Magnetorheological Damper System Research Articles

Multimode vibration control of stay cables using pseudo negative stiffness MR damping system

At present the vibration control of stay cable suffers from low damping effectiveness in single mode vibration caused by the limitation of damper installation position as well as the poor modal compatibility, that is, a rapid degradation performance when the actual mode deviates from the designed optimal mode. In this paper, one practical semi-active magnetorheological (MR) damper based control solution is proposed to address the problems faced in multi-modal vibration control of stay cables. The semi-active pseudo negative stiffness (PNS) control strategy takes full account of the MR damper’s mechanical characteristics and the demands of the stay cable vibration control. Compared with the linear equivalent model, the proposed time-varying model exhibits more details of the damping force and the nonlinear response of the damped stay cable, which shows its essential role in the optimal design of MR-PNS scheme. Then the optimal design method of MR-PNS multi-modal vibration control for stay cable is summarized by taking the first three modes vibration control of the J20 cable in Nanjing Baguazhou Yangtze River Bridge as simulation examples. The simulations of cross-modal, multi-modal and wind-induced vibration cases are conducted respectively, while the results show that the optimal designed multi-modal MR-PNS scheme can simultaneously exceed the passive maximum modal damping ratio within first three modes. The advantages of the proposed MR-PNS method in high damping efficiency and modal compatibility could be verified by comparing with the passive multi-modal damping solution.

Experimental study on the nonlinear vibration of a new composite magnetorheological damping system

Magnetorheological shock absorbers provide poor damping force in shearing direction. Thus, a composite magnetorheological damper composed of a rubber spring and a magnetorheological damper is proposed to withstand shear loads. A new damper tester is designed to obtain the vibration signal of this damper under external excitation. The magnetorheological vibration-reduction system is a typical nonlinear system, which has higher requirements for information extraction. To obtain the deeper correlation between crucial parameters of the damper and its performance, the autoregressive higher-order spectrum model is established. The formulas of the autoregressive trispectrum and its two-dimensional slice spectrum, diagonal slice spectrum and one-dimensional slice spectrum are derived. Then, the characteristics of the trispectrum and its slices of a magnetorheological vibration-reduction system under different loading currents, working frequencies are discussed. The experiment results show that the composite damper has good performance compared with common rubber shock absorbers, and the higher-order spectrum and its slices exhibit different the distribution density of the spectral amplitude and the distribution of spectral peaks under different working states, which are closely related to the currents and frequencies. The higher-order spectra are effective to quantificationally describe nonlinear coupling, restrain gaussian noise and reserve phase components of the vibration system.

Magnetorheological damper current estimation based on k-nearest neighbor algorithm

Magnetorheological dampers are highly nonlinear damping elements which exhibit multi-dimensional data correspondence problems in the current input and damping force output data sets. Therefore, it is inconvenient to use the traditional modeling method to predict the output damping force of the magnetorheological damper accurately. Although the neural network can predict data-driven output results to a high precision, more models, parameters, and complex structures are required to predict the expected current from the magnetorheological test data set. In this study, a prediction model of the expected current in a magnetorheological damping system was proposed by using the k-nearest neighbor algorithm based on the classification algorithm in machine learning. Then, the k-nearest neighbor prediction model was trained and tested with data obtained experimentally. In order to verify the performance of the k-nearest neighbor algorithm, a comparison was made with a prediction model based on the BP neural network, and the damping force output of the predicted current was simulated. The study results show that the k-nearest neighbor prediction model established has a more straightforward working principle, fewer input variables, and a higher approximation accuracy compared with the BP neural network control system.

Data-driven prediction-control system modeling for magnetorheological damping force

As a new type of intelligent damper, the magnetorheological damper has been widely used in robot, automobile NVH, and intelligent structure. However, for the intelligent response control from the structural excitation, it is the challenge to realize the intelligent control of the magnetorheological damping system. In this paper, the prediction-control mechanism of the magnetorheological damping system is modeled by a data-driven method, such as neural network and classification algorithm. The NARX (Nonlinear autoregressive with external input) neural network is used to predict the desired damping force required for the structural system in the forward direction, and the decision tree classification algorithm is used to reversely-control the desired current of the magnetorheological damping system in instant response to the structural system’s damping force requirement. The analysis results show that the prediction-control method is feasible to realize the intelligent control of the damper based on the state data of the damped system, which provides a new idea for the intelligent control of the magnetorheological damper system.

Vehicle body pitch control through integration of MR damping system implemented in both vehicle suspension and front-end structure

The current research work is directed to study and improve vehicle behavior during crashes. Hence, a crash-pitch controller integrated with Magneto-Rheological (MR) dampers implemented in both vehicle suspension system and front-end structure is designed and studied. The methodology of the work is based on modeling the vehicle dynamical attitude as a half-car mathematical model that is developed with 3 degrees of freedom (DOF), longitudinal, bounce, and pitch. The model is constructed to study the vehicle’s dynamic response in a full-frontal collision against a fixed barrier. Additionally, a fuzzy logic controller is developed to integrate the suspension MR dampers with another set of MR dampers implemented within the vehicle’s front-end structure. Four different vehicle cases were discussed and compared within the simulation results of the developed model. Moreover, the four mentioned cases can be clarified as first free-rolling, second replacing the vehicle’s conventional dampers with MR dampers, third implemented MR dampers within the vehicle’s front-end structure, finally the fourth case through the integration of MR dampers implemented within both front-end structure and suspension system. Hence, the fourth case was implemented through the augmentation of simultaneous crash-pitch controllers. The simulation results showed a noticeable improvement in the front-end structure deformation as it had been reduced. Moreover, the vehicle’s body attitudes had also been improved where pitch angle had been reduced as well as its settling time. Also, pitch acceleration had been reduced which benefits human body exposure.

Parameter Identification in Nonlinear Mechanical Systems with Noisy Partial State Measurement Using PID-Controller Penalty Functions

Dynamic models of physical systems often contain parameters that must be estimated from experimental data. In this work, we consider the identification of parameters in nonlinear mechanical systems given noisy measurements of only some states. The resulting nonlinear optimization problem can be solved efficiently with a gradient-based optimizer, but convergence to a local optimum rather than the global optimum is common. We augment the dynamic equations with a morphing parameter and a proportional–integral–derivative (PID) controller to transform the objective function into a convex function; the global optimum can then be found using a gradient-based optimizer. The morphing parameter is used to gradually remove the PID controller in a sequence of steps, ultimately returning the model to its original form. An optimization problem is solved at each step, using the solution from the previous step as the initial guess. This strategy enables use of a gradient-based optimizer while avoiding convergence to a local optimum. The efficacy of the proposed approach is demonstrated by identifying parameters in the van der Pol–Duffing oscillator, a hydraulic engine mount system, and a magnetorheological damper system. Our method outperforms genetic algorithm and particle swarm optimization strategies, and demonstrates robustness to measurement noise.

Validating the Model of a No-Till Coulter Assembly Equipped with a Magnetorheological Damping System

Variability in soil conditions has a significant influence on the performance of a no-till seeder in terms of an inconsistency in the depth of seeding. This occurs due to the inappropriate dynamic responses of the coulter to the variable soil conditions. In this work, the dynamics of a coulter assembly, designed with a magnetorheological (MR) damping system, were simulated, in terms of vertical movement and ground impact. The developed model used measured inputs from previously performed experiments, i.e., surface profiles and vertical forces. Subsequently, the actual coulter was reassembled with an MR damping system. Multiple sensors were attached to the developed coulter in order to capture its motion behavior together with the profiles, which were followed by the packer wheel. With the aim to validate the correctness of the simulation model, the simulation outputs, i.e., pitch angles and damper forces, were compared to the measured ones. The comparison was based on the root-mean-squared error (RMSE) in percentage, the root-mean-squared deviation (RMSD), and the correlation coefficient. The average value of the RMSE for the pitch angle, for all currents applied on the MR damper, was below 10% and 8% for the speeds of 10 km h−1 and 12 km h−1, respectively. For the damper force, these figures were 15% and 13%. The RMSD was below 0.5 deg and 1.3 N for the pitch angle and the damper force, respectively. The correlation coefficient for all datasets was above 0.95 and 0.7 for the pitch angle and the damper force, respectively. Since the damper force indicated a comparatively lower correlation in the time domain, its frequency domain and coherence were investigated. The coherence value was above 0.9 for all datasets.

Fuzzy logic with a novel advanced firefly algorithm and sensitivity analysis for semi-active suspension system using magneto-rheological damper

Semi-active suspension control with magnetorheological (MR) damper is one of the fascinating systems being studied in improving the vehicle dynamics. By using the MR damper system, a controllable system can be produced dynamically and the majority of the performance of a fully active system can potentially be achieved. Since the conventional optimization method always has a problem in identifying the optimum values and it is time consuming, the evolutionary algorithm is the best approach in replacing the conventional method as it is very efficient and consistent in exploring the values for every single space. In this study, the semi-active control schemes, namely fuzzy logic based controllers tuned using a novel optimization algorithm called advanced firefly algorithm (AFA) is proposed to regulate the body of the vehicle’s suspension from any disturbances acted to the system. The AFA is to be introduced based on the improvement of the original firefly algorithm (FA) to enhance the solution quality of the FA. The comparative assessment study of the proposed optimizer with other evolutionary algorithm, called the particle swarm optimization (PSO) is also presented. A simulation of semi-active suspension system with two degree of freedom is developed within MATLAB Simulink environment. The simulation result indicates that the FL-AFA exhibits an improvement in terms of sprung acceleration and sprung displacement response, with 51.4% and 52.3% as compared with the FL-FA controller, FL-PSO controller, FL controller and passive systems.

Magneto-rheological damper design characteristics for vehicle airbag replacement

Vehicle crashes continue to occur despite all the human efforts to prevent them resulting in injuries and loss of lives. The implementation of airbags has been shown to offer passenger safety in a collision. However, premature deployment and malfunction of airbag has resulted in fatalities and injuries to drivers and front seat passengers. In this study, a magneto-rheological (MR) damper is used as a replacement of airbag in vehicles to serve as a protective system. MR damper is a smart damping device which can be programmed to dynamically absorb shocks and high impact force when used in application such as passenger cars. In this paper, G-force profile of the airbag vehicle crashing system is compared with the G-force profile obtained from the MR damper vehicle crashing system. Subsequently, for this purpose MR damper characteristics are designed and Fuzzy Logic Controller (FLC) and Proportional Integral Derivative (PID) controller are proposed for MR damper current control. Simulation results proved that fuzzy based MR damper system yields better results compared to PID based MR damper system and airbag vehicle crashing system.

Fractional modeling and analysis of coupled MR damping system

The coupled magnetorheological (MR) damping system addressed in this paper contains rubber spring and magnetorheological damper. The device inherits the damping merits of both the rubber spring and the magnetorheological damper. Here a fractional-order constitutive equation is introduced to study the viscoelasticity of the combined damper. An introduction to the definitions of fractional calculus, and the transfer function representation of a fractional-order system are given. The fractional-order system model of a magnetorheological vibration platform is set up using fractional calculus, and the function of displacement is presented. It is indicated that the fractional-order constitutive equation and the transfer function are feasible and effective means for investigating of magnetorheological vibration device.

Damping Force Tracking Control of MR Damper System Using a New Direct Adaptive Fuzzy Controller

This paper presents a new direct adaptive fuzzy controller and its effectiveness is verified by investigating the damping force tracking control of magnetorheological (MR) fluid based damper (MR damper in short) system. In the formulation of the proposed controller, a model of interval type 2 fuzzy controller is combined with the direct adaptive control to achieve high performance in vibration control. In addition,H∞(Hinfinity) tracking technique is used in building a model of the direct adaptive fuzzy controller in which an enhanced iterative algorithm is combined with the fuzzy model. After establishing a closed-loop control structure to achieve high control performance, a cylindrical MR damper is adopted and damping force tracking results are obtained and discussed. In addition, in order to demonstrate the effectiveness of the proposed control strategy, two existing controllers are modified and tested for comparative work. It has been demonstrated from simulation and experiment that the proposed control scheme provides much better control performance in terms of damping force tracking error. This leads to excellent vibration control performance of the semiactive MR damper system associated with the proposed controller.

Control performance evaluation of railway vehicle MR suspension using fuzzy sky-ground hook control algorithm

This paper presents control performance evaluation of railway vehicle featured by semi-active suspension system using magnetorheological (MR) fluid damper. In order to achieve this goal, a nine degree of freedom of railway vehicle model, which includes car body and bogie, is established. The wheel-set data is loaded from measured value of railway vehicle. The MR damper system is incorporated with the governing equation of motion of the railway vehicle model which includes secondary suspension. To illustrate the effectiveness of the controlled MR dampers on suspension system of railway vehicle, the control law using the sky-ground hook controller is adopted. This controller takes into account for both vibration control of car body and increasing stability of bogie by adopting a weighting parameter between two performance requirements. The parameters appropriately determined by employing a fuzzy algorithm associated with two fuzzy variables: the lateral speed of the car body and the lateral performance of the bogie. Computer simulation results of control performances such as vibration control and stability analysis are presented in time and frequency domains.

The Box-Cox Transformation-Based ARFNNs for Identification of Nonlinear MR Damper System with Outliers and Skewness Noises

In this paper, the Box–Cox transformation-based annealing robust fuzzy neural networks (ARFNNs) are proposed for identification of the nonlinear Magneto-rheological (MR) damper with outliers and skewness noises. Firstly, utilizing the Box-Cox transformation that its object is usually to make residuals more homogeneous in regression, or transform data to be normally distributed. Consequently, a support vector regression (SVR) method with Gaussian kernel function has the good performance to determine the number of rule in the simplified fuzzy inference systems and initial weights in the fuzzy neural networks. Finally, the annealing robust learning algorithm (ARLA) can be used effectively to adjust the parameters of the Box-Cox transformation-based ARFNNs. Simulation results show the superiority of the proposed method for the nonlinear MR damper systems with outliers and skewness noises.

Improving vehicle performance and operator ergonomics: Commercial application of smart materials and systems

This article will discuss how controllable material technology, such as the use of active magnetorheological dampers, improves primary and secondary suspensions of vehicle. Although relatively new to the marketplace, semiactive suspensions in commercial automobiles and off-highway vehicles have been proven through the use of active magnetorheological dampers since 1998. In fact, magnetorheological suspension dampers are found today on the commercial vehicles of an increasing number of automotive original equipment manufacturers and leading off-highway original equipment manufacturers. Magnetorheological fluid dampers are simple in design and have the advantage of no moving parts. The resistive force from a magnetorheological damper is generated as iron particles, suspended in the magnetorheological fluid, pass through a magnetic field controlled by the electrical current passing through an electric coil contained within a moving piston surrounded by the fluid. By adjusting the current to the damper coil in response to feedback from vehicle sensors and a controller, the damping response of the suspension can be optimized and controlled in real time to provide optimal operator comfort. The magnetorheological damper system has a full-scale step response of less than 10 ms. Sophisticated control algorithms adapt to large changes in payload, enabling the vehicle to meet ride metrics without pneumatic load leveling. Other benefits of the magnetorheological damping system include higher speed in North Atlantic Treaty Organization double-lane change tests, reduced risk of rollover, improved accuracy of mounted weapons, and improved vehicle durability and readiness.

Analysis of Fractional Derivative Model for MR Damping System

A generalized element which has the behaviors both of dashpot and spring is utilized to describe the visco-elasticity of a type of MR (Magneto-Rheological) Damper. A fractional derivative equation of motion which needs 4 parameters is developed to consider the nonlinear characteristics of the MR Damping system. It is demonstrated that the controlling current affects the order of the fractional system significantly, the increasing of the currents lead to the increasing of systemic order, strengthen the influence of viscosity remarkably and weaken the influence of inertia simultaneously. Nonlinear characteristics for shearing thin MRF damping system are also studied.

Semiactive nonlinear control of a building with a magnetorheological damper system

This paper proposes a linear matrix inequality (LMI)-based systematic design methodology for nonlinear control of building structures equipped with a magnetorheological (MR) damper. This approach considers stability performance as well as transient characteristics in a unified framework. First, multiple Lyapunov-based controllers are designed via LMIs such that global asymptotical stability of the building structure is guaranteed and the performance on transient responses is also satisfied. Such Lyapunov-based state feedback controllers are converted into output feedback regulators using a set of Kalman estimators. Then, these Lyapunov-based controllers and Kalman observers are integrated into a global nonlinear control system via fuzzy logic. To demonstrate the effectiveness of the proposed approach, a three-story building structure employing an MR damper is studied. The performance of the nonlinear control system is compared with that of a traditional linear optimal controller, i.e., H 2/linear quadratic Gaussian (LQG), while the uncontrolled system response is used as the baseline. It is demonstrated from comparison of the uncontrolled and semiactive controlled responses that the proposed nonlinear control system design framework is effective in reducing the vibration of a seismically excited building structure equipped with an MR damper. Furthermore, the newly developed controller is more effective in mitigating responses of the structure than the H 2/LQG controller.

사장교에 장착된 MR 댐퍼의 비용효율성 평가 및 최적설계 연구

지진응답 제어를 위하여 사장교 구조물에 장착된 준능동MR 댐퍼의 경제적 효율성 평가기법을 제안하였으며, 다양한 지반운동 특성에 대하여 비용효율성을 극대화하는 MR 댐퍼의 최적용량에 대한 분석을 수행하였다. MR 댐퍼의 비용효율성 평가를 위하여 생애주기비용 개념을 적용하였으며, 생애주기비용을 이루는 비용항목 중 손상비용의 기대값을 평가하기 위하여 지진재해로 인한 사장교의 파괴확률을 추정하였다. 사장교의 파괴로 인한 직 간접 손상비용의 규모를 매개변수로 하여 비용효율성을 평가하였다. 비용효율성 평가지수는 MR 댐퍼의 장착으로 인한 추가 투자비용과 사장교 구조물의 손상비용으로 이루어진 함수로서, 탄성받침이 사용된 기존의 설계에 대한 경제적 효율성을 나타내도록 정의하였다. 사장교의 지진응답 제어를 위하여 장착된 MR 댐퍼는 경제적으로 효율적인 대안인 것으로 나타났다. 지반운동의 특성과 손상비용 규모에 대한 MR 댐퍼의 최적 용량을 분석한 결과, 지진위험도 및 손상비용 규모가 커짐에 따라 가장 높은 비용효율성을 가지는 MR 댐퍼용량이 증가하는 것을 확인할 수 있었다. A method is presented for evaluating the economic efficiency of a semi-active magneto-rheological (MR) damper system for cable-stayed bridges under earthquake loadings. An optimal MR damper capacity maximizing the cost-effectiveness is estimated for various seismic characteristics of ground motion. The economic efficiency of MR damper system is addressed by introducing the life-cycle cost concept. To evaluate the expected damage cost, the probability of failure is estimated. The cost-effectiveness index is defined as the ratio of the sums of the expected damage costs and each device cost between a bridge structure with the MR damper system and a bridge structure with elastic bearings. In the evaluation of cost-effectiveness, the scale of damage cost is adopted as parametric variables. The results of the evaluation show that the MR damper system can be a cost-effective design alternative. The optical capacity of MR damper is increased as the seismic hazard becomes severe.

Smart passive system based on magnetorheological damper

Magnetorheological (MR) dampers are one of the most promising control devices for civilengineering applications to earthquake hazard mitigation, because they have manyadvantages such as small power requirement, reliability, and low price to manufacture. Toreduce the responses of the controlled structure by using MR dampers, a controlsystem including a power supply, controller, and sensors is needed. However,when a lot of MR dampers are applied to large-scale civil structures, such ascable-stayed bridges and high-rise buildings, the control system becomes complex. Thus,it is not easy to install and to maintain the MR damper-based control system.In this paper, to resolve the above difficulties, a smart passive system is proposed, which isbased on an MR damper system. The smart passive system consists of an MR damper andan electromagnetic induction (EMI) system that uses a permanent magnet and a coil.According to the Faraday law of induction, the EMI system that is attached to the MRdamper produces electric energy. The produced energy is applied to the MR damper tovary the damping characteristics of the damper. Thus, the smart passive systemdoes not require any power at all. Furthermore, the output of electric energy isproportional to input loads such as earthquakes, which means the smart passivesystem has adaptability by itself without any controller or corresponding sensors.Therefore, it is easy to build up and maintain the proposed smart passive system.To verify the effectiveness of the proposed smart passive system, the performance iscompared with that of the normal MR damper-based control system. The numerical resultsshow that the smart passive system has comparable performance to the normal MRdamper-based control system.

Dynamic Modeling of Large-Scale Magnetorheological Damper Systems for Civil Engineering Applications

Magnetorheological (MR) dampers are one of the most promising new devices for structural vibration mitigation. Because of their mechanical simplicity, high dynamic range, low power requirements, large force capacity, and robustness, these devices have been shown to mesh well with earthquake and wind engineering application demands and constraints. Quasistatic models of MR dampers have been investigated by researchers. Although useful for damper design, these models are not sufficient to describe the MR damper behavior under dynamic loading. This paper presents a new dynamic model of the overall MR damper system which is comprised of two parts: (1) a dynamic model of the power supply and (2) a dynamic model of the MR damper. Because previous studies have demonstrated that a current-driven power supply can substantially reduce the MR damper response time, this study employs a current driver to power the MR damper. The operating principles of the current driver, and an appropriate dynamic model are provided. Subsequently, MR damper force response analysis is performed, and a phenomenological model based on the Bouc-Wen model is proposed to estimate the MR damper behavior under dynamic loading. This model accommodates the MR fluid stiction phenomenon, as well as fluid inertial and shear thinning effects. Compared with other types of models based on the Bouc-Wen model, the proposed model has been shown to be more effective, especially in describing the force rolloff in the low velocity region, force overshoots when velocity changes in sign, and two clockwise hysteresis loops at the velocity extremes.

Selective combined control stiffness and magnetorheological damping system in nonlinear multistorey structures

AbstractThe application of a combined controlled stiffness and magnetorheological (MR) damping system in a base‐isolated nonlinear multistorey structure with amplifying braces is described. Passive control theory is used to obtain the viscous characteristics of the MR damper fluid. Selective control of the proposed system is used to enhance the behaviour of a structure during earthquakes. The nonlinear equations of motion are solved using the Wilson θ method. The control forces are obtained using instantaneous control theory with the predictive control approach. The efficiency of the proposed system is demonstrated by a numerical simulation of a seven‐storey building subjected to four different earthquakes. The stimulation shows that the behaviour of the selective controlled structure with the proposed damping system is significantly improved compared to that of an uncontrolled structure. The energy required for the adjustment of the proposed system with amplifying braces is much lower compared to that of the case of MR dampers connected directly to chevron braces. The response of the predictive controlled structure is close to that of an instantaneous controlled structure. Copyright © 2002 John Wiley & Sons, Ltd.