• Transactions of the Korean Society of Mechanical Engineers A
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• v.28 no.8 s.227
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• pp.1203-1211
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• 2004

A traction control systems (TCSs) composed of either a wheel slip controller or a throttle valve controller or an integrated controller of both systems are proposed in this study. To validatethe dynamic characteristics of a vehicle and TCS, a full car model that can simulate the responses of both front wheel drive (2WD) and four wheel drive (4WD) vehicle is also developed. The wheel slip controller uses a sliding mode control scheme and the throttle valve is controlled by a PID controller. The results shows that tHe brake TCS and the engine TCS achieve rapid acceleration, and reduce slip angle on slippery road. When a vehicle is cornering and accelerating maneuver with the brake or engine TCS, understeer or oversteer occur, depending on the driving conditions. The integrated TCS prevents most of these problems and improves the stability and controllability of the vehicle.

• The Journal of Korea Robotics Society
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• v.18 no.3
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• pp.299-307
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• 2023

In the midst of accelerating wars around the world, unmanned robot technology that can guarantee the safety of human life is emerging. ERP-42 is a modular platform that can be used according to the application. In the field of defense, it can be used for transporting supplies, reconnaissance and surveillance, and medical evacuation in conflict areas. Due to the nature of the military environment, atypical environments are predominant, and in such environments, the platform's path followability is an important part of mission performance. This paper focuses on reducing the minimum turning radius in terms of improving path followability. The minimum turning radius of the existing 2WS/2WD in-wheel platform was reduced by increasing the torque of the independent driving in-wheel motor on the rear wheel to generate oversteer. To determine the degree of oversteer, two GPS were attached to the center of the front and rear wheelbases and measured. A closed-loop speed control method was used to maintain a constant rotational speed of each wheel despite changes in load or torque.

• Transactions of the Korean Society of Automotive Engineers
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• v.7 no.9
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• pp.212-219
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• 1999

This paper describes the NANDO VDC (Vehicle Dynamics Control) system for the vehicle stability enhancement and consists of the control strategies , computer simulation and tests on the various road surface. This VDC system controls the dynamic vehicle motion in the emergency situation such as the final oversteer/understeer andallows the vehicle to follow the course as desired by the driver. The system is based on an active yaw control and its performance verified by the test is shown. Also the comparison between the MANDO VDC System and a competitor is carried out.

• Transactions of the Korean Society of Automotive Engineers
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• v.20 no.5
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• pp.113-119
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• 2012

CTBA(Coupled Torsion Beam Axle) has been adapted as the rear suspension of a compact car. Because that has the advantage of cost and weight in comparison with multi-link type. But CTBA has the disadvantage in vehicle stability to become oversteer occurring toe-out of the rear wheel when cornering and braking. In this study, we suggested CTBA Geometry Compensation System to overcome the disadvantage of CTBA. We predicted braking and cornering vehicle performance from proposed equation and numerical simulation. And also, the results were compared to objective and subjective evaluation in vehicle.

• Proceedings of the Korean Society of Precision Engineering Conference
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• 2002.10a
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• pp.443-446
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• 2002

A vehicle oversteered or cornering at excessive speed leaves tire yaw mark on the road surface. A yaw mark is a sign that the tire was sideslipping and exceeded its frictional limit because of centrifugal force. Problems exist with the traditional equation, “critical speed formula (CSF)”, that limits its practical use in traffic accident reconstruction. A major problem is that the equation dose not account for vehicle dynamics and interface between tire and road. The literature refers to that the accuracy of the critical speed formula varies with several factors. New equations that account for vehicle dynamics are introduced in this paper. A comparison of the accuracy of the new method and the traditional method in the calculation of speed is conducted.

• International Journal of Automotive Technology
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• v.7 no.2
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• pp.201-208
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• 2006

This paper describes the control philosophy of ESP(Electronic Stability Program) which consists of the stability control the fault diagnosis and the fault tolerant control. Besides the functional performance of the stability control, robustness of control and fault diagnosis is focused to avoid the unnecessary activation of the controller. The look-up tables are mentioned to have the accurate target yaw rate of the vehicle and obtained from vehicle tests for the whole operation range of the steering wheel angle and the vehicle speed. The wheel slip control with a design goal of wheel slip invariance is implemented for the yaw compensation and the target wheel slip is determined by difference between the target yaw rate and actual yaw rate. Since the ESP has a high severity level and the robust control is required, the robustness margin for the stability control is determined according to several uncertainties and the robust fault diagnosis is performed. Both computer simulation and test results are shown in this paper.

• Journal of the Korean Society for Aviation and Aeronautics
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• v.32 no.2
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• pp.1-10
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• 2024

Gimpo International Airport is only available for alternate airport for code F aircraft and it is difficult to operate larger aircraft capable of transporting more passengers than B747-400. This study has conducted to review the compatibility based on risk assessment to introduce the B747-8 operation procedures, excluding the A380 for practical reasons. Risk factors for main gear deviation when driving on curved sections of the taxiway was identified. The risk was analyzed as "high" level. As a risk reduction measure, the proceduralization of specific taxiing method "judgemental oversteer" was reviewed, and the result of the risk re-evaluation was lowered to a "low" level. As a result, the B747-8 was analyzed to be compatible. Additionally, It is suggested that review of pavement strength, de/anti-icing facilities, and passenger boarding bridge is necessary for actual operations.

• Transactions of the Korean Society of Mechanical Engineers A
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• v.22 no.3
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• pp.603-610
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• 1998

This paper develops a 7 DOF vehicle model to study the effects of the active suspension on ride. The model is used to derive a control law for the active suspension using a full state linear optimal control technique. A wheelbase preview type active suspension is also considered in the control law derivation. The time delay between wheelbases is approximated using Pade approximation technique. The ride model is extended to a 14 DOF handling model. The 14 DOF handling model includes lateral, longitudinal, yaw and four wheel spin motions in addition to the 7 DOF ride model. A control law which is derived considering only ride related parameters is used to study the effects of the active suspension on a vehicle handling. J-turn maneuver simulation results show that the active suspension has a slower response in lateral acceleration and yaw rate, a bigger steady state lateral acceleration and an oversteer tendency. Lane changing maneuver simulation results show that the active suspension has a little bigger lateral acceleration but a much smaller roll angle and roll motion. Braking maneuver simulation results show that the active suspension has a much smaller pitch angle and pitch motion.

• Proceedings of the Korean Institute of Surface Engineering Conference
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• 2017.05a
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• pp.140-140
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• 2017

4륜 장착 자동차의 토크 전달은 2륜 구동, 4륜 구동 모드를 간단히 전환하는 방식(part time 4WD)과 항시 사륜 구동 모드에서 전후륜의 토크 전달비를 제어하는 방식(AWD, all wheel drive)이 있다. 경제의 발달에 따라서 취미 인구의 확대로 국내에만 180만 명의 R/C car 사용자가 있다. 이 중 2WD-4WD의 전환을 differential lock mechanism으로 구현한 수입산 모델의 가격이 1,000,000원을 호가하지만 가변 제어 방식이 아닌, 정차 후 2-4륜 구동 전환 방식을 적용하고 있으며 상대적으로 내구성이 떨어진다. DC motor의 출력이 늘어나고 배터리의 성능이 좋아진 현재 소형 RC car의 최고 속도는 80 km/h 정도로 빨라졌다. 그러나 마찰 계수가 낮은 노면(실내의 대부분 평활 처리된 복도)에서는 2륜 구동 모드의 활용도가 매우 낮다. 미끄러운 노면에서 후륜 구동 모드로는 oversteer가 발생하여 차량이 스핀하기 쉽고 전륜 구동 모드로는 understeer가 발생하여 제대로 된 코너링이 어렵다. 상시 4륜 구동 모드는 에너지 소모가 크고 전후륜이 tight coupling되어 있는 문제 때문에 일반적인 노면에서 부드러운 코너링이 잘 이루어지지 않는 문제가 있다. 본 연구에서 제안하는 방식은 그림 1와 같이 center shaft의 중간에 영구 자석으로 만들어진 토크 전달용 판이 있고 그 사이에 자계를 차폐할 수 있는 강자성체 셔터를 서보 기구에 연결하여 서보 회전각에 따라서 구동 쪽의 토크가 피구동축으로 전달되는 양을 연속 가변제어할 수 있다. 토크 전달용 판의 차폐 면적에 따른 토크 전달양을 전/후륜 바퀴의 Static torque를 통해 측정하였으며(그림 2), 공중 상태에서 즉 공기저항만을 고려한 상태에서의 RPM 회전수 차이 측정(그림3)을 통해 구동 쪽의 회전수가 피구동축으로 전달되는 양을 측정하여 연속가변 토크 제어 전달 기구의 성능을 확인하였다. 이 기구는 현재 1차적으로는 remote controller의 ch 3(ON/OFF제어 방식)에 연결하여 특정한 양의 토크를 전륜 쪽으로 보낼 수 있도록 구현이 가능하며, ch 2(PID제어 방식)에 연결하여 연속 가변 조절이 가능하도록 구현이 가능하다. 부가적으로 Arduino board를 내장하여 전후륜의 휠센서에서 입력되는 신호를 감지하여 자동적으로 전후륜에 배분되는 토크를 제어할 수 있도록 설계 중에 있다.

• Journal of the Korean Society for Precision Engineering
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• v.20 no.12
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• pp.55-63
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• 2003

The traffic accident is the prerequisite of the traffic accident reconstruction. In this study, the traffic accident (forward collision) and traffic accident reconstruction (inverse collision) simulations are conducted to improve the quality and accuracy of the traffic accident reconstruction. The vehicle and tire models are used to simulate the trajectories for the post-impact motion of the vehicles after collision. The impact dynamic model applicable to the forward and inverse collision simulations is also provided. The accuracy of impact analysis for the vehicular collision depends on the accuracy of the coefficients of restitution and friction. The neural network is used to estimate these coefficients. The forward and inverse collision simulations for the multi-collisions are conducted. The new method fur the accident reconstruction is proposed to calculate the pre-impact velocities of the vehicles without using the trial and error process which requires the repeated calculations of the initial velocities until the forward collision simulation satisfies with the accident evidences. This method estimates the pre-impact velocities of the vehicles by analyzing the trajectories of the vehicles. The vehicle slides on a road surface not only under the skidding during an emergency braking but also under the steering. A vehicle over steering or cornering with excessive speed loses the traction and leaves tile yaw marks on the road surface. The new critical speed formula based on the vehicle dynamics is proposed to analyze the yaw marks and shows smaller errors than ones of the existing critical speed formula.