Semi-active Vibration Suppression Research Articles

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.

Development of LuGre Friction Model for Large-Scale Magneto—Rheological Fluid Dampers

This paper presents a new hysteresis model, based on the LuGre friction model, to analyze the dynamic behavior of large-scale Magneto-rheological (MR) damper (MR-9000 type MR-damper) accurately and efficiently. The gradient based optimization technique and the least square method will be utilized to identify the modal parameters. The dynamic behavior of MR-damper under different types of excitation and input currents has been predicted using the proposed model. The results were compared with those predicted using the modified Bouc—Wen model to verify the validity of the proposed model. Furthermore, based on the proposed LuGre friction model, an effective inverse MR-damper model has been presented, which can be readily used in the design of the semi-active vibration suppression devices.

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.

Performance of Simple and Sophisticated Control in Energy-recycling Semi-active Vibration Suppression

The semi-active energy-recycling methods studied in this article suppress vibration by controlling switches in inductive shunt circuits connected to piezoelectric transducers in vibrating structures. This article compares the performances of simple and sophisticated methods that can be used for multiple-mode vibration. Although it should be obvious that the performance of the latter is superior, we need to know whether the superior performance of the sophisticated method justifies the expense incurred by its complexity. The performance comparisons were done by numerically simulating the vibration suppression of a truss structure with a piezoelectric transducer. We simulated transient free vibrations, forced sinusoidal vibrations, and forced random vibrations. In all cases, both methods were shown to be effective for the first and second modes of vibration. The ways and situations in which the sophisticated method is superior to the simple method were also elucidated. A vibration suppression experiment using a truss was also carried out and demonstrated that the sophisticated method worked well under random excitation.

Novel Approach to Self-Sensing Actuation for Semi-Active Vibration Suppression

A novel self-sensing method using piezoelectric actuators for semi-active vibration suppression is proposed and investigated. By using extended system equations, this self-sensing method can be implemented with a Kalman filter instead of the conventional bridge circuit technique. The method separates electrical status into two cases concerning electrical current, and characterizes each of these to establish the self-sensing system. This method is applicable to multiple-degree-of-freedom structures with multiple piezoelectric actuators. A numerical vibration suppression simulation demonstrated that the self-sensing method works well on a truss structure and has significant robustness against parameter variations. Experimental results also demonstrated that the self-sensing method suppresses not only single-mode vibration but also multiple-mode vibration.

Comprehensive Assessment of Semi-Active Vibration Suppression Including Energy Analysis

This paper presents an extensive investigation on the LR-switching method (also called the energy-recycling semi-active method). Compared with the energy-dissipative R-switching method, the LR-switching method has been shown to have significantly better vibration suppression performance. However, certain essential issues affecting a system employing the LR-switching method remained to be dealt with. In particular, we had to clarify its vibration suppression mechanism from the viewpoint of mechanical and electrical energy exchange. Second, the robustness of the method against model errors and control time delays had to be verified. The experiments and numerical simulations that we conducted on a 10-bay truss structure demonstrate that the LR-switching method outperforms other suppression methods under sinusoidal and random excitations, which are more common in real systems and more difficult to deal with than transient vibrations. This paper provides fundamental insights on the LR-switching method and gives the method a guarantee for actual applications.

Investigation of performance in suppressing various vibrations with energy-recycling semi-active method

We conducted various investigations of energy-recycling semi-active vibration suppression by using piezoelectric transducers attached to structures. In this method, the converted electrical energy is recycled to suppress the vibration of structures instead of simply being dissipated. First, the energy-recycling semi-active method was applied to vibration suppression of a beam that is a typical continuous structure. Then, the method was applied to suppress the transient vibration of a membrane that is a typical tension-stabilized structure. Through these investigations, the energy-recycling method was found to be effective for use with various systems.

Behavior of Piezoelectric Transducer on Energy-Recycling Semiactive Vibration Suppression

Behavior of Piezoelectric Transducer on Energy-Recycling Semiactive Vibration Suppression

621 圧電素子の電圧測定のみによるセルフセンシング準能動的制振

This paper presents a self-sensing method for semi-active vibration suppression that measures only the value of piezoelectric voltage. The method separates electrical status into two cases concerning electrical current, and characterize each of these to establish a self-sensing system. Experiments revealed that the self-sensing system suppressed vibrations by combining the state-switching control or the synchronized-switching control. We confirmed that the self-sensing method is robust against model errors through the vibration suppression experiment subject to model errors caused by intentional frequency shift.

Low Energy-Consumption Hybrid Vibration SuppressionBased on Energy-Recycling Approach

An innovative method of hybrid vibration suppression using piezoelectric materials is proposed. It combines bang‐bang active vibration suppression and energy-recycling semiactive vibration suppression. The piezoelectric materials are electromechanically coupled and convert mechanical energy into electrical energy and vice versa. With this method, a part of the electrical energy needed for suppressing vibration is obtained from the mechanical energy of the vibrating structures and is efficiently recycled. Furthermore, the actively supplied energy is stored in the transducers and is reused many times for vibration suppression. Therefore, the hybrid method has better performance than the case where the bang‐bang active method and the energy-recycling semiactive method are both used, but independently. The hybrid method saves the actively supplied energy and is thus a low-energyconsumption vibration control. Its effectiveness in suppressing vibrations was proven in numerical simulations and experiments using a 10-bay truss structure. Moreover, a novel method to prevent undesired control chattering is proposed to further save energy supplied from the external source.

Semi-Active Vibration Suppression of Beam Structures Based on Energy-Recycling Method

An innovative method of semi-active vibration suppression based on an energy-recycling approach using piezoelectric transducers is described. Piezoelectric transducers attached to or embedded in structures can convert the mechanical energy of the structure into electrical energy or, conversely, electrical energy into mechanical energy. Conventional methods have focused on how to effectively dissipate the transferred electrical energy. With our new energy-recycling method, the electrical energy is stored in the transducer functioning as a capacitor and is reused to suppress vibration of the structure, instead of simply being dissipated. This paper presents an advanced energy-recycling method to suppress multiple-mode vibration of beam structures with multiple transducers. Several control strategies based on active control theories are derived from formulae on the dynamics of a beam structure with piezoelectric transducers and electricity. We demonstrate the ability to suppress not only transient vibrations but also vibrations excited by sinusoidal and random forces.

Energy-Recycling Semi-Active Method for Vibration Suppression with Piezoelectric Transducers

*A novel energy-recycling method is studied that enables effective semi-active vibration suppression with piezoelectric transducers embedded or bonded to a structure. In this method, the energy converted from the mechanical energy of a vibrating structure is collected in the capacitor of a piezoelectric transducer as an electric charge, and to suppress vibration, rather than dissipate the energy, the polarity of the charge is changed according to the state of vibration. With this method, no energy is supplied to the total system of the structure and transducers with shunt circuit, which means that the system is stable. A simple electric circuit and a control law for multiple-degree-offreedom systems with multiple piezoelectric transducers are proposed for this method based on energy recycling. Numerical simulation of vibration suppression of a truss structure shows that this method is more effective in suppressing vibration than both a semi-active method without energy-recycling and that based on the use of an optimally tuned passive system. A preliminary experiment with a truss structure also shows that this method can effectively suppress vibration in an actual structure. However, there was some discrepancy in the experimental results compared to the results of the numerical simulation performed assuming ideal linear characteristics of the piezoelectric transducers estimated from a static test. Nomenclature

An experimental study of a semiactive magneto-rheological fluid variable damper for vibration suppression of truss structures

The purpose of this paper is to demonstrate that vibrations of a truss structure can be suppressed nicely by a magneto-rheological (MR) fluid variable damper for semiactive vibration suppression. A variable MR fluid damper was designed and fabricated for this study. The principal characteristics of an MR damper were measured in dynamic tests, and a mathematical model of the damper was proposed. To investigate if the variable damper effectively suppresses the vibration of actual truss structures, semiactive vibration suppression experiments were performed using a cantilevered ten-bay truss beam. The experimental result has shown that the vibration was suppressed nicely by the variable MR damper, and that was compared with that of an electro-rheological (ER) damper investigated in previous research. The MR damper showed a higher performance than that of the ER damper.

Improved Electrorheological-Fluid Variable Damper Designed for Semiactive Vibration Suppression

The studied damper can be modeled as a variable coulomb-friction damper. The friction in the damper is not zero, even when no voltage is applied to the electrode of the damper, and is an increasing function of the absolute value of the voltage. Semiactive vibration suppression exploits this variation of friction. To suppress large-amplitude vibrations to small-amplitude ones effectively, we need to vary the friction over a large range. In other words, the ratio of the maximum and minimum values of the frictional force needs to be large. An investigation of decreasing the minimum frictional force by vibrating the electrode of the damper to increase this ratio is reported. The effectiveness of the electrode vibration was demonstrated in static experiments, as well as in semiactive vibration suppression experiments, indicating that electrode vibration reduces the minimum frictional force by 1/3-1/2 without changing the maximum frictional force, thereby greatly reducing the vibration amplitude.

Characteristics of a Liquid-Crystal Type ER-Fluid Variable Damper for Semiactive Vibration Suppression

A liquid-crystal type ER-fluid variable damper was fabricated to semiactively suppress the vibration of space truss structure. The principal characteristics of a liquid-crystal variable damper were measured in quasi-static tests, and a simple mathematical model of the damper was proposed. Semiactive control laws were derived from this model and the LQR theory. Numerical simulations were performed to compare the effectiveness of the semiactive vibration suppression using liquid-crystal type and particle-dispersion type ER-fluid variable dampers. The results indicated that the proposed control laws resulted in much better damping performances than is obtained with an optimally tuned passive system. In some cases such as large amplitude vibration, a variable damper using liquid-crystal type ER-fluid showed higher performance than one using particle-dispersion type ER-fluid. The results of semiactive vibration suppression experiments with a ten-bay truss beam also demonstrated that the liquid-crystal variable damper effectively suppresses vibration. [S0739-3717(00)00304-4]

Improved electrorheological-fluid variable damper designed for semiactive vibration suppression

Improved electrorheological-fluid variable damper designed for semiactive vibration suppression

滑り状態制御を参考にした可変ダンパによる準能動的制振

For semiactive vibration suppression of truss structures with variable dampers, on-off control laws are newly derived suggested by the sliding-mode control theory. The control laws are shown to be in the same form as previously proposed control laws which are derived suggested by LQR control theory. The vibration suppression performances of the new control laws are investigated and compared with those of the previously proposed control laws by using numerical simulations. The results of the simulation show that the vibration suppression by the new control laws is effective and that performances of them are approximately the same as the previous laws although they result in different values of control law constants.

Semiactive Vibration Suppression with Electrorheological-Fluid Dampers

Semiactive vibration suppression with electrorheological (ER)-fluid variable dampers is proposed and demonstrated to be a robust approach to suppressing the vibration of space structures. The principal characteristics of an ER-fluid variable damper are measured, and a simple mathematical model of the damper is proposed. Based on the mathematical model of the damper, several semiactive on-off control laws are proposed. Their performance is investigated through both numerical simulations and experiments of cantilevered truss beams with ER-fluid variable dampers. Simulation results indicate that most of the proposed laws result in much more effective vibration suppression than is obtained when using an optimally tuned passive system. Under an ill condition, they are also shown to be much more robust than linear quadratic Gaussian active vibration controls whose vibration suppression performance is almost the same. A semiactive vibration suppression experiment with a cantilevered 10-bay truss beam demonstrates that vibrations are suppressed effectively by the ER-fluid variable damper.

Semi-active vibration suppression of truss structures by electro-rheological fluid

To semi-actively suppress the vibration of space truss structures, a variable damper using electro-rheological (ER) fluid is designed and fabricated. The characteristics of the damper are measured in quasi-static tests, and a simple mathematical model of the damper is proposed. Based on this mathematical model and the LQR control theory, a semi-active control scheme is proposed for vibration suppression. To investigate the performance of the scheme, numerical simulations of the semiactive vibration suppression of a 10-bay truss beam with an ER fluid damper are performed. Simulation results indicate the higher performance of the semi-actively controlled system than the optimally tuned passive system. Vibration tests and semi-active vibration suppression experiments of the 10-bay truss beam with the ER fluid damper are also performed. The characteristics of the damper obtained from the vibration tests are consistent with those from the quasi-static tests. The semi-active vibration suppression experiment results are consistent with the numerical simulation, and demonstrate the effectiveness of the present approach.

Semiactive vibration suppression by variable-damping members

A semiactive vibration suppression approach is proposed and investigated. It is to control the damping of viscous dampers installed in structures. By using a single-degree-of-freedom (SDOF) example first, vibration damping is shown to be much enhanced by a suitable variation of the damping of the damper according to the phase of vibration. Next, several types of control logic for this approach are proposed, which are applicable to multiple-degree-of-freedom (MDOF) structures with multiple variable dampers. The performance of these types of control logic are investigated by using an SDOF example and an MDOF truss structure example with three variable-damping truss members excited by impulsive and random forces. Numerical investigations demonstrate that the vibration suppression capabilities of most of them are much higher than that of the optimally tuned passive system, keeping the robustness of passive systems.