• Journal of Biosystems Engineering
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• v.21 no.2
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• pp.134-145
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• 1996

Since the skid-steer loader is able to work for excavating, lifting and transporting load even at the narrow space, they are widely used in the regular farm and the livestock farm. The skid-steer loader normally adopts the hydrostatic transmission because the power to move the machine backward and forward should be delivered independently on both sides of wheels. Contrast to the mechanical system such as chain and belt transmissions, however, the hydrostatic transmission is less efficient in the use of energy and more difficult in the maintenance. This study was intended to investigate the feasibility of using triangular-type belt clutch and V-belt transmission for the newly developed skid-steer loader in order to overcome the problems stated in the hydrostatic transmission. In the developed triangular-type belt clutch, the centers of driving, driven and idler sheaves are arranged in the triangular shape in a plane, and V-belts were loaded loosely on three sheaves. The power is transmitted by pressing the idler connected to a lever on the loosened V-belt. Contrast to the normal belt clutch using two sheaves, the newly developed belt clutch has the characteristics of small contact-angle of the driving sheave at no bucket load and increasing contact-angle at the time of power transmission. The results of research can be summarized as follows: 1) The developed triangular-type belt clutch adopted a spring-loaded slackside idler which could transmit more power than a fixed idler could by sacrificing the belt life. The life of V-belt used in the power transmission reached at 500 hours(6 months) when the engine power of 11.8 ㎾ was transmitted. Also, it was feasible to develop the large industrial skid-loader with the V-belt transmission by using the proper set of sheaves. 2) The developed skid-steer loader changed the rotating radius and speed with bucket loads as the conventional skid steer loader did. The rotating speed was 47 deg/s at the maximum bucket load of 2.74 kN when the minimum rotating radius was 1.5m. 3) The power required in turning at the bucket load of 2.74 kN was 4 ㎾ and the slippage of V-belt was less than 1%.

• 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.

• Journal of Korean Society of Transportation
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• v.27 no.1
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• pp.43-51
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• 2009

This paper investigates the accuracy of vehicle pre-braking speed estimates based upon tire/roadway coefficient of friction (drag factor) measurements and skid mark measurements Data for pre-braking and pre-skidding speeds were collected to determine if there were any correlations between pre-braking speeds and pre-skidding speeds. Braking tests were performed on two vehicles using various measurement devices including a fifth wheel, a speed gun, and a vericom 2000. The vehicle speeds, braking distances, skid mark distances, and deceleration histories were recorded. From these data. coefficients of friction and vehicle pre-skidding speeds for the tested road surface were calculated. The pre-skidding speeds were then compared to the actual pre-braking speeds of the vehicles in order to establish relationships between pre-skidding and pre-braking speed. A correlation between the Pre-skidding speed and the actual pre-braking speed was established for the study data.

• Journal of the Korean Society for Aviation and Aeronautics
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• v.25 no.2
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• pp.18-24
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• 2017

Results of the experimental research are described in this thesis, which are about braking characteristics of aircraft ABS brake system with different ground conditions. Dynamo-tests were conducted with the state of the application aircraft condition and with two different ground conditions. The Braking characteristics on each ground condition were drawn from the results of occurrence of skid, braking distance and deceleration. The braking performance of the application aircraft could be anticipated and the efficient range of braking operation could be set with those results.

• Journal of Institute of Control, Robotics and Systems
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• v.20 no.12
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• pp.1278-1283
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• 2014

This study proposes a NN (Neural Networks)-based adaptive control method for a 6X6 skid-type UGV (Unmanned Ground Vehicle) with 6 in-wheel motors. The UGV experiences lots of uncertainties and, thus, the control performance can degrade significantly without a compensation of the unknown terms. To improve the control performance of the UGV, the NN is utilized to design the adaptive controller. Then, the designed overall force and moment are optimally distributed into 6 traction forces with the assumption that six vertical forces of the UGV are known exactly, because the six traction forces are original source to be excited to the UGV to move. Finally, numerical simulations with the TruckSim model are performed to validate the effectiveness of the proposed approach.

• Proceedings of the Korea Information Processing Society Conference
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• 2006.05a
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• pp.353-356
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• 2006

자동차사고는 소득증대와 차량증가와 함께 도로확충 및 정비가 필수임에도 불구하고 자동차 사고는 갈수록 대형화되고 있다. 그러나 교통사고 발생시 누가 가해자이고 피해자인지를 정확하게 구별하기는 매우 어려운 일이다. 특히 교통사고 발생시 목격자가 없을 경우에는 교통사고원인을 규명하기가 더욱 어려워진다. 본 연구에서는 이러한 문제점을 해결하기위해서 뺑소니 교통사고 발생시에 퍼지 및 지능형 알고리즘을 시용해서 스키드마크 길이를 입력하면 도로의 종류, 타이어의 종류, 자동차 종류, 날씨 조건을 고려하여 최적의 자동차 속도를 산출하였으며, 컴퓨터 시물레이션을 통해서 기존의 방법보다 20-30% 정확하게 예측하였다.

• Proceedings of the KSME Conference
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• 2008.11a
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• pp.795-800
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• 2008

The paper presents research for the established experiment environment of multi vehicle robot, localization algorithm that is based on vehicle control, and path tracking. The established experiment environment consists of ultrasonic positioning system, vehicle robot, server and wireless module. Ultrasonic positioning system measures positioning for using ultrasonic sensor and generates many errors because of the influence of environment such as a reflection of wall. For a solution of this fact, localization algorithm is proposed to determine a location using vehicle kinematics and selection of a reliable location data. And path tracking algorithm is proposed to apply localization algorithm and LOS, finally, that algorithms are verified via simulation and experimental

• Proceedings of the Korean Institute of Intelligent Systems Conference
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• 2008.04a
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• pp.366-369
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• 2008

무선 센서 네트워크(Wireless Sensor Network)는 차세대 IT 기술로서 소형, 저가, 저전력을 필요로 하며, 외부 환경의 모니터링과 제어기능을 수행할 수 있다. 이것은 소형 장치 안에 마이크로프로세서, 각종 센서, 액추에이터, 유 ${\cdot}$ 무선 통신 장치를 내장하는 수백 혹은 수천 개의 센서 노드로 구성된다. 본 논문에서는 이러한 센서 네트워크를 이용하여 기상의 악천 후 속에서 차량 및 도로 상황 정보를 실시간으로 미리 획득하고 분석하여 운전자에게 미리 도로의 안전속도를 통보할 수 있는 실시간 차량 안전속도 서비스 시스템을 설계하고 구현된 결과를 보여 주고자 한다. 본 시스템은 노면의 종류 및 기상 상태 등에 대한 정보를 수집하여 이를 바탕으로 운전자에게 안전 속도를 알려줌으로써 교통사고를 효과적으로 예방할 수 있는 방법을 제공할 수 있다.

• 제어로봇시스템학회:학술대회논문집
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• 2000.10a
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• pp.40-40
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• 2000

Generally a RF AGC controls the roll gap using the variation of rolling force caused by the roll eccentricity and the entry thickness of material, but these can not be classified. The Feed- forward AGC method, which controls the next stand roll 9ap by estimation the skid mark of the previous stand output thickness is needed to supplement the shortage of RF AGC. In this paper, an improved filtering method of skid mark which take account of the kinds of materials, the final objective thickness and the roll speed is proposed, In addition, an improved estimation method of control point using the speedometer and looper angle is suggested, Via simulation, the performance improvement of the suggested FF AGC method is verified.

• Journal of Institute of Control, Robotics and Systems
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• v.18 no.3
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• pp.251-257
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• 2012

Unmanned ground vehicles have important military, reconnaissance, and materials handling application. Many of these applications require the UGVs to move at high speeds through uneven, natural terrain with various compositions and physical parameters. This paper presents a framework for high speed autonomous navigation based on the integrated real time traversability. Specifically, the proposed system performs real-time dynamic simulation and calculate maximum traversing velocity guaranteeing safe motion over rough terrain. The architecture of autonomous navigation is firstly presented for high-speed autonomous navigation. Then, the integrated real time traversability, which is composed of initial velocity profiling step, dynamic analysis step, road classification step and stable velocity profiling step, is introduced. Experimental results are presented that demonstrate the method for a $6{\times}6$ autonomous vehicle moving on flat terrain with bump.