• 한국자동차공학회논문집
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• 제7권8호
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• pp.190-198
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• 1999

Continuously controlled semi-active suspension system may improve ride and handling properties. Here, as a mechanism to control the fluid flow solenoid valve mechanism is introduced and added to the basic passive damper to create damping forces of the shock absorbers. The system may produce continuously controlled damping forces in both solenoid valve only and combination with passive shock absorber including fluid flow is studied, and then the combined model is added to the full vehicle model to evaluate its ride and handling performance. Finally, the simulation results are compared to the vehicle models having similar suspension system.

• 제어로봇시스템학회:학술대회논문집
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• 제어로봇시스템학회 2001년도 ICCAS
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• pp.47.5-47
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• 2001

In this paper. a road-adaptive LQG control for the semiactive Macpherson strut suspension system of hydraulic type is investigated. A new control oriented model, which incorporates the rotational motion of the unsprung mass, is introduced. A semi-active suspension controller adapting to road variations is proposed. First, based on the extended least squares estimation algorithm, a LQG controller adapting to the estimated road characteristics is designed. Through the computer simulations, the performance of the proposed semi-active suspension is compared with that of a non-adaptive one. The results show better control performance of the proposed system over the compared one.

• 대한기계학회논문집A
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• 제21권12호
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• pp.2179-2186
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• 1997

In this paper, the performance of a semi-active suspension system for a passenger car has been investigated. Alternative semi-active suspensions control laws has been compared via simulations. The control laws investigated in this study are : sprung mass velocity feedback control law, sky-hook damping control law, and state feedback control law. Simulation results show that a semi-active suspension has potential to improve ride quality of automobiles.

• 대한기계학회논문집A
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• 제21권12호
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• pp.2187-2195
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• 1997

A semi-active suspension test system was designed and built for the experimental study. Vehicle parameters were estimated through tests and a quarter-car model was validated by comparing computer simulation results and laboratory test results. Alternative semi-active suspension control laws have been tested using the test system. Modulable damper used in this study is a "reverse" damper with 42 states which is controlled by a stepper motor. Experimental results have shown that semi-active suspensions have potential to improve ride quality of automobiles.tomobiles.

• Coupled systems mechanics
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• 제7권6호
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• pp.707-729
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• 2018

The semi-active optimal vibration control of nonlinear torsion-bar suspension vehicle systems under random road excitations is an important research subject, and the boundedness of MR dampers and the uncertainty of vehicle systems are necessary to consider. In this paper, the differential equations of motion of the coupling torsion-bar suspension vehicle system with MR damper under random road excitation are derived and then transformed into strongly nonlinear stochastic coupling vibration equations. The dynamical programming equation is derived based on the stochastic dynamical programming principle firstly for the nonlinear stochastic system. The semi-active bounded parametric optimal control law is determined by the programming equation and MR damper dynamics. Then for the uncertain nonlinear stochastic system, the minimax dynamical programming equation is derived based on the minimax stochastic dynamical programming principle. The worst-case disturbances and corresponding semi-active bounded parametric optimal control are obtained from the programming equation under the bounded disturbance constraints and MR damper dynamics. The control strategy for the nonlinear stochastic vibration of the uncertain torsion-bar suspension vehicle system is developed. The good effectiveness of the proposed control is illustrated with numerical results. The control performances for the vehicle system with different bounds of MR damper under different vehicle speeds and random road excitations are discussed.

• 한국자동차공학회논문집
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• 제23권1호
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• pp.11-17
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• 2015

Recently, the in-wheel motor vehicle is rapidly developed to solve energy exhaustion and environmental problems. Especially, it has the advantage of independently driving the torque control of each wheel in the vehicle. However, due to the weight increase of wheel, the comfort of vehicle riding and performance of road holding become worse. In this paper, to compensate the poor performance, a simultaneous control of the driving torque and semi-active suspension system is investigated. A vehicle model is generated using CarSim Software and validated by field tests. Co-simulation of CarSim and MATLAB/Simulink with control logics is carried out, and it is found that simultaneous control of the driving torque and semi-active suspension system can improve driving stability and durability of the in-wheel motor system.

• 한국생산제조학회지
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• 제21권4호
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• pp.683-690
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• 2012

In this work, the semi-active control of a large-sized bus suspension system with an MR damper was studied. An MR damper model that can aptly describe the hysteretic characteristics of an MR damper was adopted. Parameter values of the MR damper model were suitably modified by considering the maximum damping force of a passive damper used in the suspension system of a real large-sized bus. In addition, a fuzzy logic controller was developed for semi-active control of a suspension system with an MR damper. The vertical acceleration at the attachment point of the MR damper and the relative velocity between sprung and unsprung masses were used as input variables, while voltage was used as the output variable. Straight-ahead driving simulations were performed on a road with a random road profile and on a flat road with a bump. In straight-ahead driving simulations, the vertical acceleration and pitch angle were measured to compare the riding performance of a suspension system with a passive damper with that of a suspension with an MR damper. In addition, a single lane change simulation was performed. In the simulation, the lateral acceleration and roll angle were measured in order to compare the handling performance of a suspension system using a passive damper with that of a suspension system using an MR damper.

• 제어로봇시스템학회논문지
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• 제8권3호
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• pp.199-207
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• 2002

In this paper, a self-tuning gain-scheduled skyhook control for semi-active suspension systems is investigated. The dynamic characteristics of a continuously variable damper including electro-hydraulic pressure control valves is analyzed. A 2-d.o.f. time-varying quarter-car model that permits variations in sprung mass and suspension spring coefficient is considered. The self-tuning skyhook control algorithm proposed in this paper requires only the measurement of body acceleration. The absolute velocity of the sprung mass and the relative velocity of the suspension deflection are estimated by using integral filters. The skyhook gains are gain-scheduled in such a way that the body acceleration and the dynamic tire force are optimized. An ECU prototype is discussed. Experimental results using a 1/4-ear simulator are discussed. Also, a suspension ECU prototype targeting real implementation is provided.

• 한국생산제조학회지
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• 제9권4호
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• pp.85-90
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• 2000

In this paper, a robust $H_{\infty}$ a controller for semi-active suspension system is proposed. For the improvement of ride quality, the robust $H_{\infty}$ controller is designed to satisfy robust stability and road disturbance attenuation using an $H_{\infty}$ control design procedure. The performances of the design controller for some road conditions are evaluated by computer simulation and finally these simulation results show the usefulness and applicability of the proposed robust $H_{\infty}$ controller.

• 한국정밀공학회지
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• 제20권7호
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• pp.128-137
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• 2003

Continuously variable damper can yield diverse damping forces for a single damping velocity. It is widely used in the semi-active suspension system since, with right control logics, it can enhance ride comfort compared to the passive damper while not degrading driving safety. A key to the successful design of the continuously variable damper is the knowledge of its complex and nonlinear characteristics. In this paper, research has been done for analyzing characteristics of the continuously variable damper. Various damper components have been investigated and their effects upon the force-velocity characteristics of the damper have been examined. The effects of the damper characteristics change upon ride comfort and driving safety have also been investigated by numerical simulations.