检索结果-内蒙古大学图书馆

Model reduction & frequency weighted optimal vibration control of smart panels

Proceedings of SPIE - The International Society for Optical Engineering 2000年 3984卷 377-386页

作者： Chang, W. Varadan, V.V. Pennsylvania State Univ University Park United States

The optimal control algorithm is one of the feasible feedback algorithms for vibration suppression of flexible structures. One of the commonly encountered problems of the optimal control implementation is the spillover problem. The spillover generally occurs when modeling a continuous structure that has infinite number of resonance modes as a nominal model with finite modes for controller design. This paper presents a design of an optimal controller that is low order and can prevent the spillover problem when the unmodeled resonance modes perturb the feedback control loop. For low order controller design, this paper proposes modal Hankel singular values (MHSV) for efficient nominal model reduction. Low order controller can be derived from the reduced nominal model. For design of more stable controller, this paper applies frequency dependant weight functions to the cost function. The weight functions prevent the spillover by making optimal controller not to excite the resonance modes that are not included in nominal model. The optimal controller is derived the nominal model. This weight function approach optimizes the control performance and control stability by smoothening the discrepancy between the weights on the modeled modes to be controlled and unmodeled modes to be stabilized. A finite element model is exploited to develop the controller and to test its control performance and stability against high resonance mode spillover.

关键词： Optimal control systems

来源：评论

学校读者我要写书评

暂无评论

Reconfigurable arrays of collocated sensors and actuators for modal isolation

引用

Proceedings of SPIE - The International Society for Optical Engineering 2000年 3984卷 540-552页

作者： Fripp, Michael L. Atalla, Mauro J. Hagood, Nesbitt W. Massachusetts Inst of Technology Cambridge United States

Arrays of sensors and actuators designed to provide robust broadband feedback control with high performance and limited modeling are the subject of this paper. The reconfigurable array technique proposed here enables the design of reduced-order controllers for complex structures and offers the potential to improve closed-loop robustness and to broaden the region of good performance even as the plant changes. The weighted summation of sensor signals senses the modes that are relevant to performance while rejecting the remaining modes; therefore reducing the required complexity of the controller. These weights are obtained from the minimization of a cost function and under certain assumptions; it can be shown that a single optimum solution exists. The use of reconfigurable arrays is motivated by the need to control the vibration of complex structures. A thirty element collocated actuator and sensor array was bonded to a cylinder section. Array weights were computed and successfully applied to isolate target modes. Different methods of computing the weights are implemented and compared. The deleterious effects of spatial aliasing and the performance as a function of the array size are experimentally explored.

关键词： Feedback control

来源：评论

学校读者我要写书评

暂无评论

Programme of vibration control to variable thickness plates with piezoelectric sensors and actuators based on wavelet theory

引用

Proceedings of SPIE - The International Society for Optical Engineering 2000年 3984卷 553-561页

作者： Zhou, You-He Wang, Jizeng Jiang, Qing Lanzhou Univ Lanzhou China

This paper is to present a numerical program of dynamic control for suppressing external disturbance to variable thickness beam-plates with sensors and actuators of piezoelectric layers on/in the structures using the scaling function transform of the Daubechies wavelet theory for approximation of functions. After the generalized Gaussian integral is applied to the scaling function transform, an explicit expression of identification of deflection configuration of the structures is expressed by the electric charge/current signals measured from the piezoelectric sensors. When a control law of negative feedback of the identified deflection and velocity signals is employed, the wavelet Galerkin method or wavelet weighted residual method is used to determine control voltage applied on the piezoelectric actuators. Due to that the scaling function transform is like a low-pass filter which can automatically filter out high-order signals of vibration or disturbance from the measurement and the controller employed here, this control approach does not lead to the undesired phenomenon of control instability that is often generated in a control system and caused by the spilling over of high-order signals from measurement and controller if no special technique is used in the control system. Some numerical simulations are carried out to show the efficiency of the proposed approach.

关键词： Vibration control

来源：评论

学校读者我要写书评

暂无评论

Analytical solution technique for multiple-patch piezoelectric sensor-actuator vibration control problems

引用

Proceedings of SPIE - The International Society for Optical Engineering 2000年 3984卷 478-489页

作者： Sloss, James M. Bruch Jr., John C. Sadek, Ibrahim S. Adali, Sarp Univ of California Santa Barbara United States

An analytical method is given for the determination of the eigenfunctions and eigenfrequencies for one-dimensional structural vibration problems in the presence of patch sensors and patch actuators. The method is based on converting the differential equation formulation of the problem to an integral equation formulation. The conversion is accomplished by introducing an explicit Green's function. The Green's function consists of two parts, one taking account of the stiffness and the other taking account of the control moments induced by the distributed actuators. The control moments involve piezoelectric constants and feedback voltages made up of gains times the sensor signals. Obtaining the eigenvalues and eigenfunctions of this integral equation gives the solution to the piezo-control problem.

关键词： Piezoelectric devices

来源：评论

学校读者我要写书评

暂无评论

controlled continuous tuning of an adaptively tunable vibration absorber incorporating shape memory alloys

引用

Proceedings of SPIE - The International Society for Optical Engineering 2000年 3984卷 564-575页

作者： Williams, Keith A. Chiu, George T.-C. Bernhard, Robert J. Purdue Univ West Lafayette United States

controlled continuous tuning of the stiffness of shape memory alloy (SMA) spring elements of an adaptively tunable vibration absorber (ATVA) is a novel concept for adaptive-passive vibration control. Minimization of the vibration of a primary system is achieved indirectly via stiffness control of the SMA structural elements supporting a secondary mass. Stiffness control is further achieved via the heating of the SMA elements. In this paper a control law to achieve phase-tracking by controlling the heating of the SMA elements is developed and implemented. Successful analytical and experimental results demonstrate the feasibility of continuous control of the SMA ATVA. Performance of the SMA ATVA is compared to the performance of comparable passive tuned vibration absorbers (TVA). The comparison shows that substantial improvements in vibration attenuation can be achieved through the implementation of the SMA ATVA.

关键词： Vibration control

来源：评论

学校读者我要写书评

暂无评论

control of a directly-excited structural dynamic model of an F-15 tail section using positive position feedback

引用

Proceedings of SPIE - The International Society for Optical Engineering 2000年 3984卷 216-227页

作者： El-Badawy, Ayman A. Nayfeh, Ali H. Virginia Polytechnic Inst of State Univ Blacksburg United States

We investigated the use of positive position feedback (PPF) to suppress high-amplitude vibrations of a structural dynamic model of a twin-tail assembly of the F-15 fighter when subjected to primary resonance excitations. We developed the nonlinear differential equations of motion and obtained an approximate solution using the method of multiple scales. Then, we conducted bifurcation analyses for the open- and closed-loop response of the system and investigated theoretically the performance of the control strategy. The theoretical findings indicate that the control law leads to an effective vibration suppression and bifurcation control. We conducted experiments to verify the theoretical analysis. We built a digital control system that consists of the SIMULINK modeling software and a dSPACE controller installed in a personal computer, and we used actuators made of piezoelectric ceramic material. The experimental results show that PPF is effective in suppressing the steady-state vibrations.

关键词： Vibration control

来源：评论

学校读者我要写书评

暂无评论

Genetic algorithms for optimal design and control of adaptive structures

引用

Proceedings of SPIE - The International Society for Optical Engineering 2000年 3984卷 268-278页

作者： Ribeiro, Rui Da Mota Silva, Suzana Rodrigues, Jose D. Vaz, Mario CERN - European Lab for Particle Physics Geneva Switzerland

Future High Energy Physics experiments require the use of light and stable structures to support their most precise radiation detection elements. These large structures must be light, highly stable, stiff and radiation tolerant in an environment where external vibrations, high radiation levels, material aging, temperature and humidity gradients are not negligible. Unforeseen factors and the unknown result of the coupling of environmental conditions, together with external vibrations, may affect the position stability of the detectors and their support structures compromising their physics performance. Careful optimization of static and dynamic behavior must be an essential part of the engineering design. Genetic Algorithms (GA) belong to the group of probabilistic algorithms, combining elements of direct and stochastic search. They are more robust than existing directed search methods with the advantage of maintaining a population of potential solutions. There is a class of optimization problems for which Genetic Algorithms can be effectively applied. Among them are the ones related to shape control and optimal placement of sensors/actuators for active control of vibrations. In this paper these two problems are addressed and numerically investigated. The finite element method is used for the analysis of the dynamic characteristics. For the case of the optimal placement of sensors/actuators a performance index, proportional to the damping of the system in closed-loop, is used. Genetic algorithms prove their efficiency in this kind of optimization problems.

关键词： Intelligent structures

来源：评论

学校读者我要写书评

暂无评论

Position tracking control of an optical pick-up device using piezoceramic actuator

引用

Proceedings of SPIE - The International Society for Optical Engineering 2000年 3984卷 370-376页

作者： Choi, Seung-Bok Kim, Hyoung-Kyu Lim, Soo-Cheol Kim, Jae-Hwan Inha Univ Inchon Korea Republic of

This paper presents a new type of an optical pick-up for CD-RIM drive feeding system. The optical pick-up is activated by a pair of bimorph piezoceramic actuators in order to achieve fine motion control of the objective lens. Following the derivation of the governing equation of motion, a control model, which take into account the hysteresis behavior of the actuator and also parameter variation such as frequency changes, is established in a state space form. A robust controller is then formulated and experimentally realized. Various position trajectories to be followed by the optical pick-up are adopted and tracking control responses are presented in time domain. In addition, control durability is demonstrated in order to provide a practical feasibility.

关键词： Optical devices

来源：评论

学校读者我要写书评

暂无评论

Evaluation of gantry control strategies for X-ray steppers

引用

Proceedings of SPIE - The International Society for Optical Engineering 2000年 3984卷 597-606页

作者： Sullivan, Gerald A. Suiter, Kari Huston, Dryver Univ of Vermont Burlington United States

Results of an experimental study on the performance of a high speed, precision gantry system for application to X-ray stepper systems are presented. In particular a cross coupled control system design was compared to a master-master controller design on a gantry test bed powered by two linear motors. Tests were performed for the case where only inertial loads were present, as well as for the case where static loads were added to simulate gravity loading. The experiments demonstrated that high speed positioning to an accuracy of +/- 3micron or less could be obtained with both the cross-coupled and the master-master control strategies. Finally, it was observed that the changes in the dynamics of the closed loop gantry system appear to take place during continuous operation, leading to significant variations in the closed loop performance. It was concluded that robust controller design methods or adaptive control methods would be necessary to meet all performance goals for gantry based X-ray steppers.

关键词： Algorithms

来源：评论

学校读者我要写书评

暂无评论

Wing shaping for optimum roll performance using independent modal-space control technique

引用

Proceedings of SPIE - The International Society for Optical Engineering 2000年 3984卷 80-91页

作者： Khot, N.S. Oz, H. Wright-Paterson AFB United States

A technique for deforming a flexible wing to achieve a specified roll rate within a specified time at different Mach Numbers is examined. Rather than using an aileron system for roll, antisymmetric elastic twist and camber is determined to achieve the required rolling moment for a specified roll rate. The elastic twist and camber is achieved by providing a system of actuating elements distributed within the internal substructure of the wing to provide control forces. The modal approach is used to develop the dynamic equilibrium equations which culminates in the steady roll maneuver of a wing subjected to aerodynamic loads and the actuating forces. The distribution of actuating forces to achieve the specified steady flexible roll rate within a specified time was determined by using Independent Modal-Space control (IMSC) design approach. Here, a full-scale realistic wing is considered for the assessment of the strain energy required to produce the antisymmetric twist and camber deformation to achieve the specified roll performance.

关键词： Wings

来源：评论

学校读者我要写书评

暂无评论

建议与咨询留下您的常用邮箱和电话号码，以便我们向您反馈解决方案和替代方法

时间限定

文献类型

馆藏选择

核心期刊

语言

文献类型

帮助

文字说明：

检索规则说明：

检索范例：

分类表

所选分类

限定检索结果

文献类型

馆藏范围

日期分布

学科分类号

主题

机构

作者

语言

请选择保存的检索档案：

请选择收藏分类：

通借通还

建议与咨询 留下您的常用邮箱和电话号码，以便我们向您反馈解决方案和替代方法

时间限定

文献类型

馆藏选择

核心期刊

语言

文献类型

帮助

文字说明：

检索规则说明：

检索范例：

分类表

所选分类

限定检索结果

文献类型

馆藏范围

日期分布

学科分类号

主题

机构

作者

语言

请选择保存的检索档案： 新增检索档案 确定 取消

请选择收藏分类： 新增自定义分类 确定 取消

通借通还

建议与咨询留下您的常用邮箱和电话号码，以便我们向您反馈解决方案和替代方法

请选择保存的检索档案：

请选择收藏分类：