Design of a control system using linear matrix inequalities for the active vibration control of a plate

The study of algorithms for active vibration control in smart structures is an area of interest, mainly due to the demand for better performance of mechanical systems, such as aircraft and aerospace structures. Smart structures, formed using actuators and sensors, can improve the dynamic performance with the application of several kinds of controllers. This article describes the application of a technique based on linear matrix inequalities (LMI) to design an active control system. The positioning of the actuators, the design of a robust state feedback controller and the design of an observer are all achieved using LMI. The following are considered in the controller design: limited actuator input, bounded output (energy) and robustness to parametric uncertainties. Active vibration control of a flat plate is chosen as an application example. The model is identified using experimental data by an eigensystem realization algorithm (ERA) and the placement of the two piezoelectric actuators and single sensor is determined using a finite element model (FEM) and an optimization procedure. A robust controller for active damping is designed using an LMI framework, and a reduced model with observation and control spillover effects is implemented using a computer. The simulation results demonstrate the efficacy of the approach, and show that the control system increases the damping in some of the modes.

Observer-based state-feedback versus H-infinity output feedback control solved by LMI approach for applications in smart structures

This paper aims with the use of linear matrix inequalities approach (LMIs) for application in active vibration control problems in smart strutures. A robust controller for active damping in a panel was designed with piezoelectrical actuators in optimal locations for illustration of the main proposal. It was considered, in the simulations of the closed-loop, a model identified by eigensystem realization algorithm (ERA) and reduced by modal decomposition. We tested two differents techniques to solve the problem. The first one uses LMI approach by state-feedback based in an observer design, considering several simultaneous constraints as: a decay rate, limited input on the actuators, bounded output peak (output energy) and robustness to parametic uncertainties. The results demonstrated the vibration attenuation in the structure by controlling only the first modes and the increased damping in the bandwidth of interest. However, it is possible to occur spillover effects, because the design has not been done considering the dynamic uncertainties related with high frequencies modes. In this sense, the second technique uses the classical H. output feedback control, also solved by LMI approach, considering robustness to residual dynamic to overcome the problem found in the first test. The results are compared and discussed. The responses shown the robust performance of the system and the good reduction of the vibration level, without increase mass.

Optimal and robust modal control of a flexible structure using an active dynamic vibration absorber

This paper is concerned with feedback vibration control of a lightly damped flexible structure that has a large number of well-separated modes. A single active electrical dynamic absorber is used to reduce a particular single vibration mode selectively or multiple modes simultaneously. The absorber is realized electrically by feeding back the structural acceleration at one position to a collocated piezoceramic patch actuator via a controller consisting of one or several second order lowpass filters. A simple analytical method is presented to design a modal control filter that is optimal in that it maximally flattens the mobility frequency response of the target mode, as well as robust in that it works within a prescribed maximum control spillover of 2 dB at all frequencies. Experiments are conducted with a free-free beam to demonstrate its ability to control any single mode optimally and robustly. It is also shown that an active absorber with multiple such filters can effectively control multiple modes simultaneously.

Formation Mechanism via a Heterocoagulation Approach of FePt Nanoparticles Using the Modified Polyol Process

Fundação de Amparo à Pesquisa do Estado de São Paulo (FAPESP)

Controle ativo de vibrações em estruturas espaciais tipo treliças usando controladores IMSC

Coordenação de Aperfeiçoamento de Pessoal de Nível Superior (CAPES)

Implicações nacionais da integração regional: as eleições diretas do parlamento do Mercosul

O processo de institucionalização do MERCOSUL verificado nos últimos anos aumentou o peso da integração regional nas políticas internas dos Estados-membros. No caso brasileiro, o projeto de lei que regulamenta as eleições diretas para o Parlamento do MERCOSUL (Parlasul) em 2014 é um exemplo dessa influência, porque inclui aspectos que estão relacionados às discussões acerca da reforma do sistema político brasileiro, tema gerador de intenso debate e polêmica dentro do Congresso Nacional. Este artigo discute os possíveis impactos que a sua aprovação terá na condução da reforma política no Brasil, partindo da hipótese de que o referido projeto representa um transbordamento da reforma política brasileira para o plano regional. Supomos que sua aprovação pode se tornar um ensaio da reforma política planejada, ao executar no plano regional mudanças ainda em discussão no legislativo brasileiro. Lembramos que a decisão e aprovação dos critérios para realização das eleições diretas do Parlasul é de competência de cada Estado-membro.

Implicações nacionais da integração regional: as eleições diretas do Parlamento do Mercosul

The process of institutionalization of MERCOSUR in recent years has increased the weight of regional integration in the internal policies of the Member States. In the Brazilian case, the bill that regulates direct elections for the MERCOSUR Parliament (Parlasul) in 2014 is an example of this influence, because it includes aspects that are related to discussions on the reform of the Brazilian political system, generating intense debate and controversy within the Congress. This article discusses the possible impacts that its adoption will have on the conduct of political reform in Brazil, on the assumption that this project represents a spillover of political reform for Brazilian regional plan. We assume that its approval can become a test of political reform planned to perform at the regional changes still under discussion in the brazilian legislature. We remind that the decision and approval of the criteria for the Parlasul direct elections is a competence of each Member-State.

Estudos parasitológicos em cães domésticos errantes e carnívoros selvagens generalistas no Parque Nacional do Iguaçu, Foz do Iguaçu

Fundação de Amparo à Pesquisa do Estado de São Paulo (FAPESP)