Distributed Actuation Effectiveness of Flexible Parabolic Cylindrical Panels

2012 ◽  
Author(s):  
S. D. Hu ◽  
H. Li ◽  
H. S. Tzou
Keyword(s):  
Active Vibration Control ◽  
Cylindrical Panel ◽  
Modal Control ◽  
Control Force ◽  
Control Effect ◽  
Control Effectiveness ◽  
Cylindrical Panels ◽  
Total Control ◽  
Shell Panel ◽  
Active Vibration

Open parabolic cylindrical panel plays a key role in radial collection and transmission applied to radar antennas, space reflectors, solar collectors, etc. Piezoelectric active vibration control can suppress unexpected fluctuation and maintain precision surface and operations. This study aims to investigate the distributed actuation behavior of adaptive open parabolic cylindrical panels using piezoelectric actuator patches. Motion equations of parabolic cylindrical panels laminated with a piezoelectric patch is presented first. Then, the actuator induced modal control force is derived with an assumed mode shape function. As the area of actuator patch varies due to the curvature change, the normalized actuation effectiveness (i.e., modal control force divided by actuator area) is further evaluated. When the actuator area shrinks to infinitesimal, the expression of microscopic point modal control force is obtained to theoretically predict the actuation distribution behavior. The actuation behaviors of the total control force and its components exhibit distinct characteristics with respect to shell geometries, modes and actuator properties. Analyses show that the control force component contributed by the membrane force dominates the total control effect. The bending-contributed component increases with corresponding vibration mode number, while the membrane-contributed component decreases. Three shell geometries from shallow to deep are evaluated in case studies. Analysis of optimal actuator location shows that actuators are preferred to locate where the curvature of shell panel is larger in order to maximize the control effectiveness.

Spatial Actuation Effectiveness of Segmented Actuators on Parabolic Cylindrical Panels

2012 ◽  
Author(s):  
S. D. Hu ◽  
H. Li ◽  
H. S. Tzou
Keyword(s):  
Shape Control ◽  
Cylindrical Panel ◽  
Design Parameters ◽  
Modal Control ◽  
Control Force ◽  
Optimal Position ◽  
Meridional Direction ◽  
Cylindrical Panels ◽  
Active Vibration ◽  
Control Forces

With the distinct capability of line-focusing, open parabolic cylindrical panels are commonly used as key components of radar antennas, space reflectors, solar collectors, etc. These structures suffer unexpected vibrations from the fluctuation of base structure, non-uniform heating and air flow. The unwanted vibration will reduce the surface reflecting precision and even result in structure damages. To explore active vibration and shape control of parabolic cylindrical panels, this study focuses on actuation effectiveness induced by segmented piezoelectric patches laminated on a flexible parabolic cylindrical panel. The mathematical model of a parabolic cylindrical panel laminated with distributed actuators is formulated. The segmentation technique is developed and applied to parabolic cylindrical panels, and the piezoelectric layer is segmented uniformly in the meridional direction. The distributed actuator patches induced modal control forces are evaluated. As the area of actuator patch varies in the meridional direction, modal control force divided by actuator area, i.e., actuation effectiveness, is investigated. Spatial actuation effectiveness, including its membrane and bending components are evaluated with respect to design parameters: actuator size and position, shell curvature, shell thickness and vibration mode in case studies. The actuation component induced by the membrane force in the meridional direction mainly contributes to the total actuation effectiveness for lower modes. Average and cancellation effect of various actuator sizes and the optimal actuator position are also discussed. Results suggest that for odd vibration modes, the maximal actuation effectiveness locates at the ridge of the panel; while for even modes, the peak/valley closest to the ridge is the optimal position to obtain the maximal actuation effectiveness. A segmentation scheme of the meridian interval angle 0.0464rad for the investigated standard panel is a preferred tradeoff between the actuation effectiveness and practical feasibility. The modal actuation effectiveness increases with the shell curvature, whereas decreases when the shell thickens.

Precision Microscopic Actuations of Parabolic Cylindrical Shell Reflectors

2015 ◽  
Vol 137 (1) ◽  
Author(s):  
S. D. Hu ◽  
H. Li ◽  
H. S. Tzou
Keyword(s):  
Cylindrical Shell ◽  
Piezoelectric Actuator ◽  
Cylindrical Shells ◽  
Active Vibration Control ◽  
Modal Control ◽  
Control Force ◽  
Signal Collection ◽  
Shell Panel ◽  
Active Vibration ◽  
Radar Antennas

An open parabolic cylindrical shell panel plays a key role in radial signal collection, reflection, and/or transmission applied to radar antennas, space reflectors, solar collectors, etc. Active vibration control can suppress unexpected fluctuation and maintain its precision surface and operations. This study aims to investigate the distributed active actuation behavior of adaptive open parabolic cylindrical shell panels using piezoelectric actuator patches. Dynamic equations of parabolic cylindrical shells laminated with piezoelectric actuator patches are presented first. Then, the actuator induced modal control force is defined based on a newly derived mode shape function. As the actuator area varies due to the curvature change, the normalized actuation effectiveness (i.e., modal control force per unit actuator area) is further evaluated. When the actuator area shrinks to infinitesimal, the expression of microscopic local modal control force is obtained to predict the spatial microscopic actuation behavior on parabolic cylindrical shells. The total control force and its three components exhibit distinct characteristics with respect to shell geometries, modes, and actuator properties. Analyzes suggest that the control force contributed by the membrane force component dominates the total actuation effect. The bending-contributed component increases with the corresponding mode number, while the membrane-contributed component decreases. Actuation effectiveness of two shell geometries, from shallow to deep, and actuator sizes are evaluated. Analysis of optimal actuator locations reveals that actuators placed at the maximal shell curvature are more effective and maximize the control effects.

Optimal Placement of Piezoelectric Sensors and Actuators for Controlled Flexible Linkage Mechanisms

2005 ◽  
Vol 128 (2) ◽  
pp. 256-260 ◽  
Author(s):  
Xianmin Zhang ◽  
Arthur G. Erdman
Keyword(s):  
Vibration Control ◽  
Simulation Analysis ◽  
Active Vibration Control ◽  
Optimal Placement ◽  
Control Effect ◽  
Sensors And Actuators ◽  
Piezoelectric Sensors And Actuators ◽  
Active Vibration ◽  
Flexible Mechanism ◽  
Flexible Linkage

The optimal placement of sensors and actuators in active vibration control of flexible linkage mechanisms is studied. First, the vibration control model of the flexible mechanism is introduced. Second, based on the concept of the controllability and the observability of the controlled subsystem and the residual subsystem, the optimal model is developed aiming at the maximization of the controllability and the observability of the controlled modes and minimization of those of the residual modes. Finally, a numerical example is presented, which shows that the proposed method is feasible. Simulation analysis shows that to achieve the same control effect, the control system is easier to realize if the sensors and actuators are located in the optimal positions.

Active Vibration Control of a Triple Flexible Structures Combined With Actuators

1995 ◽  
Author(s):  
Kazuto Seto ◽  
Yoshihiro Toba ◽  
Fumio Doi
Keyword(s):  
Vibration Control ◽  
Large Scale ◽  
Active Vibration Control ◽  
Flexible Structures ◽  
Low Frequency ◽  
Tall Buildings ◽  
Control Force ◽  
Active Vibration ◽  
Strong Winds ◽  
Lq Control

Abstract In order to realize living comfort of tall buildings by reducing the vibration of higher floors by strong winds, this paper proposes a new method of vibration control for flexible structures with a large scale. The higher a tall building the lower its natural frequency. Since obtaining sufficient force to control the lower frequency vibrations of tall buildings is a difficult task, controlling the vibration of ultra-tall buildings using active dynamic absorbers is nearly impossible. This problem can be overcome by placing actuators between a pair of two or three ultra-tall buildings and using the vibrational force of each building to offset the vibrational movement of its paired mate. Therefore, it is able to obtain enough control force under the low frequency when the proposed method is used. In this paper, a reduced-order model expressed by 2DOF system under taking into consideration for preventing spillover instability is applied to control each flexible structure. The LQ control theory is applied to the design of such a control system. The effectiveness of this method is demonstrated theoretically as well as experimentally.

Effects of Actuators and Sensors Position on Independent Modal Control Performance

2012 ◽  
Author(s):  
Simone Cinquemani ◽  
Ferruccio Resta
Keyword(s):  
Natural Frequencies ◽  
Acoustic Noise ◽  
Dynamic Performance ◽  
Active Vibration Control ◽  
Spillover Effects ◽  
Point Of View ◽  
Control Technique ◽  
Modal Control ◽  
Sensors And Actuators ◽  
Active Vibration

Independent modal control technique allows to change the eigenvalues of a system, without changing its eigenvectors. From a mechanical point of view, it means it is possible to modify the natural frequencies and the damping of a n-DoF system, letting modal shapes unchanged. Independent modal control can be profitably used in active vibration control increasing the damping of the system without changing its natural frequencies and vibration modes. A control of this type can improve the dynamic performance, reduce the vibratory phenomenon (and the resulting acoustic noise) and increase the fatigue strength of the system. This work demonstrates how the performance of the control depends on the number and position of sensors and actuators used besides, obviously, on the reduced model used to synthesize the control itself. Finally the paper suggests a simple optimum function to minimize the spillover effects due to unmodeled modes. Theoretical aspects are supported by numerical simulations.

Verification of the Relation Between the Directions of Control Force and Responses in Active Seismic Isolation Device

2018 ◽  
Author(s):  
Keigo Nakamura ◽  
Nanako Miura ◽  
Akira Sone
Keyword(s):  
Active Control ◽  
Seismic Isolation ◽  
Seismic Waves ◽  
Base Isolation ◽  
Active Vibration Control ◽  
Control Force ◽  
Control Power ◽  
Active Vibration ◽  
Self Powered ◽  
Isolation Device

In this research, the focus is on the energy problem in active vibration control of a seismic isolation device using self-powered active control that regenerates electric power from kinetic energy of vibration system and uses it as control power. In recent years, it is proposed to install semi-active control or active control in an isolated structure to deal with seismic waves of various periods. However, since energy is required for control, there is a problem that the desired response reduction performance cannot be achieved when energy supply is interrupted at the time of a power outage. In our previous device, power is always given to the motor to control, thus power consumption is high. Therefore, the purpose of this research is to propose input method of control force that can reduce control power while keeping base isolation performance by classifying the role of the control force for each control phase and considering various combinations of input control force.

scholarly journals A Comparative Study Based on Different Control Algorithms for Suppressing Multistage Gear Transmission System Vibrations

2018 ◽  
Vol 2018 ◽  
pp. 1-16
Author(s):  
Wenhao Sun ◽  
Feng Zhang ◽  
Weidong Zhu ◽  
Han Wang ◽  
Shunan Luo ◽  
...  
Keyword(s):  
Vibration Control ◽  
Active Vibration Control ◽  
Transmission System ◽  
Gear Transmission ◽  
Control Algorithms ◽  
Control Force ◽  
The Finite Element Method ◽  
Control Schemes ◽  
Gear Transmission System ◽  
Active Vibration

A modal analysis (MA) was preconsidered to determine a novel active vibration control (AVC) structure of multistage gear transmission system (MGTS) and an appropriate actuating position for the piezoelectric actuator (PZT); the results of the calculating method and the finite element method (FEM) were compared to validate the reliability of MA. The controllers based on different control algorithms were designed to drive the PZTs to output the control force for suppressing the host structure vibrations. To analyze the feasibility of the applied control schemes and discuss the control effects dominated by the different control algorithms, a series of active vibration control numerical simulations were studied. The cosimulation results validate the practicability of the proposed control schemes and provide a forcible guidance for the further experimental works.

Active Vibration Control of the Axially Moving String Using Space Feedforward and Feedback Controllers

1996 ◽  
Vol 118 (3) ◽  
pp. 306-312 ◽  
Author(s):  
S. Ying ◽  
C. A. Tan
Keyword(s):  
Vibration Control ◽  
Feedforward Control ◽  
Active Vibration Control ◽  
Upstream Region ◽  
Control Force ◽  
Feedback Controllers ◽  
Axially Moving String ◽  
Downstream Region ◽  
Active Vibration ◽  
Axially Moving

Active vibration control of an axially moving string using space feedforward and feedback controllers is presented. Closed-form results for the transverse response of both the uncontrolled and controlled string are given in the s domain. The space feedforward controller is established by employing the idea of wave cancellation. The proposed control law indicates that vibration in the region downstream of the control force can be cancelled. With the space feedforward control, the mode shapes of the axially moving string are changed such that the free response tends to zero in the downstream region. An interesting physical interpretation is that the control force acts effectively as a holder (active support) which limits the vibration of the string to the upstream region and eliminates any vibration in the downstream region. Simulation results show that the response of the string to both sinusoidal and random excitations is suppressed by applying the space feedforward control. The feedback controller is introduced to attenuate the response of the string due to undesired disturbances in the downstream.

Micro-Control Actions of Actuator Patches Laminated on Hemispherical Shells

2002 ◽  
Author(s):  
P. Smithmaitrie ◽  
H. S. Tzou
Keyword(s):  
Distributed Control ◽  
Pressure Vessels ◽  
Control Force ◽  
Control Effect ◽  
Control Effectiveness ◽  
Control Actions ◽  
Spatially Distributed ◽  
Membrane Bending ◽  
Control Forces ◽  
Electromechanical Actuation

Spherical shell-type structures and components appear in many engineering systems, such as radar domes, pressure vessels, storage tanks, etc. This study is to evaluate the micro-control actions and distributed control effectiveness of segmented actuator patches laminated on hemispheric shells. Mathematical models and governing equations of the hemispheric shells laminated with distributed actuator patches are presented first, followed by formulations of distributed control forces and micro-control actions including meridional/circumferential membrane and bending control components. Due to difficulties in analytical solution procedures, assumed mode shape functions based on the bending approximation theory are used in the modal control force expressions and analyses. Spatially distributed electromechanical actuation characteristics resulting from various meridional and circumferential actions are evaluated. Distributed control forces, patch sizes, actuator locations, micro-control actions, and normalized control authorities of a free-floating hemispheric shell are analyzed in a case study. Parametric analysis indicates that 1) the control forces and membrane/bending components are mode and location dependent and 2) the meridional/circumferential membrane control actions dominate the overall control effect.

Multi-frequency rotor vibration suppressing through self-optimizing control of electromagnetic force

2016 ◽  
Vol 23 (5) ◽  
pp. 701-715 ◽  
Author(s):  
Yao Jianfei ◽  
Gao Jinji ◽  
Wang Weimin
Keyword(s):  
Electromagnetic Force ◽  
Search Algorithm ◽  
Control Strategies ◽  
Active Vibration Control ◽  
Control Force ◽  
Rotor Vibration ◽  
Control Current ◽  
Active Vibration ◽  
Optimizing Control ◽  
Rotor Bearings

In this paper, the attention is confined to the suppression of multi-frequency rotor vibration. A method to control rotor’s multi-frequency periodic vibration in rotor-bearings system is proposed which uses active magnetic exciter (AME) to produce active control force to suppress rotor’s vibration and to reach a self-optimizing control of the rotor vibration. The control strategies include an arithmetic to optimize the amplitudes and phases of the control current using on-line self-optimizing algorithms in AME and applied multiple frequency-matched control force that AME generates to reduce the measured amplitudes of rotor. The model of rotor-bearings system with AME is established firstly. An active vibration control scheme for controlling transverse vibration of the rotor due to multi-frequency excitation is designed. The whole circle search algorithm and fast optimizing search algorithm about the amplitude and phase of control current are proposed. Finally, the experiments for controlling multi-frequency vibration of the rotor are carried out on the rotor-bearings test rig. The experimental results indicate that the proposed method can effectively suppress the rotor vibration for multi-frequency components through self-optimizing control of electromagnetic force.

Sign in / Sign up

Export Citation Format

Share Document