Microelectromechanical systems or MEMS have evolved into multiple component mechanisms. MEMS may consist of mechanical elements such as flexible beams and optical components, these elements may require precision struc...
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ISBN:
(纸本)0819424595
Microelectromechanical systems or MEMS have evolved into multiple component mechanisms. MEMS may consist of mechanical elements such as flexible beams and optical components, these elements may require precision structural pointing or Vibrations from MEMS elements and environmental disturbances may interfere with precision motion Specific MEMS applications examined that may require microactuation control include scanning probe microscopes and microgrippers. A device merging smart material and microelectromechanical system concepts is presented as a response to MEMS active control needs. The device, approximately 2000 x 200 x 800 mu m is a strain amplification mechanism composed of electroplated nickel. The device amplifies stroke of piezoelectric material and is constructed using the LIGA technique. Experimental results are presented along with finite element analysis of the mechanical microamplifier indicating a viable design solution exits for solid-state microactuators.
Material interfaces are commonly encountered in the fabrication of smart structural elements. Common examples are electrode-actuator-host material interfaces. Interface behavior is a very critical issue in the develop...
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ISBN:
(纸本)0819424528
Material interfaces are commonly encountered in the fabrication of smart structural elements. Common examples are electrode-actuator-host material interfaces. Interface behavior is a very critical issue in the development of a reliable smart structure technology. This study presents a set of analytical solutions that can be used in the computational fracture mechanics analysis of interface cracks in electronic materials and in smart structural elements. Exact solutions for 2D governing equations of piezoelectric and ideal elastic media are used. Shear and opening dislocations are modeled as discontinuities in the displacements at a piezoelectric-elastic interface. The interface is assumed to be electrically insulated. Closed form solutions are developed for stress and electric fields in a bi-material system. These solutions can be used in the analysis of interface fracture problems involving smart structural elements by applying the displacement discontinuity method.
We study dynamic deformations of a neo-Hookean composite plate with PZT sensors and actuators bonded to its top and bottom surfaces. The constitutive relation for the PZT is taken to be linear in the Green-Lagrange st...
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ISBN:
(纸本)0819424528
We study dynamic deformations of a neo-Hookean composite plate with PZT sensors and actuators bonded to its top and bottom surfaces. The constitutive relation for the PZT is taken to be linear in the Green-Lagrange strain tensor but quadratic in the driving voltage. It is shown that a simple feedback algorithm suffices to control the deformations of the plate.
The accuracy of stabilized, turreted gun systems like the 120mm gun on the M1A2 Abrams tank and the 30mm gun on the Apache helicopter are limited by, among other things, structural flexure of the gun barrel and suppor...
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ISBN:
(纸本)0819424528
The accuracy of stabilized, turreted gun systems like the 120mm gun on the M1A2 Abrams tank and the 30mm gun on the Apache helicopter are limited by, among other things, structural flexure of the gun barrel and support structure. An advanced actuation system based on piezoelectric translators and an optical fiber strain sensing system are described in conjunction with a rapid prototyping workstation for the design of distributed parameter control systems to actively minimize the effects of vibrations caused by traversing rough terrain or weapon firing.
control of longitudinal vibration and wave in a cantilevered beam is studied in this paper. The algorithm of the control system is based on the concept of active attenuation, the traveling wave of the structural respo...
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ISBN:
(纸本)0819424528
control of longitudinal vibration and wave in a cantilevered beam is studied in this paper. The algorithm of the control system is based on the concept of active attenuation, the traveling wave of the structural response can be annihilated by a control wave of opposite signature. Experimental tesults showed that the longitudinal vibration and wave have been substability suppressed in a beam.
We study the behavior of several organizations for a market based distributed control of unstable physical systems and show how a hierarchical organization is a reasonable compromise between rapid local responses with...
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ISBN:
(纸本)0819424528
We study the behavior of several organizations for a market based distributed control of unstable physical systems and show how a hierarchical organization is a reasonable compromise between rapid local responses with simple communication and the use of global knowledge. We also introduce a new control organization, the multihierarchy, and show that is uses less power than a hierarchy in achieving stability. The multihierarchy also has a position invariant response that can control disturbances at the appropriate scale and location.
A 3D finite element closed loop model is presented for modeling smartstructures to predict the effects of both active and active/passive damping on vibrating structures. A comprehensive finite element formulation is ...
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ISBN:
(纸本)0819424528
A 3D finite element closed loop model is presented for modeling smartstructures to predict the effects of both active and active/passive damping on vibrating structures. A comprehensive finite element formulation is presented that includes a control algorithm to relate the sensor voltage to the actuator voltage in a closed lop. Two control approaches based on charge or voltage as the active control force applied to the actuator are studied in the time and frequency domains. Constant velocity and constant displacement feedback control algorithms are subsequently implemented to investigate vibration controllability of structures. A model superposition in conjunction with direct integration is used in the time domain to overcome the numerical difficulties associated with an unsymmetric active damping matrix. A parametric study considers different types of controller as well as feedback gain. Comparisons are made between active constrained layer damping (ACLD) and purely active damping in the frequency domain. Some design studies are presented which examine the performance of ACLD modeling as a function of gain and viscoelastic materials thickness.
Model predictive control (MPC) is a control method which uses future predicted outputs of a system to determine the inputs to the system. The predictive control methods are well suited for systems where model identifi...
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ISBN:
(纸本)0819424528
Model predictive control (MPC) is a control method which uses future predicted outputs of a system to determine the inputs to the system. The predictive control methods are well suited for systems where model identification is difficult and expensive or where the parameters of the plant and environment change frequently. All of the predictive control methods are tracking controllers by nature. Most predictive control algorithms have been developed for use in the process control industry for set point tracking. The main advantage of MPC controllers over other tracking controllers is that they can act in advance of the actual time when there is a change in the set point. The use of predictive control for vibration suppression of smart structural systems investigated in this paper. For vibration suppression purposes, the set point of the predictive control is set to zero and the effect of the disturbances on the system performance is to be minimized. Many of the predictive control algorithms do not allow for the system output to substantially depart from its predicted values. However, the predictive controller proposed by Gawronski allow the prediction to converge to the correct value after a disturbance has occurred, even if the disturbance causes the output to oscillate as in the vibrations of smartstructures. We have proposed a modification to the predictive control algorithms by incorporating the prescribed degree of stability concept in the design. In order to demonstrate the capabilities of the proposed predictive controllers, we have designed and implemented the controllers on two simple test structures. The experimental closed-loop response of single input/single output and multi-input/multi-output structures is presented in the paper. The response of the predictive control system is compared with that of Linear Quadratic Gaussian controllers. The advantages and limitations of the predictive controllers are discussed in the paper.
Neural network based controllers for vibration suppression of smart structural systems have been reported in several recent studies. These studies have shown that in addition to conventional controller design methodol...
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ISBN:
(纸本)0819424528
Neural network based controllers for vibration suppression of smart structural systems have been reported in several recent studies. These studies have shown that in addition to conventional controller design methodologies, neural networks offer an effective basis for design and implementation of controllers. With the introduction of neural network chips like the electronically trainable analog neural network (ETANN) chip i80170NX by Intel and the Ni1000 chip by Nestor Corp., stand alone hardware implementation of neural network based controllers is possible. In this paper the capabilities of Intel's ETANN chip to implement linear and nonlinear controllers for smart structural systems have been investigated. A neural network based optimizing controller design methodology that integrates the ETANN chip and its capabilities of on-line adaptation has been developed. Apriori information of the smart structural systems such as actuator/sensor bandwidth limits and control effort limits can be directly accommodated in this method. Simulation studies of the performance of a closed loop time varying linear and nonlinear system has also been presented with and without on-line adaptation.
The goal of this paper is to examine the use of covariance control to directly design reduced-order multi-objective controllers for gust alleviation using adaptive materials as the control effector. It will use piezoe...
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ISBN:
(纸本)0819424528
The goal of this paper is to examine the use of covariance control to directly design reduced-order multi-objective controllers for gust alleviation using adaptive materials as the control effector. It will use piezoelectric actuators as control effectors in a finite element model of a full-size wing model. More precisely, the finite element model is of the F-16 Agile Falcon/Active Flexible Wing that is modified to use piezoelectric actuators as control effectors. The paper will also examine the interacting roles of important control design constraints and objectives for designing an aeroservoelastic system. The paper will also present some results of multiobjective control design for the model, illustrating the benefits and complexity of modern practical control design for aeroservoelastic systems that use adaptive materials for actuation.
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