• The KIPS Transactions:PartA
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• v.17A no.1
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• pp.19-26
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• 2010

As standard of living is higher and aging society is coming, it is needed to develop transportation that is easy to use for weak person. To comply with the demands, it is started to make Bi-modal Tram that is on KRRI(Korea Railroad Research Institute)'s hands. This tram has to have good accessibility like bus, be low level from ground like subway, and park accurately so wheel chair's or passenger's foot can't fall into the gap. But Bi-modal Tram have long length, so it need development of All Wheel Steering System. The Bi-modal Tram that have all wheel steering system steer not only the first axle but also the second and third axle from the first axle or articulation angle, and velocity, and so on. At this study, we discuss AWS ECU's development process.

• Proceedings of the Korean Society for Agricultural Machinery Conference
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• 2017.04a
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• pp.152-152
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• 2017

본 연구에서는 비례제어밸브를 이용한 자율주행 트랙터 조향 시스템 제어를 위하여 저가의 임베디드 시스템을 사용한 제어기를 개발하였다. 차륜의 조향각 측정을 위하여 전륜 킹핀에 포텐시오미터를 설치하였으며, 비례제어밸브는 -10 ~ +10V의 전압으로 밸브 스풀의 위치제어를 수행하도록 하였다. 조향각 측정과 비례제어밸브의 위치제어를 위하여 각각에 AT90CAN128 AVR보드를 사용하였으며, CAN통신으로 조향각 데이터가 비례제어밸브 제어용 데이터로 전송될 수 있도록 하였다. 비례제어밸브 제어 보드에는 DAC기능을 추가하였으며 0 ~ 5V의 출력을 -10 ~ +10V의 전압으로 변환해 주는 인터페이스회로를 추가하였다. 일반적으로 GPS 등의 데이터 수신율이 20 Hz인 점을 감안하여 비례제어 밸브는 50 ms의 주기로 P-제어를 수행할 수 있도록 하였다. 향후 트랙터의 방향각을 설정하는 또 하나의 시스템으로부터 목표 조향각을 부여받는 것을 가상하여 별도의 MCU를 통해 목표 조향각을 송신한 후, 조향 유압실린더에 의한 전륜의 조향각 시간 응답 특성을 조사하였다. 실험은 트랙터의 전륜을 지면으로부터 들어올린 무 부하 상태에서 진행하였으며, 목표 조향각은 $7.5^{\circ}$, $15.0^{\circ}$, $22.5^{\circ}$ 등 3단계로 변경하며 시간응답 특성을 측정하였다. 최대 오버슈트 11%, 최소 오버슈트 8.6%, 정상상태 오차 약 $0.825^{\circ}$, 시정수(Time Constant)는 3단계의 목표 조향각 설정에서 각각 0.706초, 0.488초, 0.38초로 나타났다.

• Journal of the Korean Institute of Intelligent Systems
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• v.25 no.6
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• pp.578-584
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• 2015

In this study a moving platform for a mobile robot that can be traveling with a full automatic standing arm was developed. Conventional mobile robots generally may equip 4 wheels or 3 wheels with a caster wheel or independent driven wheels and have good statistic stability. When a mobile robot travels on a sharply perpendicular and narrow crossroad, it may need a special steering scheme such as going forward and backward repeatedly or it is sometimes physically impossible for the robot to go through the crossroad because of the size limit. The upright running mobile robot changes its posture to the upright posture which has a small planar area and is able to go through the crossroad. The upright control which was manually performed step by step before such as sequences of uprighting (returning), checking, and balancing, is now automated.

• Transactions of the Korean Society of Automotive Engineers
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• v.6 no.4
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• pp.160-165
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• 1998

In this paper, We discuss the directional stability of a Mini-bus with varying suspension design parameters. We analyzed the vehicle behavior during the cornering in a transient steering condition. We made a vehicle model by use of DADS, which is dynamic analysis software, in order to carry out many cases of simulation with varying design parameters. The effect of toe-geometry change to vehicle stability is evaluated by computer simulation and the actual test. In order to reduce the under steer characteristics of a mini-bus, the amount of toe geometry change should be less than current value.

• Transactions of the Korean Society of Automotive Engineers
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• v.5 no.4
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• pp.190-198
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• 1997

Traction control systems are used to prevent the wheel slippage and to maximize the traction force. A new scheme of controlling the wheel slip during cornering by varying the slip ration as a function of the slip angle is proposed and dynamically simulated with the model of a front wheel driven passenger vehicle. Simulation results show that the proposed scheme is superior to conventional ones based on the fixed slip ratio during cornering and lane changes.

• Journal of the korean Society of Automotive Engineers
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• v.2 no.2
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• pp.21-24
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• 1980

차량의 제동장치는 제동시 차량의 조향안정성을 유지하면서 최소한의 제동거리를 확보하는 장 치라 할 수 있다. 제동시 차량의 조향안정성 유지와 최소제동거리를 확보하기 위해서는 차량의 적절한 제동능력에 필요한 전제동토오크를 전후륜의 제동장치에 적당하게 배분시켜야 한다. 그러나 차량의 각차륜의 하중 상태는 여러 가지 적재상태와 제동시중량이동 등에 따라 변하게 되므로 고정된 제동장치로서는 전후륜의 제동토오크를 가변시킬 수 없어 설계시 빈도가 높은 조건에 맞추어 제동장치의 구성부품을 확정할 수밖에 없다. 차량에 따라서는 축하중상태의 변 화가 큰 경우와 공용화를 위하여 여러 모델의 차량에 동일제동 장치를 적용하려고 할 경우에 문제점이 따르기 마련이다. 본고에서는 제동장치의 전후륜의 제동토오크 배분에 대하여 고찰하여 설계개념을 파악하고자 한다.

• Journal of the Korean Society for Railway
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• v.20 no.3
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• pp.311-319
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• 2017

The primary suspension system of a railway vehicle restrains the wheelset and the bogie, which greatly affects the dynamic characteristics of the vehicle depending on the stiffness in each direction. In order to improve the dynamic characteristics, different stiffness in each direction is required. However, designing different stiffness in each direction is difficult in the case of a general suspension device. To address this, in this paper, an optimization technique is applied to design different stiffness in each direction by using a conical rubber spring. The optimization is performed by using target and analysis RMS values. Lastly, the final model is proposed by complementing the shape of the weak part of the model. An actual model is developed and the reliability of the optimization model is proved on the basis of a deviation average of about 7.7% compared to the target stiffness through a static load test. In addition, the stiffness value is applied to a multibody dynamics model to analyze the stability and curve performance. The critical speed of the improved model was 190km/h, which was faster than the maximum speed of 110km/h. In addition, the steering performance is improved by 34% compared with the conventional model.