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Broadband active structural-acoustic control of a fuselage test-bed using collocated piezoelectric sensors and actuators

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Proceedings of SPIE - The International Society for Optical Engineering 2000年 3984卷 136-147页

作者： Savran, Cagri A. Atalla, Mauro J. Hall, Steven R. Massachusetts Inst of Technology Cambridge United States

We describe structural-acoustic control experiments on a model fuselage test-bed, using collocated pairs of piezoelectric sensors and actuators. The test-bed is a hybrid-scaled model fuselage designed to be representative of complex aircraft structures with rib and stringer construction, which results in a structure with high modal density and complex behavior. The sensor/actuator pairs consist of PVDF film and PZT ceramic sheets bonded to the surface of the model fuselage. Closed-loop control of the fuselage skin was carried out with 30 collocated sensor/actuator pairs, covering approximately 10% of the surface area of the test-bed. The disturbance source is a PZT patch bonded to an adjacent panel. Rate feedback was applied to each collocated pair simultaneously (independent loop closure). Accelerometers attached to the panels and microphones located inside the test-bed were used as performance sensors. The experimental results show a reduction of as much as 20 dB in structural acceleration and up to 10 dB of attenuation in the interior acoustic pressure levels at resonant peaks, over the frequency range of 100-2000 Hz.

关键词： Acoustic variables control

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Natural frequencies of a smart plate with segmented piezoelectric patches

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Proceedings of SPIE - The International Society for Optical Engineering 2000年 3984卷 468-477页

作者： Gopinathan, Senthil V. Varadan, Vasundara V. Varadan, Vijay K. Pennsylvania State Univ University Park United States

Classical Plate Theory (CPT) has been applied successfully in the past to the plates with distributed piezoelectric patch bonded to the surface or embedded within the layers [1-7]. In all earlier models the mass and stiffness' contributions from sensor and actuator patches were neglected for estimating the natural frequencies of the smart plate. Also the thickness direction electric fields and strain fields inside the patches are assumed to be constant over the entire area of the patch. The validity of these assumptions depends on the size and relative stiffnesses of the patches and is not investigated before. In this paper the CPT is used to estimate the natural frequencies of a plate structure with surface bonded piezoelectric patches without the above-mentioned assumptions. A detailed modeling of the patches is developed by expressing the electric potential inside the patch as a quadratic function of thickness coordinate. The equations of motion are derived for a generally isotropic plate with surface bonded segmented patches. Solution to the dynamic equation of motion are obtained using Fourier series method for a plate with collocated piezoelectric actuator/sensor patches. The effect of the passive and active stiffness' of the surface bonded actuator and sensor patches on the dynamic characteristics of host plate structure is investigated.

关键词： Plates (structural components)

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Vibration distribution reconstruction and control of a thin plate by using distributed PVDF sensors affixed to the plate

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Proceedings of SPIE - The International Society for Optical Engineering 2000年 3984卷 576-586页

作者： Nagayasu, Katsuyoshi Uchida, Norio Hayashi, Takuro Takahashi, Hiroshi Toshiba Corp Kanagawa Japan

In this study, vibration distribution of a thin plate is detected using outputs from a number of long-span piezoelectric films that serve as distributed vibration sensors affixed on the plate. Using long-span piezoelectric films, only the integrated strains along the direction of the sensor span could be obtained. However, in the case that plural sensors were affixed and a kind of transformation was used, the vibration distribution could be obtained. We are considering applying the method for vibration control of space structures, namely antennas and/or solar battery paddles. In this study, basic technology for realizing the applications is presented. The strain distributions and the sensor outputs are predicted and calculated using NASTRAN (Finite Element Method). The strain distributions of a vibrating rectangular thin plate to which a number of long-span PVDF films were affixed are detected by experiment. These PVDF films are cut into several kinds of sinusoidal shapes and the outputs of the films are composed to the vibration distribution. This method is based on the theory that waves of any kind are composed by the sum of trigonometric function series. The usefulness of this approach is confirmed by comparing the calculational and experimental results.

关键词： Sensors

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Active structural acoustic control of a thick-walled cylindrical shell

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Proceedings of SPIE - The International Society for Optical Engineering 2000年 3984卷 112-124页

作者： Song, Kyungyeol Atalla, Mauro J. Hall, Steven R. Massachusetts Inst of Technology Cambridge United States

We consider the problem of reducing the noise radiation from a thick-walled cylindrical shell by actively controlling the motion of the shell's outer surface. Because the shell is very stiff, it is difficult to directly control the shell deflections. Instead, the proposed approach is to cover the shell's outer surface with curved active composite panels. Each panel contains several embedded accelerometers mounted to its outer and inner surfaces, which can sense both the motion of the panel base (i.e., the outer motion of the shell) and the outer surface of the panel (i.e., the radiating surface). The accelerometers are used in both feedback and feedforward architectures, in which the accelerometer signals are used to command the panel displacement, in order to reduce the motion of the panel outer surface, reducing the radiated noise. Experimental results show that, in the best case, 10-30 dB of surface vibration reduction can be achieved in the frequency range of interest, which is 250-2000 Hz.

关键词： Acoustic variables control

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Enhancement of the operating speed and accuracy of parallel and cooperating robots with smart materials

Enhancement of the operating speed and accuracy of parallel ...

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smart structures and materials 2000 Conference

作者： Yuan, LF Rastegar, JS SUNY Stony Brook Dept Mech Engn Stony Brook NY 11794 USA

ISBN: (纸本)0819436038

Robot manipulators with parallel kinematics chains and two or more robots manipulating an object form closed kinematics chains. When revolute joints are used in the construction of such robotic manipulation systems, the presence of closed chains and their associated kinematics nonlinearity demands high harmonic motions in at least a number of the actuated joints. This is the case even if all the links are relatively rigid and attempt is made to synthesise the joint motions with minimal harmonic content. The presence of high harmonic components in the actuated joint motions is undesirable since as the operating speed is increased, their frequencies would rapidly increase and move beyond the dynamic response limitations of the actuating drives, thereby causing vibration and control problems. The performance of the system in terms of cycle time, tracking precision and the like would therefore suffer. This is particularly the case since the dynamics of such systems is also highly nonlinear and require higher harmonic components in the actuating torques (forces). In this paper, a systematic method is presented for optimal integration of smart (active) materials based actuators into the structure of cooperating robots and robot manipulators with parallel kinematics chain for the purpose of eliminating the high harmonic components of their actuated joint motions. As the result, the potential excitation of the natural modes of vibration of such systems and their related control problems can be greatly reduced. The resulting robotic systems should therefore be capable of operating at higher speeds with increased precision.

关键词： Actuators Robots smart materials Kinematics control systems Robotic systems Complex systems Vibration control Optimization (mathematics) Robotics

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Design of robust controllers for smart structural systems with structured uncertainties

Design of robust controllers for smart structural systems wi...

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smart structures and materials 2000 - mathematics and control in smart structures

作者： Sana, Sridhar Rao, Vittal S. Univ of Missouri-Rolla Rolla MO United States

A controller synthesis procedure based on Popov stability results for reducing the conservatism in the design is introduced. This design procedure is applied on a smart structural test article and the results are pres... 详细信息

关键词： Intelligent structures

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Uncertainty models for control of distributed actuator and sensor arrays

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Proceedings of SPIE - The International Society for Optical Engineering 2000年 3984卷 415-424页

作者： Gorinevsky, Dimitry Stein, Gunter Honeywell Technology Cent Cupertino United States

This paper considers control analysis approaches for systems incorporating large actuator and sensor arrays. Applications of such systems are increasingly common because of the development of micro-systems technology. Many imaging systems have large one-dimensional or two-dimensional arrays of actuators. This includes RF or optical reflectors, display, printing, and other systems. Signal processing for large sensor arrays has well-established theory and applications, especially in imaging. At the same time, approaches to control of large distributed actuator and sensor arrays are much less developed. This paper considers one of the fundamental issues and design and analysis of large actuator and sensor array systems. The key notion in modern feedback control theory is the notion of uncertainty and associated notion of control robustness to this uncertainty. In control of dynamical systems evolving in time, structured uncertainty models are commonly accepted for theoretical analysis (Structured Singular Value or μ-analysis) and practical control design. In control of spatially distributed processes, there is a need to establish appropriate models of the uncertainty of the system spatial and dynamical characteristics. This paper discusses an extension of structured uncertainty models towards controlled systems with spatially distributed arrays of actuators and sensors. Unlike a dynamical uncertainty, spatial uncertainty is not causal in the spatial coordinate. This leads to related but different uncertainty models in the two case. For spatial coordinates, boundary effects also contribute to the modeling error. By using the discussed uncertainty models, the existing methods of robust control design and analysis can be extended towards spatially distributed systems. As an illustrative example, this paper demonstrates an application of the developed approach to a one-dimensional model of a flexible reflector with a distributed actuator array for shape control.

关键词： Uncertain systems

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Fuzzy finite-element analysis of smart structures

Fuzzy finite-element analysis of smart structures

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smart structures and materials 2000 - mathematics and control in smart structures

作者： Akpan, U.O. Koko, T.S. Orisamolu, I.R. Gallant, B.K. Martec Ltd Halifax NS Canada

A fuzzy finite element based approach is developed for modelling smart structures with vague or imprecise uncertainties. Fuzzy sets are used to represent the uncertainties present in the piezoelectric, mechanical, thermal, and physical properties of the smart structure. In order to facilitate efficient computation, a sensitivity analysis procedure is used to streamline the number of input fuzzy variables, and the vertex fuzzy analysis technique is then used to compute the possibility distributions of the responses of the smart structural system. The methodology has been developed within the framework of the smartCOM computational tool for the design/analysis of smart composite structures. The methodology developed is found to be accurate and computationally efficient for solution of practical problems.

关键词： Intelligent structures

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Robust disturbance rejection for flexible mechanical structures

Robust disturbance rejection for flexible mechanical structu...

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smart structures and materials 2000 - mathematics and control in smart structures

作者： Enzmann, Marc R. Doschner, Christian Otto-von-Guericke-Univ Magdeburg Magdeburg Germany

A procedure to determine controller parameters using principles from Internal Model control (IMC) in combination with Quantitative Feedback Theory (QFT) for robust vibration control of flexible mechanical structures is presented. This design process is demonstrated using a simply structured plant as an example. Through this example, the important features of the design process are illuminated.

关键词： Vibration control

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Neural control and system identification using a similarity approach

Neural control and system identification using a similarity ...

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smart structures and materials 2000 - mathematics and control in smart structures

作者： Brueckner, Steffen Rudolph, Stephan Universitaet Stuttgart Stuttgart Germany

For nonlinear and adaptive control of smart structures direct and indirect neural network control strategies have been suggested. In indirect neural network control the identified plant models are usually implemented as black-box neural networks using no a priori knowledge. Designing a neural network for system identification using dimensional analysis results in neural networks, where in contrary to black-box solutions no dimensionally inhomogeneous states can occur. Furthermore, the generalization and learning properties of neural networks designed using dimensional analysis are usually improved compared to conventional black-box networks. This work describes a technique of using neural networks for system identification and control, where the neural network has been constructed according to a dimensional analysis of the governing equations.

关键词： Intelligent structures

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