Magnetorheological Semi-active Suspension Research Articles

Hybrid controller of magnetorheological semi-active seat suspension system for both shock and vibration mitigation

The impact caused by the detonation of landmines and improvised explosive devices may directly lead to spine fracture and injury of seated occupants on special vehicles. The vibration transmitted f...

MR-SAS variable universe fuzzy control in steering situation based on wheelbase preview

In order to make the vehicle meet the requirements of complex conditions, the dynamic model of 1/2 vehicle magneto-rheological (MR) semi-active suspension (SAS) based on wheelbase preview in steering situation was established, and the variable universe adaptive fuzzy controller based on fuzzy neural network (FNN) was designed. The universe size of the system fuzzy controller can be adjusted automatically by FNN controller according to system deviation, avoided subjectivity of universe division, improved the fuzzy control accuracy. The damping of MR damper can be adjusted by controlling the current size, so the vehicle will remain the ride comfort and safety in steering situation, and the vehicle dynamic performance can be improved. Through the comparison of simulation, the vehicle performance of variable universe FNN control system based on wheelbase preview were superior to passive system and fuzzy control system and without preview system in the same situation.

Minimal Control Synthesis-Skyhook Mixed Control for Magneto-Rheological Semi-Active Suspension

Standard skyhook control algorithm is inefficient in controlling of the parameter-varying magneto-rheological semi-active suspension system. Based on model reference adaptive control theory, a minimal control synthesis-skyhook (MCS-SH) mixed control algorithm was designed. Ideal skyhook control was taken as the reference model; the feedback control law of MCS algorithm was improved based on the feature of magneto-rheological damper (MRD). The results illustrate that the sprung mass acceleration and suspension deflection are decreased through MCS-SH algorithm, the ride comfort of vehicles can be improved significantly, and the MCS-SH algorithm can adapt to the variation of suspension parameters.

Computer Simulation on Fuzzy Control of Semi-active Suspension System Based on the Whole Vehicle

With the development of technology, new materials have been invented, which have been applied to improve the performance of structures. Recently, researchers pay their attention to controllable fluids and its applications. Magneto rheological (MR) damper is a kind of devices that uses rheological fluids to modify their mechanical properties. Their mechanical simplicity, large dynamic range, low power requirements, large force capacity, robustness and safe manner operation in case of failure have made them attractive devices to semi-active control in civil, aerospace and automotive fields. The characteristics of the MR damper will change when the rheological fluid is exposed to a magnetic field changing its stiffness and damping coefficients. In this paper, the mathematical models of a seven-degree-of-freedom suspension system based on the whole vehicle are established and the fuzzy controller of vehicle semi-active suspension system is designed. Using Matlab/Simulink software package, the simulation results show that the performance of MR semi-active suspension system with fuzzy controller is better than that of passive suspension system. It is a successful reference for the application of MR semi-active suspension in the vehicle.

Skyhook-based semi-active control of full-vehicle suspension with magneto-rheological dampers

The control study of vehicle semi-active suspension with magneto-rheological (MR) dampers has been attracted much attention internationally. However, a simple, real time and easy implementing semi-active controller has not been proposed for the MR full-vehicle suspension system, and a systematic analysis method has not been established for evaluating the multi-objective suspension performances of MR full-vehicle vertical, pitch and roll motions. For this purpose, according to the 7-degree of freedom (DOF) full-vehicle dynamic system, a generalized 7-DOF MR and passive full-vehicle dynamic model is set up by employing the modified Bouc-wen hysteretic force-velocity (F-v) model of the MR damper. A semi-active controller is synthesized to realize independent control of the four MR quarter-vehicle sub-suspension systems in the full-vehicle, which is on the basis of the proposed modified skyhook damping scheme of MR quarter-vehicle sub-suspension system. The proposed controller can greatly simplify the controller design complexity of MR full-vehicle suspension and has merits of easy implementation in real application, wherein only absolute velocities of sprung and unsprung masses with reference to the road surface are required to measure in real time when the vehicle is moving. Furthermore, a systematic analysis method is established for evaluating the vertical, pitch and roll motion properties of both MR and passive full-vehicle suspensions in a more realistic road excitation manner, in which the harmonic, rounded pulse and real road measured random signals with delay time are employed as different road excitations inserted on the front and rear two wheels, by considering the distance between front and rear wheels in full-vehicle. The above excitations with different amplitudes are further employed as the road excitations inserted on left and right two wheels for evaluating the roll motion property. The multi-objective suspension performances of ride comfort and handling safety of the proposed MR full-vehicle suspension are thus thoroughly evaluated by comparing with those of the passive full-vehicle suspension. The results show that the proposed controller can ideally improve multi-objective suspension performances of the ride comfort and handling safety. The proposed harmonic, rounded pulse and real road measured random signals with delay time and asymmetric amplitudes are suitable for accurately analyzing the vertical, pitch and roll motion properties of MR full-vehicle suspension system in a more realistic road excitation manner. This research has important theoretical significance for improving application study on the intelligent MR semi-active suspension.

Control system with magnetorheological fluid device for mitigation of the railway vehicle hunting oscillations

The paper presents the opportunity of using a magnetorheological device to control the lateral oscillations of a passenger railway vehicle to increase its comfort and speed features. High speed generates large amplitude oscillations in horizontal plan at the axles, bogies and carbody levels which beyond a specific value – the critical speed – leads to unstable movement of the vehicle. The lateral dynamics of the vehicle is simulated using the multibody method. It is build a model with 17 degrees of freedom considering the lateral, yawing and rolling oscillations. An original device with magnetorheological fluid based on the balance logic strategy to control the anti-yaw damper is integrated in the secondary suspension of the railway vehicle. The conception and the design of the magnetorheological device are presented. It is demonstrated that the magnetorheological semi-active suspension improves the safety and the comfort of the railway vehicle.

Delay-dependent H2/H∞ Control for Vehicle Magneto-rheological Semi-active Suspension

The exist researches of the magneto-rheological semi-active suspension(MSAS) control mainly focus on the design of control laws,which aim at obtaining an optimal control strategy to improve the ride comfort and handling stability.In the controller design,the stability of the MSAS system cannot be confirmed owing to the control input time delay considered little.In this paper,a quarter vehicle MSAS model with time-delay is built.Therefore,through formulating the sprung mass acceleration suitably as the optimization object,suspension deflection and tyre dynamic load and coulomb damping force as the constraint objects,with considering the control input time-delay,a delay-dependent state feedback H2/H∞ controller is designed.According to Lyapunov-Krasovskii functional theory,the sufficient conditions for asymptotic stability and the existence of delay-dependent H2/H∞ controller are obtained,and the controller design is transformed into the minimization problem for linear function through linear matrix inequality(LMI).Random road excitation simulations and experiments are carried out.The simulation and experiment results show that the design can preserve the closed-loop stability and achieve the performances for MSAS system in spite of the existence of the control input time-delay.The present study can provide an important basis and method for research on time-delay problem in MSAS and other chassis subsystems..

Modelling of magnetorheological semi-active suspension system controlled by semi-active damping force estimator

This paper presents the simulation study of magnetorheological semi-active suspension system controlled by a new proposed algorithm. The control algorithm named as Semi-Active Damping Force Estimator (SADE) is proposed to control the operations of the magnetorheological damper. The simulation of semi-active suspension system was done by considering actual dynamics behaviour of a custom-made magnetorheological damper, where its characteristic testing and modelling are described. The performance of magnetorheological semi-active car suspension system controlled by SADE in term of ride comfort is evaluated in comparison with normal suspension system. The performance of SADE semi-active suspension system is also compared with the skyhook-controlled semi-active suspension system performance. It is shown that magnetorheological semi-active suspension system controlled by SADE is able to improve vehicle's ride comfort significantly compared to passive suspension system. The SADE-controlled semi-active suspension system performs more or less the same as skyhook-controlled semi-active suspension system.

Fuzzy semi-active damping force estimator (fSADE) and skyhook semi-active suspension systems

This paper presents the comparative study on semi-active suspension controlled by skyhook algorithm and fuzzy semi-active damping force estimator (fSADE). The damping element used in the semi-active suspension is non-pressurised magnetorheological (MR) damper. The performance of magnetorheological semi-active suspension system controlled by fSADE in terms of ride comfort is evaluated in comparison with normal suspension system and skyhook semi-active suspension system. The study is also focusing on the effects of the number of fuzzy rules used in fSADE algorithm performance. Other aspects studied are the current consumption used by the MR damper as well as the damper’s ability to execute the damping forces as estimated by the controllers. The vehicle ride comforts are evaluated based on the vehicle’s vertical motions (jerk, acceleration, displacement) and pitch motions (pitch rate and pitch angle). It is shown that magnetorheological semi-active suspension system controlled by fSADE is able to improve vehicle’s ride comfort significantly compared to passive suspension and was better than the skyhook semi-active suspension system in terms of power consumption. It was also shown that the number of fuzzy rules used did affect the overall performance of the fSADE algorithm in semi-active suspension system.

Fuzzy Hybrid Control of Vibration Attitude of Full Car via Magneto-rheological Suspensions

A magneto-rheological(MR) semi-active suspension system with the controllable damping forces has received more attention in reducing the vibration of a vehicle. However, many control strategies only discussed one or two vibration states of the vehicle based on a quarter-car model or a half vehicle model via MR suspensions. They cannot provide a satisfying whole-vehicle performance on a road test. Hence, a full car vibration model via an MR suspension system is proposed. To reduce the heave, pitch and roll motion of the vehicle body and the vertical vibration of four wheels, a fuzzy hybrid controller for vibration attitude of full car via MR suspensions is proposed. First, a skyhook-fuzzy control scheme is designed to reduce the heave, roll and pitch motion of the vehicle body. Second, a revised ground hook control strategy is adopted to decrease the vertical vibration of the wheels. Finally, a hybrid control scheme based on a fuzzy reasoning method is proposed to tune the hybrid damping parameter, which is suitable for coordination the attitude of the vehicle body and the wheels. A test and control system for the vibration attitude of full car is set up. It is implemented on a car equipped with four MR suspensions. The results on random highway and rough road indicate that the fuzzy hybrid controller can decrease the vibration accelerations of the vehicle body and the wheels to 65%–80% and 80%–90%, respectively. It reduces the automotive vibrations of heave, roll and pitch more effectively than a passive suspension and an MR suspension with a traditional hybrid control scheme so that it achieves better ride comfort and road holding concurrently. This paper proposes a new fuzzy hybrid control(FHC) method for reducing vibration attitude of full car via MR suspensions and develops a road test to evaluate the FHC.

Time Lag of Magnetorheological Damper Semi-active Suspensions

Time delay causes unsynchronized controllable damping force of magnetorheological damper, which degrades the performance and stability of vehicle semi-active suspension, therefore time-delay problem is one of the hot spots of research on semi-active suspension. Based on the response characteristics of RD-1005-3 magnetorheological damper and the theoretical analysis of critical time delay of semi-active suspension, the mathematical model and the transfer function of magnetorheological semi-active suspension with time delay are established, and the effect of time delay on the amplitude frequency characteristics of suspension is analyzed. Through analyzing the numerical solution of critical time delay, theoretical basis is provided for the research on time-delay of control system of magnetorheological semi-active suspension. Based on fuzzy control strategy, Smith forecasting compensation control is used to carry out compensation of time delay for the system, and simulation analysis is carried out in Matlab. Bench test is carried out for the built single mass magnetorheological semi-active suspension system, and the data of simulation and test show that the time delay compensated system improves the performance of suspensions well.

Study on MR Semi-active Suspension System and its Road Testing

A magnetorheological (MR) damper model is established and linearized based on theory analyses and real testing. Since the mathematical model of the suspension system is nonlinear and complicated, a model-free fuzzy control algorithm is employed to design a controller for achieving vibration isolation. As a pilot study, two MR dampers are used to replace the passive ones of the front half-car. A quarter-car fuzzy intelligent controller is employed to control the two MR independent suspension systems, respectively. The performance of the MR suspension system is evaluated by road testing. The test results indicate that the vibration of the vehicle body and unsprung mass are both reduced significantly.