Luiz Goes

Instituto Tecnológico de Aeronáutica, Divisão De Engenharia Mecânica-Aeronáutica -Iem, Faculty Member

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Electronic Engineer ITA 1975; Master in Plasma Physics ITA 1978; PhD Electrical Engineering Univ. Wisconsin-madison-USA, 1986. Professor at ITA since 1971. Presently FUll Professor and Head of the Mechatronics Department, Mechanical Engr Division-ITA. teaching and research on Modeling and Simulation of Aeronautical Systems, System Identification with UAV Flight Tests.
Supervisors: Prof. Jose Pantuso Sudano (ITA) and Prof. Juda Leon Shohet (UW-Madison)

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The Use of Gramian Matrices for Aeroelastic Stability Analysis

by Clayton Marqui and Luiz Goes

Mathematical Problems in Engineering, 2013

ABSTRACT Most of the established procedures for analysis of aeroelastic flutter in the developmen... more ABSTRACT Most of the established procedures for analysis of aeroelastic flutter in the development of aircraft are based on frequency domain methods. Proposing new methodologies in this field is always a challenge, because the new methods need to be validated by many experimental procedures. With the interest for new flight control systems and nonlinear behavior of aeroelastic structures, other strategies may be necessary to complete the analysis of such systems. If the aeroelastic model can be written in time domain, using state-space formulation, for instance, then many of the tools used in stability analysis of dynamic systems may be used to help providing an insight into the aeroelastic phenomenon. In this respect, this paper presents a discussion on the use of Gramian matrices to determine conditions of aeroelastic flutter. The main goal of this work is to introduce how observability gramian matrix can be used to identify the system instability. To explain the approach, the theory is outlined and simulations are carried out on two benchmark problems. Results are compared with classical methods to validate the approach and a reduction of computational time is obtained for the second example.

Aeroelastic stability analysis using linear matrix inequalities

by Clayton Marqui, Douglas D Bueno, and Luiz Goes

The present work describes an alternative methodology for identification of aeroelastic stability... more The present work describes an alternative methodology for identification of aeroelastic stability in a range of varying parameters. Analysis is performed in time domain based on Lyapunov stability and solved by convex optimization algorithms. The theory is outlined and simulations are carried out on a benchmark system to illustrate the method. The classical methodology with the analysis of the system's eigenvalues is presented for comparing the results and validating the approach. The aeroelastic model is represented in state space format and the unsteady aerodynamic forces are written in time domain using rational function approximation. The problem is formulated as a polytopic differential inclusion system and the conceptual idea can be used in two different applications. In the first application the method verifies the aeroelastic stability in a range of air density (or its equivalent altitude range). In the second one, the stability is verified for a range of velocities. These analyses are in contrast to the classical discrete analysis performed at fixed air density/velocity values. It is shown that this method is efficient to identify stability regions in the flight envelope and it offers promise for robust flutter identification.

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Flutter analysis including structural uncertainties

by Douglas D Bueno and Luiz Goes

Meccanica, 2015

Dynamics, Control, and Identification Experiments in Space Robotics

Nonlinear Dynamic Modelling, Identification and Control of a Flexible Structure

54th International Astronautical Congress of the International Astronautical Federation, the International Academy of Astronautics, and the International Institute of Space Law, 2003

Electron-Cyclotron Resonance Preionization and Heating in the Proto-Cleo Torsatron

ECR-breakdown and heating in a bifurcated torsatron topology are investigated with extra-ordinary... more ECR-breakdown and heating in a bifurcated torsatron topology are investigated with extra-ordinary mode injection from the high-field side (7.2 GHz/2 KW/10 ms). The breakdown characteristics are explained by stochastic heating enhanced by helical ripple effects. In the quasi-stationary regime (0.01n(,cr) < n < 0.6 n(,cr)), two-dimensional plasma profiles indicated heating inhomogeneities associated with RF power absorption near the UHR layer.

ACOUSTIC CAVITIES DESIGN PROCEDURES

Combustion instability is recognized as one of the major problems frequently faced by engineers d... more Combustion instability is recognized as one of the major problems frequently faced by engineers during the development of either liquid or solid propellant rocket engines. The performance of the engine can be highly affected by these high frequencies instabilities, possibly leading the rocket to an explosion. The main goal while studying combustion chambers instability, either by means of baffles or acoustic absorbers, is to achieve the stability needed using the simplest possible manner. This paper has the purpose of studying combustion chambers instabilities, as well as the design of acoustic absorbers capable of reducing their eigenfrequencies. Damping systems act on the chamber eigenfrequency, which has to be, therefore, previously known

MODELING AND SIMULATION OF A POSITION CONTROL OF A MULTI-LINK FLEXIBLE STRUCTURE

The objective of this work is to describe the positional control of an unconstrained multi-link f... more The objective of this work is to describe the positional control of an unconstrained multi-link flexible structure. The experimental apparatus was designed to be representative of a flexible space structure such as a satellite with multiple flexible appendages. In this work we describe the analytical modeling and the simulation of a position control using a Linear Quadratic Regulator.

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Investigation of Resonances on a Harmonically Forced Non-Linear Slewing Beam

Non-linear dynamics Modelling, Identification and Control of a Slewing Flexible Structure

Dynamic Modelling and Control of Multibody Experiments with Flexible Links

Semi active suspension control techniques using only one measurement sensor

In this paper two control strategies are addressed-the Linear Quadratic Regulator (LQR) and the I... more In this paper two control strategies are addressed-the Linear Quadratic Regulator (LQR) and the Internal Model Control (IMC). These techniques were tested in a system where saturation is present, the semi-active suspension problem. They are then evaluated by some performance indexes that characterize the problem as optimization problems, and solved by the use of some specific tools of the MATLAB software. The main goal is to obtain optimal performance, in order to minimize the sprung mass (chassis) acceleration and to ensure road-holding characteristics, while minimizing the number of feedback sensors used. To make-up for the minimum sensor usage, state observers are designed. A comparison is then made, by means of numerical simulation, using a quarter-car model and real road profiles as well.

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SEMI-ACTIVE SUSPENSION CONTROL WITH ONE MEASUREMENT SENSOR USING H ∞ TECHNIQUE

In this paper the H ∞ control strategy is addressed. This control technique was tested in a syste... more In this paper the H ∞ control strategy is addressed. This control technique was tested in a system where saturation is present, the semi-active suspension problem and was evaluated using performance indexes regarding comfort and road handling, and solved by the use of some specific tools of the MATLAB software. The main goal is to obtain optimal performance, in order to minimize the sprung mass (chassis) acceleration and to ensure road-holding characteristics. A comparison is then made with a passive system, by means of numerical simulation, using a quarter-car model, real road profiles, by means of the performance indexes and frequency response comparisons. A single-sensor approach is also suggested, to reduce the number of sensors used per quarter-car model.

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An overview of experimental strain-based modal analysis methods

The most established way of performing experimental modal analysis is to use acceleration or velo... more The most established way of performing experimental modal analysis is to use acceleration or velocity based transducers that lead to the calculation of the displacement mode shapes. However, there are applications where the use of strain measurements makes for a more attractive and interesting option. Strain gauges have been commonly used for static load testing of mechanical products in the aeronautic, automotive and mechanical industry. Moreover, fatigue testing, durability analysis and lifetime prediction has also been a common application where strain gauges are used. This sort of testing is a common part of the product development process, and additional information on product durability and dynamic performance can be assessed by obtaining the modal parameters of the system, while still using the same instrumentation. Moreover, since strain measurements are more directly related to stress, fatigue and failure, strain-based measurement methods can be a good option for structural...

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IDENTIFICAÇÃO DAS DERIVADAS DE ESTABILIDADE E CONTROLE LONGITUDINAIS DE UMA AERONAVE EM VÁRIOS PONTOS DO ENVELOPE DE VÔO ATRAVÉS DE TÉCNICAS DE ESTIMAÇÃO POR MÁXIMA VEROSSIMILHANÇA E REDES NEURAIS ARTIFICIAIS

Neste trabalho é apresentado um procedimento para identificação das derivadas de estabilidade e c... more Neste trabalho é apresentado um procedimento para identificação das derivadas de estabilidade e controle do movimento longitudinal de uma aeronave militar, em diferentes pontos do envelope de vôo. Além disso, é feita a extrapolação dos parâmetros do modelo para pontos do envelope não contemplados nos ensaios em vôo, fornecendo assim uma excelente ferramenta para análise aerodinâmica e de estabilidade e desempenho de aeronaves. Para isso, são utilizados métodos baseados na técnica de estimação paramétrica por máxima verossimilhança e algoritmo de otimização de Levenberg-Marquardt em conjunto com técnicas baseadas em Redes Neurais Artificiais. A metodologia é aplicada a dados reais de ensaio em vôo de uma aeronave militar, o Xavante AT-26 da Força Aérea Brasileira (FAB).

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Formation flight control of multirotor helicopters with collision avoidance

2015 International Conference on Unmanned Aircraft Systems (ICUAS), 2015

Among the main sub-areas covering the cooperative control problem of Unmanned Aerial Vehicles (UA... more Among the main sub-areas covering the cooperative control problem of Unmanned Aerial Vehicles (UAVs), formation flight has attracted great interest and has been widely investigated. The main purpose of the formation flight control is to establish a desired shape of formation for a group of vehicles by controlling the positions of each vehicle. The present paper deals with the problem of position formation flight control of a group of three multirotor helicopters with collision avoidance. In order to solve the problem, we propose a decentralized scheme based on model predictive controllers (MPC) for formation according to a virtual structure approach. For collision avoidance, a set of convex constraints on the vehicle's positions are included. The proposed method is evaluated on the basis of computational simulations considering that the vehicles are subject to disturbance forces. Simulation results show the effectiveness of the method with primary focus on treatment of anti-collision constraints.

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AIR DAMPING ANALYSIS OF A DIFFERENTIAL CAPACITIVE ACCELEROMETER

by Janderson Rodrigues, Luiz Goes, and Carlos Mateus

We describe the behavior of the gas between the electrodes of a capacitive accelerometer with the... more We describe the behavior of the gas between the electrodes of a capacitive accelerometer with the compressible-gas-film Reynolds equation, which relates pressure, density, viscosity and the surface velocity for the specific geometry of bounded film. This equation assumes that inertial forces are small compared to viscous forces, and that the gap is large compared to the mean free path of the gas. Assuming a small displacement of the moving electrode, small pressure variation around the ambient pressure and under the assumption of isothermal film, the analytical solution of the pressure is obtained. The pressure has two terms: one represents the damping and one represents the spring-like behavior of the gas. The integral of the pressure over the electrodes area lead directly to expressions for damping and air spring constant coefficients. The importance of compressible effects, represented by the spring constant coefficient, can be analyzed through of the squeeze number. For a very l...

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A brief comment on the dynamical behavior of a forced nonlinear slewing beam: 1. Superharmonic resonance

Journal of the Brazilian Society of Mechanical Sciences and Engineering, 2005

Modeling and robust analysis of a liquid rocket engine

36th AIAA/ASME/SAE/ASEE Joint Propulsion Conference and Exhibit, 2000

AEROSERVOELASTIC MODELING OF A FLEXIBLE WING FOR WIND TUNNEL FLUTTER TEST

This paper presents the design of a flexible wing that employs an active control system for flutt... more This paper presents the design of a flexible wing that employs an active control system for flutter suppression. The design of this wing considers that all pitch and plunge loads are resisted by an aluminum longeron whose dimensions is specified according to the wind tunnel available for the flutter test and using NASTRAN. The same software is used for the determination of the various modes of pitch, plunge and their couplings. The airfoil is the NACA 0012. In this modeling the flutter speed is found using ZAERO software. For aerodynamic modeling, a panel method, such as doublet lattice method, is used and the same software gives this support. An active control system that makes flutter suppression by piezoelectric actuation is used during the wind tunnel tests. The purpose of this study is a future comparison between the results obtained herein and those that will be determined further from wind tunnel test.

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