APLICATIVO DE GONIOMETRIA PARA DISPOSITIVO MÓVEL (ANDROID®)

Introdução: A goniometria é um método de avaliação utilizado para medir os ângulos articulares do corpo. É um método amplamente utilizado na prática clínica quanto em pesquisas científicas, com a finalidade de aferir a amplitude de movimento (ADM) das articulações. Objetivo: Desenvolver um aplicativo de goniometria para dispositivo móvel que auxiliasse fisioterapeutas e profissionais na área afins a obter dados quanto à amplitude de movimento articular (ADM). Métodos: O projeto foi desenvolvido em três fases (Desenvolvimento; Depuração; Validação). Resultados: Entre os sensores existentes, o acelerômetro, se mostrou o mais adequado para a criação desse aplicativo. Conclusão: Os resultados apresentados confirmam que o dispositivo móvel para goniometria pode ser uma ferramenta útil para fisioterapeutas e profissionais da área afins

Measurement Model and Precision Analysis of Accelerometers for Maglev Vibration Isolation Platforms

High precision measurement of acceleration levels is required to allow active control for vibration isolation platforms. It is necessary to propose an accelerometer configuration measurement model that yields such a high measuring precision. In this paper, an accelerometer configuration to improve measurement accuracy is proposed. The corresponding calculation formulas of the angular acceleration were derived through theoretical analysis. A method is presented to minimize angular acceleration noise based on analysis of the root mean square noise of the angular acceleration. Moreover, the influence of installation position errors and accelerometer orientation errors on the calculation precision of the angular acceleration is studied. Comparisons of the output differences between the proposed configuration and the previous planar triangle configuration under the same installation errors are conducted by simulation. The simulation results show that installation errors have a relatively small impact on the calculation accuracy of the proposed configuration. To further verify the high calculation precision of the proposed configuration, experiments are carried out for both the proposed configuration and the planar triangle configuration. On the basis of the results of simulations and experiments, it can be concluded that the proposed configuration has higher angular acceleration calculation precision and can be applied to different platforms

APPLICATION OF NONLINEAR SYSTEM FREQUENCY ANALYSIS AND DESIGN TO VIBRATION ISOLATION AND ENERGY HARVESTING

Vibration is naturally present in the environment including engineering systems and structures. The presence of vibration can be beneficial or destructive, depending on the nature of the affected system and also the level of vibration. Vibrations at dangerously high levels can be reduced by the addition of some energy dissipation elements (dampers) or/and energy storage elements (springs). Energy dissipation elements, such as dampers, dissipate some of these destructive mechanical vibrations as heat. However, mechanical spring systems absorb and store this mechanical vibration energy as potential energy. Nonlinear analysis is primarily applied in system analysis and design of engineering systems. Many methods are available to perform this purpose including averaging method, perturbation method, harmonic balance and the recently developed Output frequency response function (OFRF). The studies presented in this thesis focus on the application of nonlinear system frequency domain analysis and design to vibration isolation and energy harvesting systems. The OFRF method is the analytical and design tool adopted for all studies presented in this thesis. This method is chosen due to its advantage over other methods. This is because the OFRF reveals a significant relationship between the system output spectrum and the parameters that define the system nonlinearities. Therefore, it can facilitate a systematic analysis, design and optimisation process which other approaches are unable to realize. The first study considered in this thesis is a frequency domain analysis, design and optimisation of a vehicle suspension system which is illustrative of a vibration isolation system. In this study, the suspension system is analysed and designed based on a performance criterion. The main aim of the study is to minimise the transmitted vibration force to a tolerable level. At the specified level, some of the vibration energy is dissipated as heat by the damping system. However, this energy can be harvested into electricity, a process known as energy harvesting. This leads to subsequent studies in this thesis. The next study considers a vibration energy harvester system with nonlinear cubic damping characteristic. In this study, a concept is investigated, using the OFRF method, which increases the average power harvested by the harvesting device compared to an equivalent linear harvester. An extension of this study is further considered with the addition of a nonlinear hardening stiffness element to primarily broaden the operational bandwidth of the harvesting device. A final study is then considered where a dual-function system is investigated. The primary function of the system is vibration isolation while its secondary function is energy harvesting. The system is therefore called a dual-function vibration isolation and energy harvester system. This system is optimised for the best dual-function performance subject to existing constraints. For all the systems considered in this thesis, nonlinearities have been integrated into the existing systems to improve their performance, correspondingly, based on a selected criterion. In addition, the OFRF method has been employed in the analysis, design and optimisation of all the systems considered