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In recent years, magnetorheological dampers (MRD) have played a significant role in vibration control in various fields such as vehicles, military, building structures, etc. However, the mechanical model of MRD is very complex due to its hysteresis, which makes it difficult to identify the model's parameters. In addition to experimental data, under the condition of no other prior knowledge, eight unknown parameters of the Bouc-Wen model are identified in this study based on the particle swarm optimization (PSO) algorithm. According to the trend of parameter variation with current, fitting research is conducted, and the variation law of parameters with current is summarized. Based on the identified parameters, the MRD's output force is predicted under any current other than the experimental current. Subsequently, the application of MRD in semi-active control of power equipment is performed out, and proposed Simulink calculation programs for single-stage and two-stage vibration control systems are built. Then, a comparative study with passive and active control is conducted. In this paper, linear quadratic regulator (LQR) control is adopted for the active control, and the controller's parameters are optimized based on the PSO algorithm. The results show that the adopted semi-active control can significantly reduce the transmitted force from power equipment to the foundation and can effectively mitigate the disturbance of power equipment to the environment. This study offers important guidance for the vibration control of MRD in industrial engineering. [ABSTRACT FROM AUTHOR]

AbstractMagnetorheological (MR) dampers, utilizing the unique properties of advanced materials, are extensively applied in vibration control systems. However, their performance is often compromised by the structural limitations of conventional designs. The damping force in conventional MR dampers is highly sensitive to velocity variations, primarily due to the interdependence between the piston area and the dimensions of the throttling channels, which are typically inseparable. This inherent coupling restricts the simultaneous optimization of the damping force and adjustable damping ratio, reducing the effectiveness of the magnetorheological dampers in velocity-sensitive environments. Moreover, conventional MR dampers are often characterized by complex structures and large sizes. To overcome these limitations, a novel double-rod bypass magnetorheological damper is proposed. Through the application of fluid mechanics principles and the rheological behavior of MR fluids, the velocity distribution within the throttling channel is thoroughly examined. The Bingham model is employed to establish both the velocity profile and the corresponding mechanical model, and the theoretical results align closely with experimental data, confirming the accuracy of the quasi-static model. Experimental results further demonstrate the proposed damper’s superior sensitivity to low velocities. This approach provides valuable theoretical guidance for the design of advanced MR dampers. [ABSTRACT FROM AUTHOR]

This paper proposes a novel design method for a magnetorheological (MR) damper-based semi-active suspension system. An improved MR damper model that accurately describes the hysteretic nature and effect of the applied current is presented. Given the unfeasibility of installing sensors for all vehicle states, an MR damper current controller that only considers the suspension deflection and deflection rate is proposed. A linear matrix inequality problem is formulated to design the current controller, with the objective of enhancing ride safety and comfort while guaranteeing vehicle stability and robustness against any road disturbance. A series of experiments demonstrates the enhanced performance of the proposed MR damper model, which exhibits greater accuracy than other state-of-the-art damper models, such as Bingham or bi-viscous. An evaluation of the vehicle behavior under two simulated road scenarios has been conducted to demonstrate the performance of the proposed output feedback MR damper-based semi-active suspension system. [ABSTRACT FROM AUTHOR]

To improve the characteristics of traditional model predictive control (MPC) semi-active suspension that cannot achieve the optimal suspension control effect under different conditions, a variable horizon model predictive control (VHMPC) method is devised for magnetorheological semi-active suspension with air springs. Mathematical models are established for the magnetorheological dampers and air springs. Based on the improved hyperbolic tangent model, a forward model is established for the magnetorheological damper. The adaptive fuzzy neural network method is used to establish the inverse model of the magnetorheological damper. The relationship between different road excitation frequencies and the control effect of magnetorheological semi-active suspension with air springs is simulated, and the optimal prediction horizons under different conditions are obtained. The VHMPC method is designed to automatically switch the predictive horizon according to the road surface excitation frequency. The results demonstrate that under mixed conditions, compared with the traditional MPC, the VHMPC can improve the smoothness of the suspension by 2.614% and reduce the positive and negative peaks of the vertical vibration acceleration by 11.849% and 6.938%, respectively. Under variable speed road conditions, VHMPC improved the sprung mass acceleration, dynamic tire deformation, and suspension deflection by 7.191%, 7.936%, and 22.222%, respectively, compared to MPC. [ABSTRACT FROM AUTHOR]

AbstractMagnetorheological dampers (MRD) are widely used in vibration control due to their rapid response and adjustable damping forces. However, conventional MRD designs with closed rectangular magnetic circuits suffer from limited effective working lengths and inadequate damping force for vehicle suspensions. To address this, a novel full-channel effective MRD with shunt and bending magnetic circuit (FEMRD_SB) is proposed. This design increases the effective working length of the damping channel by incorporating a bending motion in the magnetic circuit. Magnetic circuit shunting is integrated to mitigate magnetic leakage during bending, improving energy utilization efficiency. To better meet the practical needs of vehicle suspension, a quasi-static mathematical model aiming to explain the mechanical properties of the damper is investigated. Traditional models often overlook the uneven distribution of magnetic fields, which leads to poor modeling accuracy. To improve the precision of the quasi-static model, a multiphysical field coupling quasi-static modeling method is proposed. This method, utilizing the Takagi–Sugeno fuzzy neural network establishes the relationship between magnetic field and displacement, facilitating the integration of magnetic, flow, and solid fields for more precise modeling outcomes. Simulations and experiments validate the effectiveness of the FEMRD_SB and the quasi-static model. The real-vehicle experiments demonstrate that the FEMRD_SB effectively suppresses the sprung mass acceleration of a vehicle, improving the vehicle’s ride comfort. [ABSTRACT FROM AUTHOR]

The sting support faces an issue of being prone to resonance due to its low-damping characteristics, which will compromise the accuracy of test data in wind tunnel experiments. Magnetorheological damper (MRD)-based tail support (MRSS) features varying stiffness and damping abilities, enabling it to suppress the vibration with random, time-variation characteristics in a self-adaptive way, and it also exhibits excellent fail–safe properties. This work aims to validate its controllability and fail–safe property in a wind tunnel environment. First, the natural frequency, root mean square (RMS), and power spectral density (PSD) of the designed MRSS’ response for random excitation were theoretically analyzed. Then, wind tunnel experiments were conducted to test the response under different attack angles, wind speeds, and test currents. Subsequently, the controllability and fail–safe property were demonstrated by analyzing the aircraft model response. Also, the variable stiffness and damping properties of MRD behind the observed phenomena were revealed based on the theoretical analysis. Results demonstrate that as the input current increases and the MRD’s stiffness continues to increase, the damping initially increases and then decreases. Increasing wind speed leads to a decrease in the MRD’s stiffness. Additionally, approximately 50% reduction in RMS and a multi-modal response attenuation was achieved. [ABSTRACT FROM AUTHOR]

Scissor-like isolation platform (SIP) with magnetorheological damper (MRD) has been commonly studied and applied successfully in vehicle vibration isolation. This paper concerns passive nonlinear magnetorheological (MR) characteristics of the SIP via geometric nonlinearity induced by MRD's layout ways. A dynamic parametric model of the SIP with six assembly types is derived based on Lagrange equation. Then, the parameter analysis is performed to estimate MR damping function in SIP. The analytical steady-state response of the isolator is derived using harmonic balance method, and its effectiveness is validated with numerical results. Metrics are defined to access the performance of the isolator, followed by comparison on displacement transmissibility for six types. The effect of MR damping coefficient and input amplitude on the performance of the isolator is investigated. Finally, comparative study with existing isolators is conducted. Results indicate that, passive MR damping is dependent on vibration displacement, which is beneficial to suppressing peak transmissibility with a little effect at non-resonant frequencies. The results also reveal that the isolator by type 1 or 3 has broader isolation band over other types. And the SIP in type 1 has wider isolation band and lower peak transmissibility compared with existing isolators in allowable workspace. [ABSTRACT FROM AUTHOR]

Conventional active controllers generally adopt initial dynamic properties of intact structures to calculate optimal control force for magnetorheological damper, which eventually leads to ideal damping force of the device. Also, they cannot assure trade-off between damping force and response reduction under non-stationary excitations. To this end, an adaptive semiactive control algorithm for magnetorheological damper is proposed. Using wavelet packet transform, an improved control law determines optimal control forces in terms of resonant and non-resonant frequency bands in time interval. Both frequency bands are established based on natural frequency(ies) of structures, making damping force rely on actual structural properties and achieving trade-off under non-stationary disturbances. A refined clipped-optimal control algorithm is then deployed to convert optimal control force to the device's voltage. A numerical study of a six-degree-of-freedom structure under four near- and far-fault ground accelerations reveals that the scheme outperforms existing controllers while attaining cost-effectiveness of damping force versus response alleviations. [ABSTRACT FROM AUTHOR]

The inherent nonlinear nature caused by the hysteresis characteristics of the forcedisplacement and force-velocity relationships poses a challenge to the modelling and control of magnetorheological (MR) dampers. In this review, two types of modelling methods, parametric modelling and non-parametric modelling, are critically reviewed and discussed, with a focus on how to improve modelling accuracy. Although the force-displacement behaviour is well represented by most of the proposed dynamic models for MR dampers, no simple parametric models with high accuracy can be found for MR dampers. In addition, nonparametric modelling methods can improve the accuracy of the model, but the complexity of the model and the computational burden cause difficulties in designing the closed-loop controller. Finally, the control methods based on different modelling methods are discussed, and future research directions are also recommended. [ABSTRACT FROM AUTHOR]

A methodology for design of magnetorheological dampers for damping vibration of overhead power lines with voltages above 110 kV is proposed, which includes a finite element model of the behavior of the working magnetorheological fluid in a hydraulic channel, and a Matlab model of dynamic processes in a loaded damper. This technique uses tables of damping coefficient values instead of the hysteretic displacement variable characteristic of the Bouc–Wen model, i.e., they use variables and parameters with a physical meaning, known at the stage of formulating technical requirements or determined by calculations. To verify and evaluate the accuracy of the technique, a vibration model of a section of AC 150/19 wire is studied as a system with lumped parameters, suspended on garlands of intermediate support insulators using magnetorheological dampers. [ABSTRACT FROM AUTHOR]

To improve the dynamic performances of nonlinear magnetorheological (MR) semi-active suspension, a hybrid damping control (HDC) based on Kalman observer of nonlinear suspension system is proposed. Firstly, the mechanical test of MR damper is carried out, and the mechanical model of MR damper and suspension system model are established. On this basis, a feedback linearization Kalman observer (FLKO) based on differential geometry theory is designed. Then, the working modes of the MR suspension system are divided according to different driving roads. HDC is proposed to achieve the dynamic control objectives under different working modes, and genetic algorithm is used to optimize the coefficients of skyhook, groundhook and distribution. The simulation results show that the estimation accuracy of FLKO is more than 85%. Compared with passive suspension, the tire dynamic load is optimized by 15.53% on A class road, improving the road holding. On B class road, the body acceleration, suspension deflection and tire dynamic load are optimized by 2.22%, 23.76% and 1.47% respectively, optimizing the dynamic performances comprehensively. On C class road, the body acceleration is optimized by 17.69%, improving the ride comfort effectively. Finally, a test bench is built, and the test results are basically consistent with simulation, which verifies the effectiveness of the designed FLKO and HDC. [ABSTRACT FROM AUTHOR]

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The suspension system integrating both vibration control and energy harvesting capabilities is denoted as Dual-function Suspension (DFS). The principal objectives for DFS encompass lightweight structure, high output force, extensive adjustability in damping, and minimized energy consumption. In pursuit of optimizing the linear motor and magnetorheological damper (MRD) amalgamated into the DFS, a multi-objective Particle Swarm Optimization (PSO) algorithm is conceived, emphasizing primary and secondary objectives to enhance the holistic performance of the DFS. A comprehensive mathematical model of the DFS is established, and subsequent to this modeling, the structural parameters of DFS are meticulously analyzed. Drawing upon the insights from this analysis, primary and supplementary optimization objectives are delineated, employing PSO for the refinement of the DFS structure. Following this, the Pareto solution set, derived from the optimization process, is judiciously selected utilizing fuzzy theorem principles. The outcomes reveal that, under the constraints of unaltered suspension packaging dimensions and overall energy consumption, the optimized suspension system manifests a 50% augmentation in output force, a 30% expansion in adjustable damping range, and a 39% reduction in thrust ripple compared to its pre-optimized state. [ABSTRACT FROM AUTHOR]

An adaptive Fuzzy Logic Controller (FLC) is proposed to actuate MR damper smartly. Minimizing the excessive responses of buildings should be considered as a multiobjective optimization problem. The new-generation structural systems should be designed based on the seismic performance level. Designing based on performance requires dynamic, heavy, and repetitive time history analyses. The Endurance Time Analysis method (ETA) is a modern dynamic method based on the performance of the structure, which leads to the reduction of time and number of structural analyses. To investigate the effciency of Dolphin Echolocation-Fuzzy Logic Controller (DE-FLC) and ETA, several ET simulations were performed. The seismic responses of 11th-story benchmark building equipped with MR dampers were investigated in two cases of seven time-history analysis and six-generation ET functions. By using dolphin echolocation, the optimal arrangement and the number of sensors and dampers are determined. The proposed DE-FLC controller exhibits its effciency by reducing the excessive displacement under seismic excitations in comparison with the uncontrolled case and classical FLC. Furthermore, the results demonstrate that the sixth generation of ETA can simulate responses of several time-history analyses well with proper accuracy, without necessitating any computational burden. [ABSTRACT FROM AUTHOR]

It is found during the tests that the damping characteristics of the magnetorheological (MR) damper vary with the excitation amplitude and frequency. However, the existing MR damper models are not able to accommodate the change of excitation amplitude and frequency, which will lead to significant modeling errors. To deal with this problem, this paper analyzes the experimental data and obtains the regularity of the damping characteristics varying with the excitation. Subsequently, an excitation-adaptive MR damper model is constructed based on the hyperbolic tangent function. The proposed model is not only able to adapt to the change of excitation amplitude and frequency but also able to inverse, which is essential for MR damper controller construction. The fitting results show that compared with the existing models, the three normalized errors of the proposed model are improved from 22.61%, 13.96%, and 19.42%–6.30%, 3.81%, and 6.97%, respectively, indicating that the model excitation adaptivity is significantly improved. Furthermore, this study also proposed a damper controller based on the new model, and the simulation results verify the effectiveness of the controller. The proposed model brings the acceleration signal into the model to improve the model adaptivity, which introduces a novel approach to enhance the adaptivity of MR damper models. [ABSTRACT FROM AUTHOR]

Vertical mass isolation (VMI) is one of the novel methods for the seismic control of structures. In this method, the entire structure is assumed to consist of two mass and stiffness subsystems, and an isolated layer is located among them. In this study, the magnetorheological damper in three modes: passive-off, passive-on, and semi-active mode with variable voltage between zero and 9 volts was used as an isolated layer between two subsystems. Multi-degrees-of-freedom structures with 5, 10, and 15 floors in two dimensions were examined under 11 pairs of near field earthquakes. On each level, the displacement of MR dampers was taken into account. The responses of maximum displacement, maximum inter-story drift, and maximum base shear in controlled and uncontrolled buildings were compared to assess the suggested approach for seismic control of the structures. According to the results, the semi-active control method can reduce the response by more than 12% compared to the uncontrolled mode in terms of maximum displacement of the mass subsystem of the structures. This method can reduce more than 16% and 20% of the responses compared to the uncontrolled mode in terms of maximum inter-story drift and base shear of the structure, respectively. [ABSTRACT FROM AUTHOR]

The paper is focused on the design of a mobile wheeled platform able to move in uneven/ unstructured terrains and particularly intended for supporting the work in agriculture. An independent double wishbone suspension is chosen to obtain a light and compact structure. Furthermore, a semi-active suspension with magnetorheological dampers and the ability to change the track of wheels is proposed to minimize uncontrolled vertical movements of the platform. A dynamic model is formulated to carry out simulations including various obstacles and cases with constant/controlled damping coefficients. As a final result, a conceptual CAD model is built with selected motors and standardized parts. [ABSTRACT FROM AUTHOR]

Purpose: Semi-active control is considered to be very interesting for its engineering sophistication/effectiveness like the active control strategy, however, requiring significantly lesser amount of control effort/input. In view of the devastating damages of soft-storey building structures in case of real-life seismic events, a study on semi-active vibration control for vulnerable structures like soft-storey buildings appears very interesting. Methods: The magnetorheological (MR) damper is taken as the control device which produces control force through modulating its damping coefficient with the help of external input voltages in a semi-active control framework based on the widely used Linear Quadratic Gaussian (LQG) control. The Bouc–Wen hysteresis model is considered to calculate the control force. A realistic five-storey building with soft-storey at the ground is considered for validation. Besides, the performance of LQG control is compared with the proportional-integral-derivative (PID) control. Results: It is observed that LQG-based semi-active control strategy has been able to perform satisfactorily (in reducing soft-storey response) with the cost of surprisingly insignificant amount of control effort (with supply voltage in the range, 0–2.5 V) by reducing the peak response as 67.5%, 78.05%, 67.57%, 75%, and 51.02% against El Centro, Northridge, Kobe, Bhuj, and Tohoku earthquakes, respectively, while 68.85%, 79.42%, 65.26%, 73.38%, and 51.65% in case of root-mean-square response. Higher range of supply voltage is found to provide even better control performance. Conclusion: In view of the satisfactory control performance, the semi-active control with MR dampers using LQG control is well encouraging in protecting the highly vulnerable soft-storey building structures under seismic events. [ABSTRACT FROM AUTHOR]

This research presents an augmented Kalman estimator and an equivalent replacement-based Taylor series (ERBTS)-linear quadratic Gaussian (LQG) control strategy to cope with the control accuracy and response delay of magnetorheological (MR) dampers for vehicle semi-active suspensions. The parameters in the MR model are identified from experimental measurements. Then, two main sources of control error, namely, modelling error and real-time variety of the MR damper output force, are defined as an integrated compound real-time variety. Subsequently, they are written into a differential equation with characteristics of the minimum system to augment the state equation of the semi-active suspension system. The augmented Kalman estimator is constructed to estimate the abovementioned compound real-time variety. To calculate an acceptable time-delay compensation predictive control force, an equivalent operation is implemented beforehand in the suspension comprehensive performance index by replacing a part of the squared time-delay control force with the corresponding predictive control force. Simulation results verify the effectiveness of the proposed augmented Kalman estimator, and the newly developed ERBTS-LQG controller almost achieves control effectiveness of the ideal time delay free semi-active suspension. [ABSTRACT FROM AUTHOR]

During the walking process of lower limb exoskeleton rehabilitation robots, inevitable collision impacts will occur when the swinging leg lands on the ground. The impact reaction force from the ground will induce vibrations in the entire robot's body from bottom to top. To address this phenomenon, considering the limitations of traditional active compliance and passive compliance methods, a variable stiffness and damping actuator (VSDA) leg structure using a magnetorheological damper (MRD) is proposed. Firstly, experimental methods are used to obtain the ground reaction force (GRF) exerted on a normal person during walking. Then, a mathematical model of the VSDA leg structure is constructed, and its working principle is analyzed. Based on human mass and dimensions, a 3D model is designed and selected. Finally, a simulation model is built in the MATLAB/Simulink environment using the fuzzy switch damping control strategy to simulate the acceleration and displacement of the human body under sinusoidal and random excitations. The results indicate that under sinusoidal excitation, employing fuzzy switch damping control optimizes human displacement by 72.47% compared to the high stiffness and high damping system, and by 16.95% compared to the switch damping system. Human acceleration is optimized by 52.09% compared to the high stiffness and high damping system, and by 25.2% compared to the switch damping system. Under random excitation, adopting fuzzy switch damping control optimizes human displacement by 59.09% compared to the high stiffness and high damping system, and by 21.74% compared to the switch damping system. Human acceleration is optimized by 78.74% compared to the high stiffness and high damping system, and by 31.66% compared to the switch damping system. This validates the VSDA design structure and control method, demonstrating certain advantages in improving the compliance and stability of lower limb exoskeleton rehabilitation robots. [ABSTRACT FROM AUTHOR]

We investigated a damping switching control law with simplicity and high performance for semi-active suspension with time delay. The present law simply switches damping according to the sign of the condition function of ( + 0) using target and base velocity and 0, respectively, whereas a skyhook-based law does it by ( − 0). We conducted the simulations and experiments of vibration suppression for a single degree-of-freedom system with a semi-active magnetorheological damper to compare both the law. The key findings of this study are as follows: (1) In the time delay of 10–100 ms, the ON–OFF control using the present law maintains the vibration suppression performance under sine excitations although that using a skyhook-based law degrades it increasing with time delay. At least, over the time delay of 50 ms, the present law has the vibration suppression performance higher than a skyhook-based law in the overall range of frequency ratio of 0–4. (2) The velocity-proportional damping control using the present law shows the vibration suppression performance higher than or equal to the ON–OFF control using the present law under sine excitations. (3) Under a road surface excitation, the velocity-proportional damping control using the present law shows the ideal vibration suppression performance that the response displacement in the control is equal to that in the ON state around the natural frequency and close to that in the OFF state over the frequency ratio of √2.

ABSTRACTAiming at reducing the effect of time delay on the control performance of magnetorheological (MR) damper semi-active suspension, a control strategy with strong robustness to time delay is investigated in this study, including the force controller of MR damper, the robust controller and the predictive compensator. The force controller of MR damper is built based on the hyperbolic tangent function; the robust controller is built based on the simplified model of car body lateral vibration and is designed by μ-synthesis method considering the effect of time delay; then the Smith predictive model and the lateral velocity predictor are designed, which form the predictive compensator of semi-active controller to reduce the effect of time delay. To validate the effectiveness of the proposed control strategy, several conventional semi-active controllers are designed as comparative objects. The simulation results show that the proposed semi-active control strategy can maintain good performance when time delay is in the range of 0–100 ms and has better robustness to time delay compared with the conventional control strategy.

This paper proposes a novel design method for a magnetorheological (MR) damper-based semi-active suspension system. An improved MR damper model that accurately describes the hysteretic nature and effect of the applied current is presented. Given the unfeasibility of installing sensors for all vehicle states, an MR damper current controller that only considers the suspension deflection and deflection rate is proposed. A linear matrix inequality problem is formulated to design the current controller, with the objective of enhancing ride safety and comfort while guaranteeing vehicle stability and robustness against any road disturbance. A series of experiments demonstrates the enhanced performance of the proposed MR damper model, which exhibits greater accuracy than other state-of-the-art damper models, such as Bingham or bi-viscous. An evaluation of the vehicle behavior under two simulated road scenarios has been conducted to demonstrate the performance of the proposed output feedback MR damper-based semi-active suspension system.

To improve the characteristics of traditional model predictive control (MPC) semi-active suspension that cannot achieve the optimal suspension control effect under different conditions, a variable horizon model predictive control (VHMPC) method is devised for magnetorheological semi-active suspension with air springs. Mathematical models are established for the magnetorheological dampers and air springs. Based on the improved hyperbolic tangent model, a forward model is established for the magnetorheological damper. The adaptive fuzzy neural network method is used to establish the inverse model of the magnetorheological damper. The relationship between different road excitation frequencies and the control effect of magnetorheological semi-active suspension with air springs is simulated, and the optimal prediction horizons under different conditions are obtained. The VHMPC method is designed to automatically switch the predictive horizon according to the road surface excitation frequency. The results demonstrate that under mixed conditions, compared with the traditional MPC, the VHMPC can improve the smoothness of the suspension by 2.614% and reduce the positive and negative peaks of the vertical vibration acceleration by 11.849% and 6.938%, respectively. Under variable speed road conditions, VHMPC improved the sprung mass acceleration, dynamic tire deformation, and suspension deflection by 7.191%, 7.936%, and 22.222%, respectively, compared to MPC.

Tower fatigue and strength are crucial operational concerns of floating offshore wind turbines (FOWTs) due to the escalation of the vibration phenomena observed on these structures as compared to land-based ones. FOWT towers are excited by wave and wind polyperiodic disturbances yielding continual transient states of structural vibration that are challenging for vibration mitigation systems. Thus, the paper investigates a novel implementation of nonlinear optimal-based vibration control solutions for the full-scale, tension leg platform (TLP)-based, NREL 5MW wind turbine tower-nacelle model with a 10-ton tuned vibration absorber (TVA), equipped with a magnetorheological (MR) damper, located at the nacelle. The structure is subjected to excessive wave and wind excitations, considering floating platform motions derived from model experiments in a wave tank. The MR damper operates simultaneously with an electromagnetic force actuator (forming a hybrid TVA) or independently (a semiactive TVA). The study includes both actuators' nonlinearities and dynamics, whereby the former are embedded in the Hamilton-principle-based nonlinear control solutions. The TVA is tuned either to the NREL 5MW tower-nacelle 1st bending mode frequency (TVA-TN) or to the TLP surge frequency (TVA-TLP). The optimal control task was redeveloped concerning the TVA stroke and transient vibration minimisation, including the implementation of the protected structure's acceleration and relative displacement terms, as well as the nonzero velocity term in the quality index. The regarded model is embedded in a MATLAB/Simulink environment. On the basis of the obtained results, the TVA-TN solution is by far superior to the TVA-TLP one. All the regarded TVA-TN solutions provide a tower deflection safety factor of ca. 2, while reference systems without any vibration reduction solutions or with a passive TVA-TLP are at risk of tower structural failure as well as the hybrid TVA-TLP system. The obtained TVA stroke reductions of 25.7%/22.0% coincide with 3.6%/10.3% maximum tower deflection reductions for the semiactive/hybrid TVA-TN case (respectively) with regard to the previously developed approaches. Moreover, these reductions are obtained due to the sole control algorithm enhancement; thus, no additional resources are necessary, while this attainment is accompanied by a reduction in the required MR damper force. The lowest obtained TVA stroke amplitude of 1.66 m is guaranteed by the newly introduced semiactive control. Its hybrid equivalent ensures 8% lower primary structure deflection amplitude and reduced nacelle acceleration levels thanks to the utilisation of the force actuator of the relatively low power (ca. 6 kW); the trade-off is an increased TVA stroke amplitude of 2.19 m, which, however, is the lowest among all the tested hybrid solutions. The analysed reference passive TVA systems, along with a modified ground-hook hybrid solution, can hardly be implemented in the nacelle (especially along the demanding side–side direction). The latter, being the well-proven hybrid solution for steady-state tower deflection minimisation, yielded unsatisfactory results. The achievements of the study may be used for an effective design of a full-scale vibration reduction system for the TLP-based floating wind turbine structure. [ABSTRACT FROM AUTHOR]

This study investigates the semi-active control of railway bridges using an MR damper to reduce the excessive displacement in the bearings of isolated bridges under severe earthquakes. Within the study context, the variable-oval-control (VOC) rule based on structural response displacement feedback is applied to the MR damper and compared with a passive control and clipped optimal semi-active control algorithm. The simulation results show that the dynamic response of railway bridge piers can be effectively reduced, and seismic safety can be significantly improved using MR dampers based on a variable ellipse control strategy. MR damper, based on the VOC rule, directly adopts structural response displacement to perform control force state change. The VOC method only requires the minimum control force to achieve a good displacement control effect, high control efficiency, and stable control effect. [ABSTRACT FROM AUTHOR]

In order to describe and predict the damping force of the magnetorheological damper with radial damping gap, a more accurate damping force calculation model is proposed through theoretical modeling. Firstly, according to the working environment of the heavy vehicle, a magnetorheological damper with radial damping gap is designed in a limited installation space, which has the characteristics of large damping force and tensile damping force greater than compression damping force. Secondly, based on the Bingham model for theoretical modeling, the analytical solution of the pressure drop gradient of the radial damping gap is obtained, and then a theoretical model that can more effectively reflect the mechanical characteristics of the radial damping gap is proposed. The dynamic characteristics of the designed magnetorheological damper are tested, and the experimental results verify that the designed structure has a good magnetorheological effect. When the current is 3 A, the maximum damping force of the damper exceeds 16 kN. Finally, by comparing the simulation results of the theoretical model with the experimental results, the results show that the established mathematical model can describe the experimental results well. The accuracy of the theoretical model is verified by comparing the proposed model with two commonly used models. [ABSTRACT FROM AUTHOR]

As a typical intelligent device, magnetorheological (MR) dampers have been widely applied in vibration control and mitigation. However, the inherent hysteresis characteristics of magnetic materials can cause significant time delays and fluctuations, affecting the controllability and damping performance of MR dampers. Most existing mathematical models have not considered the adverse effects of magnetic hysteresis characteristics, and this study aims to consider such effects in MR damper models. Based on the magnetic circuit analysis of MR dampers, the Jiles–Atherton (J-A) model is adopted to characterize the magnetic hysteresis properties. Then, a weight adaptive particle swarm optimization algorithm (PSO) is introduced to the J-A model for efficient parameter identifications of this model, in which the differential evolution and the Cauchy variation are combined to improve the diversity of the population and the ability to jump out of the local optimal solution. The results obtained from the improved J-A model are compared with the experimental data under different working conditions, and it shows that the proposed J-A model can accurately predict the damping performance of MR dampers with magnetic hysteresis characteristics. [ABSTRACT FROM AUTHOR]

Aiming at reducing the effect of time delay on the control performance of magnetorheological (MR) damper semi-active suspension, a control strategy with strong robustness to time delay is investigated in this study, including the force controller of MR damper, the robust controller and the predictive compensator. The force controller of MR damper is built based on the hyperbolic tangent function; the robust controller is built based on the simplified model of car body lateral vibration and is designed by μ-synthesis method considering the effect of time delay; then the Smith predictive model and the lateral velocity predictor are designed, which form the predictive compensator of semi-active controller to reduce the effect of time delay. To validate the effectiveness of the proposed control strategy, several conventional semi-active controllers are designed as comparative objects. The simulation results show that the proposed semi-active control strategy can maintain good performance when time delay is in the range of 0–100 ms and has better robustness to time delay compared with the conventional control strategy. [ABSTRACT FROM AUTHOR]

Magnetorheological dampers (MRDs) are applied to hydraulic systems, which not only improve the underdamped characteristics of valve-controlled cylinder systems, but also help hydraulic actuators to resist high load impact. However, the high power density leads to the complexity of the internal flow channel of the damper, which seriously affects the output accuracy of the damping force. It can lead to the fact that existing dynamics models cannot accurately describe the hysteresis characteristics of the MRD. Therefore, this study proposes a simple and general dynamic model of MRD, which solves the problem that existing models are complex and difficult to invert. Firstly, the hydraulic damping actuator with the series MRD is taken as the research object. Based on the stress–strain hysteresis characteristics under the cyclic constitutive model, the hyperbolic tangent curve is reorganized and normalized. It can accurately describe the yield formation and yield dissipation stages of the hysteresis loop. Secondly, the relationship between the parameters of the dynamic model and the current is obtained according to the mechanical experimental data. Then the inverse model of the MRD is established by using the method of section-backstepping. Finally, in the static experiment, the mean absolute percentage error (MAPE) of the force at different velocity is less than 7.5%; in the dynamic experimental test, the MAPE of the force is 9.7%. The inverse dynamics model is verified to have high tracking performance under both static and dynamic forces. And it also indirectly confirms the effectiveness of the forward model. [ABSTRACT FROM AUTHOR]

• The Riccati transformations for track subsystems are obtained by a novel dynamic recursive method. • Dynamic modeling of tracked vehicles using both the overall transfer equation and the recurrence relations. • Dynamic modeling considers the nonlinear characteristics of track systems and magnetorheological dampers. • Compared with passive suspension, magnetorheological semi-active suspension improves the tracked vehicle performance. The magnetorheological technology has been widely used in automotive applications, whereas less research has been done on tracked vehicles. Hence, this research focuses on the dynamic modeling of the whole system of a tracked vehicle, for analyzing the effect of magnetorheological semi-active suspension on track tension and chassis vibration during driving. Applying the multibody system transfer matrix method and a dynamic recursive method, the dynamic models of the chassis subsystem and the double track subsystems are developed, respectively. These three subsystems are coupled by nonlinear contact forces, where the meshing shock, polygon effect, and rolling effect during contact are also taken into consideration. Subsequently, the normalized Bouc-Wen model is adopted to describe the nonlinear characteristics of rotary magnetorheological dampers. Then, a semi-active suspension control of the tracked vehicle is implemented with rotary magnetorheological dampers and the independent skyhook control method. Finally, numerical simulations are performed under different operating conditions. Comparing with the case of passive suspension, it reveals that, the magnetorheological semi-active suspension not only improves the distribution of the track tension but also effectively reduces the chassis vibration. It provides a theoretical basis for the design and application of magnetorheological semi-active suspensions for tracked vehicles. [ABSTRACT FROM AUTHOR]

Due to the characteristics of smart material magnetorheological (MR) fluid, such as short response time and large controllable range, semi-active suspension based on MR fluid has been widely used. In order to improve the steering stability of vehicles, a semi-active suspension with tapered flow mode MR was proposed. The magnetic circuit of the proposed structure was designed, its dynamic model was established, and the finite element simulation analysis was carried out. By establishing the optimization objectives and constraints, the MR damper was optimized by NSGA-II and MOST algorithms. The vehicle dynamics model with MR damper was established, and the vehicle dynamics simulation was carried out under the control system based on the vehicle dynamics simulation software CarSim-Simulink before and after optimization. The results show that the NSGA-II optimized MR damper can reduce vehicle roll and significantly improve vehicle handling stability. This paper provides a new idea for improving vehicle handling stability by optimizing the MR damper. [ABSTRACT FROM AUTHOR]

The temperature-dependence (T-dependence) characteristics of magnetorheological fluids (MRFs) cause the damping force of magnetorheological dampers (MRDs) to change with temperature. The rapid temperature rise can lead to performance degradation or even failure of MRFs, reduced damping force of MRDs, and decline in control performance. In this paper, numerical simulations and predictions of the temperature rise characteristics of the MRD are performed and heat sinks are designed and optimized. The experimental results verify the efficiency of the simulations and predictions, and the heat sinks can significantly reduce the rate of temperature increase and improve the ability of the damper to operate for long hours. In order to accurately compensate for T-dependence characteristics of the MRD, a T-dependence hysteresis model and a model-based feedforward force tracking control method with disturbance observation of the MRD are proposed and validated by experiments. The experimental results indicate that the proposed T-dependence model has better prediction accuracy than the general hysteresis model, and the feedforward control method achieves good force tracking performance even without expensive force sensors. [ABSTRACT FROM AUTHOR]

Commercial vehicles are usually equipped with suspension seats to improve ride comfort. As a semi-active intelligent device, magnetorheological damper can effectively improve seat comfort when applied to seat suspension. Firstly, a novel damper with built-in magnetorheological valve (MRVD) based on the squeeze mode of magnetorheological fluid (MRF) is designed, which integrates the magnetorheological valve (MRV) into the piston. This structure adopts a bidirectional controllable flow channel, double coil, and double squeeze chamber. Secondly, the mathematical model of the MRVD is derived based on the Bingham plastic model of the MRF. Then, the distribution of magnetic flux density in the effective damping gaps is simulated using finite element method. Finally, it is shown from a comparative work between the simulation results from the derived mathematical model and experimental test results of the MRVD that the established mathematical model can predict the field-dependent damping force well. The idea of integrating the MRV into the piston provides a new approach for the application of magnetorheological technology. [ABSTRACT FROM AUTHOR]

The suspension system is one of the important parts of the vehicle, which plays a substantial role in the steering and comfort characteristics of it. In the present research work, the optimization of the suspension system parameters has been carried out with the aim of reducing the vehicle vibrations. In this study, the magnetorheological damper (MR damper) is added to the one-half car model with four degrees of freedom and the effects of improving the efficiency of the suspension system have been investigated. In order to model the vehicle system, MATLAB/Simulink software is employed. The particle swarm optimization (PSO) algorithm has been applied to optimize the variables of the suspension system in order to decrease the vehicle vibrations and passenger comfort. The optimization of suspension system variables has been done for two bond-limited white noise and sinusoidal wave inputs. The outcomes revealed that the addition of MR damper in any mode reduces the vehicle vibrations. The maximum reduction in the vehicle vibrations was related to the state where all the variables of the suspension system were optimized and the amount of the objective function in that state was improved by about 32%.

An active passive hybrid control system (MRTMD) was proposed to combine a magnetorheological damper (MRD) and a tuned mass damper (TMD). The vibration of water supply and drainage pipelines was controlled when passing through embankments caused by the operation of pumping station units. Linear quadratic regulator (LQR) based optimal control algorithm was utilized to optimize the parameters of the active passive hybrid vibration control system, in order to minimize the acceleration of the structure. Magnetorheological damper damping was stable enough to change the damping frequency in the new system, compared with the traditional single-tuned mass damper. Firstly, a simulation signal was constructed to simulate the load excitation of pump station units during operation, the vibration response of pump station pipeline was also used to compare with a single TMD and MRD control, in order to verify the applicability and effectiveness of the MRTMD for pump station pipeline vibration reduction. Secondly, shock waves were used as excitation to simulate and analyze the control effect of pipeline dynamic response, in response to the phenomenon of water hammer during opening and closing of the unit or the abnormal vibration under extreme working conditions. The damping force and displacement hysteresis curve were used to explore the robustness and vibration reduction of the output resistance force; Finally, MRTMD was applied to the water supply and drainage pipeline project in the Beijiang Dam in Guangdong Province. The simplified two-degree-of-freedom mass, stiffness, and damping matrices of the pipeline were solved using load inversion and then established the pipeline vibration dynamics equation. Taking the vibration reduction efficiency as the evaluation index, the vibration reduction efficiency of the new system on the water supply and drainage pipeline structure passing through the embankment was analyzed from the time domain perspective. The effective vibration reduction frequency range and energy reduction efficiency of each main frequency of MRTMD were also analyzed from the frequency domain perspective. The results show that the damping force provided by MRTMD shared a wide range, stable output, and strong energy dissipation. Better control was achieved in the acceleration response of pipeline structure, when passing through the embankment, with a damping efficiency of 37.56%-38.07%. There was a slightly better control in the displacement response of the structure, compared with the acceleration response, with a damping efficiency of 40.23%-41.38%, and a damping effect of 33.9% at the pipeline passing through the embankment. The vibration reduction was superior to single TMD and MRD control; There was the weakening effect of MRTMD on the main frequency energy of various vibration sources during operation in a frequency domain. Among them, the mechanical vibration energy caused by the rotation of the main shaft (such as rotation frequency and doubling frequency) was reduced to 27.46% and 75.88%, respectively, while the vibration energy was significantly reduced to 36.46% for medium to low frequency vibration that caused by water flow impact and axial vortices formed in the impeller. [ABSTRACT FROM AUTHOR]

In the mine hoisting system, rigid guide failures and the influence of internal and external airflow intensify vessel transverse vibration, heightening demands on operational safety and equipment reliability. This paper focuses on integrating magnetorheological dampers and disc springs as the roller cage shoe buffer for vibration control, resulting in an innovative buffer device. The structure and magnetic circuit were meticulously designed. Using Maxwell simulation, we analyzed the impact of magnetic circuit parameters—specifically the damping gap and core radius—on the magnetorheological damper. We optimized these parameters through orthogonal testing to enhance damping and vibration reduction. This led to a notable 58% increase in the damper output force. A virtual prototype of the lifting system under actual working conditions was established. A simulation analysis verified the vibration-damping performance of the optimized roller cage shoe. The results indicate that the new roller cage shoes effectively inhibit transverse vibration, surpassing traditional roller cage shoe performance. This is scientifically and practically significant for ensuring safe cage shoe lifting system operation. This paper can provide a crucial theoretical basis for the design of roller cage shoes in ultra-deep mine lifting systems. [ABSTRACT FROM AUTHOR]

This paper presents an approach to model the impact behaviour of a dual-acting magnetorheological elastomer (MRE) damper using 4th-order polynomial functions optimized with a gravitational search algorithm. MRE is a type of smart material that can change its mechanical properties in response to an injected current, making it well-suited for a wide range of applications such as vibration absorption, noise cancellation, and shock mitigation. The proposed model uses a combination of polynomial functions designed to predict the nonlinearity of MRE during compression and extension stages. The model is tuned and validated using experimental data from impact tests conducted on the MRE damper under various currents. The results indicate that the developed model can accurately track the impact behaviour of MRE with minimum error. Additionally, an interpolation model is proposed to estimate the appropriate forces for median currents. The interpolation model predicts the force between the upper and lower currents, demonstrating the model's ability to predict MRE behaviour accurately. The main contribution of this study is proposing a non-parametric model of MRE that is able to identify the hysteretic behaviour of the MRE based on specific current applied. In addition, an interpolation model is introduced in this study to cover not only the input current starting from 0 A to 2 A but also the intermediate current such as 0.3 A, 0.7 A, 1.3 A and 1.7 A. [ABSTRACT FROM AUTHOR]

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Backgrounds: In this paper, a kind of mining MR damper with shear and valve working mode is designed. Compared with the traditional damper, this MR damper has better energy dissipation characteristics and can provide greater damping force in a short time. Its damping can be adjusted with the excitation current. Purposes: The aim of the present paper is to analyze and study the performance of this novel mining MR damper and test the working performance and feasibility of this MR damper. Methods: Optimizing and establishing a Simulink dynamic simulation model based on Bingham model and testing the performance parameters of the MR damper. The vibration mitigation experiment of mining vibrating screen based on spring damper is designed. Results: This paper compares the experimental and simulation results and found that the error of the maximum damping force shall not exceed 3%.Compared with traditional metal spring and ROSTA spring, the MR damper can reduce the downtime of the vibrating screen by more than 80%. Conclusions: From the results, the present paper provides theoretical basis for the performance test of the damper. The excitation current is the main factor affecting the maximum damping force of the MR damper. The correlation between the excitation current and the maximum damping force is more than 90%. MR damper can not only effectively avoid the resonance of the vibrating screen, but also will not affect the stable amplitude of the vibrating screen when it works, and can also greatly reduce the downtime of the vibrating screen. [ABSTRACT FROM AUTHOR]