In this paper a robust controller has been implemented on a smart structure test article using the Intel's Electronically Trainable Analog Neural Network (ETANN) chip i80170NX. The smart structure test article use...
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ISBN:
(纸本)0819417912
In this paper a robust controller has been implemented on a smart structure test article using the Intel's Electronically Trainable Analog Neural Network (ETANN) chip i80170NX. The smart structure test article used in this study was a cantilever plate with a pair of PZTs as actuators and PVDF film sensors. A two step connectionist approach was used to design and implement the neural network based controller. To meet the desired closed loop performance requirements, a simple linear quadratic regulator (LQR) controller is designed. The spatially distributed sensors allow the direct measurement and feedback of the states of the system. A copy of this controller is transferred into the ETANN chip and the trained chip is used to control the test system. A custom board and electronic circuits were developed for interfacing the neural network chip and the smart structure test article. The steps involved in training and implementing robust controllers on a smart structure have been outlined. Some of the practical considerations of implementing a robust controller using the ETANN chip have been pointed out and dealt with. Experimental verification of the closed loop performance of the conventional LQR controller as well as the neural network controller are also shown.
This paper describes an approach for designing a structure- control system based on the linear quadratic regulator (LQR) which suppresses vibrations in structures. Bounds are placed on the control forces to simulate r...
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ISBN:
(纸本)0819417912
This paper describes an approach for designing a structure- control system based on the linear quadratic regulator (LQR) which suppresses vibrations in structures. Bounds are placed on the control forces to simulate real actuators. The control system is optimized with an objective function of the time to reduce the energy of the vibrations to 5% of its initial value. The design variables are the bounds on each control force with a constraint on the sum of the bounds. As an example to illustrate the application of an approach, a wing box idealized by rod elements is used. control systems are designed for this structure using four and eight actuators for several locations.
In recent years, polyvinylidene fluoride (PVDF) film has been extensively used in the development of distributed sensors. However, very few results are available for shaping distributed sensors for control of two dime...
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ISBN:
(纸本)0819417912
In recent years, polyvinylidene fluoride (PVDF) film has been extensively used in the development of distributed sensors. However, very few results are available for shaping distributed sensors for control of two dimensional structures. In this study, we have utilized simple geometric shapes for the implementation of feedback controllers on a cantilevered plate system. Multiple distributed sensors along with their time derivatives are used for system identification and the implementation of complex controllers. The resulting direct implementation minimizes the electronic hardware requirements of the controller. A system identification technique for deriving a state variable representation of the structural system using distributed sensors is studied. The state variables of the model are defined as the quantities being measured by the distributed sensors. This technique was originally developed for one-dimensional structures and is extended to the two-dimensional plate system in this paper. The availability of the states of the system simplifies the state space control system design and the implementation of full-state feedback controllers. Linear quadratic regulator (LQR) and H∞ controllers can be implemented with simple analog hardware. A full state feedback LQR controller is implemented on the experimental system which incorporates all of the necessary signal conditioning electronics. The results of simulation and experimental results are presented.
In this work, the problem of optimal placement of piezoelectric actuators along a flexible structure is considered. The design goal is to optimize the actuators' performance in vibration suppression of a beam cant...
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ISBN:
(纸本)0819417912
In this work, the problem of optimal placement of piezoelectric actuators along a flexible structure is considered. The design goal is to optimize the actuators' performance in vibration suppression of a beam cantilevered on one end to a rotating hub. First the control problem is presented as an infinite-dimensional linear quadratic regulator problem. Then an approximation framework based on a Legendre polynomials based Galerkin method for approximating the control system is developed. Two different approximate performance measures that are based on the LQR cost function are considered and numerical examples are presented to illustrate efficacy of each measure.
Ferroelectric crystals are widely used for manufacturing smart actuators owing to their strong electromechanical coupling effect and the prompt response to the applied electric fields. Many ferroelectric actuators are...
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ISBN:
(纸本)0819417912
Ferroelectric crystals are widely used for manufacturing smart actuators owing to their strong electromechanical coupling effect and the prompt response to the applied electric fields. Many ferroelectric actuators are operated under cyclic loading conditions. The cyclic-loading strengths of these materials are, however, substantially lower than their monotonic-loading strengths. It has been observed that the macroscopic properties of these materials deteriorate after a large number of cycles of the applied electric field. This is the so-called electric fatigue. Recent experimental investigations suggest that microcracking may be the major cause of electric fatigue. The authors investigated the interactions of ferroelectric twins with grain boundaries and pre-existing microcracks. They have demonstrated that the stress fields exhibit a power-law singularity at the intersecting points of twinning planes and grain boundaries. This concentration in stresses may initiate microcracks at the intersecting points. They have also shown that the formation of ferroelectric twins at a pre-existing crack tip results in stronger singularities of the stress and electric fields than the common (root)r-singularity. This indicates that the interaction between the ferroelectric twins and the microcracks may promote crack growth.
This paper discusses the Adaptive Neural control (ANC) Architecture for on-line system identification and adaptive control. After reviewing results to-date involving control of structural vibration, we describe extens...
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ISBN:
(纸本)0819417912
This paper discusses the Adaptive Neural control (ANC) Architecture for on-line system identification and adaptive control. After reviewing results to-date involving control of structural vibration, we describe extensions of the ANC architecture to handle adaptive control of smartstructures involving large numbers of distributed actuators and sensors.
In this paper, we study a mathematical model which describes a particular fluid/structure interaction system of current interest at the NASA Langley Research Center.
ISBN:
(纸本)0819417912
In this paper, we study a mathematical model which describes a particular fluid/structure interaction system of current interest at the NASA Langley Research Center.
We investigate the prospects for intelligent control of smart composites (containing sensors, actuators, power supply, and signal conditioning) that are envisioned for applications in rotorcraft systems (rotor blades,...
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ISBN:
(纸本)0819417912
We investigate the prospects for intelligent control of smart composites (containing sensors, actuators, power supply, and signal conditioning) that are envisioned for applications in rotorcraft systems (rotor blades, power shafts, fuselage shell). This paper is concerned with multi-dimensional wavelets and relevant heuristic procedures for fast and parsimonious identification. We also discuss some control techniques based on the idea of a homogeneous system model.
The paper deals with determination of specific material properties of a complex material architecture consisting of the elastic layer of finite thickness, the thin viscoelastic layer and the porous halfspace. Those pr...
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ISBN:
(纸本)0819417912
The paper deals with determination of specific material properties of a complex material architecture consisting of the elastic layer of finite thickness, the thin viscoelastic layer and the porous halfspace. Those properties should sustain specific external thermomechanical loadings.
The approach to modeling and control of smart flexible structures presented in this paper is based on the claim that an intelligent structure requires an internal knowledge of self which may be acquired from local mod...
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ISBN:
(纸本)0819417912
The approach to modeling and control of smart flexible structures presented in this paper is based on the claim that an intelligent structure requires an internal knowledge of self which may be acquired from local models of substructure dynamics. This approach employs analog models of the flexible structures in model-based controller designs. These analog models are created using VLSI circuitry and are embedded into the physical structure. The model of a composite structure is formed by interconnecting the analog models of single finite elements. The goal of this research is to devise such analog VLSI circuit models of single elements that can be easily connected together to model flexible structures. The circuit models are highly repetitive and, thus, are amenable to integration on a VLSI chip. A simple finite element circuit model has been integrated on an analog VLSI chip. Results clearly show that the poles of the circuits correspond very closely with the theoretical poles of the beam.
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