Most current space robotics vehicles use solar energy as their prime energy source. In spherical robotic vehicles the use of solar cells is very restricted. Focusing on the particular problem, an improved method to generate electrical power will be developed; the innovation is the use of an internal pendulum-generator mechanism to generate electrical power while the ball is rolling. This concept will enable spherical robots on future long-duration planetary exploration missions. Through a developed proof-of-concept prototype, inspired by the Russian thistle plant, or tumbleweed, this thesis will demonstrate power generation capabilities of such a mechanism. Furthermore, it will also present and validate a parametric analytical model that can be used in future developments as a design tool to quantify power and define design parameters. The same model was used to define the design parameters and power generation capabilities of such a system in Martian environment.

The restoration of arm-free standing in paraplegic individuals can be accomplished with the help of functional electrical stimulation (FES). The key component of such a system is a controller that can modulate FES induced muscle contractions in real-time, such that artificially produced forces in the legs and abdominal muscles are able to generate stable standing posture. A 57 year-old individual with chronic ASIA-A (American Spinal Injury Association), T3/4 level spinal cord injury (SCI) participated in this study. The objective was to determine if a proportional-derivative (PD) or proportional-integral-derivative (PID) controller could be used to regulate FES induced muscle contractions in the ankle joint to allow it to maintain balance of the entire body during quiet standing, while exhibiting physiological dynamics seen in able-bodied individuals while doing so.

The objective of this thesis is to describe the design, construction, implementation and performance of a prototype adaptive pendulum tuned mass damper (APTMD). Furthermore the thesis aims at demonstrating the performance improvements obtained when the tuned mass damper (TMD) parameters are optimized. The study considers the effect of adjusting the APTMD tuned frequency and damping ratio on a two storey test structure subjected to broadband and narrowband excitation. An analytical model of the APTMD for a single-degree-of-freedom (SDOF) structure is used to demonstrate the performance improvements when the APTMD parameters are optimized. The optimized model considers the effects of adjusting the frequency ratio, damping ratio, and mass ratio of the combined system to reduce the maximum deflection when the structure is subjected to a harmonic excitation force. The analytical model is used to simulate the optimal performance of the APTMD system. The experimental APTMD is capable of identifying the structural vibration modes in real time and tuning to the desired mode. The structural vibration modes are identified by calculating the windowed power spectral density of the structure’s acceleration, followed by peak-picking algorithm to identify the modal frequencies. Tuning is performed by moving the pivot location of the pendulum arm via a tuning frame along a set of rails. The design also allows for changes in the external dampening force. An adjustable damper is attached to the pendulum mass to allow for control of the APTMD damping ratio. A prototype of the APTMD is built and tested in a modal testing setup. The test structure is a two-storey model of a building structure. The structure is excited using a shaker fixed to the lower storey of the structure. The performance of the APTMD under broadband and narrowband excitation is examined for various tuning and damping parameters. The performance of the APTMD system under optimally tuned and detuned conditions is investigated. The results of the experimental studies demonstrate the importance of optimizing the TMD tuned frequency and damping ratio to reduce structural vibrations. Since the APTMD is designed to autonomously update both parameters, it is an effective tool in mitigating structural vibrations where user interaction is either difficult or expensive. Further study on the performance of a prototype APTMD applied to a large scale structure is required before implementation on full-scale structures.

abstract: This thesis describes an approach to system identification based on compressive sensing and demonstrates its efficacy on a challenging classical benchmark single-input, multiple output (SIMO) mechanical system consisting of an inverted pendulum on a cart. Due to its inherent non-linearity and unstable behavior, very few techniques currently exist that are capable of identifying this system. The challenge in identification also lies in the coupled behavior of the system and in the difficulty of obtaining the full-range dynamics. The differential equations describing the system dynamics are determined from measurements of the system's input-output behavior. These equations are assumed to consist of the superposition, with unknown weights, of a small number of terms drawn from a large library of nonlinear terms. Under this assumption, compressed sensing allows the constituent library elements and their corresponding weights to be identified by decomposing a time-series signal of the system's outputs into a sparse superposition of corresponding time-series signals produced by the library components. The most popular techniques for non-linear system identification entail the use of ANN's (Artificial Neural Networks), which require a large number of measurements of the input and output data at high sampling frequencies. The method developed in this project requires very few samples and the accuracy of reconstruction is extremely high. Furthermore, this method yields the Ordinary Differential Equation (ODE) of the system explicitly. This is in contrast to some ANN approaches that produce only a trained network which might lose fidelity with change of initial conditions or if facing an input that wasn't used during its training. This technique is expected to be of value in system identification of complex dynamic systems encountered in diverse fields such as Biology, Computation, Statistics, Mechanics and Electrical Engineering. / Dissertation/Thesis / M.S. Electrical Engineering 2011

Falls are one of the most serious problems among the elderly, resulting in fatal physical injuries. Early identification of people at a high risk of falling is needed to facilitate rehabilitation to reduce future fall risk. The overall goal of this dissertation was to develop biomechanical models that identify dynamic limits of balance control in daily functional activities associated with falling, including sit-to-stand (STS) movement, standing (stance perturbation), and walking. Poor performance of STS movement has been identified as one of the risk factors of falls among elderly individuals. We proposed a novel method to identify dynamic limits of balance control during STS movement using whole body center of mass (COM) acceleration and assessed its feasibility to differentiate individuals with difficulty in STS movement from healthy individuals. The results demonstrated that our model with COM acceleration could better differentiate individuals with difficulty in STS movement from healthy individuals than the traditional model with COM velocity. Poor postural control ability is also a risk factor of falls. Postural recovery responses to backward support surface translations during quiet standing were examined for healthy young and elderly adults. The results demonstrated that functional base of support (FBOS) and ankle dorsiflexor strength could be sensitive measures to detect elderly individuals with declined balance control. Our biomechanical model, which determines a set of balance stability boundaries, showed a better predictive capability than the statistical model for identifying unstable balance recovery trials, while the statistical model better predicted stable recovery trials. Lastly, walking requires a fine momentum control where COM acceleration could play an important role. Differences in control of dynamic stability during walking were examined with our proposed boundaries of dynamic stability. Elderly fallers adapted a more conservative gait strategy than healthy individuals, demonstrating significantly slower forward COM velocity and acceleration with their COM significantly closer to the base of support at toe-off, which could be indicative of a poor momentum control ability. Overall, this study demonstrated that COM acceleration would provide further information on momentum control, which could better reveal underlying mechanisms causing imbalance and provide an insightful evaluation of balance dysfunction. This dissertation includes unpublished co-authored material.

Submitted by Luciana Ferreira (lucgeral@gmail.com) on 2016-07-14T12:48:19Z No. of bitstreams: 2 Dissertação - Jean Carlo de Sousa e Silva - 2016.pdf: 1067779 bytes, checksum: b4f60747c4efb9967cd66d2dba3afc20 (MD5) license_rdf: 0 bytes, checksum: d41d8cd98f00b204e9800998ecf8427e (MD5) / Approved for entry into archive by Luciana Ferreira (lucgeral@gmail.com) on 2016-07-14T12:49:42Z (GMT) No. of bitstreams: 2 Dissertação - Jean Carlo de Sousa e Silva - 2016.pdf: 1067779 bytes, checksum: b4f60747c4efb9967cd66d2dba3afc20 (MD5) license_rdf: 0 bytes, checksum: d41d8cd98f00b204e9800998ecf8427e (MD5) / Made available in DSpace on 2016-07-14T12:49:42Z (GMT). No. of bitstreams: 2 Dissertação - Jean Carlo de Sousa e Silva - 2016.pdf: 1067779 bytes, checksum: b4f60747c4efb9967cd66d2dba3afc20 (MD5) license_rdf: 0 bytes, checksum: d41d8cd98f00b204e9800998ecf8427e (MD5) Previous issue date: 2016-03-30 / The simple pendulums have oscillatory and periodic movements. Thus, if we analyze some of them with independent movements, they may again return to be in the same spot, if your periods are comensurávies. We present the basic concepts needed to understand this phenomenon. Ending with a hint of implementation. / Os pêndulos simples possuem movimentos oscilatórios e periódicos. Assim, se analisarmos alguns deles com movimentos independentes, eles poderão voltar a se encontrar no mesmo ponto se seus períodos forem comensurávies. Para isso apresentamos os conceitos básicos necessários para a compreensão desse fenômeno. Finalizando com uma sugestão de aplicação do mesmo.

Orientadores : Hans Ingo Weber, Jose Manoel Balthazar, João Maurício Rosário / Tese (doutorado) - Universidade Estadual de Campinas, Faculdade de Engenharia Mecanica / Made available in DSpace on 2018-08-01T20:05:10Z (GMT). No. of bitstreams: 1 Belato_Debora_D.pdf: 22468929 bytes, checksum: b008a52ab3fb5afd92f7489482994f7e (MD5) Previous issue date: 2002 / Resumo: Sistemas dinâmicos da mecânica muitas vezes unem o comportamento descrito por leis de movimento à dinâmica do seu funcionamento. Sua solução passa por hipóteses simplificadoras adotadas para obter um modelo matemático representativo e útil. Quando a fonte de energia utilizada no acionamento do movimento possui potência limitada, isto é, não há potência suficiente no motor para um correto funcionamento do mecanismo, o sistema dinâmico é dito não-ideal. Sob esta suposição, investiga-se numericamente neste trabalho o sistema não linear de um problema específico procurando identificar as condições não lineares e não-ideais de movimento. São empregadas técnicas clássicas de análise de sistemas não lineares, porém é desenvolvida uma técnica numérica nova, capaz de descrever o comportamento dinâmico das principais soluções do sistema. Esta técnica consiste no cálculo de funções polinomiais capazes de descrever a estabilidade de um conjunto de soluções em uma região limitada do retrato de fase e que fornecem também um completo diagrama de bifurcação das soluções sem que tenha sido feita qualquer simplificação nas equações diferenciais / Abstract: Several times the mechanical systems join the behavior described by laws of motion to the dynamic of their operation. Their solution pass by adopted simplified hypotheses in order to obtain a representative and helpful mathematical model. When the energy source used in the bringing to the action of the motion has limited power, i.e., there is not sufficient power in the motor for a proper working of the mechanism and the dynamic system is called nonideal. On this supposition, we numerically investigate in this work the nonlinear system of a specific problem looking for identify the nonideal and nonlinear conditions of the motion. Classical techniques of analyses of nonlinear systems are used, however it is develop a new numerical approaching, able to describe the dynamical behavior of the main solutions of the system. This technique consists in the calculation of the polynomials functions that describe the stability of a set of solutions concerning a bounded region on the phase portrait and they also provide a complete bifurcation diagram of the solutions without that any simplification in the diferential equations has been done / Doutorado / Mecanica dos Sólidos e Projeto Mecanico / Doutor em Engenharia Mecânica

This dissertation investigates the idea of creating an engaging public place by introducing productive activity in a dormant area of Mamelodi where the effects of Pendulum migration and waste accumulation have caused public spaces to become inaccessible and functional only as spaces of departure. The site selection will involve looking for a space with a highly layered construct that captures the essence of what Mamelodi has become overtime. This proposed programme will aid in the investigation of testing whether a dormant space has the potential to inspire transformation and change in the social and public realm of this informal settlement. Through the theoretical premise of Place Making, the investigation will focus on whether social spaces, activity generators, existing contexts and past events could be layered to create a functional public place. The hierarchy and transition of spaces from one to another could allow one to understand the process of change on site, as well as the process of change in terms of waste material that is reused and transformed into something useful. This thesis document explores the idea of a building as a threshold and solvent of different spaces that would normally be split from each other. / Dissertation MArch(Prof)--University of Pretoria, 2014. / Architecture / MArch(Prof) / Unrestricted

Seismic isolation systems are widely used to protect reinforced concrete (RC) structures against the effects of strong ground motions. After a magnitude 6.6 earthquake, the outpatient building of Lushan People’s hospital in China remained in good condition due to the seismic isolation technology, while the non-isolated older outpatient building nearby experienced major damage. The building provides a good opportunity to study and assess the contribution of isolation systems to seismic performance of RC structures. In the current research project, the isolated outpatient building was modelled and analyzed using computer software SAP2000. The post-yield behaviour of the structure was modelled by assigning multi-linear plastic links to frame objects. The rubber isolators were represented by rubber isolator link elements, assigned as a single joint element between the ground and the superstructure. The isolated structure was subjected to four earthquake records with increasing intensity. The performances of the isolated structure were compared with those of the fixed-base structures in terms of lateral inter-storey drifts, peak absolute floor accelerations, and residual drifts. The laminated rubber bearings, the high damping isolation devices, composed of rubber bearings and viscous dampers, and the hybrid isolation system of rubber bearings and friction pendulum bearings were analysed. The effectiveness of the three base isolation systems considered in enhancing structural performance was investigated. The results show the level of improvement attained in seismic response by each system. They also illustrate that the rubber bearings coupled with friction pendulum bearings produce the best drift control without causing excessive horizontal displacements at the base level and without adversely affecting floor accelerations.

This diploma thesis deals with inverse pendulum control. There are described types of inverse pendulums, used power electronics, sensors and their connection to the MF624 control card and to external hardware. Further is described the identification of parameters, including the assembly of a custom algorithm for identification of viscous friction in the pendulum rotary coupling. For identification of moments of inertia are used 3D CAD models, where the thesis describes also use of these models for VRML visualization. The thesis also describes how to build a dynamic model by using Matlab-Simulink and the Simscape-Multibody toolbox. This model is further used in design of the controller using LQR and its simulation testing. The controller is complemented by swing-up algorithm, security elements and MF624 driver interface is designed. The control is tested on a real inverse pendulum assembly and implemented in external hardware.