Vibration Control Of Smart Structures Research Articles

Effect of porosity on active vibration control of smart structure using porous functionally graded piezoelectric material

The present work investigates the active vibration control of host structure bonded with functionally graded piezoelectric material (FGPM) as sensor and actuator layer. The effect of porosity volume fraction (ψ) and volume fraction index (λ) on active vibration attenuation is investigated and compared with the dense FGPM sensor and actuator layer. For more real life applications of FGPMs, two piezoelectric materials (PZT-5H and PZT-4) are modelled smoothly in a particular direction. The mechanical and piezoelectric properties of FGPMs vary across the thickness and calculated using power – law expressions. In addition to dense FGPM, two different distributions of the porosities are investigated. Shear deformation theory of first order is used to simulate the vibration response of the host composite plate based on Hamilton’s principle. A well-established negative velocity feedback controller is deployed to obtain active vibration control of the composite structure. The numerical results reveal that the volume fraction index (λ) plays vital role in the active damping of structural vibration. The FGPM-◊ demonstrates 5.7% and 6.32% improved active vibration damping performance compared to FGPM-UD at ψ = 0.1 and ψ = 0.2 respectively. The present investigation can be utilized for further studies on active vibration control of host structures integrated with FGPMs.

An experimental study on dynamic analysis and active vibration control of smart laminated plates

Dynamic analysis and active vibration suppression of smart plates is presented in this work. An experimental set-up has been developed to carry out experimentation. The setup is composed of a specimen laminated composite plate, a data acquisition device, signal conditioning elements, a LabView based controller and cables/wires for electrical connections. Experiments are performed with laminated plates of different layups. Aluminium, polycarbonate and medium density polyethylene sheets are used as layup materials. Tensile tests are performed to determine the mechanical properties of the constituting material layers. Piezoelectric patches integrated with elastic layers of specimen plate are used as sensor and actuator pair. The open and closed loop responses are obtained for each specimen plate and the fundamental frequencies are determined experimentally. The closed loop responses are obtained using PID controller configured in LabVIEW graphical program. The experimental results have demonstrated the validity and efficiency of PID controller in active vibration control of smart structures. The problem plates are also modelled using ANSYS workbench for modal analysis. The experimental results of fundamental natural frequencies of specimen plates are validated through ANSYS finite element results. The results are in good agreement and thus can be used as a touchstone for analytical/numerical work.

Identification of Smart Structures with Robust Control under Stochastic Excitation

In light of past research in this field, this paper intends to discuss some innovative approaches in vibration control of smart structures, particularly in the case of structures with embedded piezoelectric materials. In this work, we review the principal problems in mechanical engineering that the structural control engineer has to address when designing robust control laws: structural modeling techniques, uncertainty modeling, and robustness validation under stochastic excitation. Control laws are desirable for systems where guaranteed stability or performance is required despite the presence of multiple sources of uncertainty.

Identification of Smart Structures with Robust Control under Stochastic Excitation

In light of past research in this field, this paper intends to discuss some innovative approaches in vibration control of smart structures, particularly in the case of structures with embedded piezoelectric materials. In this work, we review the principal problems in mechanical engineering that the structural control engineer has to address when designing robust control laws: structural modeling techniques, uncertainty modeling, and robustness validation under stochastic excitation. Control laws are desirable for systems where guaranteed stability or performance is required despite the presence of multiple sources of uncertainty.

Multi-agent replicator controller for sustainable vibration control of smart structures

Developed in the artificial intelligence community, an intelligent agent is an autonomous abstract or software entity that observes through sensors and acts upon an environment in an adaptive or intelligent manner. In a centralized control system, one central controller uses the global measurement data collected from all the sensors installed in the structure to make control decisions and to dispatch them to control devices. The centralized controller itself represents a single point of potential failure. To overcome this shortcoming, decentralized control is used to improve redundancy. This paper introduces three ideas to vibration control of smart structures: agent technology, replicator dynamics from evolutionary game theory, and energy minimization. It presents two new methods: 1) a single-agent Centralized Replicator Controller (CRC) and a decentralized Multi-Agent Replicator Controller (MARC) for vibration control of smart structures. The use of agents and a decentralized approach enhances the robustness of the entire vibration control system. The proposed control methodologies are applied to vibration control of a 3-story steel frame and a 20-story steel benchmark structure subjected to two sets of seismic loadings: historic earthquake accelerograms and artificial earthquakes and compared with the corresponding centralized and decentralized conventional Linear Quadratic Regulator (LQR) control algorithm.

Application of a Fractional Order Integral Resonant Control to increase the achievable bandwidth of a nanopositioner.

This paper proposes a Fractional-order modification of the traditional Integral Resonant Controller named as FIRC. The fractional integral action utilised in the proposed FIRC is a simple, robust, and well-performing technique for vibration control in smart structures with collocated sensor-actuator pairs such as nanopositioning stages. The proposed control scheme is robust in the sense of being insensitive to spillover dynamics and maintaining closed-loop stability even in the presence of model inaccuracies or time-delays in the system. The experimental and simulated results have showed that the proposed FIRC can provide a closed-loop bandwidth which spans up to a 95.2% of the first resonant mode of the experimental system, thus improving the bandwidth achieved by classical integer-order IRC implementations.

Recent advances in control algorithms for smart structures and machines

AbstractThis paper presents a state‐of‐the‐art review of recent control algorithms used primarily for vibration control of smart structures and machines. Control algorithms can be divided into open loop, feedback, feedforward, and combined feedback and feedforward control. Solutions proposed can be subdivided into (a) classical control, (b) optimal control, (c) robust control, (d) intelligent control, and (e) self‐sustaining solutions and energy harvesting used in centralized and decentralized configurations. The most recent research on novel autonomous control systems intersects distributed control theory, agent‐based modeling, bioinspired computational learning, and optimization algorithms.

Analysis of sensor-debonding failure in active vibration control of smart composite plate

In this article, the effect of a sensor-debonding failure on the active vibration control of a smart composite plate is investigated numerically. A mathematical model of the smart structure with a partially debonded piezoelectric sensor is developed using an improved layerwise theory, a higher-order electric-potential field that serves as the displacement field, and the potential variation through the piezoelectric patches. A state-space form that is based on the reduced-order model is employed for the controller design. A control strategy with a constant gain and velocity feedback is used to assess the vibration-control characteristics of the controller in the presence of the sensor-debonding failure. The obtained results show that sensor-debonding failure reduces the sensor-output, control-input signal, and active damping in magnitude that successively degrades the vibration attenuation capability of the active vibration controller. The settling time and relative tip displacement of the controlled structure increase with the increasing length of partial debonding between the piezoelectric sensor and host structure. Furthermore, a damage-sensitive feature along with multidimensional scaling showed excellent results for the detection and quantification of sensor-debonding failure in the active vibration control of smart structures.

Fractional-order integral resonant control of collocated smart structures

This paper proposes a fractional-order integral controller, FI, which is a simple, robust and well-performing technique for vibration control in smart structures with collocated sensors and actuators. This new methodology is compared with the most relevant controllers for smart structures. It is demonstrated that the proposed controller improves the robustness of the closed-loop system to changes in the mass of the payload at the tip. The previous controllers are robust in the sense of being insensitive to spillover and maintaining the closed-loop stability when changes occur in the plant parameters. However, the phase margin of such closed-loop systems (and, therefore, their damping) may change significantly as a result of these parameter variations. In this paper the possibility of increasing the phase margin robustness by using a fractional-order controller with a very simple structure is explored. This controller has been applied to an experimental smart structure, and simulations and experiments have shown the improvement attained with this new technique in the removal of the vibration in the structure when the mass of the payload at the tip changes.

New discrete-time robust H2/H∞ algorithm for vibration control of smart structures using linear matrix inequalities

In real structural systems, such as a building structure or a mechanical system, due to inherent structural modeling approximations and errors, and changeable and unpredictable environmental loads, the structural response unavoidably involves uncertainties. These uncertainties can reduce the performance of a control algorithm significantly and possibly make it unstable. In this paper, based on the theories of the Bounded Real Lemma and the linear matrix inequalities (LMI), a novel discrete-time robust H2/H∞ control algorithm is presented which not only reduces the structural peak response caused by external dynamic forces but also is robust and stable in the presence of parametric uncertainties which is always the case in real-life structures. To facilitate practical implementation, the uncertainties of structural parameters are considered in the time domain as opposed to the frequency domain. Compared with traditional H∞ control methods, the new control algorithm proposes a convenient design procedure to facilitate practical implementations of active control of complex and large structural systems through the use of a quadratic performance index and the LMI-based solution method. The effectiveness of the new discrete-time robust H2/H∞ adaptive control algorithm is demonstrated using a three-story frame with active bracing systems (ABS) and a ten-story frame with an active tuned mass damper (ATMD).

Adaptive Fuzzy Vibration Control of Smart Structure with VFIFE Modeling

ABSTRACTThe vibration control of smart structure is considered in this paper. Membrane SAR antenna structure with piezoelectric sensors and actuators is taken as an example. The dynamic model is build up based on vector form intrinsic finite element (VFIFE) method. The four nodes membrane element, sensor element and actuator element for VFIFE are presented. By decentralized control stratagem, the bending and torsional vibrations of the membrane SAR antenna can be decoupled on measurement and driving control. The fuzzy control and adaptive fuzzy control are applied to suppress the bending and torsional vibrations of the membrane SAR structure. In the numerical experiment section, form finding is first carried out, then vibration control simulations are studied. The results demonstrate that adaptive fuzzy control algorithm can suppress the vibrations more effectively than the fuzzy control algorithm.

Consensus positive position feedback control for vibration attenuation of smart structures

This paper presents a new network-based approach for active vibration control in smart structures. In this approach, a network with known topology connects collocated actuator/sensor elements of the smart structure to one another. Each of these actuators/sensors, i.e., agent or node, is enhanced by a separate multi-mode positive position feedback (PPF) controller. The decentralized PPF controlled agents collaborate with each other in the designed network, under a certain consensus dynamics. The consensus constraint forces neighboring agents to cooperate with each other such that the disagreement between the time-domain actuation of the agents is driven to zero. The controller output of each agent is calculated using state-space variables; hence, optimal state estimators are designed first for the proposed observer-based consensus PPF control. The consensus controller is numerically investigated for a flexible smart structure, i.e., a thin aluminum beam that is clamped at its both ends. Results demonstrate that the consensus law successfully imposes synchronization between the independently controlled agents, as the disagreements between the decentralized PPF controller variables converge to zero in a short time. The new consensus PPF controller brings extra robustness to vibration suppression in smart structures, where malfunctions of an agent can be compensated for by referencing the neighboring agents’ performance. This is demonstrated in the results by comparing the new controller with former centralized PPF approach.

Improving Neural Network based Vibration Control for Smart Structures by Adding Repetitive Control

Neural networks (NN) has been a popular vibration control method because of its robustness and practicability to reject broad band disturbances for complex systems such as smart structures. However, the benign characteristic of NN, suppressing a wide range frequency of disturbances, may also limit its control performance at specific frequencies and inevitably cause no n-minimum output responses in particular under persistent excitatio n. To alleviate this limitation and improve the performance of NN based control methods, this paper presents a hybrid control strategy comprising a neural controller and a repetitive controller for a ctive vibration control of smart structures. The neural controller is a fund amental controller which applies back-propagation networks for performance evaluation. To add repetitive control into the existing NN control system, the work transforms a feedback controller to a feedforward control problem with the solutions of a bezout identity embedded with known internal models of injecting disturbances. The presented hybrid control provides a synergetic effect and aims for better suppression performance subject to complicated disturbances in stringent environments. Experimental results on a flexible beam demon strate the effectiveness of the proposed control method.

A quasi-modal approach to overcome FBG limitations in vibration control of smart structures

Embedding FBG sensors in carbon fiber structures is a very attractive procedure, due to the small fiber cross section and to the possibility of manufacturing arrays of many gratings into a single optical fiber. This embedding is particularly useful for the manufacturing of smart structures, enabling improvement of their characteristics thanks to the embedded sensors and actuators. However, the low precision of FBG measurements makes the effectiveness of such signals in control applications limited. This paper deals with the possibility of reducing vibrations in structures by using distributed sensors embedded in carbon fiber structures through the so-called sensor-averaging technique. This method provides a properly weighted average of the outputs of a distributed array of sensors generating spatial filters on a broad range of undesired resonance modes without adversely affecting phase and amplitude. This approach combines the positive aspects of decentralized control techniques, because the control forces applied to the system are independent, with, as for centralized controls, the possibility of exploiting the information from all the sensors. Theoretical aspects are supported by experimental applications on a large flexible system composed by a thin cantilever beam with 30 longitudinal FBG sensors and six piezoelectric actuators (PZT).

Vibration control of smart structures using an array of Fiber Bragg Grating sensors

Optical strain gauges, such as Fiber Bragg Grating (FBG) sensors, are widely used to monitor the health of structures and their state of deformation. This paper proposes exploiting the measurements of these sensors as feedback for active vibration control applications. The advantages of this solution are the possibility of monitoring a large number of sensors (to approximate distributed measurements) and of embedding them in carbon fiber structures with negligible load effects. Experimental tests confirm that smart structures with embedded FBG sensors can be profitably designed to suppress vibrations.

Genetic algorithm based wireless vibration control of multiple modal for a beam by using photostrictive actuators

The lanthanum-modified lead zirconate titanate (PLZT) actuator, which are capable of converting photonic energy to mechanical motion, have great potential in applications of remote structural vibration control of smart structures and machines. In this paper, a novel genetic algorithm based controlling algorithm for multi-modal vibration control of beam structures via photostrictive actuators is proposed. Two pairs of photostrictive actuators are laminated with the beams and the alternation of light irradiation is in accordance with the changing of the corresponding modal velocity direction. The modal force indexes for beams with different boundary conditions are derived and a binary-coded GA is used to optimize the locations and sizes of photostrictive actuators to maximize the modal force index and guarantee the overall modal force index induced by two pairs of photostrictive actuators is positive. The control effect of multiple vibration modes of beams under irradiation of set/variable light intensity is analyzed. Numerical results demonstrate that the method is robust and efficient, and the use of strategically positioned actuator patches can effectively control the first two bending modes that dominate the structural vibration.

Modeling of Active Vibration Control in Smart Structures

The paper presents active control of smart structures within a focused frame of piezoelectric applications in active vibration and noise attenuation with potential applications in mechanical and civil engineering. Smart structure has become an increasingly common term describing a structure embedded or bonded with a large number of lightweight active electro-mechanical sensors and actuators. In this paper, we consider the modelling and control issues related to smart structures bonded with piezoelectric sensors and actuators with emphasis on robust control design taking into account structural uncertainties using the H Infinity control theory. The results show that the vibrations can be significantly suppressed by H Infinity controller.

Robust Active Vibration Control of Smart Structures; a Comparison between Two Approaches: µ-Synthesis & LMI-Based Design

The purpose of this paper is comparing the performance of two robust control designing approaches in smart structures. First, an accurate model of a homogeneous plate with special boundary conditions is derived by using of modal analysis. Then, some primitive p late's modes are considered as nominal system and the remaining modes are left as a mu ltip licat ive unstructured modelling uncertainty. Next, t wo robust controller are designed using µ-Synthesis & LMI-Based Design approaches based on the augmented plant composed of the nominal model and its accompanied uncertainty. Finally, the robustness of two uncertain closed-loop models and the d ifference between t wo controller performances has been investigated. Obtained results show the higher performance of LMI-Based Design approach in rejection of random disturbances.

B32 調和入力を仮定した予測制御によるスマート構造のエネルギー回生振動制御(M-OS3-1 制御/センシング,M-OS3 スマート構造システム,「海を越え,国を越え,世代を超えて!」)

Conventional controllers used for active vibration control of smart structures often evaluate amplitude of control inputs as part of objective functions and suppress the amplitude of the inputs. The major intents of the control input amplitude suppression are energy consumption suppression and saturation prevention. However, energy regenerative vibration control systems regenerate vibration energy and larger inputs do not mean larger energy consumption. Therefore, the first intent of the control input amplitude suppression is not suitable for energy regenerative vibration control systems. In addition, saturation prevention, the second intent, should be treated as a constraint rather than part of objective functions. In this paper, a novel controller suitable for energy regenerative vibration control systems is proposed. The controller is based on model predictive control and the computational cost is reduced by using harmonic functions as basis functions of input. The approach gives good prediction of averaged regeneration power in future and the prediction can help power management of energy regenerative vibration control systems.

An H2 norm approach for the actuator and sensor placement in vibration control of a smart structure

In active vibration control of smart structures, the actuator and sensor placement is a key point of the control system design. Even the most robust control logics could easily make a structure unstable if the actuators and sensors were not correctly positioned. The objective of this paper is to propose an H2 norm approach for the actuator and sensor placement. Unlike most modal H2 norm actuator and sensor placement methodologies, this work aims not only to maximize the norms of the controlled modes but also to reduce spillover problems by taking into account the residual modes and minimizing their H2 norms. It discusses the optimal actuator and sensor configuration in a finite element model of a square plate fixed on three sides with piezoelectric patch actuators and acceleration sensors. Finally, downstream of the actuator and sensor positioning, IMSC, PPF and NDF controls have been tested and discussed.