Active Control of Elastodynamic Vibrations of a Flexible Mechanism With Piezoelectric Actuator

1999 ◽  
Author(s):  
Ching-I Chen
Keyword(s):  
Control Theory ◽  
Active Control ◽  
Piezoelectric Actuator ◽  
Control Strategies ◽  
Piezoelectric Actuators ◽  
Structural Vibration ◽  
Control Technique ◽  
Vibration Modes ◽  
Time Sharing ◽  
Transient Dynamic

Abstract This study focused on the application of active vibration control strategies for flexible moving structures which degrade into transient dynamic vibration problem. These control strategies are based primarily on modal control methods in which the flexible moving structures are controlled by reducing their dominant vibration modes. This work numerically investigated active control of the elastodynamic response of a four-bar mechanical system, using a piezoelectric actuator. A controller based on the modified independent modal space control theory was also utilized. This control theory produced overall excellent performance in terms of achieving the desired closed-loop structural damping. The merits of this technique include its ability to manage the spill-over effect, i.e. eliminate the magnitude of vibrations associated with uncontrolled modes, using only a few selected modes for control. This control was accomplished using a time sharing technique, which reduces the number of piezoelectric actuators required to control a large number of vibration modes. Furthermore, this algorithm implements a procedure for determining the optimal locations for the piezoelectric actuators. The dynamics of a steel four-bar linkage was selected with a flexible coupler separated by six elements and one piezoelectric actuator was used in the numerical simulation. The optimal actuator position was located at the third element from the right to the left. Results in this study demonstrated that a highly desired the structural vibration damping could be achieved. This control technique can be applied to transient dynamic systems.

The Use of Damping Based Semi-Active Control Algorithms in the Mechanical Smart-Spring System

2017 ◽  
Vol 140 (2) ◽  
Author(s):  
Wander Gustavo Rocha Vieira ◽  
Fred Nitzsche ◽  
Carlos De Marqui
Keyword(s):  
Active Control ◽  
Control Algorithm ◽  
Control Strategies ◽  
Vibration Reduction ◽  
Flow Analysis ◽  
Coupled Systems ◽  
Control Technique ◽  
Control Algorithms ◽  
Control Techniques ◽  
Spring Mechanism

In recent decades, semi-active control strategies have been investigated for vibration reduction. In general, these techniques provide enhanced control performance when compared to traditional passive techniques and lower energy consumption if compared to active control techniques. In semi-active concepts, vibration attenuation is achieved by modulating inertial, stiffness, or damping properties of a dynamic system. The smart spring is a mechanical device originally employed for the effective modulation of its stiffness through the use of semi-active control strategies. This device has been successfully tested to damp aeroelastic oscillations of fixed and rotary wings. In this paper, the modeling of the smart spring mechanism is presented and two semi-active control algorithms are employed to promote vibration reduction through enhanced damping effects. The first control technique is the smart-spring resetting (SSR), which resembles resetting control techniques developed for vibration reduction of civil structures as well as the piezoelectric synchronized switch damping on short (SSDS) technique. The second control algorithm is referred to as the smart-spring inversion (SSI), which presents some similarities with the synchronized switch damping (SSD) on inductor technique previously presented in the literature of electromechanically coupled systems. The effects of the SSR and SSI control algorithms on the free and forced responses of the smart-spring are investigated in time and frequency domains. An energy flow analysis is also presented in order to explain the enhanced damping behavior when the SSI control algorithm is employed.

Combining Pole Placement and Online Empirical Mode Decomposition Methods to Adaptive Active Control of Structural Vibration

2019 ◽  
Vol 141 (4) ◽  
Author(s):  
S. H. Momeni Massouleh ◽  
S. A. Hosseini Kordkheili ◽  
H. Mohammad Navazi ◽  
H. Bahai
Keyword(s):  
Empirical Mode Decomposition ◽  
Active Control ◽  
Pole Placement ◽  
Structural Vibration ◽  
Control Technique ◽  
Time Frequency ◽  
Mode Decomposition ◽  
Optimal Gains ◽  
Excitation Frequencies ◽  
Emd Method

Using a combination of the pole placement and online empirical mode decomposition (EMD) methods, a new algorithm is proposed for adaptive active control of structural vibration. The EMD method is a time-frequency domain analysis method that can be used for nonstationary and nonlinear problems. Combining the EMD method and Hilbert transform, which is called Hilbert–Huang transform, achieves a method that can be implemented to extract instantaneous properties of signals such as structural response dominant instantaneous frequencies. In the proposed algorithm, these estimated instantaneous properties are utilized to improve the pole-placement method as an adaptive active control technique. The required active control gains are obtained using a genetic algorithm scheme, and optimal gains are calculated corresponding to preselected excitation frequencies. An algorithm is also introduced to choose excitation frequencies based on online EMD method resolution. In order to investigate the efficiency of the proposed method, some case studies that include a discrete model, continuous samples of beam and plate structures, and experimental cantilevered beam are carried out, and the results of the proposed method are compared with the preset (nonadaptive) optimal gains conditions.

Active Control of Non-Linear System by a Fuzzy-Optimal Control Technique

2010 ◽  
Author(s):  
Takashi Mochio
Keyword(s):  
Optimal Control ◽  
Nonlinear System ◽  
Control Theory ◽  
Real Time ◽  
Active Control ◽  
Optimal Control Theory ◽  
Time Dependent ◽  
Control Technique ◽  
The Real ◽  
Non Linear System

The purpose of this paper is to estimate the real time vibration control of an actively-controlled nonlinear structure due to non-stationary external loads. When the optimal control theory is adopted as a control law against the concerned task, the derivation of time dependent optimal control gains may be required because of a remarkable non-stationarity of response amplitude. In addition, since the system is nonlinear, it takes more time to calculate those time dependent gains. This means that it is difficult to strictly execute the real time active control with optimal control theory as for the non-stationary and nonlinear system. In this paper, therefore, one approximate technique, coupled fuzzy-optimal control, is proposed in order to realize the real time control of non-stationary and nonlinear system. Finally, results by deterministic analysis based on numerical simulations are compared with those by stochastic analysis using statistical equivalent linearization technique.

Distributed Piezoelectric Actuators for Shell Interior Noise Control

1996 ◽  
Vol 118 (4) ◽  
pp. 676-681 ◽  
Author(s):  
J. Q. Sun ◽  
M. A. Norris ◽  
D. J. Rossetti ◽  
J. H. Highfill
Keyword(s):  
Control System ◽  
Structural Control ◽  
Acoustic Radiation ◽  
Control Strategies ◽  
Piezoelectric Actuators ◽  
Interior Noise ◽  
Theoretical Development ◽  
Structural Vibration ◽  
Control Approach ◽  
Wide Range

Structural controls have been recently used to reduce acoustic radiation from vibrating structures. It is well known that in some cases, a control system can reduce the noise and, at the same time, increase the structural vibration. This is one of the concerns with the structural control approach to solve the noise problem. Developing a control system that can reduce the noise and structural vibration at the same time is an important task. This paper proposes one of possible approaches for accomplishing this task. The emphasis of the present approach is not on control strategies, but rather on the design of distributed piezoelectric actuators for the structural control system. In the paper, we study the interior noise radiation and the structural vibrations of uniform cylindrical shells, which are taken as a simplified model of a fuselage section. Two distributed piezoelectric actuators are developed based upon the understanding of the structural-acoustic coupling properties of the system. These actuators can reduce the shell structural vibration and the interior noise at the same time in a wide range of frequencies by using only the acoustic error sensors. Hence, an optimal noise reduction is achieved. Computer simulations and the experiments have shown that the actuators can lead to global noise and vibration reduction. Excellent agreement between the analytical predictions and the experiments strongly supports the theoretical development.

Semi-Active Control for Benchmark Building Using Innovative TMD with MRE Isolators

2020 ◽  
Vol 20 (06) ◽  
pp. 2040009
Author(s):  
Xinchun Guan ◽  
Jingcai Zhang ◽  
Hui Li ◽  
Jinping Ou
Keyword(s):  
Active Control ◽  
Control Strategies ◽  
Variable Stiffness ◽  
Control Device ◽  
Structural Vibration ◽  
Control Force ◽  
Linear Quadratic ◽  
Structure System ◽  
Magneto Rheological ◽  
Active Damper

Tuned Mass Damper (TMD) with magneto-rheological elastomer isolators (MRE-TMD) is a novel control device for suppressing structural vibration caused by earthquakes. It is a nonlinear hybrid vibration absorber and the stiffness & damping can be controlled by changing the current of isolators’ coil. Using MRE-TMD as an adaptive frequency TMD to mitigate vibration and treating it as only a passive damper is the focus of most nowadays researches. In this paper, semi-active control theory is introduced to the MRE-TMD-structure system which means that the control force can be obtained through variable stiffness & damping technology, and MRE-TMD is a semi-active damper instead of a passive one. A control system sketch, as well as principles and control strategies of a semi-active MRE-TMD-structure system for vibration control is designed. An improved limited sliding (ILSL) algorithm based on linear quadratic optimal theory is also introduced. Numeric simulations of a five-story benchmark building model equipped with semi-active MRE-TMD subjected to several benchmark earthquake records are conducted to investigate the control performance of the proposed semi-active MRE-TMD. Control force characteristics of the structural MRE-TMD systems are also evaluated. The results indicate that semi-active MRE-TMD can provide control force to the system and it shows superior ability to suppress the structural vibrations of comparing to the passive MRE-TMD.

Piezo-Elastic Actuation for Micro-Positioning of Lateral Tape Motion

2011 ◽  
Author(s):  
Jen-Yuan James Chang
Keyword(s):  
Piezoelectric Actuator ◽  
Traveling Waves ◽  
Structural Vibration ◽  
Lateral Motion ◽  
Vibration Modes ◽  
Pzt Actuator ◽  
Modal Superposition ◽  
Lateral Tape Motion ◽  
Alternative Means ◽  
Actuator System

In this paper, development of a prototypical microcontroller controlled ultrasonic actuator system incorporating a plate-like piezoelectric actuator is discussed to provide an alternative means in actively guiding the tape laterally. Structural vibration modes are first experimentally examined through standard modal analyses. Method of modal superposition is used in programming the micro-controller so as to provide excitations to the PZT actuator resulted in traveling waves in the plate-like structure. Promising results are demonstrated in the proposed system that have rich implications in providing active guiding mechanism to minimize and even actively control the tape’s lateral motion.

Active Control Technique Evaluation for Spacecraft (ACES)

1988 ◽  
Author(s):  
R. D. Irwin ◽  
Victoria Jones ◽  
Sally C. Rice ◽  
Sherman M. Seltzer ◽  
Danny K. Tollison
Keyword(s):  
Active Control ◽  
Control Technique ◽  
Technique Evaluation

scholarly journals Analysis of a Linear Model for Non-Synchronous Vibrations Near Stall

2021 ◽  
Vol 6 (3) ◽  
pp. 26
Author(s):  
Christoph Brandstetter ◽  
Sina Stapelfeldt
Keyword(s):  
Linear Model ◽  
Linear Models ◽  
Structural Vibration ◽  
Experimental Investigations ◽  
Vibration Modes ◽  
Critical Problem ◽  
Safety Critical ◽  
Unstable Vibration ◽  
Aero Engines ◽  
Lock In

Non-synchronous vibrations arising near the stall boundary of compressors are a recurring and potentially safety-critical problem in modern aero-engines. Recent numerical and experimental investigations have shown that these vibrations are caused by the lock-in of circumferentially convected aerodynamic disturbances and structural vibration modes, and that it is possible to predict unstable vibration modes using coupled linear models. This paper aims to further investigate non-synchronous vibrations by casting a reduced model for NSV in the frequency domain and analysing stability for a range of parameters. It is shown how, and why, under certain conditions linear models are able to capture a phenomenon, which has traditionally been associated with aerodynamic non-linearities. The formulation clearly highlights the differences between convective non-synchronous vibrations and flutter and identifies the modifications necessary to make quantitative predictions.

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