Vibration Suppression Of System Research Articles

A COMPARATIVE STUDY OF PHENOMENOLOGICAL MODELS OF MR BRAKE BASED ON NEURAL NETWORKS APPROACH

In this paper a full-scale commercially available magnetorheological (MR) brake installed in a semi-active suspension (SAS) system is modeled and simulated. Two well-known phenomenological hysteresis models are explored: Bouc–Wen and Dahl ones. In particular, influence of their parameters on the response is evaluated and assessed. The next step is to introduce the artificial neural networks and discuss their application in the field of systems identification. Subsequently, two feedforward neural networks are created and trained to estimate parameters characterizing each of the MR damper models described. The semi-active suspension (SAS) system equipped with a MR brake is described and the detailed procedure for acquisition of the reference data used in the models validation stage is elaborated. The models outputs obtained by simulating them with the values of coefficients as identified by the networks are compared to each other as well as to the reference experimental data. Thanks to that, the comparative analysis between the suggested vibration suppression models and the full-scale MR brake is done and it is concluded which of the discussed models has a better performance. The usability of neural networks in the field of parameters estimation of the mathematical models of the real world phenomena is described as well. The novelty of the presented methodology is the application of artificial intelligence methods to estimate model parameters of a MR brake utilized in a SAS system. The results of this approach have a strong potential to be successfully implemented in the area of model-based control of semi-active vibration suppression systems.

Adaptive vibration suppression system: an iterative control law for a piezoelectric actuator shunted by a negative capacitor

An adaptive system for the suppression of vibration transmission using a single piezoelectric actuator shunted by a negative capacitance circuit is presented. It is known that by using a negative-capacitance shunt, the spring constant of a piezoelectric actuator can be controlled to extreme values of zero or infinity. Because the value of spring constant controls a force transmitted through an elastic element, it is possible to achieve a reduction of transmissibility of vibrations through the use of a piezoelectric actuator by reducing its effective spring constant. Narrow frequency range and broad frequency range vibration isolation systems are analyzed, modeled, and experimentally investigated. The problem of high sensitivity of the vibration control system to varying operational conditions is resolved by applying an adaptive control to the circuit parameters of the negative capacitor. A control law that is based on the estimation of the value of the effective spring constant of a shunted piezoelectric actuator is presented. An adaptive system which achieves a self-adjustment of the negative capacitor parameters is presented. It is shown that such an arrangement allows the design of a simple electronic system which offers a great vibration isolation efficiency under variable vibration conditions.

Innovative Digital Self-Powered Autonomous System for Multimodal Vibration Suppression

A novel invention, a digital self-powered autonomous system, is proposed to achieve sophisticated vibration suppression dealing with multimodal vibrations. This vibration suppressor can be used ubiquitously at any site because it does not require an external power supply or a central control authority. The digital approach enables the system to be programmed, and thus, it affords some versatility with regard to control schemes. The proposed system is a vast improvement over conventional analog-autonomous systems whose fine-tuning is very difficult. The digital unit can be implemented in multi-input/multi-output systems to suppress complicated structural vibrations, such as multimodal vibrations. This paper provides an analytical discussion on the energy-harvesting effect on suppression performance in terms of the power balance andflow.Experiments demonstrate that the vibrationmagnitude reduces dramatically by as much as 79.7% under force excitation, although the self-powered control unit is used.

A new method for accurately determining the modal equivalent stiffness ratio of bonded piezoelectric structures

This paper describes new methods for measuring the modal equivalent stiffness ratios and modal electromechanical coupling coefficients of piezoelectric elements attached to a host structure such as a beam. Modal equivalent stiffness ratios and modal electromechanical coupling coefficients are essential for estimating the performance and determining an optimum design of active vibration control and passive vibration suppression systems that use piezoelectric elements. Accurate determination of these modal parameters is also useful for other systems including piezoelectric sensors and energy generators. This paper not only describes the measurement methods but also presents the theoretical formulations derived by taking into account the effect of adhesive bonds. The formulations in this paper demonstrate the necessity of experimental measurements and the accuracy enhancements that the theoretical estimations can provide. Conventional methods for obtaining the modal equivalent stiffness ratios are sensitive to measurement errors, which result in the loss of accuracy, rendering these methods unreliable for many practical applications. The proposed methods use an inductor instead of an open circuit to address the abovementioned issue and, thereby, provide significant improvement in the accuracy. Because the loss factors of the experimental apparatus tend to compromise the accuracy of the proposed methods, a method using a negative resistor is proposed, theoretically analyzed, and confirmed to eliminate some of the errors introduced by loss factors. The advantages of the proposed methods and the effectiveness of theoretical analysis, considering the effect of adhesive bonds, are verified experimentally.

Application of Taguchi Optimization Method in Active Vibration Control of a Smart Beam

Cantilevered beams can serve as a basic model for a number of structures used in various fields of industry, such as airplane wings, turbine blades and robotic manipulator arms.In this paper, the active vibration control of a smart cantilevered beam with a piezoelectric patch is studied. Additionally, the optimization of influential parameters of piezoelectric actuator for the purpose of vibration suppression is performed. Initially, the finite element modeling of the cantilevered beam and its piezoelectric patch is described and the implementation of a control system for vibration suppression is introduced. Transient response of the system under impact loading, with and without controller, is simulated using ANSYS. Taguchi’s design of experiments method is used to investigate the effect of five geometric parameters on the vibrational behavior of the system. It is shown that, optimal selection of levels for geometry of the piezoelectric actuator and sensor, can dramatically improve the dynamic response of the smart beam.

Comparison of Analog and Digital Self-Powered Systems in Multimodal Vibration Suppression

This paper compares our analog and digital self-powered systems for vibration suppression, and shows experimental results of multimodal vibration suppression for both self-powered systems. The experimental results are evaluated in light of the damping performance and adaptability under various vibrational conditions. We demonstrate various examples of our innovative vibration suppression method, called “digital self-powered.” Proper status switching of an electric circuit made up of an inductor and a selective switch connected to a piezoelectric transducer attenuates the vibrations. The control logic calculation and the switching events are performed with a digital microprocessor that is driven by the electrical energy converted from the mechanical vibration energy. Therefore, this vibration suppression system runs without any external power supply. The self-powering feature makes this suppression method useful in various applications. To realize an ideal vibration suppression system that is both self-powered and effective in suppressing multimode vibration, sophisticated control logic is implemented in the digital microprocessor. We demonstrate that our digital self-powered system can reduce the vibrational displacements of a randomly excited multimodal structure, by as much as 35.5%.

631 磁気粘弾性エラストマを用いた可変剛性型動吸振器の開発

Dynamic Vibration Absorber (DVA) is well known as one of the representatives of vibration suppression systems. DVA is classified to be passive system and has the advantage that it is reliable and inexpensive, but does not work effectively beyond the designed range. To solve this problem, Magneto-rheological elastomers (MREs) are adopted to DVA to make DVA with variable stiffness. MREs are one of smart materials whose rheological or viscoelastic properties can be varied by applying external magnetic field. In this paper, the stiffness controllable elastomer composites known as MREs are first fabricated and their field- dependent static and dynamic properties are tested as the basis of this study. The MRE is then applied to DVA to control the vibration of one-degree of freedom structure model. Experimental investigations show that the vibration of the one-degree of freedom structure that is exposed to base excitation can be effectively reduced by actuating DVA with variable stiffness.

Fault Detection of Dampers of Railway Vehicles Focused on Phase Difference between Translational and Rotational Motion

The authors have developed a vibration suppression system with variable vertical oil dampers in primary or secondary suspensions of railway vehicles for improvement of riding comfort due to vertical vibration. In order to apply this system into practical use, the function to detect the failure and stop the control in case some damper fails is required. This paper presents a technique for damper fault detection based on the phase difference between the bounce and the pitch vibration of bogie frames or car bodies obtained with inertial sensors, as a method without mounting sensors in oil dampers. The result of vibration excitation test with one vehicle on a testing plant demonstrates the fault of a primary vertical damper was detectable by evaluating the phase difference between the bounce and the pitch vibration of the bogie frames. The result of running test in a meter-gauge line demonstrated the fault of a secondary vertical damper was detectable based on the phase difference of that of car bodies. These results have suggested the proposed method is effective for the fault detection of both primary and secondary vertical damper.

Modeling and Identification for Lightweight High-Speed Machines with Loads Variation

The positioning performance of high-speed, high-accuracy light-weight motion control systems is usually restricted by the structure flexibility and model parameter-varying caused by load mass variation. It needs to develop novel motion control algorithm to eliminate the residual vibration in the end-effectors, as well as to be robust over the load mass variation. This paper addresses the first and crucial step of this problem, modeling and identification technique. The linear parameter-varying model of the system is constructed and analyzed. The parameters and affine function identification method based on nonlinear least-squares and principle component analysis technique is proposed. The validity of the proposed method is demonstrated through a lightweight machine experimental setup. It is general enough to be applicable to the dynamic behaviors analysis and gain-scheduling robust control design for industrial lightweight vibration suppression and motion control systems that possess flexible elements and variable loads.

Adaptive regulation—Rejection of unknown multiple narrow band disturbances (a review on algorithms and applications)

The paper addresses the problem of attenuation (rejection) of unknown and time varying multiple narrow band disturbances without measuring them. In this context the disturbance model is unknown and time varying while the model of the plant is known (obtained by system identification) and almost invariant. This requires to use an adaptive feedback approach. The term “adaptive regulation” has been coined to characterize this control paradigm. Application domains include: mechanical and mechatronics systems, active vibration and noise suppression systems, some types of bio-chemical reactors. The paper reviews the various techniques proposed for solving this problem. It will focus on the presentation of the direct and indirect adaptive regulation strategies using the internal model principle and the Youla–Kucera parametrization which have been extensively used in applications. The paper also reviews a number of applications including: active suspension systems, active vibration control systems, active noise control, bio-chemical reactors, distributed flexible mechanical structures and Blu-ray disc drives. Real time results obtained on various applications will illustrate the methodology.

On the assessment of passive devices for structural control via real-time dynamic substructuring

In this work, the applicability of a dynamic testing technique known as real-time dynamic substructuring (RTDS) for the assessment of passive vibration suppression systems in seismic protection of buildings is analysed. RTDS is an efficient method for the assessment of dynamic and rate-dependent behaviour of systems subjected to dynamic excitation at real scale and in real scenarios. The actuators used in RTDS test introduce additional undesirable dynamics into the system, which are often not fully compensated for in the actuator controller—these dynamics are commonly approximated as a feedback delay. To guarantee the validity and accuracy of an RTDS simulation, a stability analysis of the substructured system that includes the feedback delay should be carried out. In this paper, we present explicit analyses that provide a dynamic characterization of the delay-induced phenomena in RTDS simulations when considering passive vibration suppression systems with strong nonlinearities. We present a complete set of closed-form expressions to describe the main phenomena because of delay in terms of dynamic stability in an RTDS simulation. Through an experimental study, we confirm the existence of self-sustained oscillations caused by very small delay in the feedback loop. This lead the system to instability in the form of high-frequency oscillations. Copyright © 2011 John Wiley & Sons, Ltd.

Robust adaptive sliding mode attitude control and vibration damping of flexible spacecraft subject to unknown disturbance and uncertainty

This paper is concerned with the development of a control system for rotational manoeuvre and vibration suppression of a flexible spacecraft. The design approach presented here treats the problem of spacecraft attitude control separately from the elastic vibration suppression problem. As a stepping stone, a state feedback sliding mode control command is designed to achieve the reference trajectory tracking control of attitude angle. This is followed by the design of an adaptive sliding mode control law using only output for robust stabilization of spacecraft in the presence of parametric uncertainty and external disturbances. Even if this controller has the ability to reject the disturbance and deal with uncertainty, it excites the elastic modes of flexible appendages. The undesirable vibration is then actively suppressed by applying feedback control voltages to the piezoceramic actuators, in which the modal velocity feedback control method is adopted here for determining the control voltages. The effectiveness of the control schemes in handling external disturbance and uncertainty in the system parameters is also studied. Both analytical and numerical results are presented to show the theoretical and practical merit of this hybrid approach.

Semi-Active Vibration Control of Smart Structures with Sliding Mode Control

In this study, a semi-active vibration suppression system comprising piezoelectric elements is developed for flexible structures. The vibration suppression system comprises a cantilevered beam with bimorph piezoelectric ceramic tiles shunted by an RL electrical circuit with a switch. A general design method for vibration suppression of the beam is theoretically analyzed using mode analysis, wherein it is assumed that the piezoelectric elements are sufficiently thin and do not change the mode shape of the beam. With this assumption, the vibration suppression system for the beam is designed by tuning the optimal resistance and inductance parameters of the shunted RL network. In this paper, we propose a semi-active vibration control law to improve the damping effect while maintaining the stability of the passive control system. The proposed control law is similar to a sliding-mode control that accelerates the convergence of the system by using switching functions. As an example, numerical simulations have been performed for a cantilevered beam. This study shows that the resonant circuit functions as a type of a dynamic damper for mechanical systems and that sliding-mode control is very effective in damping the multi-mode responses. The results of the numerical simulations show that the semi-active vibration control system is practically more effective in damping vibrations than the passive control system.

Vertical Vibration Suppression System for Railway Vehicles Based on Primary Suspension Damping Control — System Development and Vehicle Running Test Results —

Suppression of vertical bending vibration is essential to improve ride comfort on railway vehicles. For this purpose, a primary suspension damping force control system is being developed. This paper describes the composition of the system and reports on the results from vehicle running tests on some Shinkansen lines using actual Shinkansen vehicles fitted with the developed variable primary vertical dampers. The results of these tests demonstrate that this system is effective in reducing vertical vibration acceleration in the first bending mode of the car body and improves ride comfort. In addition, a progress report is also given on its ongoing development.

A Neural Fuzzy System for Vibration Control in Flexible Structures

An adaptive neural fuzzy (NF) controller is developed in this paper for active vibration suppression in flexible structures. A recurrent identification network (RIN) is developed to adaptively identify system dynamics of the plant. A novel recurrent training (RT) technique is suggested to train the RIN so as to optimize nonlinear input-output mapping and to enhance convergence. The effectiveness of the developed controller and the related techniques has been verified experimentally corresponding to different control scenarios. Test results show that the proposed RIN can effectively recognize the time-varying dynamics of the plant. The RT-based hybrid training technique can improve the adaptive capability of the control system to accommodate different system conditions and enhance the training convergence. The developed NF controller is a robust and stable vibration suppression system, and it outperforms other related NF controllers.

Reliability Analysis of Kinematic Accuracy of a Three Degree-of-Freedom Parallel Manipulator

The reliability of kinematic trajectory of manipulators describes the ability that manipulators keep kinematic accurate. It is an important parameter to evaluate the performance of manipulators. The kinematic accuracy of manipulators can be improved when piezoelectricity material are used as a transducer to suppress the vibration of flexible manipulators. First, a 3 degree-of-freedom parallel manipulator system and its dynamic equations are introduced. The theory and experiment of a vibration suppression system are then presented. The calculation method of both error and reliability of kinematic trajectory of manipulator is further implemented. Finally, the reliability of kinematic accuracy are calculated and analyzed for the 3 degree-of-freedom parallel manipulator with or without vibration suppressing control. The results show that the reliability of kinematic accuracy is improved using vibration suppressing control.

2B15 Semi-active Vibration Control of Smart Structures with Sliding Mode Control

In this study, a semi-active vibration suppression system comprising piezoelectric elements is developed for flexible structures. The vibration suppression system comprises a cantilevered beam with bimorph piezoelectric ceramic tiles shunted by an RL electrical circuit with a switch. A general design method for vibration suppression of the beam is theoretically analyzed using mode analysis, wherein it is assumed that the piezoelectric elements are sufficiently thin and do not change the mode shape of the beam. With this assumption, the vibration suppression system for the beam is designed by tuning the optimal resistance and inductance parameters of the shunted RL network. In this paper, we propose a semi-active vibration control law to improve the damping effect while maintaining the stability of the passive control system. The proposed control law is similar to a sliding-mode control that accelerates the convergence of the system by using switching functions. As an example, numerical simulations have been performed for a cantilevered beam. This study shows that the resonant circuit functions as a type of a dynamic damper for mechanical systems and that sliding-mode control is very effective in damping the multi-mode responses. The results of the numerical simulations show that the semi-active vibration control system is practically more effective in damping vibrations than the passive control system.

Characteristics of a Reverse Guided Structure for Vibration Suppression

In this paper, based on the concept of vibration waves' guiding and suppression, we present mechanisms that can guide the vibration wave in the reverse direction and apply these mechanisms to design a reverse guided structure for vibration suppression system. The related dynamic equations are derived. Both the frequency responses and the transient responses are conducted from the dynamic model. The simulation results are good in showing the characteristics of the mechanism and the designed system of a reverse guided structure for vibration suppression. After observing the effects of system parameter variation on the performance of vibration suppression, we conclude some design guidelines for implementation in future design references.

128 圧電素子と共振回路を用いたスマート構造の受動/準能動制振

In this study, a semi-active vibration suppression system comprising piezoelectric elements is developed for flexible structures. The vibration suppression system comprises a cantilevered beam with bimorph piezoelectric ceramic tiles shunted by a RL electrical circuit with a switching part. This study shows that the resonant shunt circuit functions as a type of a dynamic damper for mechanical systems and the proposed switching control, inspired by a sliding-mode control law, is more effective than the passive damping system especially for the multi-mode vibration suppression.

鉄道車両のさらなる乗り心地向上に向けた上下振動制御装置の開発(<メカライフ特集>揺れる,揺らす)

鉄道車両のさらなる乗り心地向上に向けた上下振動制御装置の開発(<メカライフ特集>揺れる,揺らす)