• 드라이브 ㆍ 컨트롤
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• 제15권4호
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• pp.39-47
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• 2018

Recently, as environmental regulations for earth-moving equipment have been tightening, advanced systems such as electronic control, have been introduced for energy savings. An IMV (Independent Metering Valve) consisting of four 2-way valves, is an electro-hydraulic control systems that provides more flexible controllability, and potential for energy savings in excavators, when compared to the conventional 4-way spool valve system. To fully maximize use of an IMV, the bi-directional flow control valve that can regulate a large amount of flow in both directions, should be adopted. The hydraulic circuit of an IMV applied to an excavator from an overseas construction equipment company, reveals the flow control valve with the compound of proportional solenoid valve for first stage, and 2-way spool valve for the second stage. Moreover, the two spools are interconnected by a feedback spring, presumed to compensate for flow force acting on the second stage spool. This paper addresses the static analysis of flow control valve in an IMV to investigate the improvement of robustness, against flow force by the feedback spring. From the steady-state analysis of flow control valve model, it can be concluded that the feedback spring facilitates maintaining linearity of spool displacement for control input, and relatively constant flow for load disturbance.

• 드라이브 ㆍ 컨트롤
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• 제15권4호
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• pp.81-90
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• 2018

Indoor construction site such as building demolition sites, tunnel, vinyl house, and cattle shed are subject to various risk factors such as falling stones, soot and bad odors. However, most of the mini excavators have no cabin that can protect the driver from such risk factors. Therefore, researches on remote control technology of construction equipment are actively conducted as a method for protecting the driver from the risk factors occurring in the working environment. For effective remote control, it is necessary to be able to control the travelling and work using a portable small transmitter. However, due to the limitation of the size of the transmitter, complex operation control is required to control two or more actuators with a single joystick. Also, it is essential to check how remote control characteristics change in various environments such as distance, signal strength, obstacle. Therefore, in this study, an algorithm that can control two actuators simultaneously with a single joystick signal was developed, and a communication method suitable for indoor and outdoor mini construction equipment by analyzing experimentally how the remote control characteristics vary according to various work environments and telecommunication methods proposed.

• 드라이브 ㆍ 컨트롤
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• 제17권4호
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• pp.46-53
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• 2020

In this paper, the development of a manually and continuously variable impact force control mechanism for hydraulic breakers was studied. Generally, a hydraulic breaker has one or two piston strokes. Hydraulic breakers, which have two strokes, have two valve-switching ports and make short and long piston strokes. The piston stroke valve controls the piston stroke by opening and closing a short stroke-switching port. The short piston stroke mode is used to break soft rock, concrete, or asphalt. This stroke control valve system is not popular for small hydraulic breakers mounted on 1 to 14-ton excavators. To preserve the carrier-like excavator, proper breaking force is needed, and it can be easily controlled by multiple piston stroke control valves. The easiest way to control these breakers is to use several switching ports and valves but they are not easy to install in small hydraulic breakers and are expensive. To use only one switching port and valve, a method can be used to change the open area of the switching port to delay valve switching. This method provides multiple piston strokes.

• 한국재난정보학회 논문집
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• 제19권2호
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• pp.421-431
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• 2023

연구목적: 건설기계의 안전사고를 예방하기 위해 사용하는 스마트 안전 시스템의 안전성과 재해 예방효과를 분석하여 그 안전성을 실증하고자 한다. 연구방법:건설기계 중 재해다발 및 위험성이 높은 굴삭기를 대상으로 스마트 안전 시스템의 유무에 따른 근로자의 행동 패턴을 분석하였다. 연구결과: 건설기계에 스마트 안전 시스템을 설치하였을 때 건설기계와 협착 및 충돌 등에 의한 재해로부터 근로자의 안전성이 확보되었다. 결론:건설기계에 설치된 스마트 안전 시스템은 건설기계 관련 재해 감소와 중대 재해예방에 실효성을 증대시킬 수 있을 것으로 판단된다.

• 한국정밀공학회지
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• 제28권1호
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• pp.48-55
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• 2011

Hydraulic excavator is one of the most widely used heavy machines in construction sites including dismantling. In the dismantling sites, the excavators equipped with crusher or breaker carry out dangerous operations, so drivers are always exposed to unexpected danger. For safety operation, remote control of the hydraulic excavator has been studied using proportional control valve, which requires an appropriate motion control of its bucket tip. In this case, kinematics and dynamics analysis have to be preceded through modeling of excavator. However, it is difficult to acquire reasonable results from the analysis due to insufficient information of physical parameters such as mass of each links and locations of mass centers, etc. This study deals with the trajectory control of bucket tip, which is based on experimental estimation of cylinder output force. The estimated forces are fed into the control of each cylinder in order to compensate gravitational and frictional effects in the cylinders. The control was applied to horizontal trajectories that are for flattening work.

• 대한기계학회논문집A
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• 제39권4호
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• pp.397-403
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• 2015

본 논문은 개발 중에 있는 굴삭기 무인조종 로봇을 대상으로 시스템 신뢰도 평가 방법을 제안하고, 제안한 방법을 이용하여 수행한 신뢰도 보증시험에 대한 결과를 나타낸다. 로봇 시스템은 위험한 작업환경에서 작업자의 안전을 위하여 개발되었으며 전체 시스템의 신뢰도는 각 구성품의 신뢰도로부터 계산될 수 있다. 따라서 세 가지 주요 구성품 각각에 대한 전용 시험 장비를 제작하여 가속수명시험에 사용하였다. 가속수명시험 결과를 이용하여 신뢰수준에 따른 보증할 수 있는 평균수명을 추정하고, 적은 시료 수를 사용하는 시스템 신뢰도 보증 시험법을 제안하였다.

• 한국자동차공학회논문집
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• 제22권2호
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• pp.141-147
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• 2014

This study aims to investigate the influence of bevel angles on the fatigue life of V-groove butt-welded joints with back-plates made by SM490A steel material, generally used for excavators, because changes in the geometry, material and surface properties of welded regions affect the fatigue life of welded structures. Butt type test specimens were prepared by the $CO_2$ welding of rolled steel plates (SM50A steel) with a thickness of 13.5 mm at a welding speed of 30 cm/min and these Butt type test specimens had two different groove angles, which are $40^{\circ}$ (A type) and $30^{\circ}$ (B type). In order to investigate differences in fatigue life between two types, 4-point bending fatigue tests were conducted with a stress ratio of R=0.1 under the cyclic loading environment at a frequency of 5 Hz at room temperature. The fatigue life of A type specimens was approximately 7% higher than that of B type specimens. The stress concentration factors calculated by finite element analysis were 2.16 for A type and 2.25 for B type, whose difference was caused by the influence of the back-plates of butt-welded structures. The current results could provide important guidelines to determine the V-groove angle of butt-welded joints with a satisfactory fatigue life, although under severe operating conditions.

• 대한기계학회논문집A
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• 제37권11호
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• pp.1407-1413
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• 2013

하이브리드 굴삭기는 기존 굴삭기와 달리 선회구동계에 유압모터를 대신하여 선회전동기를 사용하고 있다. 하이브리드 굴삭기의 신뢰성을 평가하고 보증하기 위해서는 기계와 전기적인 고장모드가 조합되어 고려되어야 한다. 특히, 하이브리드 굴삭기용 선회감속기는 가혹한 실외환경에서 운용되므로 시작품에 대한 현장작동조건을 고려한 가속수명시험이 수행되어야 한다. 본 연구에서는 선회구동계 중선회감속기에 대한 가속수명시험 기법의 개발을 위하여 FMMA, FMAECA, FTA 및 QFD와 같은 정성적 신뢰성기법을 활용하였고, 개발된 가속조건에 의한 수명시험결과를 유분석 기법 등을 활용 분석하여 평가대상 시료가 목표 신뢰도를 만족함을 확인하였다.

• 로봇학회논문지
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• 제15권3호
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• pp.293-300
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• 2020

The purpose of our sensor system is to transparentize the large hydraulic manipulators of a six-ton dual arm excavator from the operator camera view. Almost 40% of the camera view is blocked by the manipulators. In other words, the operator loses 40% of visual information which might be useful for many manipulator control scenarios such as clearing debris on a disaster site. The proposed method is based on a 3D reconstruction technology. By overlaying the camera image from front top of the cabin with the point cloud data from RGB-D (red, green, blue and depth) cameras placed at the outer side of each manipulator, the manipulator-free camera image can be obtained. Two additional algorithms are proposed to further enhance the productivity of dual arm excavators. First, a color correction algorithm is proposed to cope with the different color distribution of the RGB and RGB-D sensors used on the system. Also, the edge overlay algorithm is proposed. Although the manipulators often limit the operator's view, the visual feedback of the manipulator's configurations or states may be useful to the operator. Thus, the overlay algorithm is proposed to show the edge of the manipulators on the camera image. The experimental results show that the proposed transparentization algorithm helps the operator get information about the environment and objects around the excavator.

• 대한토목학회논문집
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• 제37권1호
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• pp.167-174
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• 2017

토공작업은 자연지반을 정지하거나 터파기를 통해서 구조물을 설치하기 위한 공간을 제공한다. 대규모 건설공사의 경우 토공작업은 굴삭기, 도저, 덤프트럭 등 대형장비가 투입되며, 장비와 장비간 그리고 토공작업에 투입되는 관리자간 인터페이스(interface)가 발생된다. 따라서 토공작업의 효과를 높이기 위해서는 건설장비 조종원간 커뮤니케이션(communication)이 필요하며, 토공작업의 프로세스를 분석하여 커뮤니케이션을 향상시켜야 한다. 본 연구는 건설공사의 토공작업 프로세스를 분석하고, 스마트 글래스 기술을 적용하여 커뮤니케이션 효과를 높이는 것을 목적으로 한다. 본 연구에서는 프로세스 다이어그램을 사용하여 토공작업을 모델링 했으며, 토공작업 프로세스 상에서 생성되는 데이터에 대한 클래스 다이어그램을 작성했다. 또한 토공작업에서 생성되는 데이터를 저장하고 재사용하기 위해서 데이터베이스가 구축되었다. 최종적으로 스마트 글래스 기술을 적용하여 토공작업 중 데이터 인터페이스 효과를 높이기 위한 프로토타입이 개발됐다. 프로토타입 개발 결과 스마트 글래스는 수신호, 경적소리 등 단순한 데이터 전달방식을 벗어나서 토공작업에 참여하는 관리자와 건설장비 조종원간 지속적인 의사소통이 가능하게 할 것으로 평가된다.