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1.
It has been proved in the authors' latest paper that the effective location of active control devices for building vibration caused by periodic excitation acting on intermediate story is the adjacent three floors to the vibration source. However, in terms of the Discrete‐Optimizing control method, the control forces are on‐line calculated step‐by‐step and time‐delay must exist. The degradation of control effect caused by time‐delay can not be avoided. In this paper, QN control method is proposed in order to resolve this practical problem. Since the external excitations which the building structure would experience are supposed to be periodic to some degree, Quasi‐Newton method is applied into the close‐loop Linear–Quadratic optimal control method and the new control method is called the ‘QN control method’. In this new control method, instead of solving the Riccati equation, the feedback gain matrix is determined by optimizing the quadratic performance index of the structure with the Quasi‐Newton method, one of the most commonly used minimization of functions. The new control law can easily be implemented for time‐delay problems, the degradation can be greatly improved with compensated feedback gain matrix. As a result, the QN control method is proved to be an efficient method to determine the feedback gain matrix. Copyright © 2000 John Wiley & Sons, Ltd. 相似文献
2.
It is well known that the classical optimal control method requires all the state variables of the controlled system to be measurable and available for control feedback. However, for a high‐order or complex system some state variables are possibly unmeasurable in practice. In addition, the control cost will be higher if more sensors are used, because it is expensive to install sensors. On the other hand, when using the optimal control method with full‐state feedback, some state variables in control feedback have only a small effect on control performance. Neglecting these state variables does not affect the control performance greatly. Good control effectiveness can be obtained by using only the state variables that have a big effect on the control performance. So the questions become how to determine those state variables which have a big effect on the control performance? and how to design the optimal controller using only the determined state variables? The discrete sub‐optimal control method with partial‐state feedback is investigated in this paper. Firstly, the continuous control system and performance index are both transformed into discrete forms. Then the state variables, which have a big effect on the control performance, are determined using the second‐order sensitivity which is the second‐order derivative of the performance index with respect to control gain. The sub‐optimal controller is finally designed using only the determined state variables. Numerical examples are worked out to demonstrate the application of the proposed control algorithm. It is shown that the relative importance of each state variable can be indicated clearly by the second‐order sensitivity. The sub‐optimal control method presented is effective in reducing maximum responses of the structure. Copyright © 2003 John Wiley & Sons, Ltd. 相似文献
3.
This paper analyzes the soil–structure interaction (SSI) effect on vibration control effectiveness of active tendon systems for an irregular building, modeled as a torsionally coupled (TC) structure, subjected to base excitations such as those induced by earthquakes. An H∞ direct output feedback control algorithm through minimizing the entropy, a performance index measuring the trade-off between H∞ optimality and H2 optimality, is implemented to reduce the seismic responses of TC structures. The control forces are calculated directly from the multiplication of the output measurements by a pre-calculated frequency-independent and time-invariant feedback gain matrix, which is obtained based on a fixed-base model. Numerical simulation results show that the required numbers of sensors, controllers and their installation locations depend highly on the degree of floor eccentricity. For a large two-way eccentric building, a one-way active tendon system placed in one of two frames farthest away from the center of resistance (C.R.) can reduce both translational and torsional responses. The SSI effect is governed by the slenderness ratio of superstructure and by the stiffness ratio of soil to superstructure. When the SSI effect is significant, the proposed control system can still reduce the structural responses, however, with less effectiveness than that of the assumed fixed-base model. Therefore, the TC and SSI effects should be considered in the design of active control devices, especially for high-rise buildings located on soft site. 相似文献
4.
5.
In conventional methods of modal control, the number of controllable structural modes is usually restrained by the number of sensors that feedback the structural signals. In this paper a modal control scheme where the feedback gain is formulated in an augmented state space is proposed. The advantage of the proposed method is that it increases the number of the controllable modes without adding extra sensors. The method is verified experimentally by an earthquake simulation test with a full‐scale building model. The proposed modal control was also compared with the conventional ones in the test. For the building model tested, the performance of the proposed control with only one feedback signal can be as efficient as that of modal control with full state feedback. Copyright © 2001 John Wiley & Sons, Ltd. 相似文献
6.
A fuzzy‐logic control algorithm, based on the fuzzification of the MR damper characteristics, is presented for the semiactive control of building frames under seismic excitation. The MR damper characteristics are represented by force–velocity and force–displacement curves obtained from the sinusoidal actuation test. The method does not require any analytical model of MR damper characteristics, such as the Bouc‐Wen model, to be incorporated into the control algorithm. The control algorithm has a feedback structure and is implemented by using the fuzzy‐logic and Simulink toolboxes of MATLAB. The performance of the algorithm is studied by using it to control the responses of two example buildings taken from the literature—a three‐storey building frame, in which controlled responses are obtained by clipped‐optimal control and a ten‐storey building frame. The results indicate that the proposed scheme provides nearly the same percentage reduction of responses as that obtained by the clipped‐optimal control with much less control force and much less command voltage. Position of the damper is found to significantly affect the controlled responses of the structure. It is observed that any increase in the damper capacity beyond a saturation level does not improve the performance of the controller. Copyright © 2011 John Wiley & Sons, Ltd. 相似文献
7.
Optimal control of base-isolated and non-base-isolated buildings subjected to earthquake excitation is considered. The control force at any instant is determined on-line through minimizing a quadratic time-dependent performance index based on the total energy imparted to the structure and the control effect. This control algorithm is based upon the use of discrete actuators and sensors that exert the control force and monitor the response of the building. Having constant gain matrices makes this algorithm efficient and easy to implement. The effect of time delay on the efficiency of the algorithm is investigated. Comparisons have been made to demonstrate the effectiveness of the proposed method. 相似文献
8.
Makola M. Abdullah 《地震工程与结构动力学》1999,28(2):127-141
The dynamic responses of tall civil structures due to earthquakes are very important to the civil engineer. These dynamic responses can produce situations that can range from uncomfortable to unsafe for the building occupants. In recent years classical control theory has been used in civil engineering to reduce the dynamic responses of tall civil structures. Most optimal control algorithms for civil structures involve full state feedback control which requires good estimates of the velocity and displacements throughout the structure. However, there are several important advantages of output feedback control: it takes less computational effort and it has the robustness of passive systems. In this paper, optimal control algorithms are formulated for the optimization of feedback gains and controller placement for building structures. The fundamental basis for these algorithms is the calculation of the gradient of the performance function with respect to the gain matrix. The effectiveness of the algorithm is demonstrated for deterministic earthquake loads in the time domain. Copyright © 1999 John Wiley & Sons, Ltd. 相似文献
9.
A predictive-adaptive (PA) control algorithm has been developed for a structure under a seismic excitation. This algorithm analyses information of an observed seismic excitation, estimates future structural responses and determines the control force for the structure, based on the linear quadratic regulator. That is, at a given moment tk: (1) seismic excitation information is converted to an autoregressive model, which forms the state equation for the excitation; (2) the identification model is combined with the structural model to build a state equation in an augmented space; (3) the weighted quadratic norm of the state vector and the future control force is formed as a cost function for estimating future responses; (4) the Ricatti equation is solved to find the optimum value of the cost function; and (5) the optimum gain matrix is obtained, and the control force is determined. The PA algorithm is not restricted to one type of control system, but can be applied to both an active driver system and an active tendon system. Its effectiveness is confirmed by numerical experiments for 1DOF and 3DOF structural models under sine and seismic excitations. 相似文献
10.
Chin‐Hsiung Loh Jerome P. Lynch Kung‐Chun Lu Yang Wang Chia‐Ming Chang Pei‐Yang Lin Ting‐Hei Yeh 《地震工程与结构动力学》2007,36(10):1303-1328
The performance aspects of a wireless ‘active’ sensor, including the reliability of the wireless communication channel for real‐time data delivery and its application to feedback structural control, are explored in this study. First, the control of magnetorheological (MR) dampers using wireless sensors is examined. Second, the application of the MR‐damper to actively control a half‐scale three‐storey steel building excited at its base by shaking table is studied using a wireless control system assembled from wireless active sensors. With an MR damper installed on each floor (three dampers total), structural responses during seismic excitation are measured by the system's wireless active sensors and wirelessly communicated to each other; upon receipt of response data, the wireless sensor interfaced to each MR damper calculates a desired control action using an LQG controller implemented in the wireless sensor's computational core. In this system, the wireless active sensor is responsible for the reception of response data, determination of optimal control forces, and the issuing of command signals to the MR damper. Various control solutions are formulated in this study and embedded in the wireless control system including centralized and decentralized control algorithms. Copyright © 2007 John Wiley & Sons, Ltd. 相似文献
11.
Genetic Algorithms (GAs) have been applied as an effective optimization search technique in various fields, including the field of control design. In this paper, a new control method using GAs is proposed to attenuate the responses of a structure under seismic excitation. The proposed controller uses the state-space reconstruction technique based on the embedding theorem to obtain full-state performance from the available reduced order feedback. The parameters of the new controller are optimized using GAs. The proposed GA-based control method is verified on a benchmark problem—active mass driver system, and the results are compared with other control methods. The robustness of the proposed control method is also examined. Copyright © 1999 John Wiley & Sons, Ltd. 相似文献
12.
Time-delay causes unsynchronized application of the control forces which may not only degrade the performance of the control system but also even induce instability to the dynamic system. Time-delay control algorithm is developed in this paper to solve this practical problem. The control system is first formulated in discrete-time form. In the presence of time-delay, the motion equation of the discrete-time control system remains a difference equation which can be transformed into first-order difference equation by augmenting the state variables. Optimal time-delay control algorithm is derived based on the augmented system. The time-delay control forces are simply generated from the time-delay states multiplied by the constant feedback gain. Numerical simulation is illustrated to verify the feasibility of the proposed control algorithm. Since time-delay effect is incorporated in the mathematical model for the structural control system throughout the derivation of the proposed algorithm, system performance and dynamic stability are guaranteed. 相似文献
13.
Genetic Algorithms (GAs) have been applied as an effective optimization search technique in various fields, including the field of control design. In this paper, a new control method using GAs is proposed to attenuate the responses of a structure under seismic excitation. The proposed controller uses the state space reconstruction technique based on the embedding theorem to obtain full state performance from the available reduced order feedback. The parameters of the new controller are optimized using GAs. The proposed GA-based control method is verified on a benchmark problem—active mass driver system—and the results are compared with other control methods. The robustness of the proposed control method is also examined. Copyright © 1999 John Wiley & Sons, Ltd. 相似文献
14.
Active multiple tuned mass dampers (AMTMD) consisting of many active tuned mass dampers (ATMDs) with a uniform distribution of natural frequencies have been, for the first time, proposed for attenuating undesirable vibrations of a structure under the ground acceleration.The multiple tuned mass dampers (MTMD) in the AMTMD is manufactured by keeping the stiffness and damping constant and varying the mass. The control forces in the AMTMD are generated through keeping the identical displacement and velocity feedback gain and varying the acceleration feedback gain. The structure is represented by its mode‐generalized system in the specific vibration mode being controlled using the mode reduced‐order method. The optimum parameters of the AMTMD are investigated to delineate the influence of the important parameters on the effectiveness and robustness of the AMTMD by conducting a numerical searching technique. The parameters include the frequency spacing, average damping ratio, tuning frequency ratio, total number and normalized acceleration feedback gain coefficient. The criterion, which can be stated as the minimization of the minimum values of the maximum dynamic magnification factors (i.e. Min.Min.Max.DMF), is chosen for the optimum searching. Additionally, for the sake of comparison, the results of the optimum MTMD (the passive counterpart of AMTMD) and ATMD are also taken into account in the present paper. It is demonstrated that the proposed AMTMD can be expected to significantly reduce the oscillations of structures under the ground acceleration. It is also shown that the AMTMD can remarkably improve the performance of the MTMD and has higher effectiveness than ATMD. Copyright © 2002 John Wiley & Sons, Ltd. 相似文献
15.
The development and the applications of an active controlled viscous damping device with amplifying braces are described. The system of the dampers, defined as active viscous damping system (AVDS), connected to an amplifying brace (AB) is presented herein. Instantaneous control theory with velocity and acceleration feedback is used to obtain the control forces at each time step during an excitation. Control of the damping forces is possible due to the mechanical structure of the proposed AVDS, and the connection to the AB. The proposed system can be efficiently used to enhance the damping of a structure without modifying its stiffness. The added damping forces can be adjusted in a wide range. The efficiency of the presented system is demonstrated by a numerical simulation of a seven‐storey building subjected to earthquakes. The simulation shows a considerable reduction of control forces required for control to the AVDS with AB, compared to the same system without AB. Copyright © 2002 John Wiley & Sons, Ltd. 相似文献
16.
Seismic structural control using semi-active tuned mass dampers 总被引：8，自引：1，他引：8
This paper focuses on how to determine the instantaneous damping of the semi-active tuned mass damper (SATMD) with continuously
variable damping. An off-and-towards-equilibrium (OTE) algorithm is employed to examine the control performance of the structure/SATMD
system by considering the damping as an assumptive control action. The damping modification of the SATMD is carried out according
to the proposed OTE algorithm, which is formulated based on analysis of the structural movement under external excitations,
and the measured responses of the structure at every time instant. As examples two numerical simulations of a five-storey
and a ten-storey shear structures with a SATMD on the roof are conducted. The effectiveness on vibration reduction of MDOF
systems subjected to seismic excitations is discussed. Analysis results show that the behavior of the structure with a SATMD
is significantly improved and the feasibility of applying the OTE algorithm to the structural control design of SATMD is also
verified. 相似文献
17.
We present a numerical evaluation of the potential improvements in seismic disturbance rejection to be obtained by using active variable damping control in a structure. Using the responses to seismic excitation of an optimally controlled variable structure and of a minimax-optimal designed fixed structure, we obtain an upper bound on the achievable performance and a lower bound on the acceptable performance of a control system for a variable-damping structure. Both of these bounds are relative to an energy-function criterion. Our numerical experiments lead to the following conclusions:
- (i) The gap between the upper and lower bounds is rather small, which makes designing a feedback law, that results in performance superior to that of a minimax-optimal designed structure, very difficult. The best choice for a feedback law appears to be continuous moving horizon control, whose implementation requires ground motion prediction up to 0.2 sec ahead, possibly using sensors located a small distance away from the site.
- (ii) A minimax-optimal designed structure gives very good seismic disturbance suppression, not only for the earthquakes used in its design, but also for other earthquakes of similar intensity. Controlled variable structures are likely to offer advantages when earthquakes are moderate to severe, particularly at sites, such as landfills and dry lake beds, where resonances can be expected, but the resonance frequency cannot be estimated in advance.
18.
双向偏心结构扭转耦联地震反应的序列最优控制 总被引：1，自引：0，他引：1
本文分析了不对称建筑结构平移-扭转耦联振动的动力特性及地震作用下的响应;根据地震动输入结构的过程,推导出一种更为一般的最优控制算法,所获得的控制力表达式同时包括地震响应和地震激励。通过对一非规则四层框架结构的扭转耦联地震反应控制分析表明,该算法不仅能有效地控制结构的平移地震反应,而且更有效地抑制结构的扭转耦联地震反应。 相似文献
19.
This study investigates an electric‐type active mass driver (AMD) system for structural vibration control. Composed primarily of an electric servomotor and a ball screw, the electrical AMD system is free from noise problems, oil leakage, and labor‐intensive maintenance that commonly are associated with hydraulic AMD systems. The desired stroke amplification of the mass and the power demand of the servomotor can be adjusted via the ball screw pitch, which in turn affects the effectiveness and efficiency of the system. Meanwhile, an instantaneous optimal direct output feedback control algorithm is adopted. Numerical simulation is performed using a five‐story steel frame as the object structure under the conditions of the 1940 El Centro earthquake. The AMD system proves to be effective and efficient within a certain range of the ball screw pitch. The reductions of the peak responses can reach as high as 70% if properly designed. Requiring only the velocity measurement of the top floor for on‐line feedback control, the proposed control algorithm is recommended for practical implementation. Copyright © 2004 John Wiley & Sons, Ltd. 相似文献
20.
In this paper, an effective active predictive control algorithm is developed for the vibration control of non-linear hysteretic structural systems subjected to earthquake excitation. The non-linear characteristics of the structural behaviour and the effects of time delay in both the measurements and control action are included throughout the entire analysis (design and validation). This is very important since, in current design practice, structures are assumed to behave non-linearly, and time delays induced by sensors and actuator devices are not avoidable. The proposed algorithm focuses on the instantaneous optimal control approach for the development of a control methodology where the non-linearities are brought into the analysis through a non-linear state vector and a non-linear open-loop term. An autoregressive (AR) model is used to predict the earthquake excitation to be considered in the prediction of the structural response. A performance index that is quadratic in the control force and in the predicted non-linear states, with two additional energy related terms, and that is subjected to a non-linear constraint equation, is minimized at every time step. The effectiveness of the proposed closed-open loop non-linear instantaneous optimal prediction control (CONIOPC) strategy is presented by the results of numerical simulations. Since non-linearity and time-delay effects are incorporated in the mathematical model throughout the derivation of the control methodology, good performance and stability of the controlled structural system are guaranteed. Copyright © 1999 John Wiley & Sons, Ltd. 相似文献