• 한국자동차공학회논문집
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• 제13권1호
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• pp.166-173
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• 2005

A vehicle stability control logic for 4WD hybrid electric vehicle is proposed using the regenerative braking of the rear motor and electronic brake force distribution module. Performance of the stability control logic is evaluated for J-turn and single lane change. It is found from the simulation results that the regenerative braking at rear motor is able to provide improved stability compared with the vehicle performance without my stability control. Additional improvement can be achieved by applying the regenerative braking plus electronic brake farce distribution control. It is expected that the regenerative braking offers additional improvement of the fuel economy as well as the vehicle stability control.

• Journal of Biosystems Engineering
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• 제43권4호
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• pp.273-284
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• 2018

Purpose: Conventional headland turning typically requires repeated forward and backward movements to move the farming equipment to the next row. This research focuses on developing an upland agricultural robot with an optimized headland turning mechanism that enables a $180^{\circ}$ turning positioning to the next row in one steering motion designed for a two-wheel steering, four-wheel drive agricultural robot named the HADA-bot. The proposed steering mechanism allows for faster turnings at each headland compared to those of the conventional steering system. Methods: The HADA-bot was designed with 1.7-m wide wheel tracks to travel along the furrows of a garlic bed, and a look-ahead path following algorithm was applied using a real-time kinematic global positioning system signal. Pivot turning tests focused primarily on accuracy regarding the turning radius for the next path matching, saving headland turning time, area, and effort. Results: Several test cases were performed by evaluating right and left turns on two different surfaces: concrete and soil, at three speeds: 1, 2, and 3 km/h. From the left and right side pivot turning results, the percentage of lateral deviation is within the acceptable range of 10% even on the soil surface. This U-turn scheme reduces 67% and 54% of the headland turning time, and 36% and 32% of the required headland area compared to a 50 hp tractor (ISEKI, TA5240, Ehime, Japan) and a riding-type cultivator (CFM-1200, Asia Technology, Deagu, Rep. Korea), respectively. Conclusion: The pivot turning trajectory on both soil and concrete surfaces achieved similar results within the typical operating speed range. Overall, these results prove that the pivot turning mechanism is suitable for improving conventional headland turning by reducing both turning radius and turning time.

• 전기전자학회논문지
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• 제26권4호
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• pp.602-613
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• 2022

본 논문은 차륜형 캐터필러 및 좌석 위치 가변 구조를 갖는 휠체어 계단 이동 보조기기의 구조에서 비롯되는 계단 이동 중 직진 주행 이탈 상황을 모델링 하고 추정 및 보정하는 알고리즘을 제안하였다. 주행 이탈 상황은 플랫폼의 Yawing 상황 모델 분석으로 주행 환경 특성상 Roll, Pitch와 Yaw 사이에 관계를 이용하여 Yaw값 변화 추이를 추정 하였으며, 차륜 구동 제어기의 제어변수 및 좌석 위치 제어 변수로 활용하였다. 정량적 검증 결과 약 10°의 Yawing 상황에서 약 7초 내외로 직진성 보정을 확인 하였으며, 좌석 위치 변화로 경로 보정간 회전 각속도를 47.5% 감소 시켜 직진성 보정에 효과가 있음을 확인 하였다.

• 소음진동
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• 제9권6호
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• pp.1166-1172
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• 1999

This paper is the experimental study on the endurance characteristics of the dynamic absorber for the vibration reduction of the 4WD(4 Wheel drive) vehicle's powertrain. Employing the vehicle speed, natural frequencies of damper, modal testing results of powertrain and the weighting factor, the improved endurance test conditions are suggested to enlarge the life time of the dynamic absorber. The test results show that the life time of the dynamic absorber for Z-direction(up and down) has no problems, but the characteristics of X-direction (fore and after) will be sensitive to endurance characteristics of dynamic absorber.

• 재활복지공학회논문지
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• 제10권2호
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• pp.171-176
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• 2016

본 연구는 옴니휠을 이용한 1인승 탑승 로봇개발을 통해 장애인 및 비장애인 탑승자의 거동특성과 안정성을 고려한 사용자의 불편요소와 개선방안을 파악하여 총 6명의 사용성 평가를 실시하였다. 본 연구 결과를 보면 다음과 같다. 첫째, 대구대학교 신애5호관 기숙사에서 실험대상자들에게 옴니휠을 이용한 1인승 로봇을 사용하여 불편요소를 파악하는데 있는 승하차의 경우 비장애인이 만족도 4점보다 장애인이 만족도 1.6점으로 가장 큰 불편함을 느꼈다. 이는 휠체어 높이보다 제품의 시트높이가 10cm 더 높아 이동하기 어려웠던 것으로 분석된다. 둘째, 1인승 로봇의 주행와 안전을 위해 장착된 시트, 등받이, 암레스트, 풋레스트, 안전벨트 등 장애인과 비장애인 모다 3점 평균이하의 각각 2.33점과 2.62점의 만족도를 보였으나, 가변형설계 및 설계디자인의 경우 장애인과 비장애인 모두 3.5점의 평균 이상 만족도를 나타내었다. 셋째, 1인승 로봇의 가격의 경우 6~7백만원으로 상당히 비싸다는 의견이 많아 정부 보조금 지원이 가능하다면 전동휠체어 대용으로 구입하겠다는 의견을 나타내었다. 따라서 장애인 사용성 평가에서 나타난 불편사항과 개선방안을 토대로 추가적인 연구개발이 이루어져 교통약자들에게 스스로 탑승 및 이동하여 간단한 일상생활 하는데 있어 삶의 질을 높일 필요성이 있다.

• Journal of Biosystems Engineering
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• 제41권4호
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• pp.288-293
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• 2016

Purpose: The purpose of this study was to investigate the key factors in designing a three-wheeled two-row soybean reaper (riding type) that is suitable for soybean production, and ensure worker safety by proposing optimal work conditions for the prototype of the designed machine in relation to the slope of the road. Methods: A three-wheeled two-row soybean reaper (riding type) was designed and its prototype was fabricated based on the local soybean-production approach. This approach was considered to be closely related to the prototype-designing of the cutter and the wheel driving system of the reaper. Load distribution on the wheels of the prototype, its minimum turning radius, static lateral overturning angle, tilt angle during driving, and The working and rear overturning (back flip) angle were measured. Based on the gathered information, investigations were conducted regarding optimal work conditions for the prototype. The investigations took into account driving stability and worker safety. Results: The minimum ground clearance of the prototype was 0.5 m. The blade height of the prototype was adjusted such that the cutter was operated in line with the height of the ridges. The load distribution on the prototype's wheels was found to be 1 (front wheel: F): 1.35 (rear-left wheel: RL): 1.43 (rear-right wheel: RR). With the ratio of load distribution between the RL and RR wheels being 1: 1.05, the left-to-right lateral loads were found to be well-balanced. The minimum turning radius of the prototype was 2.0 m. Such a small turning radius was considered to be beneficial for cutting work on small-scale fields. The sliding of the prototype started at $25^{\circ}$, and its lateral overturning started at $39.3^{\circ}$. Further, the critical slope angle for the worker to drive the prototype in the direction of the contour line on an incline was found to be $12.8^{\circ}$, and the safe angle of slope for the cutting was measured to be less than $6^{\circ}$. The critical angle of slope that allowed for work was found to be $10^{\circ}$, at which point the prototype would overturn backward when given impact forces of 1,060 N on its front wheel. Conclusions: It was determined that farmers using the prototype would be able to work safely in most soybean production areas, provided that they complied with safe working conditions during driving and cutting.

• 한국공작기계학회:학술대회논문집
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• 한국공작기계학회 2002년도 춘계학술대회 논문집
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• pp.666-669
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• 2002

In this Research, we would like to perform optimal design by using theoretical equation and experimental equation for development of transmission and P.T.O on work vehicle with multi-function that is suited fruit cultures in my country. For the purpose of reducing development period about product and minimizing risk about design error, detail design and interference check are accomplished by FEM analysis and CAD software.

• Journal of Astronomy and Space Sciences
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• 제25권4호
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• pp.347-360
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• 2008

In this paper, a Hardware-In-the-Loop simulator to simulate attitude control of space craft using momentum wheels is developed. The simulator consists of a spherical air bearing system allowing rotation and tilt in all three axes, three momentum wheels for actuation, and an AHRS (Attitude Heading Reference System). The simulator processes various types of data in PC104 and wirelessly communicates with a host PC using TCP/IP protocol. A simple low-cost momentum wheel assembly set and its drive electronics are also developed. Several experiments are performed to test the performance of the momentum wheels. For the control performance test of the simulator, a PID controller is implemented. The results of experimental demonstrations confirm the feasibility and validity of the Hardware-In-the-Loop simulator developed in the current study.

• 드라이브 ㆍ 컨트롤
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• 제15권4호
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• pp.91-100
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• 2018

This study focuses on the energy saving of construction machinery, especially excavators and wheel loaders coming on a backdrop of energy shortage and environment pollution. Due to the problem of the low energy efficiency and the pollution of conventional hydraulic excavators, hybrid hydraulic excavators were developed to solve this challenge. Firstly, this paper discusses the different configurations of the hybrid hydraulic excavator and recent research trend of hybrid hydraulic excavator is reviewed. Secondly, the productions and research of the construction machine companies were analyzed and finally, the future challenges of hybrid technology to the hydraulic excavator were discussed.

• 한국정보통신학회논문지
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• 제10권2호
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• pp.392-397
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• 2006

본 논문에서는 ESP와 4WS차량의 동적성능에 관한 연구와 차량이 불안정 영역으로의 주행 시 안정영역으로의 거동으로 할 수 있게 하는 차량의 주행안정성 향상에 관한 연구를 수행하였다. 고속으로 주행하는 차량이 조향과 동시에 가${\cdot}$감속을 하는 경우 관련된 변수로는 종방향 및 횡방향의 속도변화, 요우잉 등을 들 수 있으며, 이 변수들은 타이어 특성, 차량의 중량, 제동력, 조향각등에 따른 동역학적 관계식들로 표현 할 수 있다. 본 연구는 위와 같은 제동${\cdot}$조향장치들을 제어하여, 차량의 주행 중 위급상황 시 탁월한 성능을 발휘 할 수 있는 시스템에 관하여 고찰하고, 주행시 안정성향상을 위한 제어시스템 알고리즘개발을 통하여 운전상황을 안전하게 하기 위함이다.