Vibration Control of Large Scale Flexible Structures Using Magnetorheological Dampers

Structural vibration control (SVC) of large scale structures using the magnetorheological (MR) dampers are studied. Some key issues, i.e. model reduction, suppression of spillover instability, optimal placement of actuators and sensors, modeling of the MR dampers and their applications in SVC system for large scale structures, are addressed in this work. A new model reduction method minimizing the error of a modal-truncation based reduced order model (ROM) is developed. The proposed method is implemented by using a Genetic Algorithm (GA), and can be efficiently used to find a ROM for a large scale structure. The obtained ROM has a finite H2 norm and therefore can be used for H2 controller design. The mechanism of the spillover instability is studied, and a methodology to suppress the spillover instability in a SVC system is proposed. The suggested method uses pointwise actuators and sensors to construct a controller lying in an orthogonal space spanned by the several selected residual modes, such that the spillover instability caused by these residual modes can be successfully suppressed. A GA based numerical scheme used to find the optimal locations for the sensors and actuators of a SVC system is developed. The spatial H2 norm is used as the optimization index. Because the spatial H2 norm is a comprehensive index in evaluating the dynamics of a distributed system, a SVC system using the sensors and actuators located on the obtained optimal locations is able to achieve a better performance defined on a distributed domain. An improved model of MR dampers is suggested such that the model can maintain the desired hysteresis behavior when noisy data are used. For the simulation purpose, a numerical iteration technique is developed to solve the nonlinear differential equations aroused from a passive control of a structure using the MR dampers. The proposed method can be used to simulate the response of a large scale structural system with the MR dampers. The methods developed in this work are finally verified using an industrial roof structure. A passive and semi-active SVC systems are designed to attenuate the wind-induced structural vibration inside a critical area on the roof. The performances of the both SVC systems are analyzed and compared. Simulation results show that the SVC systems using the MR dampers have great potentials in reducing the structural vibration of the roof structure

Multi-objective fuzzy optimization of sizing and location of piezoelectric actuators and sensors

Ovaj rad predstavlja višeciljnu fazi optimizaciju veličine i položaja piezoelektričnih aktuatora i senzora na tankozidu kompozitnu gredu za aktivno upravljanje vibracija koristeći stepen upravljivosti (DC) kontrolisanih modova kao kriterijum optimizacije. Proces optimizacije je izvršen uz ograničenje promene prvobitnih dinamičkih karakteristika, uključujući ograničenje u porastu mase, upotrebljavajući ili zanemarujući ograničenja stepena upravljivosti rezidualnih modova za redukciju 'spillover' efekta. Pseudociljne funkcije izvedene na bazi teorije fazi skupova na jedinstven način definišu globalne funkcije cilja eliminišući upotrebu kaznenih funkcija. Problem je definisan upotrebom metode konačnih elemenata bazirane na 'TSD' teoriji. 'Particle Swarm' optimizacija je upotrebljena za nalaženje optimalne konfiguracije. Nekoliko numeričkih primera je prikazano za slučaj konzole.This paper presents the multi-objective fuzzy optimization of sizing and location of piezoelectric actuators and sensors on the thin-walled composite beam for active vibration control, using the degree of controllability (DC) for controlled modes as optimization criteria. The optimization process is performed constraining the original dynamics properties change including the limitation of increase of the mass, using or neglecting the limitation in degrees of controllability for residual modes for reduction spillover effect. Pseudogoal functions derived on the fuzzy set theory gives a unique expression for global objective functions eliminating the use of penalty functions. The problem is formulated using the finite element method based on the third-order shear deformation theory. The particle swarm optimization technique is used to find optimal configuration. Several numerical examples are presented for the cantilever beam

Multi-objective fuzzy optimization of sizing and location of piezoelectric actuators and sensors for vibration control based on the particle swarm optimization technique (part 1: Theoretical model)

Određivanje veličine i položaja piezoelektričnih aktuatora i senzora za aktivno upravljanje vibracijama savitljivih struktura obično je bazirano na maksimalnoj efikasnosti upravljanja i postizanja maksimalnog izlaza za modove vibracija od interesa. Integracija piezoelektričnih delova utiče na masu i dinamičke performanse bazične strukutre. Ovo je prvi deo istraživanja koje predstavlja teorijski razvoj višeciljne fazi optimizacione tehnike za određivanje položaja i veličine piezoelektričnih aktuatora i senzora na tankozidnoj kompozitnoj gredi. Kriterijumi optimizacije za određivanje optimalne veličine i položaja piezoelektričnih aktuatora i senzora zasnivaju se na stepenu upravljivosti upravljanih modova. Procedura optimizacije obuhvata ograničenje promene prvobitnih dinamičkih karakteristika i ograničenje u porastu mase. Pseudociljna funkcija, zasnovana na teoriji fazi skupova, daje izraz za globalnu ciljnu funkciju eliminišući upotrebu težinskih koeficijenata i kaznenih funkcija. Optimizacija rojem čestica je upotrebljena za nalaženje optimalne konfiguracije.Sizing and location of the piezoelectric actuators and sensors for vibration control of flexible structures is usually based on maximum control effectiveness and achieving the maximum output for the vibration in the modes of interests. Integration of piezoelectric patches affects the mass and the original dynamic properties of the parent structure. This is the first part of the two-paper research which presents the theoretical development of the multi-objective fuzzy optimization technique of sizing and location of the collocated piezoelectric actuators and sensors on the thin-walled composite beam. The optimization criteria for the optimal size and location of piezoelectric A/Ss are based on the degree of controllability (DC) for controlled modes. The optimization procedure implies the constraining of the original dynamic properties change and the limitation of the mass increase. A pseudogoal function, derived based on the fuzzy set theory, gives an expression for global objective functions eliminating the use of weighting coefficients and penalty functions. the particle swarm optimization technique is used to find the optimal configuration.

Multi-objective fuzzy optimization of sizing and location of piezoelectric actuators and sensors for vibration control based on the particle swarm optimization technique (part 1: Theoretical model)

Određivanje veličine i položaja piezoelektričnih aktuatora i senzora za aktivno upravljanje vibracijama savitljivih struktura obično je bazirano na maksimalnoj efikasnosti upravljanja i postizanja maksimalnog izlaza za modove vibracija od interesa. Integracija piezoelektričnih delova utiče na masu i dinamičke performanse bazične strukutre. Ovo je prvi deo istraživanja koje predstavlja teorijski razvoj višeciljne fazi optimizacione tehnike za određivanje položaja i veličine piezoelektričnih aktuatora i senzora na tankozidnoj kompozitnoj gredi. Kriterijumi optimizacije za određivanje optimalne veličine i položaja piezoelektričnih aktuatora i senzora zasnivaju se na stepenu upravljivosti upravljanih modova. Procedura optimizacije obuhvata ograničenje promene prvobitnih dinamičkih karakteristika i ograničenje u porastu mase. Pseudociljna funkcija, zasnovana na teoriji fazi skupova, daje izraz za globalnu ciljnu funkciju eliminišući upotrebu težinskih koeficijenata i kaznenih funkcija. Optimizacija rojem čestica je upotrebljena za nalaženje optimalne konfiguracije.Sizing and location of the piezoelectric actuators and sensors for vibration control of flexible structures is usually based on maximum control effectiveness and achieving the maximum output for the vibration in the modes of interests. Integration of piezoelectric patches affects the mass and the original dynamic properties of the parent structure. This is the first part of the two-paper research which presents the theoretical development of the multi-objective fuzzy optimization technique of sizing and location of the collocated piezoelectric actuators and sensors on the thin-walled composite beam. The optimization criteria for the optimal size and location of piezoelectric A/Ss are based on the degree of controllability (DC) for controlled modes. The optimization procedure implies the constraining of the original dynamic properties change and the limitation of the mass increase. A pseudogoal function, derived based on the fuzzy set theory, gives an expression for global objective functions eliminating the use of weighting coefficients and penalty functions. the particle swarm optimization technique is used to find the optimal configuration.

Control oriented modelling of an integrated attitude and vibration suppression architecture for large space structures

This thesis is divided into two parts. The main focus of the research, namely active vibration control for large flexible spacecraft, is exposed in Part I and, in parallel, the topic of machine learning techniques for modern space applications is described in Part II. In particular, this thesis aims at proposing an end-to-end general architecture for an integrated attitude-vibration control system, starting from the design of structural models to the synthesis of the control laws. To this purpose, large space structures based on realistic missions are investigated as study cases, in accordance with the tendency of increasing the size of the scientific instruments to improve their sensitivity, being the drawback an increase of its overall flexibility. An active control method is therefore investigated to guarantee satisfactory pointing and maximum deformation by avoiding classical stiffening methods. Therefore, the instrument is designed to be supported by an active deployable frame hosting an optimal minimum set of collocated smart actuators and sensors. Different spatial configurations for the placement of the distributed network of active devices are investigated, both at closed-loop and open-loop levels. Concerning closed-loop techniques, a method to optimally place the poles of the system via a Direct Velocity Feedback (DVF) controller is proposed to identify simultaneously the location and number of active devices for vibration control with an in-cascade optimization technique. Then, two general and computationally efficient open-loop placement techniques, namely Gramian and Modal Strain Energy (MSE)-based methods, are adopted as opposed to heuristic algorithms, which imply high computational costs and are generally not suitable for high-dimensional systems, to propose a placement architecture for generically shaped tridimensional space structures. Then, an integrated robust control architecture for the spacecraft is presented as composed of both an attitude control scheme and a vibration control system. To conclude the study, attitude manoeuvres are performed to excite main flexible modes and prove the efficacy of both attitude and vibration control architectures. Moreover, Part II is dedicated to address the problem of improving autonomy and self-awareness of modern spacecraft, by using machine-learning based techniques to carry out Failure Identification for large space structures and improving the pointing performance of spacecraft (both flexible satellite with sloshing models and small rigid platforms) when performing repetitive Earth Observation manoeuvres

SPECIFIED MOTION AND FEEDBACK CONTROL OF ENGINEERING STRUCTURES WITH DISTRIBUTED SENSORS AND ACTUATORS

This dissertation addresses the control of flexible structures using distributed sensors and actuators. The objective to determine the required distributed actuation inputs such that the desired output is obtained. Two interrelated facets of this problem are considered. First, we develop a dynamic-inversion solution method for determining the distributed actuation inputs, as a function of time, that yield a specified motion. The solution is shown to be useful for intelligent structure design, in particular, for sizing actuators and choosing their placement. Secondly, we develop a new feedback control method, which is based on dynamic inversion. In particular, filtered dynamic inversion combines dynamic inversion with a low-pass filter, resulting in a high-parameter-stabilizing controller, where the parameter gain is the filter cutoff frequency. For sufficiently large parameter gain, the controller stabilizes the closed-loop system and makes the L2-gain of the performance arbitrarily small, despite unknown-and-unmeasured disturbances. The controller is considered for both linear and nonlinear structural models

Adaptive nonlinear polynomial neural networks for control of boundary layer/structural interaction

The acoustic pressures developed in a boundary layer can interact with an aircraft panel to induce significant vibration in the panel. Such vibration is undesirable due to the aerodynamic drag and structure-borne cabin noises that result. The overall objective of this work is to develop effective and practical feedback control strategies for actively reducing this flow-induced structural vibration. This report describes the results of initial evaluations using polynomial, neural network-based, feedback control to reduce flow induced vibration in aircraft panels due to turbulent boundary layer/structural interaction. Computer simulations are used to develop and analyze feedback control strategies to reduce vibration in a beam as a first step. The key differences between this work and that going on elsewhere are as follows: that turbulent and transitional boundary layers represent broadband excitation and thus present a more complex stochastic control scenario than that of narrow band (e.g., laminar boundary layer) excitation; and secondly, that the proposed controller structures are adaptive nonlinear infinite impulse response (IIR) polynomial neural network, as opposed to the traditional adaptive linear finite impulse response (FIR) filters used in most studies to date. The controllers implemented in this study achieved vibration attenuation of 27 to 60 dB depending on the type of boundary layer established by laminar, turbulent, and intermittent laminar-to-turbulent transitional flows. Application of multi-input, multi-output, adaptive, nonlinear feedback control of vibration in aircraft panels based on polynomial neural networks appears to be feasible today. Plans are outlined for Phase 2 of this study, which will include extending the theoretical investigation conducted in Phase 2 and verifying the results in a series of laboratory experiments involving both bum and plate models

A state-of-the-art assessment of active structures

A state-of-the-art assessment of active structures with emphasis towards the applications in aeronautics and space is presented. It is felt that since this technology area is growing at such a rapid pace in many different disciplines, it is not feasible to cover all of the current research but only the relevant work as relates to aeronautics and space. Research in smart actuation materials, smart sensors, and control of smart/intelligent structures is covered. In smart actuation materials, piezoelectric, magnetostrictive, shape memory, electrorheological, and electrostrictive materials are covered. For sensory materials, fiber optics, dielectric loss, and piezoelectric sensors are examined. Applications of embedded sensors and smart sensors are discussed

Emerging Technologies for the Energy Systems of the Future

Energy systems are transiting from conventional energy systems to modernized and smart energy systems. This Special Issue covers new advances in the emerging technologies for modern energy systems from both technical and management perspectives. In modern energy systems, an integrated and systematic view of different energy systems, from local energy systems and islands to national and multi-national energy hubs, is important. From the customer perspective, a modern energy system is required to have more intelligent appliances and smart customer services. In addition, customers require the provision of more useful information and control options. Another challenge for the energy systems of the future is the increased penetration of renewable energy sources. Hence, new operation and planning tools are required for hosting renewable energy sources as much as possible