Seismic response control of building structures under pulse-type ground motions by active vibration controller

In this study, a frequency-dependent algorithm is proposed in independent modal space as an improvement to the linear quadratic Gaussian (LQG) control algorithm. The passive control parameters such as mass, stiffness and damping of a dynamic system are sensitive to different frequency ratios when subjected to external excitation. Depending upon the sensitivity of these parameters, the algorithm is developed in such a way that a response reduction similar to that of an LQG algorithm can be achieved with a significantly smaller control force. An effective gain is obtained by optimizing the H2 norm of the transfer function. It is observed from the results that the algorithm works well for high frequency ratio and near resonance regimes. Thus, a combination of the LQG and the proposed algorithms is considered as a modified LQG control algorithm, where the effectiveness of both algorithms is utilized. The efficiency of the modified LQG control algorithm is demonstrated by considering a base-isolated structure when subjected to earthquake base excitations. By comparing with the results it is observed that the modified LQG control algorithm is more efficient in terms of response reduction with a much lower control force as compared to the LQG control algorithm. It is envisioned that the modified LQG control algorithm will be highly useful for response control of base-isolated structures.

Vibration Dynamics and Control

Covers advancements in spacecraft and tactical and strategic missile systems, including subsystem design and application, mission design and analysis, materials and structures, developments in space sciences, space processing and manufacturing, space operations, and applications of space technologies to other fields.

Active vibration control usually reduces vibration amplitude and mechanical energy of vibrating structure. In the situation, actuator of active vibration control system must remove energy from vibrating structure. However, the consideration is inconsistent with a common knowledge of active vibration control, active vibration control system needs external power supply to drive actuator. To find an answer to the inconsistency, power flow in an active vibration control system of a SDOF oscillator using a piezoelectric actuator has been investigated by authors analytically. The piezoelectric actuator is used because it has little internal loss and it makes easy to understand essentials of power flow in the active vibration control system. The investigation shows that the actuator is not consuming power from external source but removing and regenerating energy from the SDOF oscillator. Power consumption of the system is caused by energy loss of the amplifier to drive the actuator. The result implies that an energy regenerative active vibration control system can be realized by reducing energy loss of the amplifier. The energy loss can be reduced by using class D amplifier, high efficient amplifier based on switching operation of semiconductor devices, instead of conventional linear amplifier. The validity of energy regenerative active vibration control system using class D amplifier is shown by a numerical simulation. An advantage of proposing method compared to other energy regenerative vibration control methods and semi-active methods is that proposing method can use any controller used in ordinary active vibration control and can achieve the same control performance because difference between ordinary active vibration control methods and proposing method is only type of amplifier. In this paper, the validity and the advantage are confirmed by experimental comparison of power flow and control performance of two active vibration control systems using a conventional linear amplifier and a class D amplifier with the same controller and the same actuator.

Active vibration control usually reduces vibration amplitude and mechanical energy of vibrating structures. In the situation, actuators of active vibration control systems must remove energy from vibrating structures. However, the consideration is inconsistent with a common knowledge of active vibration control, active vibration control systems need external power supply to drive actuators. To find an answer to the inconsistency, a power flow in an active vibration control system of a SDOF oscillator using a piezoelectric actuator has been investigated by the authors analytically. The reason for using the piezoelectric actuator is that piezoelectric actuators have little internal loss and the characteristics make easy to understand essentials of power flows in active vibration control systems. The investigation shows that the actuator is not consuming power from external source but removing and regenerating energy from the SDOF oscillator. The power consumption of the system is caused by the energy loss of the amplifier to drive the actuator. The result implies that an energy regenerative active vibration control method can be realized by reducing energy losses of amplifiers. The energy losses can be reduced by using class D amplifiers, high efficient amplifiers based on switching operation of semiconductor devices, instead of conventional linear amplifiers. The validity of the approach is shown by a numerical simulation. An advantage of the proposed method compared to other energy regenerative vibration control methods and semi-active methods is that the proposed method can use any controllers for ordinary active vibration control and can achieve the same control performance because the difference between ordinary active vibration control methods and the proposed method is only type of amplifier. In this paper, the validity and the advantage are confirmed by experimental comparisons of power flows and control performance of two active vibration control systems using a conventional linear amplifier and a class D amplifier with the same controller and the same actuator.

The new generation of aircraft require innovative solutions for the reduction of cabin noise, which can deal with new designs of the aircraft and are also able to withstand new requirements for lightweight vehicles. Active control technologies offer interesting lightweight solutions for the reduction of aircraft cabin noise at low audio frequencies, which can be used effectively in combination with passive sound insulation treatments. In the introductory section, the basic principles of active noise control are presented. Also, the principal characteristics of feed‐forward and feedback control architectures are reviewed with reference to tonal and broadband random disturbances. The following three sections introduce the principal control approaches that can be implemented in aircraft. The active control of cabin noise is first discussed. In particular, the effects produced by feed‐forward active noise control and active noise and vibration control systems are investigated. Also, the possibility of implementing active headrests is discussed. The control of vibration transmission from aircraft engines and helicopter gearbox systems is then reviewed. In particular, active vibration control and adaptive tunable vibration absorber technologies are examined. Finally, the active control of sound transmission through the fuselage double wall structure is analyzed. Two approaches are considered: active structural acoustic control and decentralized active vibration control.

This paper presents an integrated passive-active (i.e. hybrid) system for seismic response control of a cable-stayed bridge. Since multiple control devices are operating, a hybrid control system could alleviate some of the restrictions and limitations that exist when each system is acting alone. Lead rubber bearings are used as passive control devices to reduce the earthquake-induced forces in the bridge and hydraulic actuators are used as active control devices to further reduce the bridge responses, especially deck displacements. In the proposed hybrid control system, a linear quadratic Gaussian control algorithm is adopted as a primary controller. In addition, a secondary bang-bang type (i.e. on-off type) controller according to the responses of lead rubber bearings is considered to increase the controller robustness. Numerical simulation results show that control performances of the integrated passive-active control system are superior to those of the passive control system and are slightly better than those of the fully active control system. Furthermore, it is verified that the hybrid control system with a bang-bang type controller is more robust for stiffness perturbation than the active controller with a μ-synthesis method, and there are no signs of instability in the over-all system whereas the active control system with linear quadratic Gaussian algorithm shows instabilities in the perturbed system. Therefore, the proposed hybrid protective system could effectively be used for seismically excited cable-stayed bridges.

Vibration control of piezoelectric smart structures based on system identification technique: Numerical simulation and experimental study

Ventilation duct with concurrent acoustic feed-forward and decentralised structural feedback active control

Multi-objective genetic algorithms for cost-effective distributions of actuators and sensors in large structures

The Conference on Active Noise and Vibration Control Methods has already had a twenty-year tradition. The conference aim is to present the results of recent research work, to exchange ideas and to share experiences with representatives from international research centres. The control of low frequency noise and vibration has always proved to be a difficult task and in many cases not feasible at all due to the long acoustic wavelength involved. If passive techniques were only considered, noise control would require large mufflers, heavy enclosures and flexible isolation systems or perhaps extensive structural damping treatment would be needed for vibration control. Active noise and vibration control methods involve the use controllable systems to reduce the transmission of vibration from one plant or structure to another. The Conference organized by the Department of Process Control AGH University of Science and Technology is held every two years. The major research areas include: active and semi-active methods of vibration control, active noise control, applications of smart materials and structures and control of noise and vibration parameters. It seems that the application of smart materials for active noise and vibration control methods has emerged as a regular theme of the meetings. The “School” held for the first time in 1993 was transformed into a Conference in 2003 and was named: Conference on Active Noise and Vibration Control Methods. This special section is the second of a two-part report on selected papers that appeared in the 11th Conference on Active Noise and Vibration Control Methods. The papers were extended by authors and placed into the rigorous review process of the Journal of Low Frequency Noise, Vibration and Active Control before acceptance. The conference featured technical scientific sessions of oral and poster presentations, divided into five sections, namely Active Vibration Control, Semiactive Vibration Control, Active Noise Control, Structural Control, and Smart Structures. The conference was held in Rytro which is uniquely situated on the edge of the Poprad River Natural Park, in one of the Southern Poland’s loveliest Mountains Beskid Sadecki. The conference was bundled with a bigger 14th International Carpathian Control Conference the focus of which is on the area of automatic control. Nearly 150 delegates participated in both conferences, and there were a total of 125 presentations given. The 11th Conference on Active Noise and Vibration Control Methods attracted the traditional number of nearly 60 delegates. The opening presentation was given by Stephen P. Banks describing “The global theory of nonlinear systems”. The second plenary lecture was given by Piotr Cupial/ who discussed the “Lord Rayleigh’s impact on vibration theory (From the past to smart structures)”. The technical sessions of the conference followed these two plenary presentations. Below is a brief description of the papers that feature in this second part report. Mateusz Koziol presented a problem of the active control of a Jeffcott rotor with the rotational speed in the supercritical range. He discussed application of

ABSTRACTYoula–Kucera parametrisation plays a very important role in adaptive active vibration control and adaptive active noise control. This concerns both vibration and noise attenuation by feedback as well as by feedforward compensation when a measurement of an image of the disturbance (noise or vibration) is available. The paper will review the basic algorithms and various extensions trying to emphasise the advantages of using Youla–Kucera parametrisation. Specific aspects related to the use of this approach in adaptive active vibration and noise control will be mentioned. A brief review of applications and experimental testing will be provided.Abbreviations: ANC: Active noise control system; AVC: Active vibration control system; FIRYK: Youla–Kucera parametrised FIR adaptive feedforward compensator using an FIR Youla–Kucera filter; IIR: IIR adaptive feedforward compensator; IIRYK:Youla–Kucera parametrised IIR adaptive feedforward compensator using an IIR Youla–Kucera filter; IMP: Internal model principle; PAA: Parameter adaptationalgorithm; QFIR: Youla–Kucera FIR filter; QIIR: Youla–Kucera IIR filter; SPR: Strictly positive real (transfer function); YK: Youla–Kucera

Research on Active Vibration Control System (AVCS) is being carried out to reduce structural vibration s caused by unwanted vibrations in many application a reas such as in space, aircraft structures, satelli tes, automobiles and civil structures (bridges), particu larly at low frequencies. The unwanted vibration ma y cause damage to the structure or degradation to the structure’s performance. The AVCS comprises physical plant, a sensor to detect the source vibration, a D SP based electronic controller using an actuator co nnected to the structure generates a counter force that is appropriately out of phase but equal in amplitude t o the source vibration. As a result two equal and opposit e forces cancel each other by the principle of supe r position and structure stops vibrating. The main ob jective of this research work is to develop an embe dded computer based real time AVCS for reducing low frequency tonal vibration response of a vibrating flexi ble cantilever beam by automatic modification of the vi brating beam’s structural response and to verify th e performance of the developed system experimentally. The developed AVCS is a generic design platform that can be applied for designing adaptive feed for ward AVC and feedback AVC. This study presents the vibration control methodology adapted for reducing tonal vibration generated by a sine generator conne cted to the primary source actuator attached to one end of the cantilever beam. The secondary actuator is attached to the beam on the other end through the A VCS to reduce primary vibration by destructive interference with the original response of the syst em, caused by the primary source of vibration. Adap tive feed forward Active Vibration Control (AVC) technique is used with Filtered-X Least Mean Square (FxLMS) algorithm using FIR digital filter. A canti lever beam was considered as plant and embedded computer based AVCS was tested and evaluated using an experimental setup. The experimental results are presented for the cantilever beam excited at one of its natural frequency using active vibration contr ol system and an appreciable reduction was achieved up to 20 dB.

A narrowband active vibration control algorithm with frequency estimator based on lattice notch filter is proposed to suppress the primary signal with multi line spectra. A adaptive iir (infinite impulse response) lattice gradient notch filter was adapted to estimated the frequency of the multi-harmonics buried in the primary signal, then the reference signal is filtered by the adaptive band pass filter. With the reference signal filtered by the adaptive band pass filter, active control algorithm is implemented. Simulations of the frequency estimation of the multi-sinusoidal signal are conducted and simulation results confirm that the proposed algorithm could achieve effective performance when the frequency of the primary disturbance is unknown. Active control of vibration has finds a lot application such as fans, engines, and air conditioners in nowadays. The basic concept of active vibration control is to suppress the primary disturbance with the secondary force which is of same amplitude and opposite phase. Signals generated by the rotating machines such as fans, diesel engines, and air conditioners is characterized with discreet frequency which cause damage to operator in the working environment. Narrowband active vibration control (NAVC) is an effective method to suppress such vibration with multi-line spectra. The application of NAVC has been implemented taken into applications since 1970's. A lot of algorithms have been proposed for suppress the primary disturbance with multi-spectral. There exists two families of algorithm in AVC system, which composed of filtered-X least mean square (FXLMS) algorithm and filtered-X recursive least square algorithm (FXRLS). Due to its simplicity and implementation efficiency, FXLMS algorithm is the most popular adaptive algorithm to suppress the primary disturbance compared to FXRLS algorithms. In the application of NAVC systems, the performance of NAVC systems is directly correlated with the reference signal and the primary signal. NAVC algorithm could not achieve effective performance if the correlation between the primary signal and the reference signal is weak. Frequency estimation of the primary signal is an effective method to adapt to improve the relativity between the reference signal and the primary signal. To estimate the frequency of a sinusoidal signal, a number of algorithm has been proposed to exploit the predictable nature of sinusoidal primary disturbance and characterize the frequency of the sinusoidal primary disturbance, such the Kalman algorithm, music, FFT (fast Fourier transform), etc. such method could be capable of tracking nonstationary or slowly-varyin g primary signals. However, they have some shortcomings in the application of NAVC systems. a lot of Kalman-based algorithms have been proposed for the frequency estimation of the sinusoidal signal in many applications such as the electrical power system, however, it requires much more computation burdens which is much more complicated compared the other algorithms. FFT methods have been proposed in the past to estimated the frequency of the primary signal, but it is has been found that the estimated result could not be accessed effectively in real-time of AVC system. Adaptive notch filter has been proposed for the frequency estimation of the sinusoidal signal in a lot of applications. Adaptive lattice filter shows much more stability and performance compared to the bilinear adaptive notch filter. In this paper, the adaptive lattice notch filter is introduced into an adaptive vibration control system to estimate the frequency of synthesized desired signal. Then, the reference signal is generated to suppress the primary vibration in the active vibration control system.

B ECAUSE the rotor of a helicopter operates in a periodic, asymmetric, unsteady aerodynamic environment, the helicopter fuselage produces a high level of vibration under the strong excitation of the rotor. The effective method for active vibration control of a helicopter fuselage by using the inertial actuators has been used in helicopters, but the inertia actuators have a considerable weight penalty for a better control effect. Meanwhile, the inertia actuators have a limited range of working frequency and a lag response to control signal. The piezoelectric stack actuator has a lot of advantages, such as light weight, large control force, wide range ofworking frequency, and fast response to control signal, and has been used as an actuation element for active control of structural vibration [1,2]. Hence, using the piezoelectric stack actuators is a newway to actively control the vibration of a helicopter fuselage. In an active vibration control system, the locations of actuators have a great influence on the effect of vibration suppression and the power requirement. Many approaches such as the controllability index [3], energy dissipation index [4],H2 norm index [5], and recent index composed of a multi-objective [6] have been developed to find the optimal actuator locations and control parameters. In the investigations of the helicopter fuselage, Hanagud and Babu [7] placed the piezoelectric actuator near the selected control location and investigated the vibration reduction of the helicopter fuselage by using H∞ control. Singhvi and Vennkatesan [8] addressed the piezoelectric stack actuator parallel with the supporting structure between the gearbox and fuselage for a simplified helicopter model. Heverly et al. [9] investigated the optimal placement of piezoelectric stack actuators in the fuselage by using the simulated annealing algorithm. The investigations indicated that the configuration of optimal distributed actuators was capable of greater vibration suppression with less control effort. However, in the existing investigations, the piezoelectric stack actuator was idealized as a force generator. In this case, the characteristic effect of the piezoelectric stack actuator was not included in the optimization process. The optimal locations of actuators may have a lot of selections at many possible positions in an actual structure. The optimal selection of actuator locations cannot uniquely be determined by using the conventional optimization techniques based on the gradient-descent methods. The genetic algorithm as a stochastic search technique has been effectively used to determine the optimal locations. Rao et al. [10] presented a modified binary-coded genetic algorithm to solve the optimal placement of discrete actuator locations in the framework of a zero–one optimization. Liu et al. [5] directly applied the binarycoded genetic algorithm to find optimal locations of actuators and sensors on plate structures. The real-coded genetic algorithm [4] was used to address the optimal locations of the piezoelectric actuators at a continuous spatial coordinate on a beam. Roy and Chakraborty [6] used the integer-coded genetic algorithm to optimize the placement of actuators and simultaneously real-coded genetic algorithm to determine the weighted matrices in the linear quadratic control. In this paper, the active control of a helicopter structural response by using piezoelectric stack actuators has been investigated. In the formulated dynamic model, the piezoelectric stack actuators and fuselage coupled composite structure was decomposed by using the substructure synthesis technique based on frequency response functions. The weighted quadratic of controlled accelerations in the frequency domain was chosen as the optimization index. An improved real-coded genetic algorithm was used to solve the optimization problem with discrete location variables and continuous weighted variables and to minimize the acceleration responses of the targeted locations. The vibration suppression of a simplified elastic helicopter fuselage model was analyzed. The numerical results show that the method proposed in this paper can effectively solve the optimal parameters and improve the control performance.