Vibration Reduction in Large Flexible Systems Through Independent Modal Control

2011 ◽  
Author(s):  
Francesco Braghin ◽  
Simone Cinquemani ◽  
Ferruccio Resta
Keyword(s):  
Acoustic Noise ◽  
Dynamic Performance ◽  
Active Vibration Control ◽  
Spillover Effects ◽  
Flexible System ◽  
Damping Matrix ◽  
Modal Damping ◽  
Active Vibration ◽  
The Stability ◽  
Modal Controller

Many systems have, by their nature, a small damping and therefore they are potentially subjected to dangerous vibration phenomena. The aim of active vibration control is to contain this phenomenon, 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. The paper introduces a new approach to the synthesis of a modal controller to suppress vibrations in structures: it turns from the traditional formulation of the problem showing how the performance of the designed controller can be evaluated through the analysis of the resulting modal damping matrix of the controlled system. Such analysis allows to evaluate spillover effects, due to the presence of un-modeled modes, the stability of the control and the consequent effectiveness in reducing vibration. The ability to easily manage this information allows the synthesis of an efficient modal controller. Theoretical aspects are supported by experimental applications on a large flexible system.

A Mechanical Approach to the Design of Independent Modal Space Control for Vibration Suppression

2013 ◽  
Vol 135 (5) ◽  
Author(s):  
S. Cinquemani ◽  
F. Resta
Keyword(s):  
Vibration Suppression ◽  
Dynamic Performance ◽  
Active Vibration Control ◽  
Flexible System ◽  
Damping Matrix ◽  
Modal Damping ◽  
Active Vibration ◽  
The Stability ◽  
Modal Space ◽  
Modal Controller

Many systems have, by their nature, a small damping and therefore they are potentially subjected to dangerous vibration phenomena. The aim of active vibration control is to contain this phenomenon, improve the dynamic performance of the system, and increase its fatigue strength. A way to reach this goal is to increase the system damping, preferably without changing its natural frequencies and vibration modes. In the past decades this has been achieved by developing the well-known independent modal space control (IMSC) technique. The paper describes a new approach to the synthesis of a modal controller to suppress vibrations in structures. It turns from the traditional formulation of the problem and it demonstrates how the performance of the controller can be evaluated through the analysis of the modal damping matrix of the controlled system. The ability to easily manage this information allows us to synthesize an efficient modal controller. Furthermore, it enables us to easily evaluate the stability of the control, the effects of spillover, and the consequent effectiveness in reducing vibration. Theoretical aspects are supported by experimental applications on a large flexible system.

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.

On Independent Modal Control of a Vibrating System

2010 ◽  
Author(s):  
Francesco Braghin ◽  
Simone Cinquemani ◽  
Ferruccio Resta
Keyword(s):  
Active Vibration Control ◽  
Spillover Effects ◽  
Mode Shapes ◽  
Modal Control ◽  
Sensors And Actuators ◽  
Controlled System ◽  
Control Techniques ◽  
Damping Matrix ◽  
Modes Of Vibration ◽  
Active Vibration

Of the multitude of available control techniques, modal control is a favourite amongst structural dynamicists because of its representation in modal coordinates. The term modal control is used to describe a wide variety of control techniques which find their origin in a description of the system through the main coordinates, defined by the modes of vibration of the system. This approach stems from the consideration that the response of a mechanical system to a disturbance is the sum of the independent responses of its vibrational modes. This motivates the desire to design a control that does not alter these mode shapes, but allows to change the natural frequency and the damping of each mode. In active vibration control the purpose is to increase the damping of modes interested in the vibratory phenomenon. The paper shows how stability, spillover effects, system controllability and sensors and actuators position are all linked to the analysis of the controlled system damping matrix and to the possibility that the forces introduced by the control is non-dissipative. Theoretical aspects are supported by numerical simulations.

scholarly journals Active vibration control of a railway pantograph

1997 ◽  
Vol 211 (2) ◽  
pp. 117-130 ◽  
Author(s):  
T. X. Wu ◽  
M. J. Brennan
Keyword(s):  
Degrees Of Freedom ◽  
Control Strategies ◽  
Dynamic Performance ◽  
Active Vibration Control ◽  
Control Force ◽  
Optimal Control Strategy ◽  
Advantages And Disadvantages ◽  
Full State Feedback ◽  
Active Vibration ◽  
The Stability

Current collection for electrical trains can be improved by the use of an active pantograph. To design such a system the behaviour of both the active pantograph and the overhead catenary system must be considered together. In this paper a two degrees-of-freedom model of an active pantograph, combined with a time-varying spring representing the catenary's influence, is employed and its dynamic performance is studied. Based on this model, three types of control strategies for an active pantograph are proposed and investigated, and all these models consider the interaction of the pantograph with the overhead wire. Two possible positions for mounting an actuator on the pantograph are considered and compared. From these active pantograph models the magnitude of the control force required can be estimated, and the advantages and disadvantages are discussed. The optimal control strategy shows the best performance, but introduces measurement difficulties because it needs full-state feedback. Classical feedback control is the least difficult to implement, but a compromise between the stability and the performance should be reached.

Active vibration control based on modal controller considering structure-actuator interaction

2018 ◽  
Vol 32 (8) ◽  
pp. 3515-3521 ◽  
Author(s):  
Jinjun Jiang ◽  
Weijin Gao ◽  
Liang Wang ◽  
Zhaohua Teng ◽  
Yongguang Liu
Keyword(s):  
Vibration Control ◽  
Active Vibration Control ◽  
Active Vibration ◽  
Modal Controller

Optimal Research of Actuator Placement for Piezoelectric Smart Structure

2009 ◽  
Vol 419-420 ◽  
pp. 173-176
Author(s):  
Wei Yuan Wang ◽  
Kai Xue ◽  
Dong Yan Shi
Keyword(s):  
Vibration Control ◽  
Control Method ◽  
Active Vibration Control ◽  
Element Model ◽  
Smart Structure ◽  
Optimal Placement ◽  
Optimal Method ◽  
Modal Damping ◽  
Active Vibration ◽  
Modal Space

The purpose of this paper is to investigate the optimal placement of piezoelectric actuator for active vibration control of smart structure. The structures can be described in the modal space based on the independent modal space control method and dynamic equations derived from finite element model. The modal damping ratios are derived from modal equations and an optimal target is given by maximizing the modal damping ratios. Accumulation method is adopted to the optimization calculation. Simulations are carried out for active vibration control of a conical shell with distributed piezoelectric actuators. Control effects proved the validity of the optimal method above by compared with the non-optimal results. The optimal method in this paper gives a useful guide for quantity optimization of actuators to piezoelectric structures.

Stall Nonlinear Flutter of Wind Turbine Blade Modeled as Thin-Walled Composite Beam Integrated with Structural Damping

2013 ◽  
Vol 291-294 ◽  
pp. 496-500
Author(s):  
Yong Sheng Ren ◽  
Ting Rui Liu
Keyword(s):  
Structural Model ◽  
Structural Damping ◽  
Aeroelastic Stability ◽  
Damping Matrix ◽  
Modal Damping ◽  
Strip Theory ◽  
Analytical Formulas ◽  
Thin Walled ◽  
The Stability ◽  
Domain Integration

The effects of structural damping on the aeroelastic stability have been investigated for composite thin-walled blade. Structural model of the composite thin-walled blade exhibits bending-bending-twist coupling, with accounting for the presence of pretwist angle. The aerodynamic model used in the present paper is the differential dynamic stall model developed at ONERA. The structural damping of the blade is predicted based on the analytical formulas of the modal damping of thin-walled composite structure. The effect of structural damping on aeroelastic stability is taken into account by using proportional damping matrix. By means of Galerkin method, the nonlinear aeroelastic equations are reduced to ordinary equations. The general aerodynamic forces are obtained from strip theory. The resulting equations are then linearized for small perturbation about the equilibrium point and the stability characteristics are investigated through eigenvalue analysis and time domain integration.

A New Vibration Controller Design Using Consensus Technique

2015 ◽  
Author(s):  
Ehsan Omidi ◽  
S. Nima Mahmoodi
Keyword(s):  
Vibration Control ◽  
Controller Design ◽  
Active Vibration Control ◽  
Flexible Structures ◽  
Network Systems ◽  
Control Approach ◽  
Active Vibration ◽  
The Stability ◽  
Virtual Leader ◽  
Aluminum Beam

This paper discusses the concept of a new methodology for active vibration control of flexible structures using consensus control of network systems. In the new approach, collocated actuation/sensingpatches communicate with one another through a network with certain directed topology. A virtual leader is assigned to enforce the vibration amplitude at the place of each agent to zero. Since the modal states of the system are not available for the vibration control task, individual optimal observers are designed for each agent first. After describing the controller and examining the stability of the system, controller performance is verified using a clamped-clamped thin aluminum beam. According to the obtained numerical results, the new control approach successfully suppresses the vibration amplitudes, while the consensus design ensures that all agents are synchronized during the performance.

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