Fuzzy Control of Base-Isolation System Using Multi-Objective Genetic Algorithm

Abstract:   In this study, a friction pendulum system (FPS) and a magnetorheological (MR) damper are employed as the isolator and supplemental damping device, respectively, of a smart base-isolation system. Neuro-fuzzy models are used to represent dynamic behavior of the MR damper and FPS. A fuzzy logic controller (FLC) is used to modulate the MR damper so as to minimize structural acceleration while maintaining acceptable base displacement levels. To this end, a multi-objective optimization scheme that uses a nondominated multi-objective genetic algorithm (NSGA-II) is used to optimize parameters of membership functions and find appropriate fuzzy rules. To demonstrate the effectiveness of the proposed multi-objective genetic algorithm for FLC, a numerical study of a smart base-isolation system is conducted using several historical earthquakes. It is shown that the proposed method can find optimal fuzzy rules and that the NSGA-II-optimized FLC outperforms not only a passive control strategy but also a human-designed FLC and a conventional semiactive control algorithm.     

相邻结构地震反应的半主动控制分析

现代城市中相邻结构大量的出现,这样就有可能导致地震中建筑碰撞破坏的加剧.针对安装了AVSD控制器与安装了MR阻尼器的相邻结构半主动控制体系,运用Matlab编程仿真分析了El-Centro波、Taft 波和Northridge波三种地震激励下控制效果.结果表明:对相邻结构中较高结构的控制AVSD系统的控制效果较好,但是...     

不同控制策略下安装磁流变阻尼器的模型结构振动台试验与分析

本文对不同控制策略下安装有磁流变(MR)阻尼器的模型结构进行了振动台试验和分析。文中首先介绍了经典最优控制(COC)、瞬时最优控制(IOC)和线性二次高斯最优控制(LQG)等三种控制算法,然后对一首层安装有最近设计制造的MRF-04K型的MR阻尼器的、1/3比例的三层钢框架模型,进行了在两种被动控制和三种半主动控制等不同控制策略下的振动台试验,最后对模型结构地震反应的控制效果以及不同控制策略对控制效果的影响和控制稳定性进行了分析。研究表明,安装有MRF-04K阻尼器的结构控制系统具有良好的控制效果,无论是被动控制还是半主动控制,模型结构各层相对位移峰值均减小了45%左右,其均方根值均减小了70%左右,加速度反应峰值均减小了30%左右,其均方根值均减小了75%左右,从而验证了MRF-04K阻尼器是结构控制工程应用的一种理想的控制装置;研究还表明,在三种半主动控制策略中,基于LQG算法的半主动控制仅需模型结构的加速度反应的反馈信息,比基于IOC算法和COC算法的半主动控制     

A hybrid LQR-PID control design for seismic control of buildings equipped with ATMD

This paper presents an efficient hybrid control approach through combining the idea of proportional-integral-derivative (PID) controller and linear quadratic regulator (LQR) control algorithm. The proposed LQR-PID controller, while having the advantage of the classical PID controller, is easy to implement in seismic-excited structures. Using an optimization procedure based on a cuckoo search (CS) algorithm, the LQR-PID controller is designed for a seismic- excited structure equipped with an active tuned mass damper (ATMD). Considering four earthquakes, the performance of the proposed LQR-PID controller is evaluated. Then, the results are compared with those given by a LQR controller. The simulation results indicate that the LQR-PID performs better than the LQR controller in reduction of seismic responses of the structure in the terms of displacement and acceleration of stories of the structure.     

磁流体阻尼器半主动控制结构的地震反应分析

对磁流变阻尼器的性能及恢复力模型进行了介绍,并对其参数进行了设计,提出了基于经典线性最优控制算法和瞬时最优控制算法的半主动控制律.通过对一装有七个MR阻尼器的七层框架结构的地震反应分析表明,基于这两种控制算法的半主动控制律是非常有效的,并且该半主动控制方法能够有效地减小结构的地震反应.     

Neuro-Fuzzy Control of Railcar Vibrations Using Semiactive Dampers

Abstract:   This article describes a new approach to reducing vertical vibrations in a 70-ton railcar using a neuro-fuzzy controller and a magnetorheological (MR) damper. A semiactive control technique is developed for a two-degree-of-freedom quarter car model of the railcar that has an installed MR damper. A fuzzy controller in real time continuously updates damping properties of the device. The controller uses feedback acceleration of the freight mass to specify a voltage signal to the MR damper. Correlations between acceleration (controller input) and voltage applied to the MR damper (controller output) are developed using Neuro Fuzzy Controller (NEFCON). To assess effectiveness of the semiactive control scheme, responses of the railcar to various haul conditions are compared with those for uncontrolled and for passive operating conditions of the MR damper. Results indicate that semiactively controlled MR dampers can reduce vibrations to acceptable levels provided that sufficient force capacity can be supplied by the damper .     

Adaptive control of base-isolated structures against near-field earthquakes using variable friction dampers

This paper investigates the effectiveness of two adaptive control strategies for modulating the control force of variable friction dampers (VFDs) that are employed as semi-active devices in combination with laminated rubber bearings for the seismic protection of buildings. The first controller developed in this study is an adaptive fuzzy neural controller (AFNC). It consists of a direct fuzzy controller with self-tuning scaling factors based on neural networks. A simple neural network is implemented to adjust the input and output scaling factors such that the fuzzy controller effectively determines the command voltage of the damper according to current level of ground motion. A multi-objective genetic algorithm is used to learn the shape of the activation functions of the network. The second controller is based on the simple adaptive control (SAC) method, which is a type of direct adaptive control approach. The objective of the SAC method is to make the plant, the controlled system, track the behavior of the structure with the optimum performance. Here, SAC methodology is employed to obtain the required control force which results in the optimum performance of the structure. For comparison purposes, an optimal linear quadratic Gaussian (LQG) controller is also developed and considered in the simulations together with maximum passive operation of the friction damper. The results reveal that the developed adaptive controllers can successfully improve the seismic response of base-isolated buildings against various types of earthquake.     

磁流变阻尼器在基础智能隔震建筑中的研究

针对橡胶隔震垫作为一种被动控制装置,存在最优控制范围窄的局限性。将磁流变阻尼器与橡胶隔震垫相结合,组成智能基础隔震系统应用于结构振动控制中,数值模拟分析了在地震力作用下原结构,普通隔震结构,隔震层附加MR阻尼器在Passive—off状态,Passive—on状态和磁流变阻尼器半主动智能状态下结构的反应。试验结果表明,结构在磁流变阻尼器半主动智能状态下控制效果最优,能有效克服被动隔震最优控制频带窄的缺点,其相对一般被动隔震装置,能同时减小隔震层位移,上部结构层间位移和各层最大加速度。     

Semi-active control of a torsionally-responsive structure

The mitigation of torsional responses in structures using semi-active devices is pursued in the current study. Multiple magnetorheological (MR) dampers are employed for real-time control of the response of a benchmark structure to earthquake excitations. MR damper resistance levels are intelligently managed by a global fuzzy logic controller (FLC). The FLC is generated using a controlled-elitist genetic algorithm (GA). Development of an optimal FLC is expedited by a discretized search space of fuzzy logic membership functions. To enable robust control an excitation is created for training by a GA using the RSPMatch2005 algorithm that modifies historic ground records in the time-domain by wavelet operations. Both numerical and large-scale experimental efforts are undertaken to validate the proposed control system. Results show that the GA-optimized FLC control provides a favorable balance in reduction of inter-story drift and absolute acceleration levels.     

Study on self‐adjustable variable pendulum tuned mass damper

Pendulum tuned mass damper (PTMD) is usually used to control the horizontal vibration of a tall building. However, traditional PTMD is highly sensitive to frequency deviation and difficult to adjust its frequency. In order to improve this problem of traditional PTMD and protect a tall building more effectively, a novel PTMD, called self‐adjustable variable pendulum tuned mass damper (SAVP‐TMD), is proposed in this paper. On the basis of the acceleration ratio between TMD and primary structure, the SAVP‐TMD can retune itself by varying the length of the pendulum according to the improved acceleration ratio‐based adjustment algorithm. PTMD and primary structural accelerations are obtained from two accelerometers respectively, and the acceleration ratio is calculated in a microcontroller, then, the stepper motor will adjust the pendulum under the guidance of the microcontroller under a specific harmonic excitation. The improved acceleration ratio‐based adjustment algorithm is proposed and compared to solve the nonconvergent retuning problem. The SAVP‐TMD can be regarded as a passive damper including a frequency adjustment device. A single‐degree‐of‐freedom structure model is used to verify the effectiveness of SAVP‐TMD through both experimental study and numerical simulation. In order to further verify the effect of SAVP‐TMD in the MDOF structure, a five‐storey structure coupled with an SAVP‐TMD is proposed as a case study. The results of experiment, simulation, and case study all show that SAVP‐TMD can retune itself to the primary structural dominant frequency robustly, and the retuned PTMD has a better vibration control effect than the mistuned one.     

新型调谐黏滞质量阻尼器对斜拉桥的减震控制分析

以一种新型的调谐黏滞质量阻尼器（Tuned viscous mass damper, TVMD）作为控制装置,实现了对斜拉桥的控制模型建立及减震控制分析,探讨了TVMD装置减震的适用性和有效性。基于TVMD装置的工作原理和力学模型,建立了多自由度空间结构多TVMD控制装置在地震激励下的状态空间控制模型和传递函数模型|基于H2控制理论,以结构控制目标响应传递函数的H2范数作为优化目标,提出了利用分步参数扫描进行多TVMD控制装置参数优化设计的方法|以南京长江三桥作为控制对象,针对其在纵桥向地震激励下的振动,分别以TVMD、调谐质量阻尼器（TMD）和黏滞阻尼器（VD）作为控制装置,进行了控制方案的设计与效果的对比分析,对比分析结果表明,TVMD减震控制装置具有更为显著的减震效果及更优的耗能效应。     

大平台多塔楼新型隔震体系的智能磁流变控制

本文将隔震技术应用到大平台多塔楼结构中,研究了这种新型隔震体系的抗震性能,并将磁流变(MR)阻尼器设置于隔震层,探讨了这种新型隔震体系智能磁流变控制的减震效果.文中以北京通惠家园某典型小区为研究对象,建立了大平台多塔楼新型隔震减震体系的运动方程,考虑了隔震支座的非线性.本研究中MR阻尼器的半主动控制算法选用限幅最优控制算法,其主控制器采用H2/LQG方法来设计.仿真分析结果表明,这种新型隔震体系可以有效地减小上部住宅结构与下部平台的地震反应,为提高大平台多塔楼结构的抗震安全性提供了一条崭新的途径.采用MR阻尼器与这种新型隔震体系相结合可以进一步减小隔震结构下部平台的地震反应与隔震层的非线性反应,提高这种新型隔震体系的抗震安全性.     

采用磁流变阻尼器对斜拉桥的半主动模糊控制

介绍了利用磁流变(MR)阻尼器的一种半主动模糊控制方法来增强斜拉桥的抗震性能。传统的半主动控制方法需要一个主要控制器去决定需要的控制力,而且需要一个次控制器通过比较需求控制力和真实的阻尼力来调节MR阻尼器的输入电压。但本文介绍的方法,采用模糊逻辑代替了主次控制器。由于模糊逻辑根据MR阻尼器的反应直接决定其输入电压,因此它提供了一个简单的设计程序,并且可以很容易地在真实结构上实施。利用对地震作用下的斜拉桥的基准控制可以评估此方法的控制性能。模拟结果表明,这种半主动控制方法可以有效地减轻斜拉桥的地震响应,并且成功地提高MR阻尼器系统的性能。     

MOGA-Based Structural Design Method for Diagrid Structural Control System Subjected to Wind and Earthquake Loads

An integrated optimal structural design method for a diagrid structure and control device was developed. A multi-objective genetic algorithm was used and a 60-story diagrid building structure was developed as an example structure. Artificial wind and earthquake loads were generated to assess the wind-induced and seismic responses. A smart tuned mass damper (TMD) was used as a structural control system and an MR (magnetorheological) damper was employed to develop a smart TMD (STMD). The multi-objective genetic algorithm used five objectives including a reduction of the dynamic responses, additional stiffness and damping, mass of STMD, capacity of the MR damper for the integrated optimization of a diagrid structure and a STMD. From the proposed method, integrated optimal designs for the diagrid structure and STMD were obtained. The numerical simulation also showed that the STMD provided good control performance for reducing the wind-induced and seismic responses of a tall diagrid building structure.     

MR智能基础隔震结构抗震性能分析

研究MR智能基础隔震结构的抗震性能。首先,建立该混合控制结构的数学模型,其中应用双线型恢复模型描述橡胶垫隔震层的弹塑性特性,运用自适应神经网络模糊系统(ANFS)计算MR阻尼器的控制力。在SIMULINK环境下对控制结构进行仿真动力分析。并对具体结构进行地震作用下的时程反应分析,仿真分析表明:自适应神经网络模糊系统可以有效地应用到结构控制中,并证实了MR基础隔震结构是一种性能优异的智能控制系统。     

Semiactive Control of Building Structures with Semiactive Tuned Mass Damper

Abstract:   This study proposed a new semiactive control device for building control. Semiactive tuned mass damper (STMD) combine a tradition tuned mass damper (TMD) and a semiactive damper. The property of semiactive damper can be adjusted online to produce the desired control force. In the present year, many types of semiactive dampers are proposed. In this study, the variable damping device and MR damper are used to illustrate the control effect of STMD. In addition, the control effect of the TMD and active tuned mass damper are also compared. The numerical simulation results show that the STMD can greatly improve the control efficiency of TMD.     

新型防泄漏磁流变阻尼器的密封构造与力学模型#br#

磁流变阻尼器采用传统动态密封装置在长时间服役后会产生漏液问题,严重影响阻尼器的性能与寿命。为此,本文提出将粘弹性材料与活塞杆和外缸筒硫化成整体制作成磁流变阻尼器的新型密封装置,以静态密封形式取代传统的动态密封形式,设计了防泄漏磁流变阻尼器。粘弹性材料在压力作用下会发生翘曲变形使得阻尼器内腔压强会发生变化,故引入压力梯度修正系数,考虑粘弹性材料翘曲变形对阻尼力的影响,在此基础上建立防泄漏磁流变阻尼器的力学模型,并进行了仿真分析。结果表明,翘曲变形对阻尼力有削弱作用,引入压力梯度修正系数的力学模型可以很好反映防泄漏磁流变阻尼器的动力特性。     

设置磁流变阻尼器的高层钢框架支撑体系的地震反应研究

磁流变(MR)阻尼器是一种性能十分优秀的减振装置,具有构造简单、调节驱动容易和反应迅速等优点,能有效减小工程结构的地震反应和风振反应,具有广阔的应用前景。本文研究了安装MR阻尼器的高层钢结构框架支撑体系的抗震性能。在介绍了MR阻尼器力学模型的基础上,推导了MR阻尼器-支撑框架系统的地震反应基本方程,并且采用了基于最优主动控制力的“开关-耗能”半主动控制策略对MR阻尼器实施控制。应用本文方法对一栋20层的高层钢结构进行了模拟计算,结果表明:安装了MR阻尼器的框架支撑体系的抗震性能明显优于纯框架支撑体系,是一种简单、方便和有效的减振系统。     

3层基准建筑非线性地震反应的智能控制

近年来,智能驱动材料、控制装置和智能控制算法的研究和发展为土木工程的抗震控制开辟了新的天地。笔者设计制作了一款新型的压电变摩擦阻尼器,并将其作为控制装置,提出了能有效抑制强烈地震激励下高层建筑结构非线性反应的模糊控制算法,并建立了量化因子、比例因子与结构响应之间的关系。对受控的3层基准建筑结构进行了非线性地震反应的数值仿真分析,并与其它的控制策略进行比较。结果表明,采用模糊控制算法,能有效抑制建筑结构的非线性地震反应,减少地震对建筑结构的破坏。     

自锚式悬索桥磁流变阻尼器减震控制研究

为了减小自锚式悬索桥的地震响应,基于桥梁结构地震动力方程及磁流变阻尼器力学模型,建立桥梁结构—磁流变阻尼器减震系统并将其程序化,对某主跨350 m的独塔自锚式悬索桥进行减震控制研究,讨论了磁流变阻尼器输入电流、数目及安装位置对减震效果的影响。研究结果表明:采用磁流变阻尼器能够有效地减小自锚式悬索桥的纵向地震响应;随安装在塔梁之间顺桥向的磁流变阻尼器输入电流的增大及数目的增加,塔顶和主梁的纵向位移逐渐减小,结构的内力响应也得到有效控制;将全部磁流变阻尼器安装在塔梁之间顺桥向时减震效果最佳。