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Nonlinear control of PZT actuated trailing edge flaps

Proceedings of SPIE - The International Society for Optical Engineering 1999年 3667卷 380-393页

作者： Kurdila, A. Li, Jing Fulton, M. Webb, Glenn Mechanics and Engineering Science Gainesville United States

While PZT exhibits only mild nonlinear response at low voltage levels, it is well-known that the response can be profoundly nonlinear at high field strengths. Moreover, the use of mechanical linkages and structural design to amplify the stroke of PZT-based actuation likewise can couple with this material nonlinearity to yield a structural level nonlinearity that is non-negligible. In this paper, we investigate such a nonlinear response in a PZT actuated trailing edge flap attached to a scaled helicopter rotor blade. While the example studied in this paper is quite specific, the methodology derived is generally applicable. We extend the recent results of [18,19] for the derivation of closed loop control for active material actuated devices. In this technique, a compensator derived from an offline identification of a Krasnoselski-Pokrovski hysteresis operator is cascaded with the plant. We show that the methodology is well-posed for the class of problems under consideration; we derive closed loop stability and robustness conditions that can be associated with the prediction error in the identified hysteresis operator. We study the performance of our methodology in numerical examples and discuss relevant experimental results.

关键词： Actuators

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Design of flextensional transducers using the homogenization design method

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Proceedings of SPIE - The International Society for Optical Engineering 1999年 3667卷 232-243页

作者： Silva, Emilio C.N. Nishiwaki, Shinji Kikuchi, Noboru Universidade de Sao Paulo Sao Paulo Brazil

Flextensional transducers consist of a piezoceramic (or a stack of piezoceramics) connected to a flexible mechanical structure that converts and amplifies the output displacement of the piezoceramic. Among the applications, they can be used as actuators and sonars. The transducer performance in these applications depends on the distribution of mass, stiffness, and flexibility in the coupling structure domain, which is related to the coupling structure topology. By designing other types of coupling structures connected to the piezoceramic, we can obtain new types of flextensional transducers with enhanced performance for a desired application. In this work, we extended the method for designing flextensional transducers in static and low-frequency applications to dynamic applications by introducing the inertia effect in the optimization problem. The method applies topology optimization technique based on the homogenization design method, which consists of finding the optimal material distribution in a perforated design domain with infinite microscale voids. The problem is posed as the design of a flexible structure coupled to the piezoceramic that produces high output displacements in a specified point of the domain and direction, in a specified frequency. Therefore, it consists of designing a flexible structure with a specified mode shape in a desired resonance frequency. As a result, designs of flextensional transducers are presented.

关键词： Intelligent structures

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Shaping of distributed piezoelectric sensors for flexural vibrations of smart beams

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Proceedings of SPIE - The International Society for Optical Engineering 1999年 3667卷 418-426页

作者： Irschik, Hans Krommer, Michael Pichler, Uwe Johannes Kepler Univ of Linz Linz Austria

This paper is concerned with flexural vibrations of smart beams. Layers made of piezoelectric material are used to perform a distributed sensing of strains. In the present contribution, special emphasis is given to the sensor shaping problem, which can be stated as follows: Seek a shape function of the distributed sensor such that a mechanical interpretation of the sensor output is possible, e.g. to interpret the output as deflection, or as a slope. The scope of the present contribution is to find a class of easy to obtain analytic solutions of this inverse problem, and to present an experimental verification. Within the context of the Bernoulli-Euler beam theory, sensor equations are derived taking into account the coupling of mechanical and electrical fields. The principle of virtual work is then applied to derive integral equations for the structural deformations e.g. deflection, slope, curvature. Comparing these integral equations, the above sensor shaping problem is solved. Beams with different boundary conditions are considered. Furthermore, shape functions responsible for non-uniqueness of the shaping problem are derived. These nilpotent solutions may be added to the above derived solution of the sensor shaping problem without influencing the measured sensor signal. The analytical results of the sensor shaping problem are realized in a series of experiments for a cantilever beam, without and including a redundant support. Deflections measured by the new type of distributed piezoelectric sensor are compared to laser based distance measurements. Excellent coincidence between these measurements is found.

关键词： Beams and girders

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Mixed multi-field finite element formulation for thermopiezoelectric composite shells

Mixed multi-field finite element formulation for thermopiezo...

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Proceedings of the 1999 smart structures and materials - mathematics and control in smart structures

作者： Lee, Ho-Jun Saravanos, Dimitris A. NASA Lewis Research Cent Cleveland OH United States

Analytical formulations are presented which account for the coupled mechanical, electrical, and thermal response of piezoelectric composite shell structures. A new mixed multi-field laminate theory is developed which combines `single layer' assumptions for the displacements along with layerwise fields for the electric potential and temperature. This laminate theory is formulated using curvilinear coordinates and is based on the principles of linear thermopiezoelectricity. The mechanics has the inherent capability to explicitly model both the active and sensory responses of piezoelectric composite shells in thermal environments. Finite element equations are derived and implemented for an eight-noded shell element. Numerical studies are conducted to investigate both the sensory and active responses of piezoelectric composite shell structures subjected to thermal loads. Results for a cantilevered plate with an attached piezoelectric layer are compared with corresponding results from a commercial finite element code and a previously developed program. Additional studies are conducted on a cylindrical shell with an attached piezoelectric layer to demonstrate capabilities to achieve thermal shape control on curved piezoelectric structures.

关键词： Shells (structures)

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Dissipativity based control of plate vibrations by piezoelectric sensors and actuators

Dissipativity based control of plate vibrations by piezoelec...

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smart structures and materials 1999 Conference

作者： Schlacher, K Kugi, A Johannes Kepler Univ Inst Automat Control A-4040 Linz Austria

ISBN: (纸本)0819431419

Piezoelectric devices represent an important new group of actuators and sensors for active vibration control systems. Indeed, this technology allows to construct spatially distributed devices. A mathematical model of a multilayered piezoelectric plate, which takes hysteresis and polarization of the piexoelectric laminae into account, is presented. Passive control for Lagrangian systems is used to derive a class of stabilizing control laws, which are based on the collocation of sensors and actuators. Therefore, the design of the spatial distribution of the sensors/actuators is considered as a part of the controller synthesis.

关键词： Sensors Actuators control systems Mathematical modeling Polarization Electrodes Vibration control Active vibration control Multilayers Software

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Reduced order modeling for low Reynolds number flow control

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Proceedings of SPIE - The International Society for Optical Engineering 1999年 3667卷 68-79页

作者： Kurdila, A.J. Carroll, B. Nishida, T. Sheplak, M. Univ of Florida Gainesville United States

This paper presents recent analytical and experimental research to modify and control low Reynolds number flows over prototypical airfoils associated with micro-air-vehicles. The simplified experimental test geometry consists of a meso-scale piezoceramic actuated flap that undergoes peak amplitude displacements of 40 microns. The flap actuator array is designed to modify separation and reattachment location on the airfoil. The location of the reattachment on the upper surface of the prototypical airfoil is measured by an array of MEM's shear stress sensors located downstream. The focus of this paper is the discussion of the status and applicability of reduced order modeling techniques for the derivation of active feedback flow control strategies for the prototypical active airfoil. Frequently, reduced order models are derived from a library of component fluid modes which serve as the basis for a low dimensional approximation of the nonlinear Navier Stokes equations. The methodology discussed in this paper differs markedly from these approaches. We derive a technique employing multiresolution and wavelet approximations of nonlinear Volterra series that represent the input-output dynamics of the system. The accuracy of the resultant low-dimensional input-output models is validated on a benchmark nonlinear aeroelastic testbed.

关键词： Flow control

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Performance considerations in the control of helicopter vibration

Performance considerations in the control of helicopter vibr...

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smart structures and materials 1999 Conference

作者： Konstanzer, P Kröplin, B Univ Stuttgart Inst Stat & Dynam Aerosp Struct D-70569 Stuttgart Germany

ISBN: (纸本)0819431419

The paper discusses feedback control strategies for the reduction of helicopter vibration using a trailing edge flap located at the outer part of the rotor blades. The problem of reducing rotor-induced vibration is considered as a disturbance rejection control problem where robust servomechanism control is applied in combination with optimal constant output, feedback. This control scheme is examined in the view of limitations in the transient performance by investigating the zeros of the multivariable system. Local control strategies in the rotating system are developed for active damping enhancement. Simulations are presented based on a BO105 helicopter.

关键词： helicopter rotor active control disturbance rejection control servomechanism control active damping

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Real-time automatic tuning of vibration controllers for smart structures by genetic algorithm

Real-time automatic tuning of vibration controllers for smar...

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smart structures and materials 1999 Conference

作者： Kwak, MK Shin, TS Dongguk Univ Dept Mech Engn Joong Gu Seoul 100715 South Korea

ISBN: (纸本)0819431419

This paper is concerned with the real-time automatic tuning of the positive position feedback controller for smart structures by the genetic algorithms. The genetic algorithms have proven its effectiveness in searching optimal design parameters without falling into local minimums thus rendering globally optimal solutions. The advantage of the positive position feedback controller is that if it is tuned properly it can enhance the damping value of a target mode without affecting other modes. In this paper, we develop a real-time algorithm for determining a tuning frequency of the PPF controller based on the genetic algorithm. Hence, the traditional positive position feedback controller can be used in adaptive fashion in real time. To this end, the digital PPF control law is downloaded to the DSP chip and a main program, which runs genetic algorithms in real time, updates the parameter of the controller in real time. The real-time tuning of the PPF controller is applied to cases of initial disturbance and persistent harmonic disturbance. In both cases, the real-time tuning is achieved successfully. Hence, vibrations are suppressed satisfactorily. The experimental results also show that the PPF controller tuned by GA gives better performance than the manually tuned PPF controller for accommodating harmonic disturbances did.

关键词： active vibration control genetic algorithm disturbance accommodating control

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control of SMA actuators in dynamic environments

Control of SMA actuators in dynamic environments

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smart structures and materials 1999 Conference

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

ISBN: (纸本)0819431419

The strain-temperature hysteresis for shape memory alloy (SMA) actuators has: been shown, to undergo large changes according to the applied load. This paper provides an adaptive hysteresis model capable of accounting for a time-varying hysteresis, specifically SMA hysteresis under a, varying applied stress. Previous research has established excellent performance, in both numerical and laboratory experiments, of the adaptive hysteresis model for actuators with fixed hysteresis. In this paper, the performance of the adaptive model when there are significant changes in the hysteresis characteristics is examined in laboratory tracking experiments.

关键词： hysteresis adaptive control SMA adaptive compensation hysteretic actuators

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Artificial Neural Network for piezoelectric control systems

Artificial Neural Network for piezoelectric control systems

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smart structures and materials 1999 Conference

作者： Bakhashwain, J Refaee, J Sunar, M Mohandes, M King Fahd Univ Petr & Minerals Dept Elect Engn Dhahran 31261 Saudi Arabia

ISBN: (纸本)0819431419

This paper presents a neural network controller for a piezoelectric controlled structure by emulating the control performance of a Linear Quadratic Gaussian (LQG) controller. The configuration of the Artificial Neural Network (ANN) is simple, yet it is efficient in terms of its high learning speed and good generalization ability. A case study is presented to demonstrate the performance of the ANN controller versus the LQG controller. The test results for different disturbances on the structure show excellent agreement between the ANN and LQG controllers.

关键词： neural network LQG controller piezoelectric structure

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