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Dinâmica do momento angular: parâmetro de controlo na exploração de padrões motores na bicicleta de equilíbrio em crianças
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Advisor(s)
Abstract(s)
A bicicleta reflete a cultura humana e a sua utilização exige equilíbrio e manutenção da estabilidade. A criança e a bicicleta formam um sistema único, o qual procura manter a sua estabilidade através da rotação das rodas que atuam como giroscópios, em constante interação com os constrangimentos da tarefa, organismo e envolvimento. A massa distribuída em cada roda não é igual, assim, o primeiro estudo desta dissertação analisou a proporção de massa entre as rodas dianteira e traseira do sistema criança-bicicleta. A amostra incluiu 18 crianças com uma média de 4,89±0,35 anos, para as quais o centro de gravidade (CG) foi calculado através do método de coordenadas, e o CG da bicicleta através do método de equilíbrio. A roda traseira apresentou uma proporção de 78,8% da massa total e a dianteira 21,3%. Considerando que a aprendizagem de andar de bicicleta resulta da interação dinâmica entre os vários constrangimentos como a massa da criança (organismo), massa e raio da roda da bicicleta (tarefa), a distribuição de massa das rodas no sistema criança-bicicleta deve ser considerada para análises posteriores da estabilidade. Neste sentido, e considerando igualmente que esta aprendizagem pode ser facilitada através de mudanças nos parâmetros de controlo, o segundo estudo investigou se o momento angular (MA) da bicicleta é um parâmetro de controlo para os padrões de ciclar na bicicleta de equilíbrio (BE). Este estudo incluiu recolhas transversais durante a aplicação de um programa de aprendizagem de ciclar. Participaram 25 crianças com uma média de 5,16±0,89 anos, as quais foram convidadas a usar livremente a BE, antes e depois da intervenção de 6 sessões com a BE. Os dados foram recolhidos através de vídeo e posteriormente categorizados para permitir a identificação dos padrões de ciclar. Adicionalmente, foram recolhidos dados de velocidade angular através de um sensor inercial fixado na roda da bicicleta, permitindo o cálculo posterior do MA. Os resultados evidenciaram que, à medida que o MA aumenta, as crianças tendem a transitar entre os padrões de ciclar. Com MA mais baixo, o padrão preferido consistiu em caminhar. A partir de 0,53 kg·m²/s, a maioria das crianças transitou para correr. E, a partir de 1,1162 kg·m²/s, a maioria das crianças transitou novamente para o padrão de planar. Com base nestes resultados, propomos que o MA é um parâmetro de controlo para a BE, sendo a velocidade linear uma expressão dele. Em conclusão, as características específicas da bicicleta e da criança influenciam o momento angular e, consequentemente, a transição entre os padrões. Todos estes aspetos devem ser considerados na promoção da aprendizagem de ciclar.
The bicycle reflects human culture, and its use requires balance and maintenance of stability. The child and the bicycle form a unique system that seeks to maintain its stability through the rotation of the wheels, which act as gyroscopes, constantly interacting with the constraints of the task, the organism, and the environment. The mass distributed in each wheel is not equal; thus, the first study of this dissertation analyzed the mass ratio between the front and rear wheels of the child-bicycle system. The sample included 18 children with an average age of 4.89±0.35 years, for whom the center of gravity (CG) was calculated using the coordinate method, and the CG of the bicycle was calculated using the balance method. The rear wheel accounted for 78.8% of the total mass, while the front wheel accounted for 21.3%. Considering that learning to ride a bicycle results from the dynamic interaction between various constraints, such as the child's mass (organism), and the mass and radius of the bicycle wheel (task), the mass distribution of the wheels in the child-bicycle system should be considered for further analyses of stability. In this regard, and also considering that this learning can be facilitated by changes in control parameters, the second study investigated whether the angular momentum (AM) of the bicycle is a control parameter for cycling patterns on the balance bike (BB). This study included cross-sectional data collection during the implementation of a cycling learning program. Twenty-five children with an average age of 5.16±0.89 years participated, who were invited to freely use the BB before and after a 6-session intervention with the BB. Data were collected through video recording and subsequently categorized to identify cycling patterns. Additionally, angular velocity data were collected using an inertial sensor fixed to the bicycle wheel, allowing for subsequent calculation of the AM. The results showed that as the AM increases, children tend to transition between cycling patterns. With lower AM, the preferred pattern was walking. Starting at 0.53 kg·m²/s, most children transitioned to running. And starting at 1.1162 kg·m²/s, most children transitioned back to a coasting pattern. Based on these results, we propose that AM is a control parameter for the BB, with linear velocity being an expression of it. In conclusion, the specific characteristics of the bicycle and the child influence the angular momentum and, consequently, the transition between patterns. All these aspects should be considered in promoting cycling learning.
The bicycle reflects human culture, and its use requires balance and maintenance of stability. The child and the bicycle form a unique system that seeks to maintain its stability through the rotation of the wheels, which act as gyroscopes, constantly interacting with the constraints of the task, the organism, and the environment. The mass distributed in each wheel is not equal; thus, the first study of this dissertation analyzed the mass ratio between the front and rear wheels of the child-bicycle system. The sample included 18 children with an average age of 4.89±0.35 years, for whom the center of gravity (CG) was calculated using the coordinate method, and the CG of the bicycle was calculated using the balance method. The rear wheel accounted for 78.8% of the total mass, while the front wheel accounted for 21.3%. Considering that learning to ride a bicycle results from the dynamic interaction between various constraints, such as the child's mass (organism), and the mass and radius of the bicycle wheel (task), the mass distribution of the wheels in the child-bicycle system should be considered for further analyses of stability. In this regard, and also considering that this learning can be facilitated by changes in control parameters, the second study investigated whether the angular momentum (AM) of the bicycle is a control parameter for cycling patterns on the balance bike (BB). This study included cross-sectional data collection during the implementation of a cycling learning program. Twenty-five children with an average age of 5.16±0.89 years participated, who were invited to freely use the BB before and after a 6-session intervention with the BB. Data were collected through video recording and subsequently categorized to identify cycling patterns. Additionally, angular velocity data were collected using an inertial sensor fixed to the bicycle wheel, allowing for subsequent calculation of the AM. The results showed that as the AM increases, children tend to transition between cycling patterns. With lower AM, the preferred pattern was walking. Starting at 0.53 kg·m²/s, most children transitioned to running. And starting at 1.1162 kg·m²/s, most children transitioned back to a coasting pattern. Based on these results, we propose that AM is a control parameter for the BB, with linear velocity being an expression of it. In conclusion, the specific characteristics of the bicycle and the child influence the angular momentum and, consequently, the transition between patterns. All these aspects should be considered in promoting cycling learning.
Description
Keywords
bicicleta sistemas dinâmicos constrangimentos giroscópio momento angular aprendizagem bicycle dynamic systems constraints gyroscope angular momentum learning