• 제어로봇시스템학회:학술대회논문집
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• 제어로봇시스템학회 1993년도 한국자동제어학술회의논문집(국내학술편); Seoul National University, Seoul; 20-22 Oct. 1993
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• pp.1194-1198
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• 1993

Active roll control can improve handling and ride comfort. Dynamic characteristics of the hydraulic actuators for active suspension, which can be modeled as the 1'st order time lag system, hinders the performance improvement. To overcome this shortcoming a predictive controller is designed based on 3 d.o.f. linear vehicle handling model. The effect of this controller is studied through the simulation based on 10 d.o.f. nonlinear vehicle model and the results is compared to that of feedforward controller which uses lateral acceleration as control signal.

• 한국자동차공학회논문집
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• 제10권3호
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• pp.245-253
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• 2002

A driver model with nervous neuromuscular system was developed to steer a vehicle along the prescribed path during handling simulations. A 3-dimensional vehicle model with 10 DOF and 3 DOF steering handle are used to perform a computer simulation. PID and fuzzy controller are used to perform single and double lane change, and their tracking abilities were compared. The effects of time delay and preview distance are also investigated, and it is demonstrated that the driver model developed can be an aid far objective evaluation of vehicle handling simulation.

• International Journal of Automotive Technology
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• 제7권7호
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• pp.813-819
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• 2006

As the vehicle becomes bigger and faster, the importance of vehicle stability in an extreme driving condition caused by sudden steering, road condition or unexpected case has been emphasized. The ESP system is being utilized to improve the handling performance and the vehicle stability. In this study, we implemented various tests and proposed estimation methods for ESP characteristics in extreme driving situations. The estimation methods for ESP proposed in this paper are expected to facilitate developing the control logic and improving the performance of the ESP system.

• Journal of Mechanical Science and Technology
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• 제17권7호
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• pp.958-965
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• 2003

Structural integrity of either a passenger car or a light truck is one of the basic requirements for a full vehicle engineering and development program. The results of the vehicle product performance are measured in terms of ride and handling, durability, noise/vibration/harshness (NVH), crashworthiness and occupant safety. The level of performance of a vehicle directly affects the marketability, profitability and, most importantly, the future of the automobile manufacturer In this study, we used the virtual proving ground (VPG) approach for obtaining the dynamic characteristics. The VPG approach uses a nonlinear dynamic finite element code (LS-DYNA3D) which expands the application boundary outside the classic linear static assumptions. The VPG approach also uses realistic boundary conditions of tire/road surface interactions. To verify the predicted dynamic results, a single lane change test has been performed. The prediction results were compared with the experimental results, and the feasibility of the integrated CAE analysis methodology was verified.

• 한국자동차공학회논문집
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• 제12권6호
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• pp.166-174
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• 2004

In urban area narrow commuter vehicles have attracted interest as a possible solution to reduce traffic congestion and parking problems. However, a narrow vehicle has an increased to overturn during hard cornering when compared to conventional vehicles. This tendency can be reduced by tilting it toward the inside of the turn. Two types of automatic tilting control systems which are Direct Tilt Control(DTC) and Steering Tilt Control(STC) have been developed. In this paper as one of the technique to improve the handling performance for the unusual vehicle the control system which blends both the DTC and the STC system is considered. It uses the merits of both the DTC and the STC system. As a control strategy for combination the switching control method is used. Finally, the fact that the unusual vehicle is safe under an emergency situation such as slippery road surface is proved by computer simulation.

• International Journal of Automotive Technology
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• 제6권3호
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• pp.243-249
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• 2005

To improve the ride comfort and handling characteristics of a vehicle, an active suspension which is controlled by external actuators can be used. An active suspension can control the vertical acceleration of a vehicle and the tire deflection to achieve the desired suspension goal. For this purpose, Model Predictive Control (MPC) scheme is applied with the assumption that the preview information of the oncoming road disturbance is available. The predictive control approach uses the output prediction to forecast the output over a time horizon and determines the future control over the horizon by minimizing the performance index. The developed method is applied to a half car model of four degrees-of-freedom and numerical simulations show that the MPC controller improves noticeably the ride qualities and handling performance of a vehicle.

• 한국항행학회논문지
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• 제9권2호
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• pp.185-192
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• 2005

본 논문은 스마트 개발 사업의 일환으로 틸트로타 항공기(TR-S4) 비선형 시뮬레이션 모델의 비행성 분석을 수행하였다. TR-S4는 이착륙을 위한 헬리콥터 모드와 천이모드, 고정익 모드로 구분할 수 있다. 본 논문에서는 헬리콥터 모드만 고려하며, 이 모드는 호버링 모드와 전진비행 모드로 구분한다. 비행성 분석은 안정성과 조종성에 영향을 주는 조종입력에 대한 항공기 응답으로 구성된다. 조종사가 정확한 출발기동과 멈춤기동을 할 수 있게 하는 비교적 변위가 작은 운동과 연관되는 단주기 응답특성 파리미터인 bandwidth를 이용하여 비행성을 분석하였다. 안정성 증강장치(SAS)와 자세 제어기를 장착한 6자유도 비선형 시뮬레이션 모델을 이용한 TR-S4 헬리콥터 모드의 비행성은 대부분 ADS-3 규격서의 level 1을 만족하였다.

• 한국자동차공학회논문집
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• 제22권4호
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• pp.72-81
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• 2014

In this study, we perform the optimization of trailing arm bush in a vehicle rear suspension to improve the ride and handling performance. A design problem was formulated considering 2 objective functions and 7 constraints related to vehicle ride and handling performance. PIAnO, one of the PIDO (Process Integration and Design Optimization) tool, was used to automate analysis procedures and perform a design optimization. In order to assess relation between performances and design variables, we perform the DOE (Design of Experiments). To find the optimal solution, we used Progressive quadratic response surface method (PQRSM), one of the design optimization techniques equipped in PIAnO. As an optimization result, we got an optimal solution and could improve lateral force steer off-center by 43.0% while decreasing brake compliance at wheel center by 8.1%.

• 한국자동차공학회논문집
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• 제7권9호
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• pp.105-111
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• 1999

The paper presents development of a Hardware-In-the-Loop simulation (HILS) system for the purpose of testing performance, stability, and reliability of an electronic power steering system(EPS). In order to realistically test an EPS by the proposed HILS apparatus, a simulated uniaxial dynamic rack force is applied physically to the EPS hardware by a pnumatic actuator. An EPS hardware is composed of steering wheel &column, a rack & pinion mechanism, andas motor-driven power steering system. A command signal for a pneumatic rack-force actuator is generated from the vehicle handling lumped parameter dynamic model 9software) that is simulated in real time by using a very fast digital signal processor. The inputs to the real-time vehicle dynamic simulation model are a constant vehicle forward speed and from wheel steering angles driven through a steering system by a driver. The output from a real-time simulation model is an electric signal that is proportional to the uniaxial rack force. The vehicle handling lumped parameter dynamic model is validated by a fully nonlinear constrained multibody vehicle dynamic model. The HILS system simulation results sow that the proposed HILS system may be used to realistically test the performance stability , and reliability of an electronic power steering system is a repeated way.

• 한국정밀공학회지
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• 제17권2호
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• pp.80-88
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• 2000

This paper presents a method to optimize the bump steer characteristics (the change of toe angle with vertical wheel travel) with respect to hard points in the double wishbone front suspension of the four-wheel-drive vehicle using the design of experiment, multibody dynamics simulation, and optimum design program. Front and rear suspensions are modeled as the interconnection of rigid bodies by kinematic joints and force elements using DADS. The design variables with respect to the kinematic characteristics are obtained through the experimental design sensitivity analysis. An object function is defined as the area of absolute differences between the desired and experimental toe angle. By the design of experiment and regression analysis, the regression model function of bump steer characteristics is extracted. The design variables that make the toe angle optimized are selected using the optimum design program DOT. The lane change simulations and tests of the full vehicle models are implemented to evaluate the improvement of vehicle handling performances by the optimization of front bump steer characteristics. The results of the lane change simulations show that the vehicle with optimized bump steer has the weaker understeer tendency than the vehicle with initial bump steer.