Pakharuddin Mohd. Samin

Effects of control techniques and damper constraint on the performance of a semi-active magnetorheological damper

Semi-active dampers change their damping force in real time by simply changing the damping coefficient according to a control policy. In this study, a number of semi-active control algorithms namely modified skyhook, modified groundhook and modified hybrid skyhook-groundhook controllers are evaluated to be used with a magnetorheological damper. The effectiveness of these control algorithms in disturbance rejection are investigated along with their ability to consistently provide the target force in the same direction with the damper velocity to overcome the damper constraint. From the simulation and experimental results, the modified hybrid skyhook-groundhook controller shows significant improvement in body acceleration, body displacement, suspension displacement without allowing excessive wheel acceleration magnitude. The modified hybrid skyhook-groundhook controller is also superior to the counterparts in overcoming the damper constraint by producing the target forces consistently in the same sign with the damper velocity.

Disturbance rejection control of a light armoured vehicle using stability augmentation based active suspension system

This paper introduces the mathematical model of 12 Degrees of Freedom (DOF) light armoured vehicle, which consists of eight DOF in vertical motion of eight tyres, three DOF in vertical, roll and pitch motions of vehicle body and one DOF in angular motion of gun turret relative to weapon platform. Two sources of disturbance considered in this study are road irregularities and reaction force at the weapon platform. The results of the study show that the stability augmentation based active suspension system is able to significantly improve the dynamic performance of the light armoured vehicle compared with the passive system.

Vehicle ride performance with semi-active suspension system using modified skyhook algorithm and current generator model

This paper presents the simulation of a semi-active suspension system by using designed parameter model of magnetorheological (MR) damper. The design is based on the performance of the original equipment shock absorber of a passenger vehicle. A 7DOF of vehicle ride model was developed and validated in order to study the performance of a passive suspension system and the designed semi active suspension system. A controller known as modified skyhook algorithm and current generator model was used in the semi-active suspension system. The simulation results show that the semi active suspension system give significant improvement on vehicles ride comfort.

Synthesis, characterization and magnetorheological properties of carbonyl iron suspension with superparamagnetic nanoparticles as an additive

Magnetorheological (MR) fluids are suspensions of micron-sized particles dispersed in carrier fluid. Due to high density magnetic particles, MR fluids are facing the problem with the instability of the suspension caused by high settling rate. Recently, researches have been conducted on the advantages of using the mixture of magnetic nanoparticles and microparticles, called bidisperse MR fluids. However, even though the sedimentation stability is improved, there is a reduction in dynamic yield stress when the nanoparticle is introduced. In this work, the investigation of magnetic iron nanoparticles (γ-Fe2O3) as an additive to magnetic carbonyl iron (CI) suspension has been proposed so as to improve the sedimentation stability and redispersibility, but at the same time enhance the MR performance. The results indicated that the addition of nanoparticles reduced the sedimentation rate, improved redispersibility and enhanced the rheological performance of MR fluids as the particle fill the voids between the microparticles and strengthened the interparticle chains contributing to well-arranged particle structures

Semi-active suspension control to improve ride and handling using magnetorheological (MR) damper

This paper presents the simulation study of a semi-active suspension system using non-parametric model of magnetorheological (MR) damper. Hybrid stability augmentation-force control (HSAS-FC) is proposed as the control algorithm. The performance of the proposed control algorithm is analysed using validated full vehicle model and compared with modified hybrid skyhook groundhook control and passive system. The HSAS-FC is used to estimate the desired force needed to simultaneously improve ride dynamics and handling performance. The stability augmentation system (SAS) is to improve ride, meanwhile the force control (FC) is used to control roll rate and pitch rate due to lateral load transfer and longitudinal load transfer. An adaptive inverse current model was developed to produce the required current by the MR damper. The results show the new system is effective in isolating vehicle body from unwanted motions at the body centre of gravity. The amplitude and settling time of unwanted body motions are reduce for ride.

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 vehicles 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.

Semi active suspension system performance under random road profile excitations

This paper presents an investigation on the performance of algorithms in semi active suspension system. A validated full car model was used for this purpose. The semi active suspension system is using the magnetorheological (MR) damper as its variable damping damper element. The Skyhook and Modified Skyhook algorithms are used to control the operation of the MR damper model in the semi active suspension systems of a full car model. The parameters of the algorithms were optimized to ensure the highest degree of ride comfort performance of the full car model based on a criteria. The models jerk, vertical acceleration, vertical displacement, roll rate, roll angle, pitch rate and pitch angle are investigated in this paper in terms of root-mean-square (RMS) values and time domain results. It was found out the overall performance of skyhook-controlled system is slightly better than the modified skyhook-controlled system by 3.2 percent due to good algorithm performance in improving pitch motions of the vehicle. The modified skyhook algorithm is better in improving vehicle vertical motions and roll motions compared to the Skyhook system.

Tyre Force control strategy for semi-active magnetorheological damper suspension system for light-heavy duty truck

A semi-active controller scheme for magnetorheological (MR) damper of a light-heavy vehicle suspension known as Tyre Force Control (TFC) is proposed. The effectiveness of the proposed TFC algorithm is compared with Groundhook (GRD) control. A simulation model was developed and simulated using MATLAB Simulink software. The performance of the semi-active MR damper using TFC is analytically studied. Ride test was conducted at three different speeds and two different bumps, and the simulation results of TFC and GRD are compared and analysed. The results showed that the proposed controller is able to reduce tyre force significantly compared to GRD control strategy.

Ground Semi Active Damping Force Estimator (gSADE) for Magnetorheological Damper Suspension System Using Quarter Heavy Vehicle Model

This paper proposed semi active controller scheme for magnetorheological (MR) damper of a heavy vehicle suspension known as Ground Semi Active Damping Force Estimator (gSADE), where it was modified from Semi Active Damping Force Estimator (SADE) algorithm. A reported algorithm known as Groundhook (GRD) was developed where its aim to minimize tire road forces and hence reduce road damage. Thus, the objective of this paper is to investigate the effectiveness of the proposed gSADE algorithm compared to GRD and SADE. These algorithms are applied to a quarter heavy vehicle models and the simulation model was developed and simulated using MATLAB Simulink software. Ride test was conducted at three different speeds and three bump heights, and the simulation results of gSADE, SADE and GRD are compared and analysed. The results showed that the proposed controller is able to reduced tire force significantly compared to GRD control strategy.

Modelling and validation of vehicle ride comfort model

This paper presents the development of a validated seven degrees of freedom (7DOF) of vehicle ride comfort model for a Malaysian made passenger vehicle. The mathematical equations of the ride model, which consists seven degrees of freedom, are represented. Ride test known as pitch mode test was conducted to validate the reliability of the developed simulation model. The test was conducted using a fully instrumented test vehicle where the sensors installed were used to gather information on vehicle’s vertical and pitch motions. The data collected are used to tune certain parameters value in the simulation model, to ensure the developed simulation model can be used to represent the ride dynamics behaviour of the test vehicle. The result shows that the developed simulation model is capable in representing the ride dynamics behaviour of the test vehicle.