Showing papers on "Magnetorheological damper published in 2012"

A self-sensing magnetorheological damper with power generation

Abstract: Magnetorheological (MR) dampers are promising for semi-active vibration control of various dynamic systems. In the current MR damper systems, a separate power supply and dynamic sensor are required. To enable the MR damper to be self-powered and self-sensing in the future, in this paper we propose and investigate a self-sensing MR damper with power generation, which integrates energy harvesting, dynamic sensing and MR damping technologies into one device. This MR damper has self-contained power generation and velocity sensing capabilities, and is applicable to various dynamic systems. It combines the advantages of energy harvesting—reusing wasted energy, MR damping—controllable damping force, and sensing—providing dynamic information for controlling system dynamics. This multifunctional integration would bring great benefits such as energy saving, size and weight reduction, lower cost, high reliability, and less maintenance for the MR damper systems. In this paper, a prototype of the self-sensing MR damper with power generation was designed, fabricated, and tested. Theoretical analyses and experimental studies on power generation were performed. A velocity-sensing method was proposed and experimentally validated. The magnetic-field interference among three functions was prevented by a combined magnetic-field isolation method. Modeling, analysis, and experimental results on damping forces are also presented.

Frequency and damping adaptation of a TMD with controlled MR damper

Abstract: This paper describes the new concept of a semi-active tuned mass damper with magnetorheological damper (MR-STMD). The real-time controlled MR damper force emulates controlled damping and a superimposed controllable stiffness force to augment or diminish the force of the passive spring stiffness which enables us to control the MR-STMD natural frequency. Both the damping and natural frequency are tuned according to Den Hartog’s formulae to the actual dominant frequency of the main structure irrespective of whether it is a resonance or a forced frequency. The MR-STMD is experimentally validated on the Empa bridge with a 15.6 m main span for different added masses to shift its resonance frequency 12.2% andC10.4% away from its nominal value. The experimental results are compared to those obtained when the MR-STMD is operated as a passive TMD that is precisely tuned to the nominal bridge. The comparison shows that the MR-STMD outperforms the TMD both in the tuned and all de-tuned cases by up to 63%. Simulations of the MR-STMD concept point out that the proposed semi-active control algorithm is most suitable for MR-STMDs due to the small amount of clipped active forces. A sensitivity analysis demonstrates that the real MR-STMD could be even more powerful if the force tracking errors in the MR damper force due to the current driver and MR fluid dynamics and remanent magnetization effects could be further reduced. The MR-STMD under consideration represents the prototype of the 12 MR-STMDs that have been running on the Volgograd Bridge since late fall 2011. (Some figures may appear in colour only in the online journal)

Performance tests and mathematical model considering magnetic saturation for magnetorheological damper

Abstract: As a semiactive control device, magnetorheological dampers have been paid more attention due to their high controllability, fast response, and low power demand. One of the important characteristics...

Magnetorheological damper—an experimental study

Abstract: A magnetorheological damper is evaluated under exhaustive experimental scenarios, generating a complete database. The obtained database includes classical tests and new proposals emphasizing the fr...

Identification and Control of an MR Damper With Stiction Effect and its Application in Structural Vibration Mitigation

Abstract: This paper presents the parameter identification and control of a magnetorheological (MR) damper with stiction effect and its application to seismic protection of a model two-story structure. This semi-active device is utilized to reduce the vibration of the model structure in response to earthquake excitations. First, modified Bingham and LuGre models which consider the stiction effect and the velocity-dependent nature of the damper force are proposed. The parameters of the models are identified by solving a nonlinear optimization problem. The Bingham model is considered because of its simple structure to be used in linear parameter varying (LPV) design framework. The parameter identification is performed while the MR damper is attached to the structure. These models are verified experimentally for different operating conditions showing an acceptable level of accuracy. The subsequent part of the paper addresses the design of different types of controllers to command the MR damper to suppress the structural vibrations of a model building due to earthquake excitations. Two types of controllers are considered in this study: 1) an H∞ inverse control based on the mixed-sensitivity design and 2) a dynamic output-feedback LPV controller. In the former one, an H∞ controller is designed for the linear structure and the modified LuGre-based inverse model is used to determine the required voltage from the commanded force. The LPV controller is designed for the combined structure and MR damper based on the modified Bingham model considering the damper velocity as the scheduling parameter. Both controllers are combined with a classical anti-windup scheme to compensate the effect of the saturation on the control voltage. An optimal passive damping design is also obtained for comparison purposes. The performance of the controllers is compared with the passive damping case and clipped-optimal controller for the El Centro and Northridge earthquake inputs with different intensities. The experimental results show the improved performance of the LPV controller design in terms of the maximum acceleration and the RMS values of the structure response.

Design, modeling, and controlling of a large-scale magnetorheological shock absorber under high impact load

Abstract: In this article, an MRD50 type of large-scale magnetorheological shock absorber was designed and manufactured in Smart Materials and Structures Laboratory of Nanjing University of Science and Technology Upon providing a brief background on magnetorheological dampers, the detailed structure of this developed large-scale magnetorheological shock absorber was depicted A suit of hardware-in-the-loop simulation platform under high impact load excitation was introduced for a weapon system A series of tests were conducted to establish the dynamic behaviors of magnetorheological shock absorber under impact loads The test results show that the inertia damping force should not be ignored like a common magnetorheological damper because of the large acceleration from the impact load Based on the theory model and the experimental data, index parameters of magnetorheological fluid and other structural parameters in Herschel–Bulkley-Inertia model were identified by using the least square algorithm In order to eval

H ∞ control of a suspension with a magnetorheological damper

Abstract: This research work presents an H ∞ controller based on a Takagi–Sugeno (T–S) fuzzy model for a two-degrees-of-freedom (2-DOF) one-quarter-vehicle semi-active suspension with a magnetorheological damper where the actuator dynamics are included in the control synthesis. These dynamics enclose nonlinear damper phenomena, avoided in many other studies, and that can improve the suspension system by means of a more accurate model. The objective is to obtain a semi-active suspension that considerably improves the passive suspension efficiency based on some frequency domain performance criteria. The advantage of having the T–S system as a reference is that each piecewise linear system can be exposed to the well-known control theory. Besides, the proposed solution is compared with the recent reported work to highlight its advantages. A case of study is included and simulation work supports the results. The methodology applied herein can be extended to a half-vehicle model, and to the four wheels to have a global c...

Efficient dynamic modelling and characterization of a magnetorheological damper

Abstract: The present work is about the dynamic modelling and the experimental testing of magnetorheological (MR) dampers, especially at low frequency. The main improvement of this work over former models is the identification of dynamic parameters which are independent of the working conditions and vary only as a function of the current. A simple model is built on the basis of the literature and of a systematic experimental campaign, with the aim of simplifying the effort in retrieving the parameters and in controlling the system. The excitation current is introduced in the model as a variable, not only reducing the amount of test needed to assess the parameters, but also obtaining a faster model useful in motion control. A second order polynomial relationship between the applied current and the three variable parameters is found, showing a saturation effect at high currents. A verification test shows the reliability and the performance of the proposed model.

Magnetorheological damper with convenience in assembly and disassembly of coil component

Abstract: The invention discloses a magnetorheological damper with convenience in assembly and disassembly of a coil component, relating to the technical field of magnetorheological dampers. The magnetorheological damper comprises a damping cylinder barrel, the coil component, a piston, a piston rod and a magnetorheological fluid, and is characterized in that the coil component is fixed on the outer side of the damping cylinder barrel, a magnetorheological fluid flow channel is arranged on the damping cylinder barrel, the coil component is not in contact with the magnetorheological fluid, the coil component is simple to assemble and disassemble, and the heat generated by energy consumption of an electromagnetic coil and the magnetorheological damper can be uniformly dissipated through the whole outer-layer cylinder barrel component and the coil component, thus the heat dissipation area is large, the temperature of the electromagnetic coil can be obviously reduced, and the service life of the electromagnetic coil can be prolonged.

Self-perception, self-power supply and adaptive control magnetorheological vibration damping system

Abstract: The invention relates to a self-perception, self-power supply and adaptive control magnetorheological vibration damping system, which consists of a dual-extension lever magnetorheological absorber, a vibration energy acquisition device, an energy storage and management module, a status self-perception module and an adaptive control system, wherein the vibration energy acquisition device, the energy storage and management module, the status self-perception module, the adaptive control system and the magnetorheological absorber are integrated; mechanical energy of the system is converted into electric energy by the energy acquisition device; the electric energy is stored and managed by the energy storage and management module so as to supply power to a sensor, a controller and the magnetorheological absorber; the perception of the operating state of the magnetorheological dapmper is realized by the status self-perception module so as to provide decision basis for an adaptive controller;and the adaptive controller regulates the operating damping force of a magnetorheological damper in an adaptive mode according to the operating state of the magnetorheological absorber, so that the adaptive control of the self-perception status and self-supply energy of the magnetorheological absorber is realized, and the application field of the magnetorheological absorber is expanded greatly

Self-adaption piezomagnetic magnetorheological damper

Abstract: The invention belongs to a magnetorheological damper, and particularly relates to a self-adaption piezomagnetic magnetorheological damper. An annular permanent magnet is arranged in the middle section of the inner wall of a main cylinder, and magnetism guiding rings are respectively arranged on the two sides of the annular permanent magnet; a left magnetism guiding block and a right magnetism guiding block are respectively arranged at the left end and the right end of a giant magnetostictive rod; one end of a piston rod of the main cylinder passes through the left end of the main cylinder to be fixedly connected with the left magnetism guiding block, one end of a piston rod of an auxiliary cylinder passes through a spring to be connected with the right wall of the auxiliary cylinder; and magnetorheological fluid is fully filled in the main cylinder, and a magnetorheological fluid flowing channel is reserved between the outer circumferential wall of a piston and the inner circumferential walls of the magnetism guiding rings and the annular permanent magnets. According to the self-adaption piezomagnetic magnetorheological damper, a control power supply does not need to be configured additionally, the structure is simple, the problem of heat generated by a power supply coil can be avoided, and the self-adaption piezomagnetic magnetorheological damper can still work normally when a power supply is in failure caused by the earthquake, so that the safety of the device is improved; and the magnetic sensing strength in a magnetic return path can be changed by utilizing a piezomagnetic effect of the giant magnetostictive rod, the output force of the damper can be adjusted in a self-adaption manner, various sensors are omitted, a time-lag effect is reduced, and the effectiveness of a control system is improved.

Fuzzy PID controller simulation for a quarter-car semi-active suspension system using Magnetorheological damper

Abstract: A quarter-car dynamic system has been modeled using Magnetorheological (MR) damper and a parallel structure of fuzzy PID controller to control the semi-active suspension system. The polynomial model is applied to estimate the behavior of MR damper. The MATLAB software and its Simulink environment are used to simulate the model of the system. The results show the use of fuzzy PID controller has successfully reduced the chassis displacement as the driving comfort objectives than PID controller and improved its robustness.

Supporting device for rotor system of magnetic suspension bearing

Abstract: The invention discloses a supporting device for a rotor system of a magnetic suspension bearing, which comprises a base, a rotor and a magnetic suspension bearing sleeved on the rotor. The magnetic suspension bearing is arranged in a sleeve and a magnetorheological fluid and a work coil which penetrates through the magnetic filed where the magnetorheological fluid is generated are further arranged in the base. The magnetorheological fluid is sealed among the sleeve, the retainer and the inner shell by using a sealing ring. The work coil is arranged in the shell formed by the retainer and the right and the left outer shells. The work coil in the shell is wound on a coil frame, the left outer shell is fixed on the base and the inner shell is fixed on the sleeve. An external cantilever rod is arranged on the left outer shell and an internal cantilever rod is arranged on the right outer shell. The other ends of the external and the internal cantilever rods are connected on a connecting disc, respectively. The rotor system of the magnetic suspension bearing is supported by a magnetorheological damper and inhibition for vibration from the magnetic suspension bearing system is improved by controlling the rigidity and damping of the magnetorheological damper.

Design, Analysis and Performance Evaluation of the Linear, Magnetorheological Damper

Abstract: The paper issues the design and analysis of the linear, magnetorheological damper. Basic information concerning the character- istics of the typical magnetorheological fluid and the damper incorporating it, were presented with the short description of the applied fluid MRF-132 DG. Basing on the computations, the prototype damper T-MR SIMR 132 DG was designed, manufactured, and tested under dif- ferent operating conditions. Presented calculations were verified with the experimental results and their accuracy was evaluated. The con- clusions and observations from the research were compiled in the summary.

Response of Piping System with Semi-active Magnetorheological Damper under Tri-directional Seismic Excitation

Abstract: Seismic loads on piping system due to earthquakes can cause excessive vibrations, which can lead to serious instability resulting in damage or complete failure of piping system. Vibrations in the piping system can be reduced using passive control, active control, semiactive control and hybrid control. In this paper, semi-active magnetorheological (MR) dampers have been studied to mitigate seismic response and vibration control in piping system used in the process industries, fossil and fissile fuel power plant. The performance of MR dampers using various control algorithms is explored. A study is also conducted on the performance of control due to variation in the command voltage of MR dampers. The effectiveness of the MR dampers in terms of the reduction in responses, namely, displacements, accelerations and base shear of the piping system are compared with uncontrolled and passive controlled responses. This study is carried out under four artificial earthquake motions with increasing amplitudes in all the three directions of motion. The analytical results demonstrate that the MR dampers under particular optimum parameters are very effective and practically implementable for the seismic response mitigation, vibration control and seismic requalification of piping system.

Trispectrum and correlation dimension analysis of magnetorheological damper in vibration screen

Abstract: In order to improve the screening efficiency of vibrating screen and make vibration process smooth, a new type of magnetorheological (MR) damper was proposed. The signals of displacement in the vibration process during the test were collected. The trispectrum model of autoregressive (AR) time series was built and the correlation dimension was used to quantify the fractal characteristics during the vibration process. The result shows that, in different working conditions, trispectrum slices are applied to obtaining the information of non-Gaussian, nonlinear amplitude-frequency characteristics of the signal. Besides, there is correlation between the correlation dimension of vibration signal and trispectrum slices, which is very important to select the optimum working parameters of the MR damper and vibrating screen. And in the experimental conditions, it is found that when the working current of MR damper is 2 A and the rotation speed of vibration motor is 800 r/min, the vibration screen reaches its maximum screening efficiency.

Modelling and identification of magnetorheological vehicle suspension

Abstract: The paper presents methods of estimation of vehicle suspension system parameters based on kinetic measurements. The vehicle suspension is assumed to include springs, linear dampers and magnetorheological (MR) dampers which are known to be nonlinear. In many cases hysteresis loop is revealed in the static characteristics of MR dampers. Nonlinear full-car vehicle suspension model is defined and adapted for using linear and nonlinear least-squares identification method. Identifications experiments are performed assuming limited number of available kinetic sensors. Solution space with respect to the location of the vehicle body's gravity center is presented as well as quality index values and time diagrams are reported based on estimated model parameters and simulation results.

Evaluation of Different Control Policies of Semi-Active MR Fluid Damper of a Quarter-Car Model

Abstract: Proportional Integral Derivative and clipped-optimal control strategy controllers are studied to control the response of Quarter-car suspension profile. A Semi-active device is used for this purpose because it carries valuable result which maintains the reliability of passive control methods and includes the advantage of the adjustable parameter characteristics of active systems. Semi-active devices like Magnetorheological fluids dampers are very effective to control vibration, which use MR fluids to produce controllable damping force and provide both the reliability of passive systems and the facility of active control systems with small power supply. The quarter car model is used here can be described as a nonlinear two degrees of freedom system which is subject to excitation from different road profile. For the best possible reduction of vibration in suspension systems, various Magnetorheological damper models are studied which Bouc-wen model, Neuro-fuzzy model and Bingham model. The performances of these models are evaluated to select a best model. The quarter-car model is executed using step input with two most common and effective control algorithm in vehicle suspension control which are linear quadratic regulator control, and Proportional Integral Derivative control algorithm. The main objective of this study is to evaluate performances of these control algorithms.

Modelling and Control of Magnetorheological Damper: Real-time implementation and experimental verification

Abstract: This thesis considers two main issues concerning the application of a rotary type magnetorheological (MR) damper for damping of flexible structures. The first is the modelling and identification of the damper property, while the second is the formulation of effective control strategies. The MR damper is identified by both the standard parametric Bouc-Wen model and the non-parametric neural network model from an experimental data set generated by dynamic tests of the MR damper mounted in a hydraulic testing machine. The forward model represents the direct dynamics of the MR damper where velocity and current are used as input and the force as output. The inverse model represents the inverse dynamics of the MR damper where the absolute velocity and absolute force are used as input and the damper current as output. For the inverse model the current output of the network must always be positive, and it is found that the modelling error of the inverse model is significantly reduced when the corresponding input is given in terms of the absolute values of velocity and damper force. This is a new contribution to the inverse modelling techniques for the control of MR dampers. Another new contribution to the modelling of an MR damper is the use of experimental measurement data of a rotary MR damper that requires appropriate filtering. The semi-systematic optimisation procedure proposed in the thesis derives an effective neural network structure, where only velocity and damper force are essential input parameters for the MR damper modelling. Thus, for proper training, the quality of the velocity data is very important. However, direct velocity measurement is not easy. From the displacement data or the acceleration data, velocity can be determined by using simple differentiation or integration, respectively, but these processes add undesirable noise to the velocity. Instead the Kinematic Kalman Filter (KKF) is an effective means for estimation of velocity. The KKF does not directly depend on the system or structural model, as it is the case for the conventional Kalman filter. The KKF fuses the displacement and the acceleration data to get an accurate and robust estimate of the velocity. The simplicity of the network and the application of velocity in terms of KKF is a novel contribution of the thesis to the generation of a training set for neural network modelling of MR dampers. The development of the control strategies for the MR damper focuses on the introduction of apparent negative stiffness, which basically leads to an increased local motion of the damper and thereby to increased energy dissipation and damping. Optimal viscous damping (VD) is chosen as the benchmark control strategy, used as reference case for assessment of the proposed control methods with negative stiffness. Viscous damping with negative stiffness (VDNS) initially illustrates the effectiveness of the negative stiffness component in structural damping. In a linear control setting negative stiffness requires active control forces, which are not realizable by the purely dissipative MR damper. Thus, these active components are simply clipped in the final control implementation. Since MR dampers behave almost as a friction damper improved damping performance can be obtained by a suitable combination of pure friction and negative damper stiffness. This is realized by amplitude dependent friction damping with negative stiffness (FDNS), where the force level of the friction component is adaptively changed to secure the optimal balance between friction energy dissipation and apparent negative stiffness. This type of control model for semi-active dampers is rate-independent and conveniently described in terms of the desired shape of the associated hysteresis loop or force-displacement trajectory. The final method considered for control of the rotary MR damper is a model reference neural network controller (MRNNC). This novel control approach is designed and trained based on a desired reference damper model, which in this case is the amplitude dependent friction damping with negative stiffness (FDNS). The idea is to train the neural network of the controller by data derived explicitly from the desired shape of the force-displacement loop at pure harmonic motion. In this idealized representation the optimal relations between friction force level, negative stiffness and response amplitude can often be given explicitly by e.g. maximizing the damping ratio of the targeted vibration mode. Consequently the idea behind this trained neural network is that the optimal properties of the desired hysteresis loop formulation can be extrapolated to more general and non-harmonic response patterns, e.g. narrow-band stochastic response due to wind, wave, traffic or even earthquake excitation. Numerical and experimental simulations have been conducted to examine the performance of the proposed control strategies. Force tracking by using an inverse neural network of the MR damper is improved by a low-pass filter to reduce the noise in the desired current and a simple switch that truncates negative values of the desired current. The performance of the collocated control schemes for the rotary type semi-active MR damper are initially verified by closed loop dynamic experiments conducted on a 5-storey shear frame structure exposed to harmonic base excitation. The MR damper is mounted on the structure so that it operates on the relative motion between the ground base and the first floor of the shear frame. The shear frame structural model is initially experimentally identified, where mass and stiffness of the model is determined by an inverse modal analysis based on the natural frequencies obtained experimentally. The damping matrix is subsequently determined from the estimated damping ratio obtained by free decay tests. The results in the thesis demonstrate that introducing apparent negative stiffness to the control of the MR damper significantly decreases both the top floor displacement and acceleration amplitudes of the shear frame structure. The structural damping ratios obtained from the response curves of the experiments correspond well to the expected values. This indicates that the mean stiffness and mean energy dissipation of the control forces are predicted fairly accurate. A final numerical investigation is based on a classic benchmark problem for earthquake protection of a multi storey building. The seismic response of the base-isolated benchmark building with an MR damper installed between the ground and the base is illustrated, and the effectiveness of negative stiffness of the control strategies is verified numerically. Similarly, the response of another wind excited benchmark building installed with MR dampers is demonstrated and the performance shows satisfactory result. The main contributions to this thesis are the novel modelling approach to the direct and the inverse dynamics of a rotary MR damper from experimental data, the development of model based semi-active control strategies for the MR damper, the effective introduction of negative stiffness in the control of semi-active dampers and the demonstration of effectiveness and closed loop implementation of the control techniques on both a shear frame structure and a numerical benchmark problem.

Magnetorheological damper capable of preventing magnetorheological fluid from precipitating

Abstract: The utility model discloses a magnetorheological damper capable of preventing a magnetorheological fluid from depositing, which aims at solving the conventional prominent problem of magnetorheological fluid deposition. The magnetorheological damper comprises a piston rod, a piston, a bearing, a screw propeller, the magnetorheological fluid, a shaft sleeve, a long shaft, a magnetorheological damper sleeve and a base body; a straight rod end of the piston rod penetrates through a through hole in the top of the magnetorheological damper sleeve, and then is fixed on the bearing; the upper end of the shaft sleeve is fixed in the middle of the piston through the bearing, and is level with the upper end of the bearing; the lower end of the bearing is fixedly provided with the screw propeller; one end of the long shaft penetrates through the shaft sleeve and stretches into the piston rod, while the other end of the long shaft is connected with the bottom of the magnetorheological damper sleeve; the long shaft is threaded with the shaft sleeve; and the magnetorheological damper sleeve is fixed on the base body. The magnetorheological damper for preventing the magnetorheological fluid from depositing disclosed by the utility model has the advantages of simple structure, high working efficiency, low power consumption, easy control, etc.

Title: SENSITIVITY OF MAGNETORHEOLOGICAL DAMPER BEHAVIOR TO PERTURBATIONS IN TEMPERATURE VIA BOUC - WEN MODEL

Abstract: In this study, the temperature dependent dynamic behavior of a magnetorheological (MR) damper was characterized. To this end, an MR damper, which was designed and fabricated for a ground vehicle seat suspension application, was tested over temperatures ranging from 0 °C to 100 °C at a constant frequency of 4 Hz and a constant amplitude of 7.62 mm on an MTS-810 material testing system equipped with a temperature-controlled environmental chamber. And, the widely adopted Bouc-Wen model was assessed to characterize the temperature dependency of the MR damper through examining the trends of the model parameters. It was observed that although mBW model could capture the MR damper behavior well, some of the model parameters did not represent the physical realization of the damper based on the physical structure of the model. This is attributed to the fact that mBW has differential terms and thus, an infinite solution space and different combinations of the model parameters may yield similar results. Therefore, it was concluded that mBW model was not successful to model the temperature dependency of MR damper behavior. Full Text: View full text in PDF format (1027KB)

Feasibility study of self-powered magnetorheological damper systems

Abstract: This paper is aimed to provide a feasibility study of self-powered magnetorheological (MR) damper systems, which could convert vibration and shock energy into electrical energy to power itself under control. The self-powered feature could bring merits such as higher reliability, energy saving, and less maintenance for the MR damper systems. A self-powered MR damper system is proposed and modeled. The criterion whether the MR damper system is self-powered or not is proposed. A prototype of MR damper with power generation is designed, fabricated, and tested. The modeling of this damper is experimentally validated. Then the damper is applied to a 2 DOF suspension system under on-off skyhook controller, to obtain the self-powered working range and vibration control performance. Effects of key factors on the self-powered MR damper systems are studied. Design considerations are given in order to increase the self-powered working range.

Self-adaptive magnetorheological clutch

Abstract: The invention discloses a self-adaptive magnetorheological clutch, which consists of an electricity generator and a rotary magnetorheological damper, wherein a rotor winding of the electricity generator and a magnet exciting coil assembly or an electromagnet of the rotary magnetorheological damper are positioned on the same shaft for forming a driving element of the self-adaptive magnetorheological clutch, and the output end of the rotor winding of the electricity generator is directly connected with the magnet exciting coil assembly or an electromagnet coil of the rotary magnetorheological damper, or is connected with the magnet exciting coil assembly or the electromagnet coil of the rotary magnetorheological damper through a rectifying control circuit, so the electric power output by the electricity generator can be directly output to the magnet exciting coil assembly or the electromagnet coil of the rotary magnetorheological damper to generate an electromagnetic field, the electromagnetic field improves the viscosity of the magnetorheological fluid or the magnetorheological grease in the rotary magnetorheological damper, the damping force during the generation of the relative rotation of the driving element and a driven element in the self-adaptive magnetorheological clutch is increased, and the driving element and the driven element of the self-adaptive magnetorheological clutch is increased for completing the coupling to realize the torque transmission.

An iterative based approach for hysteresis parameters estimation in Magnetorheological dampers

Abstract: The following work entails the problem of regenerating the hysteresis loop in the Magnetorheological (MR) dampers. The collected data from tests are not sufficient neither efficient for designing optimal controls compensating for the hysteresis in the dampers. This work presents an iterative based approach for estimating the hysteresis parameters, the method however can be generalized for different kind of dampers or actuators hence the hysteresis loop can be generalized using available test data. Some assumptions can be introduced in order to facilitate the underlines of the parameters estimation, one of the assumptions in this work is to use predetermined hysteresis parameters and regenerate the actual data using continuous state space model (SSM). The SSM can be based on verified models like Bouc-Wen, Lugre or Dahl models. In this work, Bouc-Wen model is used to generate the actual hysteresis data. The core of this work is to use the iterative approach based on Particle Swarm Optimization (PSO). The PSO algorithm is used along with other algorithms like the Root Mean Square (RMS) error which is used to evaluate the convergence of the results at each of the iterations for a defined number of iterations. The trade-off relation is the basis of evaluation when using the PSO based algorithm, dependency on initial guessing, number of iterations and desired estimation accuracy. However, the PSO algorithm tend to estimate the hysteresis parameters close enough to generate the actual hysteresis enabling a ground to develop similar algorithms for different kind of actuators or dampers.

Design of semi active knee joint with magnetorheological (MR) damper

Abstract: In this study, electronic above knee prosthesis using magnetorheological (MR) cylinder is developed. The prosthesis structure having a proper knee mechanism is used for MR cylinder damping produced for experimental studies. Movement of knee joint originated from hip is damped with these cylinders and through a control algorithm running on microcontroller the system achieves the motion closer to the natural movement of leg. The performance of MR cylinder in the prosthesis are examined while a healthy subject wearing a custom designed socket mounted to prosthesis walks interchangeably at predetermined speed. According to the results obtained by the image based Motion Analysis System (MAS) the walk with the prosthesis using the MR damper is closer to the natural gait in terms of gait cycle duration and phases. On the other hand, in terms of the required maximum knee angle, the prosthesis with pneumatic damper performs better when the natural gait cycle is considered.

Device for testing indicator characteristic of magnetorheological damper

Abstract: The invention discloses a device for testing the indicator characteristic of a magnetorheological damper. The device comprises a mechanical rack, a cam excitation unit, a magnetorheological damper power supply system and a sensor testing system. The testing device has a simple integral electromechanical structure, particularly a cam transmission mechanism is a combined integral flat-bottomed transmission mechanism, and compared with a rectangular frame structure in the traditional constant-breadth cam mechanism, the structure has the advantages that the device is convenient to assemble and disassemble and easy to process and manufacture; the cost of a variable frequency speed regulation system which is the common three-phase asynchronous motor is lower than that of a variable frequency speed regulation motor; and the device can test the indicator characteristic and speed characteristic of the magnetorheological damper, has stable and reliable working performance, and is simple and practical.

Regular paper H∞ Control of a Suspension with a Magnetorheological Damper

Abstract: This research work presents an H∞ controller based on a Takagi-Sugeno (T-S) fuzzy model for a two-degrees-of-freedom (2DOF) one-quarter-vehicle semi-active suspension with an MR damper where the actuator dynamics are included in the control synthesis. These dynamics enclose nonlinear damper phenomena, avoided in many other studies, and that can improve the suspension system by means of a more accurate model. The objective is to obtain a semi-active suspension that considerab ly improves the passive suspension effi ciency based on some frequency domain performance criteria. The advantage of having the T-S system as a reference is that each piecewise linear system can be exposed to the well-known control theory. Besides, the proposed solution is compared with recent reported work to highlight its advantages. A case of study is included and simulation work supports the results. The methodology applied herein can be extended to a half-vehicle model, and to the four wheels to have a global chassis control in order to maximize passenger comfort and vehicle stability.

A Hybrid Control of Seismic Response by Passive and Semi-active Control Strategies

Abstract: Passive and semi-active control devices are widely utilized as supplemental damping strategies for response reduction in civil engineering structures subjected to strong earthquakes and severe winds. Passive control devices require no external power supply. Total during an earthquake. Active control strategies, on the other hand, are generally more effective, but they are disadvantageous as energy cannot increase, therefore the system stays stable. But passive controllers are not as effective as semi-active, active, or hybrid ones. Semi-active control devices' input power requirements are less than active devices. This fact makes semi-active controllers useful in case of a power cut they need large amounts of power while they are in action, and they may result in instabilities of the controlled structure. A hybrid control which consists of passive and semi-active controller is studied in order to benefit from advantages of both strategies and to compensate their weak properties. In the current study, a passive base isolator and a semi-active magnetorheological damper are applied to a three-story frame structure. The benefits of hybrid application of two control systems are revealed.

Double-rod shear-valve type magnetorheological damper with adjustable damping forces

Abstract: The utility model discloses a double-rod shear-valve type magnetorheological damper with adjustable damping forces. The magnetorheological damper comprises a double-rod hydraulic cylinder, a sleeve and connection heads, the inner cavity of the double-rod hydraulic cylinder is provided with magnetorheological fluids, the double-rod hydraulic cylinder comprises a cylinder body, a piston arranged inside the cylinder body and piston rods which are arranged on two sides of the piston, end covers are arranged on the cylinder body, the piston rods penetrate through the end covers to extend out of the cylinder body, and the two end covers are installed at two ends of the cylinder body respectively; a field coil is wound in the middle of the piston, and a gap is arranged between the piston and the inner wall of the cylinder body and used for the magnetorheological fluids to flow between two cavities; and one end of the double-rod hydraulic cylinder is provided with the sleeve, an output end of one piston rod is disposed in the sleeve, one connection head is arranged at one end of the sleeve, the end of the sleeve is far away from the hydraulic cylinder, simultaneously, one end of the other piston rod is provided with one connection head, and the end of the other piston rod is far away from the sleeve. Compared with magnetorheological dampers in prior art, the magnetorheological damper has the advantages of being simple in structure and good in manufacturability and sealing property.