• Journal of Institute of Control, Robotics and Systems
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• v.22 no.12
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• pp.995-1001
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• 2016

The vehicle suspension system plays a very important part related with vehicle ride and handling. To improve the vehicle ride and handling many researches have been progressed from various damping parameter tuning techniques to the development of the electronic controlled suspension systems. In this paper, as one of the ride performance improvement a disturbance observer(DOB) based control system is applied to the quarter car vehicle model in order to show that the DOB can obtain good vibration isolation characteristics. First, the robust stability criterion for the DOB is introduced in detail, and then how DOB is applied to the 1/4 car vehicle model is represented, and finally to confirm the effectiveness of the DOB in vehicle ride performance improvement a computer simulation is carried out for various driving conditions.

• Transactions of the Korean Society of Mechanical Engineers A
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• v.40 no.3
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• pp.317-326
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• 2016

In this study, running stability and ride quality analyses, applying the 'ISO 3888 (double lane change)' and 'ISO 2631-1' (mechanical vibration and shock) tests, were performed for the suspension optimization of the Korean personal rapid transit (PRT) vehicle. The suspension optimization results for running stability and ride quality were derived by applying the multiresponse surface method. From the comparisons of the optimization results for different ratios of the objective functions of running stability and ride quality, we derived the best objective function ratio of 3.9-to-6.1 to improve both the running stability and the ride quality. With the optimized results, the suspension stiffness became 30.68 N/mm, between the value of the $S_2$ and $S_3$ models, and the damping coefficient equaled that of the $D_1$ model. When compared with the suspension of the current PRT vehicle, the roll angle, yaw rate, sideslip angle, and ride comfort were improved by 0.37, 0.37, 2.8, and 5, respectively.

• Journal of the Korean Society for Precision Engineering
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• v.20 no.7
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• pp.201-207
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• 2003

Sensitivity analysis of suspension elements of an articulated bogie for light railway vehicles is presented. The ride, stability and safety are used as dynamic performance indices. Suspension elements of 10 and a conicity of wheel are used as design variables. To analyze sensitivity of design variables. the railway vehicle dynamics analysis program AGEM is used. The results show that the secondary suspension elements have a strong effect on ride and the primary suspension elements have a moderate effect on ride. Conicity of wheel has a strong effect on the stability. The safety is not effected by all the design variables.

• Journal of KSNVE
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• v.3 no.4
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• pp.383-394
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• 1993

An automotive suspension system generally behaves like a low frequency band-pass filter(0.5 - 10 Hz). Passengers are very sensitive to this frequency range in terms of ride quality and road holding ability. In this paper, a LQG/ LTR controller is suggested to improve the ride quality and road holding ability in the specified frequency rage. It has been found by numerical simulation that the ride quality and road holding ability can be improved in the frequency ranges of 0.5 - 3.0 Hz and 0.3 - 2.1 Hz respectively. In addition, a new approach using root locus to evaluate the stability robustness of the active suspension system is studied. It is shown that the stability robustness of the LQG/LTR controller designed in this paper is improved, compared to the passive system.

• Proceedings of the KSR Conference
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• 1998.11a
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• pp.421-428
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• 1998

Sensitivity analysis of suspension elements of an articulated bogie for light railway vehicles is presented. The ride, stability and safety are used as dynamic performance index. Suspension elements of 10 and a conicity of wheel are used as design variables, To analyze sensitivity of design variables, the railway vehicle dynamics analysis program AGEM is used. The results shows that the secondary suspension elements have a strong effect on ride and the primary suspension elements have a moderate effect on ride. Conicity of wheel has a strong effect on the stability, The safety is not effected by all the design variables.

• Journal of the Korean Society for Precision Engineering
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• v.28 no.1
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• pp.31-39
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• 2011

This paper presents design and control of a quarter-vehicle magneto-rheological (MR) suspension system for ECS (electronic control suspension). In order to achieve this goal, MR shock absorber is designed and manufactured based on the optimized damping force levels and mechanical dimensions required for a commercial mid-sized passenger vehicle. After experimentally evaluating dynamic characteristics of the manufactured MR shock absorber, the quarter-vehicle MR suspension system consisting of sprung mass, spring, tire and the MR shock absorber is constructed in order to investigate the ride comfort and driving stability. After deriving the equations of the motion for the proposed quarter-vehicle MR suspension system, the skyhook controller is then implemented for the realization of quarter-vehicle MR suspension system. In order to present control performance of MR shock absorber for ECS, ride comfort and driving stability characteristics such as vertical acceleration of sprung mass and tire deflection are experimentally evaluated under various road conditions and presented in both time and frequency domain.

• Journal of the Korean Society of Manufacturing Process Engineers
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• v.15 no.2
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• pp.57-65
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• 2016

The suspension system of a subway vehicle is composed of $1^{st}$ and $2^{nd}$ springs. The suspension system is the most important parameter in determining the vibration ride comfort. If the $1^{st}$ suspension spring is designed as a spring with strong stiffness to improve the running stability at high speed, it causes vehicle vibrations. In this paper, by testing and analyzing changes of the characteristics of Chevron springs, which have been the primary suspension springs used for about 20 years, we study how changing the characteristics affects vehicle acceleration and ride comfort. The lateral and longitudinal vibrational ride comfort index levels were lower than the vertical ones. Therefore, as increasing the stiffness of Chevron springs has the greatest effect on the vertical vibrational ride comfort index level, a countermeasure for vertical vibration reduction is needed when the stiffness increases owing to aging. Finally, maintenance guidelines, including the replacement time for the Chevron rubber, were proposed based on these findings.

• Proceedings of the KIEE Conference
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• 2008.07a
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• pp.221-222
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• 2008

신재생에너지인 풍력발전이 우수한 실효성 및 경제성으로 인하여 보급이 지속적으로 증가되고 있다. 전력계통에서 발생하는 단락 및 지락고장은 고장 인접 풍력발전 설비 보호를 위해 풍력발전기를 계통으로부터 분리한다. 전력공급 신뢰도와 계통운영의 안정도를 향상시키기 위해서 풍력발기가 Fault-ride through 기능을 갖도록 하여 이를 보완한다. 본 논문에서 과도안정도 해석 프로그램을 이용하여 Fault-ride through 중요 변수인 전압저하 정도 및 고장지속 시간 등을 모의하여 실제 계통에 적용 가능한 모형을 제안한다.

• International Journal of Automotive Technology
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• v.8 no.1
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• pp.111-117
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• 2007

The nonlinear characteristics of a suspension is directly related to the ride quality of a passenger car. In this study, the nonlinear characteristics of a spring and a damper of a passenger car is analyzed by dynamic experiments using the MTS single-axial testing machine. Also, a mathematical nonlinear dynamic model for the suspension is devised to estimate the ride quality using the K factor. And the effect on the variation of the parameters of the suspension is examined. The results showed that the dynamic viscosity of the oil in a damper was the parameter that most influeced the ride quality of a passenger car for the ride quality of a passenger car.

• Proceedings of the Korean Society for Noise and Vibration Engineering Conference
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• 2002.05a
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• pp.1093-1098
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• 2002

Dynamic behaviors of the Korean High-speed Train(KHST) have been analyzed to investigate the performance on the stability, the safety and the ride comfort. Multi-body dynamics analysis program using Recursive method, called RecurDyn, have been employed in the numerical simulation. To model the wheel-rail contact, the RecurDyn uses its built-in module which uses the square root creep law. The accuracy of the rail module in RecurDyn. however, decreases in the analysis of flange contact because it linearizes the shape of the wheel and rail. To solve this problem, a nonlinear contact theory have been developed that considers the profiles of the wheel and rail. The results show that the KHST still needs more stability. The problem should be solved by the examinations of module and modeling.