Neural network based predictive control for random vibration suppression has been demonstrated on a cantilevered beam with bonded piezoelectric actuators and sensors. This real time system is run on a 60 MHz Pentium p...
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ISBN:
(纸本)0819420905
Neural network based predictive control for random vibration suppression has been demonstrated on a cantilevered beam with bonded piezoelectric actuators and sensors. This real time system is run on a 60 MHz Pentium processor and is considered a stepping stone to both adaptive flutter suppression and buffet load alleviation in advanced aerospace vehicle. An extended neural control system using Intel/Nestor's ETANN analog neural network chip is discussed. Generalized neural predictive control uses a neural network based model of a system to make predictions about the effect of future control signals on the response of the system. These predictions can be used with a tailored performance index to determine the optimal control signal for the modeled system. A comparison of this approach with both PID and pole placement control methods shows ease of implementation comparable to that of the PID controller with the approximate performance of the pole placement method. The advantages of neural control over conventional control techniques include a simpler and more cost effective design methodology as well as the capability to learn on-line the time varying nature of a system due to wear, loss of actuators, or other causes.
smartstructures lend themselves naturally to a decentralized control design framework, especially with adaptation mechanisms. The main reason being that it is highly undesirable to connect all the sensors and actuato...
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ISBN:
(纸本)0819420905
smartstructures lend themselves naturally to a decentralized control design framework, especially with adaptation mechanisms. The main reason being that it is highly undesirable to connect all the sensors and actuators in a large structure to a central processor. It is rather desirable to have local decision-making at each smart patch. Furthermore, this local controllers should be easily `expandable' to `contractible.' This corresponds to the fact that addition/deletion of several smart patches should not require a total redesign of the control system. The decentralized control strategies advocated in this paper are of expandable/contractible type. On another front, we are considering utilization of micro-strip antennas for power transfer to and from smartstructures. We have made preliminary contributions in this direction and further developments are underway. These approaches are being pursued for active vibration damping and noise cancellation via piezoelectric ceramics although the methodology is general enough to be applicable to other type of active structures.
An active vibration control of a smart flexible structure featuring a piezofilm actuator is presented in this study. A governing equation of motion for the smart beam structure is derived and a state space model is ob...
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ISBN:
(纸本)0819420905
An active vibration control of a smart flexible structure featuring a piezofilm actuator is presented in this study. A governing equation of motion for the smart beam structure is derived and a state space model is obtained in order to formulate a controller. A new discrete- time sliding mode controller is proposed for a single-input linear system with mismatched uncertainties. The main difference between the discrete-time sliding mode control and the continuous-time sliding mode control is the determination of the existence condition of the sliding mode. In the discrete-time case, both the sliding condition and the convergence condition must be satisfied. In the design of the discontinuous controller, a time-varying gain that is a function of the relation between predetermined sliding surface and representative points in the state space is adopted to minimize a sliding region. In addition, for faster reaching to the sliding surface, an equivalent controller separation method is employed. The proposed controller is applied to the smart structure, and control responses of transient and forced vibrations are evaluated by undertaking both simulation and experiment.
This paper considers an optimal control problem constrained by coupled hyperbolic and parabolic-like dynamics arising in an acoustic structure interaction. A numerical algorithm, based on the FEM, is formulated for co...
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ISBN:
(纸本)0819420905
This paper considers an optimal control problem constrained by coupled hyperbolic and parabolic-like dynamics arising in an acoustic structure interaction. A numerical algorithm, based on the FEM, is formulated for computations of solutions to associated Matrix Algebraic Riccati Equations. Results of a numerical simulation of the algorithm are presented.
In this paper a set of controllability and observability conditions are proposed for vibration control systems with viscoelastic damping. Both conditions are stated in terms of the eigenstructures (eigenvalues and eig...
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ISBN:
(纸本)0819420905
In this paper a set of controllability and observability conditions are proposed for vibration control systems with viscoelastic damping. Both conditions are stated in terms of the eigenstructures (eigenvalues and eigenvectors) of the control systems under consideration. They are similar to the well known eigenvector tests, except that to determine controllability, the knowledge of the stress-strain relations of the viscoelastic damping material is needed in addition to the modal information.
This paper is concerned with the basic mathematical aspects of a newly suggested theory of smart composite structures. The governing equations describing the behavior of a smart composite structure incorporating senso...
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ISBN:
(纸本)0819420905
This paper is concerned with the basic mathematical aspects of a newly suggested theory of smart composite structures. The governing equations describing the behavior of a smart composite structure incorporating sensors and actuators are derived. The basic optimization problems in the theory of smartstructures are formulated. The discussion on some relevant aspects of the optimal control theory, and on similarities and discrepancies between the theory of smartstructures and theory of optimal control is provided. The basic optimization problems for the smartstructures are illustrated by the applied examples of practical interest. In these examples, two major sources of control are emphasized, namely, residual strains and material properties.
Piezoceramic actuators are used in tandem with conventional actuator to design control laws for a Timoshenko slewing beam. The equations are presented in an abstract first order form. Feedback laws are obtained in the...
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ISBN:
(纸本)0819420905
Piezoceramic actuators are used in tandem with conventional actuator to design control laws for a Timoshenko slewing beam. The equations are presented in an abstract first order form. Feedback laws are obtained in the context of LQR theory. Convergent functional gains are obtained and time responses of the closed loop system are presented. It is shown that the piezoceramic actuators can significantly enhance the closed-loop response of the system.
In this paper we are concerned with smartmaterials that contain many actuators and sensors along with digital signal processing electronics that allow for the implementation of a control algorithm. smartmaterials ha...
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ISBN:
(纸本)0819420905
In this paper we are concerned with smartmaterials that contain many actuators and sensors along with digital signal processing electronics that allow for the implementation of a control algorithm. smartmaterials have been proposed for the active control of sound from a vibrating structure. Here we investigate the design of structural control systems for these smartstructures for noise suppression. First we model the radiated acoustic waves in terms of the velocity of the surface of the structure. Then we formulate an optimal control problem as a linear system that has a transmission zero in the path between the disturbance force and the shape that radiates best. A geometric description of the problem relates control problem to the acoustics. This optimal control problem is solved using a genetic algorithm.
Thanks to the recent advances in control of structures by distributed piezoelectric elements, the concept of independent control and sensing of the structural modes has reemerged in the published literature. In partic...
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ISBN:
(纸本)0819420905
Thanks to the recent advances in control of structures by distributed piezoelectric elements, the concept of independent control and sensing of the structural modes has reemerged in the published literature. In particular, to this end, piezoelectric orthogonal actuators and sensors have been introduced. On the other hand, Independent Modal-Space control (IMSC) of distributed-parameter-system (DPS) is a well-known approach advocated by the author and his associates throughout the past two decades. In the 1980's it has been shown by its proponents that the IMSC method ultimately represents a globally optimal distributed-control and distributed-sensing approach to structural control. Piezoelectric elements are not exception to the general theoretical concepts of distributed-control and sensing of DPS's via the IMSC method. By a constructive theoretical approach, it is shown in this paper that the recent results characterized by the phrases `independent modal control' and `orthogonal actuators and sensors' constitute precise piezoelectric realizations of the IMSC method of the author and his past associates, almost two decades after its introduction.
The problem of controlling the bending vibration of cantilevers modeled as thin-walled beams of closed cross-section incorporating a number of nonclassical effects, such as transverse shear, secondary warping and hete...
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ISBN:
(纸本)0819420905
The problem of controlling the bending vibration of cantilevers modeled as thin-walled beams of closed cross-section incorporating a number of nonclassical effects, such as transverse shear, secondary warping and heterogeneity, is investigated. The control is carried out by means of piezoelectric materials bonded or embedded into the host structure. The control law represents a combination of displacement, velocity and acceleration feedback. The capabilities and efficiency of this control methodology are illustrated and a number of relevant conclusions are outlined.
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