulation.
1012

Modélisation d'estimation de la verticalité pendant locomotion

Farkhatdinov, Ildar 05 June 2013 (has links) (PDF)
Dans cette thèse nous proposons une modèl nonlinéaire du système vestibulaire. Le système vestibulaire est essentiel pour locomotion stable à fin qu'il fournit les mesures idiothétiques d'orientation spatial necessaire pour contrôle de la posture. Development du model est baseé sur les principes generals de dynamique Newton-Euler. Les otolithes du système vestibulaire sont modelisé comme pendule sphérique amortie, qui oscille en référentiel non galiléen. Deux types du modèl ont été proposées. Le modèl medial consideers une oreille interne qui se trouve dans le centre de la tête. Le modèl lateral deux oreille interne qui sont situés des deux côté lateral du centre de la tête. Les differences entre les modèls ont été analysé et l'importance d'avoir deux ensembles d'organes vestibulaires ont été discuté. Test algebraic d'observabilité nonlinéaire des models a demonstré que pour avoir l'orientation spatial de la tête observable la tête doit être stabilisée pendant locomotion. Nous avons montré que le problèm d'ambiguïté gravito-inertiel peut être résolu si la tête est stabilisé horizontalement. Ces résultats ont été appliqués pour estimer la verticalité gravitationnelle lors de la locomotion dans les cas linéarisées et non linéaire. Ces résultats ont été appliqués pour estimer la verticalité gravitationnelle pendant locomotion dans les cas linéarisées et non linéaire. Les resultats des simulations ont montré que les erreurs d'estimation ont été significativement plus faible dans le cas de la tête stabilisée. Les estimateurs étaient plus rapides et plus robustes lorsque la tête a été stabilisée. Ensuite, les résultats ont été testés avec le système expérimental, qui a été spécialement conçu pour représenter le système tête-cou et les organes vestibulaires. L'inclinomètre utilisant un liquide a été exploité pour représenter les functions d'otolithes. Les résultats présentés dans cette thèse sont utiles pour l'analyse de la perception spatiale chez les humains et les animaux, et pour améliorer les capacités sensorielles des systèmes robotiques, tels que les robots humanoïdes, véhicules tout terrain, ou des drones.
1013

Étude comparative des projections des neurones dopaminergiques chez deux espèces animales

Dubé, Catherine 08 1900 (has links)
No description available.
1014

Aplicação da baropodometria no desenvolvimento de um protocolo de avaliação motora em crianças nascidas pré-termo após a aquisição da marcha / Baropodometry application in developing a motor evaluation protocol in preterm infants born after the acquisition of march

Coldebella, Cristiane 31 August 2016 (has links)
O nascimento prematuro contribui significativamente para o aumento de morbidades associadas ao desenvolvimento motor, tornando fundamental o acompanhamento contínuo destas crianças. Desta forma, a avaliação baropodométrica, por consistir em um método quantitativo de controle postural pode trazer vantagens para o diagnóstico e acompanhamento do desenvolvimento motor de crianças. Este estudo teve por objetivo desenvolver um protocolo de avaliação motora através dos dados e índices baropodométricos em crianças nascidas pré-termo. Foi realizado um estudo descritivo, onde foram avaliadas 103 crianças entre 24 e 59 meses. Destas, 40 nascidas pré-termo e 63 crianças nascidas a termo. Durante a seleção da amostra, foi preenchida uma ficha de avaliação correspondente ao pré-termo grupo e um questionário com relatos dos pais no grupo a termo. Após, foram aferidos massa corporal e estatura, seguida da aplicação da Escala de Desenvolvimento Motor. Por fim, a baropodometria foi realizada na forma estática, em três repetições, os quais consistiram de 5 segundos de adaptação da criança dobre a placa e 30 segundos onde foram aferidos dados de análise estática: pressão plantar e área do centro de oscilação corporal. Após, as pressões plantares foram transformadas em índices, o índice ânteroposterior foi definido pelas pressões plantares anterior e posterior: IAP= 1-2*│0,6-P│; e o índice látero-lateral, por sua vez, foi definido pelas pressões plantares laterais direita e esquerda: ILL= 1-│LD-LE│. Após a avaliação os dados foram submetidos ao teste de normalidade das distribuições de Shapiro-Wilk, após verificada a distribuição não-normal, foi aplicado o teste de Mann-Whitney para verificar diferença entre os grupos, a associação entre os valores obtidos pelo baropodômetro, Escala do Desenvolvimento Motor, e as principais características e intercorrências do grupo pré-termo foi verificada através da correlação de Spearman. Foi observada diferença significativa nos valores de ILL (p=0,000) entre crianças nascidas a termo e crianças nascidas pré-termo, e que esta diferença possui correlação moderada com a idade gestacional (ρ=0,304), em relação ao centro de oscilação de pressão, crianças nascidas a termo apresentaram menor oscilação quando comparado a idade cronológica (ρ=-0,354), sendo que esta relação foi contrária em crianças nascidas pré-termo (ρ=0,336). Quando analisado somente o grupo pré-termo, foi verificado que o ILL apresentou correlação moderada e inversa com o tempo de internação (ρ=-0,353) e com o tempo de ventilação mecânica (ρ=-0,317) e a aérea do centro de oscilação de pressão apresentou correlação moderada e direta com o tempo de ventilação não invasiva (ρ=0,341). A massa ao nascer apresentou correlação moderada com o ILL (ρ=0,359) e também com a idade motora (ρ=0,323) e o quociente motor (ρ=0,341) e correlação forte com a IG (ρ=0,898) em contrapartida o peso atual apresentou correlação moderada com o quociente motor (ρ=0,310), e a IG (ρ=0,381) e correlação forte com a idade motora (ρ=0,555) e a idade cronológica (ρ=0,613). Houve diferença significativa em relação a idade de aquisição da marcha das crianças que precisaram de acompanhamento fisioterapêutico das que não precisaram (p=0,013). Um índice ILL menor em prematuros, pode estar relacionado ao tempo de internação e ventilação mecânica, além da massa ao nascer, já a maior aérea do centro de oscilação de pressão possui correlação com o tempo de ventilação não invasiva. Também pode-se perceber que a massa atual e a idade cronológica influenciaram mais no desenvolvimento motor que a massa ao nascer e a idade gestacional em crianças prematuras. / Preterm birth contributes significantly to the increase of morbidities associated with motor development, making essential the continuous monitoring of these children. Thus, baropodometry analysis by consisting of a quantitative method for postural control can be advantageous for the diagnosis and monitoring of engine development of children. This study aimed to develop a motor evaluation protocol through the data and baropodometric indexes in preterm infants. It was a descriptive study, which were evaluated 103 children between 24 and 59 months. Of these, 40 preterm and 63 term infants. During the sample selection was completed an evaluation form with data from medical records corresponding to the pre-term group and a questionnaire to parents on group term. After, body mass and height were measured, then the implementation of the Motor Development Scale. Finally, baropodometry was held in static form, with three replicates, which consisted of 5 seconds of child adjustment bend the plate and 30 seconds which were measured static analysis data: plantar pressure and pressure swing center area. After, the plantar pressures were transformed into indexes, the anteroposterior index was defined by the anterior and posterior plantar pressures: API = 1-2 * │0,6-P│; and side side index, in turn, defined by the right and left side planter pressure: SSI = 1- │RS-LS│. After evaluating, the data were submitted to normality test of Shapiro-Wilk distributions, being checked the non-normal distribution, the Mann-Whitney test was used to verify differences between groups, the association between the values obtained by baropodometry analysis, Motor Development Scale, and the main characteristics and complications of preterm group was verified by Spearman correlation. Significant difference in the values of SSI (p = 0.000) among term infants and infants born preterm were observed, and this difference has moderate correlation with gestational age (ρ = 0.304) compared to the pressure oscillation center , full-term babies showed less fluctuation compared to chronological age (ρ = -0.354), and this relationship was contrary in preterm children (ρ = 0.336).When only analyzed the preterm group, it was found that the SSI had moderate and inverse correlation with the length of stay (ρ = -0.353) and the duration of mechanical ventilation (ρ = -0.317) and the air oscillation center pressure showed moderate and direct correlation with noninvasive ventilation time (ρ = 0.341).The mass at birth showed moderate correlation with SSI (ρ = 0.359) and also with the motor age (ρ = 0.323) and the ratio engine (ρ = 0.341) and strong correlation with gestational age (ρ = 0.898) in contrast current weight showed moderate correlation with the motor quotient (ρ = 0.310) and gestational age(ρ = 0.381) and strong correlation with the motor age (ρ = 0.555) and chronological age (ρ = 0.613). There was significant difference in the age of acquisition of march of the children who needed physical therapy monitoring of those who did not needed (p = 0.013). A smaller SSI index in premature infants, may be related to hospitalization time and mechanical ventilation, in addition to mass at birth, already the largest air pressure oscillation center has correlation with noninvasive ventilation time.It may also be seen that the current mass and chronological age influenced more motor development than the mass at birth and gestational age in preterm children.
1015

Aplicação da baropodometria no desenvolvimento de um protocolo de avaliação motora em crianças nascidas pré-termo após a aquisição da marcha / Baropodometry application in developing a motor evaluation protocol in preterm infants born after the acquisition of march

Coldebella, Cristiane 31 August 2016 (has links)
O nascimento prematuro contribui significativamente para o aumento de morbidades associadas ao desenvolvimento motor, tornando fundamental o acompanhamento contínuo destas crianças. Desta forma, a avaliação baropodométrica, por consistir em um método quantitativo de controle postural pode trazer vantagens para o diagnóstico e acompanhamento do desenvolvimento motor de crianças. Este estudo teve por objetivo desenvolver um protocolo de avaliação motora através dos dados e índices baropodométricos em crianças nascidas pré-termo. Foi realizado um estudo descritivo, onde foram avaliadas 103 crianças entre 24 e 59 meses. Destas, 40 nascidas pré-termo e 63 crianças nascidas a termo. Durante a seleção da amostra, foi preenchida uma ficha de avaliação correspondente ao pré-termo grupo e um questionário com relatos dos pais no grupo a termo. Após, foram aferidos massa corporal e estatura, seguida da aplicação da Escala de Desenvolvimento Motor. Por fim, a baropodometria foi realizada na forma estática, em três repetições, os quais consistiram de 5 segundos de adaptação da criança dobre a placa e 30 segundos onde foram aferidos dados de análise estática: pressão plantar e área do centro de oscilação corporal. Após, as pressões plantares foram transformadas em índices, o índice ânteroposterior foi definido pelas pressões plantares anterior e posterior: IAP= 1-2*│0,6-P│; e o índice látero-lateral, por sua vez, foi definido pelas pressões plantares laterais direita e esquerda: ILL= 1-│LD-LE│. Após a avaliação os dados foram submetidos ao teste de normalidade das distribuições de Shapiro-Wilk, após verificada a distribuição não-normal, foi aplicado o teste de Mann-Whitney para verificar diferença entre os grupos, a associação entre os valores obtidos pelo baropodômetro, Escala do Desenvolvimento Motor, e as principais características e intercorrências do grupo pré-termo foi verificada através da correlação de Spearman. Foi observada diferença significativa nos valores de ILL (p=0,000) entre crianças nascidas a termo e crianças nascidas pré-termo, e que esta diferença possui correlação moderada com a idade gestacional (ρ=0,304), em relação ao centro de oscilação de pressão, crianças nascidas a termo apresentaram menor oscilação quando comparado a idade cronológica (ρ=-0,354), sendo que esta relação foi contrária em crianças nascidas pré-termo (ρ=0,336). Quando analisado somente o grupo pré-termo, foi verificado que o ILL apresentou correlação moderada e inversa com o tempo de internação (ρ=-0,353) e com o tempo de ventilação mecânica (ρ=-0,317) e a aérea do centro de oscilação de pressão apresentou correlação moderada e direta com o tempo de ventilação não invasiva (ρ=0,341). A massa ao nascer apresentou correlação moderada com o ILL (ρ=0,359) e também com a idade motora (ρ=0,323) e o quociente motor (ρ=0,341) e correlação forte com a IG (ρ=0,898) em contrapartida o peso atual apresentou correlação moderada com o quociente motor (ρ=0,310), e a IG (ρ=0,381) e correlação forte com a idade motora (ρ=0,555) e a idade cronológica (ρ=0,613). Houve diferença significativa em relação a idade de aquisição da marcha das crianças que precisaram de acompanhamento fisioterapêutico das que não precisaram (p=0,013). Um índice ILL menor em prematuros, pode estar relacionado ao tempo de internação e ventilação mecânica, além da massa ao nascer, já a maior aérea do centro de oscilação de pressão possui correlação com o tempo de ventilação não invasiva. Também pode-se perceber que a massa atual e a idade cronológica influenciaram mais no desenvolvimento motor que a massa ao nascer e a idade gestacional em crianças prematuras. / Preterm birth contributes significantly to the increase of morbidities associated with motor development, making essential the continuous monitoring of these children. Thus, baropodometry analysis by consisting of a quantitative method for postural control can be advantageous for the diagnosis and monitoring of engine development of children. This study aimed to develop a motor evaluation protocol through the data and baropodometric indexes in preterm infants. It was a descriptive study, which were evaluated 103 children between 24 and 59 months. Of these, 40 preterm and 63 term infants. During the sample selection was completed an evaluation form with data from medical records corresponding to the pre-term group and a questionnaire to parents on group term. After, body mass and height were measured, then the implementation of the Motor Development Scale. Finally, baropodometry was held in static form, with three replicates, which consisted of 5 seconds of child adjustment bend the plate and 30 seconds which were measured static analysis data: plantar pressure and pressure swing center area. After, the plantar pressures were transformed into indexes, the anteroposterior index was defined by the anterior and posterior plantar pressures: API = 1-2 * │0,6-P│; and side side index, in turn, defined by the right and left side planter pressure: SSI = 1- │RS-LS│. After evaluating, the data were submitted to normality test of Shapiro-Wilk distributions, being checked the non-normal distribution, the Mann-Whitney test was used to verify differences between groups, the association between the values obtained by baropodometry analysis, Motor Development Scale, and the main characteristics and complications of preterm group was verified by Spearman correlation. Significant difference in the values of SSI (p = 0.000) among term infants and infants born preterm were observed, and this difference has moderate correlation with gestational age (ρ = 0.304) compared to the pressure oscillation center , full-term babies showed less fluctuation compared to chronological age (ρ = -0.354), and this relationship was contrary in preterm children (ρ = 0.336).When only analyzed the preterm group, it was found that the SSI had moderate and inverse correlation with the length of stay (ρ = -0.353) and the duration of mechanical ventilation (ρ = -0.317) and the air oscillation center pressure showed moderate and direct correlation with noninvasive ventilation time (ρ = 0.341).The mass at birth showed moderate correlation with SSI (ρ = 0.359) and also with the motor age (ρ = 0.323) and the ratio engine (ρ = 0.341) and strong correlation with gestational age (ρ = 0.898) in contrast current weight showed moderate correlation with the motor quotient (ρ = 0.310) and gestational age(ρ = 0.381) and strong correlation with the motor age (ρ = 0.555) and chronological age (ρ = 0.613). There was significant difference in the age of acquisition of march of the children who needed physical therapy monitoring of those who did not needed (p = 0.013). A smaller SSI index in premature infants, may be related to hospitalization time and mechanical ventilation, in addition to mass at birth, already the largest air pressure oscillation center has correlation with noninvasive ventilation time.It may also be seen that the current mass and chronological age influenced more motor development than the mass at birth and gestational age in preterm children.
1016

Design of a Pneumatic Artificial Muscle for Powered Lower Limb Prostheses

Murillo, Jaime January 2013 (has links)
Ideal prostheses are defined as artificial limbs that would permit physically impaired individuals freedom of movement and independence rather than a life of disability and dependence. Current lower limb prostheses range from a single mechanical revolute joint to advanced microprocessor controlled mechanisms. Despite the advancement in technology and medicine, current lower limb prostheses are still lacking an actuation element, which prohibits patients from regaining their original mobility and improving their quality of life. This thesis aims to design and test a Pneumatic Artificial Muscle that would actuate lower limb prostheses. This would offer patients the ability to ascend and descend stairs as well as standing up from a sitting position. A comprehensive study of knee biomechanics is first accomplished to characterize the actuation requirement, and subsequently a Pneumatic Artificial Muscle design is proposed. A novel design of muscle end fixtures is presented which would allow the muscle to operate at a gage pressure surpassing 2.76 MPa (i.e. 400 psi) and yield a muscle force that is at least 3 times greater than that produced by any existing equivalent Pneumatic Artificial Muscle. Finally, the proposed Pneumatic Artificial Muscle is tested and validated to verify that it meets the size, weight, kinetic and kinematic requirements of human knee articulation.
1017

Détermination des facteurs bénéfiques et néfastes à la récupération locomotrice à la suite d’une section spinale complète chez la souris

Jeffrey-Gauthier, Renaud 12 1900 (has links)
No description available.
1018

Effets des orthèses plantaires sur la biomécanique du membre inférieur chez des patients ayant une instabilité de la cheville

Moisan, Gabriel 08 1900 (has links)
L’instabilité chronique de la cheville (CAI) est un fardeau socioéconomique important qui entraine des répercussions néfastes chez la population atteinte, comme des récidives d’entorses de la cheville (ELC), qui peuvent notamment s’expliquer par des déficits biomécaniques aux membres inférieurs. Ces déficits sont notamment observés lors d’activités quotidiennes comme la marche, mais aussi lors de tâches plus difficiles comme l’atterrissage d’un saut. Par contre, les impacts biomécaniques réels d’une CAI lors de la locomotion ne sont pas encore clairement décrits. Les orthèses plantaires sont couramment utilisées dans le traitement de pathologies musculosquelettiques pour modifier les variables biomécaniques des membres inférieurs (cinématique, cinétique et électromyographie) responsables de ces pathologies. Bien que leurs effets sur la biomécanique du membre inférieur d’individus atteints d’une CAI soient encore méconnus, les orthèses plantaires pourraient permettre de les traiter plus efficacement. Les objectifs principaux de cette thèse étaient de déterminer les déficits biomécaniques associés à la CAI lors de la locomotion et lesquels de ces déficits peuvent être atténués avec le port d’orthèses plantaires. L’Étude 1 consistait à réaliser une revue systématique de la littérature sur les impacts biomécaniques d’une CAI lors d’une tâche de marche et de course. L’Étude 2 consistait à identifier les différences biomécaniques entre des individus avec et sans CAI à la marche. L’Étude 3 consistait à déterminer les différences biomécaniques entre des individus avec et sans CAI lors de l’atterrissage d’un saut unipodal sur une surface plane (DROP), inclinée (WEDGE) et instable (FOAM) ainsi qu’à l’atterrissage d’un saut latéral maximal unipodal (SIDE). Finalement, l’Étude 4 consistait à déterminer les effets des orthèses plantaires sur la biomécanique du membre inférieur d’individus atteints d’une CAI lors des tâches de marche et d’atterrissage d’un saut unipodal. À la marche, les individus atteints d’une CAI présentent de nombreux déficits biomécaniques qui pourraient les prédisposer à subir d’autres ELC, notamment une augmentation de l’inversion et de la flexion plantaire de la cheville. Ces augmentations de mouvement à la cheville contribuent à augmenter les forces verticales latérales au pied, à modifier la cinématique et la cinétique du genou ainsi que l’activité des muscles moyen fessier et long fibulaire. Lors de l’atterrissage d’un saut unipodal, les individus atteints d’une CAI présentent une augmentation de la dorsiflexion de la cheville afin de stabiliser l’articulation. Lors de la tâche WEDGE, la diminution de la préactivation musculaire du long fibulaire pourrait mettre ces individus plus à risque de subir d’autres ELC. De plus, le port d’orthèses plantaires diminue l’activité musculaire du tibial antérieur lors de la tâche DROP et du biceps fémoral à la marche chez des individus atteints d’une CAI. Elles semblent n’avoir aucun effet significatif sur la cinématique et cinétique du membre inférieur lors de la marche et l’atterrissage d’un saut unipodal. Finalement, cette thèse permet de mieux identifier les déficits biomécaniques à adresser lors de l’élaboration de plan de traitement pour les individus atteints d’une CAI et de mieux comprendre les effets des orthèses plantaires pour atténuer ces déficits. / Chronic ankle instability (CAI) is a major socioeconomic burden and has adverse repercussions for the affected population, such as recurrence of lateral ankle sprains (LAS), which could be explained by lower limb biomechanical deficits. These deficits are observed during daily activities such as walking but also during more difficult tasks such as jump landing. However, the real impact of CAI during locomotion has not yet been clearly described. Foot orthoses are commonly used to treat musculoskeletal pathologies because they modify lower limb biomechanics (kinematics, kinetics and electromyography). However, their effects on lower limb’s biomechanics of individuals with CAI are still unknown. Foot orthoses may help to treat the individuals with CAI more effectively. The main objectives of this thesis were to determine the biomechanical deficits associated with CAI during locomotion and which of these deficits can be attenuated with foot orthoses. Study 1 consisted of systematically reviewing the literature on the biomechanical deficits associated with CAI during walking and running. Study 2 consisted of identifying the biomechanical differences between individuals with and without CAI during walking. Study 3 consisted of determining the biomechanical differences between individuals with and without CAI during unilateral jump landing on even (DROP), inclined (WEDGE) and unstable (FOAM) surfaces and during a unilateral maximal side jump landing (SIDE). Study 4 consisted of determining the effects of foot orthoses on lower limb’s biomechanics of individuals with CAI during walking and unilateral jump landing. During walking, individuals with CAI present many biomechanical deficits that may predispose them to sustain recurrent LAS, including increased ankle inversion and plantarflexion. These contribute to increase the lateral vertical forces under the foot, to modify knee kinematics and kinetics as well as the activity of the gluteus medius and peroneus longus muscles. During unilateral jump landing, individuals with CAI present increased ankle dorsiflexion in order to stabilize the joint. During the WEDGE task, the decreased peroneus longus muscle preactivation could put these individuals at greater risk of sustaining recurrent LAS. In addition, wearing foot orthoses decreases the muscular activity of the tibialis anterior during the DROP task and the biceps femoris during walking in individuals with CAI. FOs have no significant effect on the kinematics and kinetics of the lower limb during walking and unilateral jump landing. Finally, the results of this thesis will help to better identify the biomechanical deficits to be addressed during rehabilitation for individuals with CAI and to better understand the effects of foot orthoses to attenuate these deficits.
1019

MULTISTABLE BIOINSPIRED SPRING ORIGAMI FOR REPROGRAMMABLE STRUCTURES AND ROBOTICS

Salvador Rojas III (17683905) 20 December 2023 (has links)
<p dir="ltr">Origami has emerged as a design paradigm to realize morphing structures with rich kinematic and mechanical properties. Biological examples augment the potential folding design space by suggesting intriguing routes for achieving and expanding crease patterns which traditional origami laws are unable to capture. Specifically, spring origami theory exploits the material system architecture and energy storage mechanism of the earwig wing featuring one of the highest folding ratios in the animal kingdom (1:18), minimal energy required for deployment and collapse of the wing, and bistability locking the wing in closed, and open configurations for crawling through tunnels, and flight, respectively. The central mechanism responsible for bistability in the wing features a non-developable crease pattern with a non-zero Gaussian curvature. Reconfiguring, or even flattening a structure with such an intrinsic property requires stretching or tearing; soft, rubbery material found in the creases of the central mechanism allows for stretching enabling shape transformations between open and closed states without tearing. In the first part of this thesis, such characteristics are transferred to a synthetic bistable soft robotic gripper leveraging the shape adaptability and conformability exhibited by the biological organism to minimize actuation energy. This is achieved by integrating soft, flexible material in the bioinspired gripper that allows kinematically driven geometries to grasp and manipulate objects without continuous actuation. Secondly, the stiffening effect from spring origami is utilized in a bioinspired wing for an aerial--aquatic robot. Transitions between air and sea in multimodal robots is challenging, however, a structurally efficient and multifunctional membrane is developed to increase locomotive capabilities and longer flights. This is motivated by the flying fish's locomotive modules and origami design principles for deployment and folding. Additionally, to keep the wing in a stiff state while gliding, spring origami bistable units are integrated into the membrane inducing self-stiffening and a global curvature reducing energy expenditure while generating lift. While the previous examples present solutions to adaptive manipulation and membrane multifunctionality, once programmed, their shapes are fixed. In the third application, a class of multistable self-folding origami architectures that are reprogrammable post fabrication are presented. This is achieved by encoding prestrain in bilayer creases with anisotropic shrinkage that change shape and induce a local curvature in the creases in response to external stimuli. The topology of the energy landscapes can thus be tuned as a function of the stimulation time and adaptable post fabrication. The proposed method and model allows for converting flat sheets with arranged facets and prestrained mountain-valley creases into self-folding multistable structures. Lasty, encoding crease prestrain is leveraged to manufacture a biomimetic earwig wing featuring the complex crease pattern, structural stability, and rapid closure of the biological counterpart. The presented method provides a route for encoding prestrain in self-folding origami, the multistability of which is adaptable after fabrication.</p>
1020

Mitigating VR Cybersickness Caused by Continuous Joystick Movement

Aditya Ajay Oka (16529664) 13 July 2023 (has links)
<p>When users begin to experience virtual reality (VR) for the first time, they can be met with some degree of motion sickness and nausea, especially if continuous joystick locomotion is used. The symptoms that are induced during these VR experiences fall under the umbrella term cybersickness, and due to these uncomfortable experiences, these users can get a bad first impression and abandon the innovative technology, not able to fully appreciate the convenience and fascinating adventures VR has to offer. As such, this project compares the effects of two cybersickness mitigation methods (Dynamic Field of View (FOV) and Virtual Reference Frame), both against each other and combined, on user-reported cybersickness symptoms to determine the best combination to implement in commercial applications to help create more user-friendly VR experiences. The hypothesis is that combining the FOV reduction and the resting frame methods can mitigate VR cybersickness more effectively without hindering the user’s experience and the virtual nose method is more potent at mitigating cybersickness compared to dynamic FOV. To test these hypotheses, an experimental game was developed for the Meta Quest 2 with five levels: a tutorial level and four maze levels (one for each scenario). The participants were asked to complete the tutorial level until they got used to the virtual reality controls, and then they were instructed to complete the maze level twice with one of the following conditions for each run: no method, dynamic field of view only, virtual nose only, and dynamic field of view and virtual nose combined. After completing each maze trial, the participants were asked to complete a simulator sickness questionnaire to get their thoughts on how much sickness they felt during the test. Upon concluding the testing phase with 36 participants and compiling the data, the results showed that while the subjects preferred the dynamic FOV method even though they were able to complete the trials significantly faster with the virtual nose method, it is inconclusive regarding which method is truly more effective. Furthermore, the results showed that it is also inconclusive if the scenario with both methods enabled is significantly better or worse than either method used separately.</p>

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