Posicast applications to electronic design: a conceptual revision

Se presenta una revisión conceptual generalizada de los conformadores de entrada de sistemas de control como herramientas para eliminar vibraciones en la salida de los sistemas. Se desarrollan los diferentes tipos de conformadores como versiones mejoradas de Posicast, el conformador original. Luego se presentan las aplicaciones de Posicast en el desarrollo de sistemas electrónicos, específicamente, en circuitos de potencia y en circuitos microelectrónicosThis work is a generalized conceptual revision of the control system input shapers. The input shapers are used to eliminate vibrations at the output of the systems. The different types of shapers are developed as improved versions of Posicast, or the original shaper. Then, Posicast applications are presented in the development of electronic systems, specifically in power circuits and microelectronic circuit

A Brief Analysis of Gravitational Search Algorithm (GSA) Publication from 2009 to May 2013

Gravitational Search Algorithm was introduced in year 2009. Since its introduction, the academic community shows a great interest on this algorith. This can be seen by the high number of publications with a short span of time. This paper analyses the publication trend of Gravitational Search Algorithm since its introduction until May 2013. The objective of this paper is to give exposure to reader the publication trend in the area of Gravitational Search Algorithm

Genetic algorithm based method of elimination of residual oscillation in mechatronic systems

summary:The paper presents control signals generation methods, preventing the excitation of residual vibration in slightly damped oscillational systems. It is focused on the feedforward methods, as most of the vibrations in examined processes are induced by the control, while the influence of disturbances is mostly negligible. Application of these methods involves ensuring of the insensitivity to natural frequency change, which can be reached in classical approach only by considerable increase of transient response duration. Genetic algorithms can be effectively applied for the numerical optimization of developed shaper while maintaining the insensitivity to parameter change and short time delay

Políticas de Copyright de Publicações Científicas em Repositórios Institucionais: O Caso do INESC TEC

A progressiva transformação das práticas científicas, impulsionada pelo desenvolvimento das novas Tecnologias de Informação e Comunicação (TIC), têm possibilitado aumentar o acesso à informação, caminhando gradualmente para uma abertura do ciclo de pesquisa. Isto permitirá resolver a longo prazo uma adversidade que se tem colocado aos investigadores, que passa pela existência de barreiras que limitam as condições de acesso, sejam estas geográficas ou financeiras. Apesar da produção científica ser dominada, maioritariamente, por grandes editoras comerciais, estando sujeita às regras por estas impostas, o Movimento do Acesso Aberto cuja primeira declaração pública, a Declaração de Budapeste (BOAI), é de 2002, vem propor alterações significativas que beneficiam os autores e os leitores. Este Movimento vem a ganhar importância em Portugal desde 2003, com a constituição do primeiro repositório institucional a nível nacional. Os repositórios institucionais surgiram como uma ferramenta de divulgação da produção científica de uma instituição, com o intuito de permitir abrir aos resultados da investigação, quer antes da publicação e do próprio processo de arbitragem (preprint), quer depois (postprint), e, consequentemente, aumentar a visibilidade do trabalho desenvolvido por um investigador e a respetiva instituição. O estudo apresentado, que passou por uma análise das políticas de copyright das publicações científicas mais relevantes do INESC TEC, permitiu não só perceber que as editoras adotam cada vez mais políticas que possibilitam o auto-arquivo das publicações em repositórios institucionais, como também que existe todo um trabalho de sensibilização a percorrer, não só para os investigadores, como para a instituição e toda a sociedade. A produção de um conjunto de recomendações, que passam pela implementação de uma política institucional que incentive o auto-arquivo das publicações desenvolvidas no âmbito institucional no repositório, serve como mote para uma maior valorização da produção científica do INESC TEC.The progressive transformation of scientific practices, driven by the development of new Information and Communication Technologies (ICT), which made it possible to increase access to information, gradually moving towards an opening of the research cycle. This opening makes it possible to resolve, in the long term, the adversity that has been placed on researchers, which involves the existence of barriers that limit access conditions, whether geographical or financial. Although large commercial publishers predominantly dominate scientific production and subject it to the rules imposed by them, the Open Access movement whose first public declaration, the Budapest Declaration (BOAI), was in 2002, proposes significant changes that benefit the authors and the readers. This Movement has gained importance in Portugal since 2003, with the constitution of the first institutional repository at the national level. Institutional repositories have emerged as a tool for disseminating the scientific production of an institution to open the results of the research, both before publication and the preprint process and postprint, increase the visibility of work done by an investigator and his or her institution. The present study, which underwent an analysis of the copyright policies of INESC TEC most relevant scientific publications, allowed not only to realize that publishers are increasingly adopting policies that make it possible to self-archive publications in institutional repositories, all the work of raising awareness, not only for researchers but also for the institution and the whole society. The production of a set of recommendations, which go through the implementation of an institutional policy that encourages the self-archiving of the publications developed in the institutional scope in the repository, serves as a motto for a greater appreciation of the scientific production of INESC TEC

Advancements in Real-Time Simulation of Power and Energy Systems

Modern power and energy systems are characterized by the wide integration of distributed generation, storage and electric vehicles, adoption of ICT solutions, and interconnection of different energy carriers and consumer engagement, posing new challenges and creating new opportunities. Advanced testing and validation methods are needed to efficiently validate power equipment and controls in the contemporary complex environment and support the transition to a cleaner and sustainable energy system. Real-time hardware-in-the-loop (HIL) simulation has proven to be an effective method for validating and de-risking power system equipment in highly realistic, flexible, and repeatable conditions. Controller hardware-in-the-loop (CHIL) and power hardware-in-the-loop (PHIL) are the two main HIL simulation methods used in industry and academia that contribute to system-level testing enhancement by exploiting the flexibility of digital simulations in testing actual controllers and power equipment. This book addresses recent advances in real-time HIL simulation in several domains (also in new and promising areas), including technique improvements to promote its wider use. It is composed of 14 papers dealing with advances in HIL testing of power electronic converters, power system protection, modeling for real-time digital simulation, co-simulation, geographically distributed HIL, and multiphysics HIL, among other topics

Nonlinear flight control with reduced model dependency

This thesis aims to innovate knowledge on nonlinear flight control algorithms with reduced model dependency by resolving the research gaps for practical applications. Two control schemes with different principles on reducing model dependency are considered in this thesis; incremental control scheme and adaptive control scheme. In incremental control scheme, state derivative and control surface deflection angle measurements are additionally utilized to substitute required model information except control effectiveness. In adaptive control scheme, uncertain model parameters are estimated online via adaptation law and these estimates are utilized in control input command calculation. Discussions in this thesis are based on incremental backstepping control (IBKS) and composite adaptive backstepping control (C-ABKS) which are obtained by applying those control schemes to backstepping control (BKS). Contributions of this thesis with each algorithm are detailed as follows. This thesis provides critical understandings on IBKS in a systematic way via theoretical analysis under various defects. As a starting point, closed-loop analyses under the model uncertainties are conducted with IBKS and BKS for theoretical interpretations on reduced model dependency in IBKS. Stability and performance of the closed-loop system with IBKS are shown to be not affected by the model uncertainties, while they significantly influence the closed-loop characteristics with BKS. One interesting observation is that the uncertainty on control effectiveness information, which is still required to implement IBKS, does not have any impact on the closed-loop system with IBKS if a control input is calculated, transmitted and reflected fast enough to an actual control surface. The next two analyses are conducted to identify how the defects on the additional measurements together with the model uncertainties affect stability and performance of the closed-loop system with IBKS. First, the closed-loop characteristics with IBKS is analyzed under biases on the additional measurements and the model uncertainties. The measurement biases result in a steady state error while not affecting the closed-loop system stability with IBKS. Unlike the analysis results only with the model uncertainties, the uncertainty in control effectiveness information has an impact on the steady-state error of the closed-loop system. Second, the closed-loop system with IBKS under delays on the additional measurements and the model uncertainties is examined with the analysis framework proposed in this thesis. New analysis framework with optimization concept is proposed to systematically and efficiently test the closed-loop system stability under measurement delays. The key finding is that the delays on the additional measurements should satisfy a specific relationship for the closed-loop stability with IBKS. Besides, it is identified that this stability condition is affected by the uncertainty on control effectiveness information. A new C-ABKS is designed by resolving research gaps of the composite adaptive control for a practical application as follows. First, parameter convergence under finite excitation (FE) is guaranteed with a new paradigm for the information matrix design which is suggested by developing a modulation-based approach. It is proven that the new information matrix is positive definite for all the time from the beginning under FE, while the accumulation-based approach in previous studies requires uncertain amount of time to populate the information matrix to be full rank. The closed-loop system with the C-ABKS utilizing the new information matrix is guaranteed to be globally exponentially stable for all the time under FE. Comparing to the accumulation-based approach, the new modulation-based approach provides advantages in adaptation speed and system robustness since the information matrix is designed to have all eigenvalues with moderate level of magnitudes. Second, the adaptation speed is improved without excessive increase of the adaptation gains in the new logarithmic regression-based composite adaptive control system. The parameter convergence speed is enhanced by slowing down the adaptation speed degeneration at the later stage where the estimation error is small; a concave and monotonically increasing characteristics of a logarithmic function is utilized for the regression term design in this research. The closed-loop system with the proposed logarithmic regression-based C-ABKS is shown to be asymptotically stable under FE by applying Lyapunov theory. Within the system boundary, the new logarithmic regression-based algorithm is proven to be always faster than the well-known linear regression-based algorithm under the same adaptation gain if its design parameters satisfy the suggested condition. In order to make the linear regression-based approach to become faster than the logarithmic regression-based approach with the design parameters satisfying this condition, the adaptation gain of the linear regression term should be increased and this can result in reduced robustness. Important findings for IBKS and C-ABKS are suggested and verified with simulations throughout the thesis. A comparative study is additionally conducted to show different properties of IBKS and C-ABKS under model uncertainties and measurement delays via numerical simulations.PhD in Aerospac

Large space structures and systems in the space station era: A bibliography with indexes (supplement 05)

Bibliographies and abstracts are listed for 1363 reports, articles, and other documents introduced into the NASA scientific and technical information system between January 1, 1991 and July 31, 1992. Topics covered include technology development and mission design according to system, interactive analysis and design, structural and thermal analysis and design, structural concepts and control systems, electronics, advanced materials, assembly concepts, propulsion and solar power satellite systems

Proceedings of the NASA Conference on Space Telerobotics, volume 5

Papers presented at the NASA Conference on Space Telerobotics are compiled. The theme of the conference was man-machine collaboration in space. The conference provided a forum for researchers and engineers to exchange ideas on the research and development required for the application of telerobotics technology to the space systems planned for the 1990's and beyond. Volume 5 contains papers related to the following subject areas: robot arm modeling and control, special topics in telerobotics, telerobotic space operations, manipulator control, flight experiment concepts, manipulator coordination, issues in artificial intelligence systems, and research activities at the Johnson Space Center