The emergence of complex and autonomous systems, such as modern aircraft, unmanned aerial vehicles (UAVs) and automated industrial processes is driving the development and implementation of new control technologies aimed at accommodating incipient failures to maintain system operation during an emergency. The motivation for this research began in the area of avionics and flight control systems for the purpose to improve aircraft safety. A prognostics health management (PHM) based fault-tolerant control architecture can increase safety and reliability by detecting and accommodating impending failures thereby minimizing the occurrence of unexpected, costly and possibly life-threatening mission failures; reduce unnecessary maintenance actions; and extend system availability / reliability. Recent developments in failure prognosis and fault tolerant control (FTC) provide a basis for a prognosis based reconfigurable control framework. Key work in this area considers: (1) long-term lifetime predictions as a design constraint using optimal control; (2) the use of model predictive control to retrofit existing controllers with real-time fault detection and diagnosis routines; (3) hybrid hierarchical approaches to FTC taking advantage of control reconfiguration at multiple levels, or layers, enabling the possibility of set-point reconfiguration, system restructuring and path / mission re-planning. Combining these control elements in a hierarchical structure allows for the development of a comprehensive framework for prognosis based FTC. First, the PHM-based reconfigurable controls framework presented in this thesis is given as one approach to a much larger hierarchical control scheme. This begins with a brief overview of a much broader three-tier hierarchical control architecture defined as having three layers: supervisory, intermediate, and low-level. The supervisory layer manages high-level objectives. The intermediate layer redistributes component loads among multiple sub-systems. The low-level layer reconfigures the set-points used by the local production controller thereby trading-off system performance for an increase in remaining useful life (RUL). Next, a low-level reconfigurable controller is defined as a time-varying multi-objective criterion function and appropriate constraints to determine optimal set-point reconfiguration. A set of necessary conditions are established to ensure the stability and boundedness of the composite system. In addition, the error bounds corresponding to long-term state-space prediction are examined. From these error bounds, the point estimate and corresponding uncertainty boundaries for the RUL estimate can be obtained. Also, the computational efficiency of the controller is examined by using the number of average floating point operations per iteration as a standard metric of comparison. Finally, results are obtained for an avionics grade triplex-redundant electro-mechanical actuator with a specific fault mode; insulation breakdown between winding turns in a brushless DC motor is used as a test case for the fault-mode. A prognostic model is developed relating motor operating conditions to RUL. Standard metrics for determining the feasibility of RUL reconfiguration are defined and used to study the performance of the reconfigured system; more specifically, the effects of the prediction horizon, model uncertainty, operating conditions and load disturbance on the RUL during reconfiguration are simulated using MATLAB and Simulink. Contributions of this work include defining a control architecture, proving stability and boundedness, deriving the control algorithm and demonstrating feasibility with an example.

Orientador: Joao Mauricio Rosario / Tese (doutorado) - Universidade Estadual de Campinas, Faculdade de Engenharia Mecanica / Made available in DSpace on 2018-08-10T02:27:46Z (GMT). No. of bitstreams: 1 Melo_LeonimerFlaviode_D.pdf: 6867936 bytes, checksum: 344026f77cc24610774519b704ddccfa (MD5) Previous issue date: 2007 / Resumo: Este trabalho apresenta a proposta de implementação de um ambiente virtual de simulação para projeto e concepção de sistema de supervisão e controle para robôs móveis, que sejam capazes de operar e de se adaptar a diferentes ambientes e condições. Este sistema virtual tem como finalidade facilitar o desenvolvimento de protótipos de sistemas embarcados, enfatizando a implementação de ferramentas que permitam a simulação das condições cinemáticas, dinâmicas e de controle, com monitoração em tempo real de todos pontos lmportantes do sistema. Para isso, é proposta uma arquitetura aberta de controle, integrando as duas principais técnicas de implementação de controle robótico a nível de hardware: sistemas microprocessadores e dispositivos de hardware reconfiguráveis. O sistema simulador implementado é composto de um módulo gerador de trajetória, de um módulo simulador cinemático e dinâmico e de um módulo de análise de resultados e erros. O módulo gerador de trajetória tem a finalidade de, uma vez conhecendo-se o ambiente em que o robô irá atuar, com seus obstáculos e particularidades, gerar uma trajetória cartesiána ótima, respeitando os limites e características do robô móvel. Todos os resultados cinemáticos e dinâmicos colhidos durante a simulação podem ser avaliados e visualizados em formatos de gráficos e tabelas, no módulo de análise de resultados, permitindo que seja feito um aperfeiçoamento no sistema, no sentido de minimizar os erros com a otimização dos ajustes necessários. Para a implementação do controlador no sistema embarcado utiliza-se a prototipagem rápida, que é a tecnologia que permite, em conjunto com o ambiente virtual de simulação, o desenvolvimento de um projeto de um controlador para robôs móveis. A validação e testes foram realizados com modelos de robôs móveis não holonômicos de transmissão diferencial / Abstract: This work presents the proposal of virtual environment implementation for project simulation and conception of supervision aild control systems for mobile robots, that are capable to operate and adapting in different environments and conditions. This virtual system has as purpose to facilitate the development of embedded architecture systems, emphasizing the implementation of tools that alIow the simulation of the kinematic conditions, dynamic and control, with real time monitoring of alI important system points. For this, an open control architecture is proposal, integrating the two main techniques of robotic control implementation in the hardware level: systems microprocessors and reconfigurable hardware devices. The implemented simulator system is composed of a trajectory generating module, a kinematic and dynamic simulator module and of a analysis module of results and errors. The kinematic and dynamic simulator module makes alI simulation of the mobile robot folIowing the pre-determined trajectory of the trajectory generator. All the kinematic and dynamic results shown during the simulation can be evaluated and visualized in graphs and tables formats, in the results analysis module, allowing an improvement in the system, minimizing the errors with the necessary adjustments optimization. For controlIer implementation in the embedded system, it uses the rapid prototyping, that is the technology that allows, in set with the virtual simulation environment, the development of a controlIer project for mobile robots. The validation and tests had been accomplish with nonholonomics mobile robots models with diferencial transmission / Doutorado / Mecanica dos Sólidos e Projeto Mecanico / Doutor em Engenharia Mecânica

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