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smart structures and materials 1999 Conference

作者： Rediniotis, O Webb, G Darmofal, D Texas A&M Univ Dept Aerosp Engn College Stn TX 77843 USA

ISBN: (纸本)0819431419

The systems theory approach to the feedback stabilization of finite-amplitude disturbances in plane Poiseuille flow results in high-order system models to accurately represent the disturbance dynamics. From a practical standpoint, a controller developed for a specific flow control task will often have to be implemented in realtime. The need for the synthesis of rigorous control theory and experimental methods has been noted by several researchers over the years. A key step to this synthesis is the development of low dimensional descriptions of flow dynamics for control synthesis. This paper examines the use of the optimal projection method for reduced-order controller synthesis for flow disturbance model systems with relatively high order (greater than 40).

关键词： optimal projection transition control reduced-order control

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Robust, compact and inexpensive analog controllers for cabin noise control

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Proceedings of SPIE - The International Society for Optical Engineering 1999年 3667卷 543-552页

作者： Chang, W. Ramanathan, K. Varadan, V.V. Varadan, V.K. Pennsylvania State Univ University Park United States

Active Noise control has been an area of research interest in the recent decades with the goal of providing reduced noise levels in automobile and aircraft enclosures. Although digital controllers are adaptable and efficient, they lack the simplicity of analog controllers due to the requirement of a computer, D/A and A/D boards. Analog controllers on the other hand can be designed to be compact using current IC technology and hence are relatively very cheap. The following paper studies the application of an analog robust controller to abate the noise radiated into a non-reverberant wooden enclosure by a clamped aluminum plate. Since only the odd-odd modes radiate efficiently, a SISO robust analog controller was designed and built inexpensively for a piezoelectric actuator and accelerometer sensor placed at the center of the plate. A reduction of 17 dB is observed when the panel is excited at its fundamental frequency, the dominant radiating mode. When the plate is excited with narrowband noise (40-316 Hz), the controller reduces the noise levels in the enclosure by 9 dB. The experimental results agree well with the controller simulation carried out using MATLAB.

关键词： Acoustic variables control

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Thermoelectric control of Shape Memory Alloy microactuators: A thermal model

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Proceedings of SPIE - The International Society for Optical Engineering 1999年 3667卷 326-336页

作者： Abadie, J. Chaillet, N. Lexcellent, C. Bourjault, A. Lab d'Automatique de Besancon Besancon France

Microtechnologies and microsystems engineering use new active materials. These materials are interesting to realize microactuators and microsensors. In this category of materials, Shape Memory Alloys (SMA) are good candidates for microactuation. SMA wires, or thin plates, can be used as active material in microfingers. These microstructures are able to provide very important forces, but have low dynamic response, especially for cooling, in confined environment. The control of the SMA phase transformations, and then the mechanical power generation, is made by the temperature. The Joule effect is an easy and efficiency way to heat the SMA wires, but cooling is not so easy. The dynamic response of the actuator depends on cooling capabilities. The thermal convection and conduction are the traditional ways to cool the SMA, but have limitations for microsystems. We are looking for a reversible way of heating and cooling SMA microactuators, based on the thermoelectric effects. Using Peltier effect, a positive or a negative electrical courant is able to pump or produce heat, in the SMA actuator. A physical model based on thermal exchanges between a Nickel/Titanium (NiTi) SMA, and Bismuth/Telluride (Te3Bi2) thermoelectric material has been developed. For simulation, we use a numerical resolution of our model, with finite elements, which takes into account the Peltier effect, the Joule effect, the convection, the conduction and the phase transformation of the SMA. We have also developed the corresponding experimental system, with two thermoelectric junctions, where the SMA actuator is one of the element of each junction. In this paper, the physical model and its numerical resolution are given, the experimental system used to validate the model is described, and experimental results are shown.

关键词： Intelligent materials

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Vibration and noise control using an optimal output feedback controller

Vibration and noise control using an optimal output feedback...

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smart structures and materials 1999 Conference

作者： Lim, YH Gopinathan, SV Varadan, VV Varadan, VK Penn State Univ Dept Engn Sci & Mech Res Ctr Engn Elect & Acoust Mat University Pk PA 16802 USA

ISBN: (纸本)0819431419

In this paper the design of an optimal controller using discretely placed collocated: sensor/actuator pairs to control the vibration of a plate structure is presented. Three-dimensional finite elements are: used to model the smart structure containing discrete piezoelectric sensors and actuators by the use of a combination of solid, transition, and shell elements. Since several discrete piezoelectric patches are spatially distributed in the structure to effectively observe and control the vibration of a structure, the system model is thus utilized to design multi-input-multi-output (MIMO) controller. The output feedback controller is then employed to emulate the optimal controller by solving the Riccati equations from modal space model. An optimal controller design for the vibration suppression of a clamped plate is presented for the steady state excitation case. The reduction in the sound pressure level inside an enclosure radiated from this optimally controlled vibrating plate is also estimated.

关键词： collocated sensor and actuators optimal feedback control Vibration and noise control

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Modeling of electrodynamic properties control in liquid impregnated porous ferrite media

Modeling of electrodynamic properties control in liquid impr...

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smart structures and materials 1999 Conference

作者： Ponomarenko, AT Ryvkina, NG Kazantseva, NE Tchmutin, IA Shevchenko, VG Catton, I Travkin, VA Russian Acad Sci Enikolopov Inst Synthet Polymer Mat Moscow 117393 Russia

ISBN: (纸本)0819431419

Model and experimental investigations of electrodynamic properties of tunable structures from liquid-impregnated porous magnetic media are presented. Microwave spectra of complex permittivity and permeability of dry and liquid-impregnated media with ethyl alcohol or water-alcohol mixtures were measured. Real and imaginary parts of permittivity were found to exceed the upper Wiener boundary. Dielectric and magnetic properties of liquid-impregnated porous ferrite media were modeled using non-local volume averaging theory (VAT). This approach accounts for several hierarchical levels and morphology of the system.

关键词： Dielectrics Magnetism Composites Particles Liquids Ferromagnetics Mathematical modeling Data modeling Electrodynamics Microwave radiation

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Modeling of sound transmitted, into a cavity through a composite plate using coupled FE/BE method and control of acoustic pressure using piezoelectric actuators

Modeling of sound transmitted, into a cavity through a compo...

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smart structures and materials 1999 Conference

作者： Shi, YC Mei, C Analyt Serv & Mat Inc Hampton VA 23666 USA

ISBN: (纸本)0819431419

A coupled finite element/boundary element method is developed for the fully coupled structural/acoustic/piezoelectric system. This approach uses the dual reciprocity boundary element method to describe time dependent acoustic field and the finite element to structures and piezoelectric materials. A time-domain formulation of the coupled method is obtained. Based on the coupled time domain formulation, a linear quadratic regulator and a feedforward controller are applied to reduce the acoustic pressure transmitted into a cavity through a composite plate using embedded piezoelectric actuators. The controls of interior acoustic fields due to excitations at different frequencies are investigated, transmission losses and deflection of the plates of the controlled and uncontrolled systems are presented.

关键词： finite element method boundary element method composites structural/acoustic interaction piezoelectric material actuators feedforward linear quadratic regulator

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Approximation of distributed control laws using distributed electronic devices for vibration control

Approximation of distributed control laws using distributed ...

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smart structures and materials 1999 Conference

作者： Lenczner, M Kader, M Mrcarica, Z Univ Franche Comte Equipe Math Besancon UMR 6623 F-25030 Besancon France

ISBN: (纸本)0819431419

In this work the control of vibration in an elastic plate, by piezoelectric transducers, is considered. The model of the plate is that presented in [2]. An approximation of the optimal controller by a derivative partial operator is given. It is based on a development in series of the Riccati operator with respect to the reverse of the stiffness. Its implementation in term of distributed analog electronic circuits, is developed. Numerical simulations, obtained by the coupling of Finite Elements code and a circuit simulator, Alecsis, are presented. To improve the preceding result an iterative algorithm. of approximation of the optimal controller, being able to be: implemented by an electronic circuit, is developed. The algorithm is inspired by the approach of [4].

关键词： Sensors Electronic circuits 3D modeling Analog electronics Vibration control Actuators control systems Differential equations Electronic components Mathematical modeling

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Position control of a two-link flexible manipulator using piezoelectric actuators

Position control of a two-link flexible manipulator using pi...

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smart structures and materials 1999 Conference

作者： Choi, SB Shin, HC Kim, HK Kim, JH Inha Univ Dept Mech Engn Smart Mat & Struct Lab Inchon 402751 South Korea

ISBN: (纸本)0819431419

This paper presents a hybrid actuator scheme to actively control the end-point position of a two-link flexible manipulator. A highly nonlinear system model including inertial effects is established using Lagrange's equation associated with assumed mode method. control scheme consists of four different actuators;two servo-motors at the hubs and two piezoceramics bonded to the surfaces of the flexible links. Two sliding hyperplanes which have time varying parameters are designed for two servo-motors. The surface gradients of the hyperplanes are determined by pole assignment technique to guarantee the stability on the hyperplanes themselves. The sliding mode controllers corresponding to the hyperplanes are then synthesized on the basis of sliding mode conditions. During the motion, undesirable oscillations caused by the torques based on the rigid link dynamics an actively suppressed by applying feedback control voltages to the piezoceramic actuators. Consequently, desired rip motion is achieved. In order to demonstrate the effectiveness of the proposed methodology experiments are performed for the regulating and tracking control problem.

关键词： flexible manipulator piezoelectric actuator position control sliding mode control

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control system design for structural systems under statistical parametric uncertainty

Control system design for structural systems under statistic...

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smart structures and materials 1999 Conference

作者： Huerta-Ochoa, R Johnson, SH Lehigh Univ Dept Mech Engn & Mech Bethlehem PA 18015 USA

ISBN: (纸本)0819431419

This paper presents a statistical approach to the controller design process for structural systems represented by uncertain models. The plant model uncertainty is here accounted for in terms of first- and second-order statistics of uncertain parameters. The basic idea is to make the closed-loop system stability as robust as possible to statistical variations of uncertain plant model parameters. First, an approximate expression for the root variance of an uncertain polynomial is derived as a function of second-order statistics of the polynomial coefficients. The expression is specialized to the case of an SISO closed-loop system characteristic polynomial, where the uncertainty is due to statistical variability of model parameters. Uncertainty cost functions intended to represent the uncertainty of the closed-loop pole locations are then constructed. By parameterizing the set of controllers that yield a desired characteristic polynomial, the uncertainty cost function minimization is converted into a constrained optimization problem. This scheme is illustrated with an SISO seismic control system previously studied in the literature. By comparing the predicted closed-loop pole variance to numerical results obtained from Monte Carlo simulations, it is concluded that the expression developed here provides an excellent approximation, with the advantage of being an analytical expression that is suitable for use in multi-objective optimization design algorithms.

关键词： structural control uncertain polynomials smart structures control uncertain models

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Impact analysis of automotive structures with distributed smart material systems

Impact analysis of automotive structures with distributed sm...

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smart structures and materials 1999 Conference

作者： Peelamedu, SM Naganathan, NG Buckley, S Univ Toledo MIME Dept Toledo OH 43606 USA

ISBN: (纸本)0819431419

New class of automobiles has structural skins that are quite different from their current designs. Particularly, new families of composite skins are developed with new injection molding processes. These skins while support the concept of lighter vehicles of the future, are also susceptible to damage up on impact. It is important that their design should be based on a better understanding on the type of impact loads and the resulting strains and damage. It is possible that these skins can be integrally designed with active materials to counter damages. This paper presents a preliminary analysis of a new class of automotive skins, using piezoceramic as a smart material. The main objective is to consider the complex system with, the skin to be modeled as a layered plate structure involving a lightweight material with foam and active materials imbedded on them. To begin with a cantilever beam structure is subjected to a load through piezoceramic and the resulting strain at the active material site is predicted accounting for the material properties, piezoceramic thickness, adhesive thickness including the effect of adhesives. A finite element analysis is carried out to compare experimental work. Further work in this direction would provide an analytical tool that will provide the basis for algorithms to predict and counter impacts in the future class of automobiles.

关键词： piezoceramic smart material impact damage health monitoring composite cars finite element method numerical methods safety systems and automobile

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